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Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/tree-vrp.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/gcc/tree-vrp.c | 5546 |
1 files changed, 0 insertions, 5546 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/tree-vrp.c b/gcc-4.2.1-5666.3/gcc/tree-vrp.c deleted file mode 100644 index a1b7f0a20..000000000 --- a/gcc-4.2.1-5666.3/gcc/tree-vrp.c +++ /dev/null @@ -1,5546 +0,0 @@ -/* Support routines for Value Range Propagation (VRP). - Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc. - Contributed by Diego Novillo <dnovillo@redhat.com>. - -This file is part of GCC. - -GCC is free software; you can redistribute it and/or modify -it under the terms of the GNU General Public License as published by -the Free Software Foundation; either version 2, or (at your option) -any later version. - -GCC is distributed in the hope that it will be useful, -but WITHOUT ANY WARRANTY; without even the implied warranty of -MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -GNU General Public License for more details. - -You should have received a copy of the GNU General Public License -along with GCC; see the file COPYING. If not, write to -the Free Software Foundation, 51 Franklin Street, Fifth Floor, -Boston, MA 02110-1301, USA. */ - -#include "config.h" -#include "system.h" -#include "coretypes.h" -#include "tm.h" -#include "ggc.h" -#include "flags.h" -#include "tree.h" -#include "basic-block.h" -#include "tree-flow.h" -#include "tree-pass.h" -#include "tree-dump.h" -#include "timevar.h" -#include "diagnostic.h" -#include "toplev.h" -#include "intl.h" -#include "cfgloop.h" -#include "tree-scalar-evolution.h" -#include "tree-ssa-propagate.h" -#include "tree-chrec.h" - -/* Set of SSA names found during the dominator traversal of a - sub-graph in find_assert_locations. */ -static sbitmap found_in_subgraph; - -/* Local functions. */ -static int compare_values (tree val1, tree val2); -static int compare_values_warnv (tree val1, tree val2, bool *); -static tree vrp_evaluate_conditional_warnv (tree, bool, bool *); - -/* Location information for ASSERT_EXPRs. Each instance of this - structure describes an ASSERT_EXPR for an SSA name. Since a single - SSA name may have more than one assertion associated with it, these - locations are kept in a linked list attached to the corresponding - SSA name. */ -struct assert_locus_d -{ - /* Basic block where the assertion would be inserted. */ - basic_block bb; - - /* Some assertions need to be inserted on an edge (e.g., assertions - generated by COND_EXPRs). In those cases, BB will be NULL. */ - edge e; - - /* Pointer to the statement that generated this assertion. */ - block_stmt_iterator si; - - /* Predicate code for the ASSERT_EXPR. Must be COMPARISON_CLASS_P. */ - enum tree_code comp_code; - - /* Value being compared against. */ - tree val; - - /* Next node in the linked list. */ - struct assert_locus_d *next; -}; - -typedef struct assert_locus_d *assert_locus_t; - -/* If bit I is present, it means that SSA name N_i has a list of - assertions that should be inserted in the IL. */ -static bitmap need_assert_for; - -/* Array of locations lists where to insert assertions. ASSERTS_FOR[I] - holds a list of ASSERT_LOCUS_T nodes that describe where - ASSERT_EXPRs for SSA name N_I should be inserted. */ -static assert_locus_t *asserts_for; - -/* Set of blocks visited in find_assert_locations. Used to avoid - visiting the same block more than once. */ -static sbitmap blocks_visited; - -/* Value range array. After propagation, VR_VALUE[I] holds the range - of values that SSA name N_I may take. */ -static value_range_t **vr_value; - - -/* Return whether TYPE should use an overflow infinity distinct from - TYPE_{MIN,MAX}_VALUE. We use an overflow infinity value to - represent a signed overflow during VRP computations. An infinity - is distinct from a half-range, which will go from some number to - TYPE_{MIN,MAX}_VALUE. */ - -static inline bool -needs_overflow_infinity (tree type) -{ - return INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type); -} - -/* Return whether TYPE can support our overflow infinity - representation: we use the TREE_OVERFLOW flag, which only exists - for constants. If TYPE doesn't support this, we don't optimize - cases which would require signed overflow--we drop them to - VARYING. */ - -static inline bool -supports_overflow_infinity (tree type) -{ -#ifdef ENABLE_CHECKING - gcc_assert (needs_overflow_infinity (type)); -#endif - return (TYPE_MIN_VALUE (type) != NULL_TREE - && CONSTANT_CLASS_P (TYPE_MIN_VALUE (type)) - && TYPE_MAX_VALUE (type) != NULL_TREE - && CONSTANT_CLASS_P (TYPE_MAX_VALUE (type))); -} - -/* VAL is the maximum or minimum value of a type. Return a - corresponding overflow infinity. */ - -static inline tree -make_overflow_infinity (tree val) -{ -#ifdef ENABLE_CHECKING - gcc_assert (val != NULL_TREE && CONSTANT_CLASS_P (val)); -#endif - val = copy_node (val); - TREE_OVERFLOW (val) = 1; - return val; -} - -/* Return a negative overflow infinity for TYPE. */ - -static inline tree -negative_overflow_infinity (tree type) -{ -#ifdef ENABLE_CHECKING - gcc_assert (supports_overflow_infinity (type)); -#endif - return make_overflow_infinity (TYPE_MIN_VALUE (type)); -} - -/* Return a positive overflow infinity for TYPE. */ - -static inline tree -positive_overflow_infinity (tree type) -{ -#ifdef ENABLE_CHECKING - gcc_assert (supports_overflow_infinity (type)); -#endif - return make_overflow_infinity (TYPE_MAX_VALUE (type)); -} - -/* Return whether VAL is a negative overflow infinity. */ - -static inline bool -is_negative_overflow_infinity (tree val) -{ - return (needs_overflow_infinity (TREE_TYPE (val)) - && CONSTANT_CLASS_P (val) - && TREE_OVERFLOW (val) - && operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)); -} - -/* Return whether VAL is a positive overflow infinity. */ - -static inline bool -is_positive_overflow_infinity (tree val) -{ - return (needs_overflow_infinity (TREE_TYPE (val)) - && CONSTANT_CLASS_P (val) - && TREE_OVERFLOW (val) - && operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)); -} - -/* Return whether VAL is a positive or negative overflow infinity. */ - -static inline bool -is_overflow_infinity (tree val) -{ - return (needs_overflow_infinity (TREE_TYPE (val)) - && CONSTANT_CLASS_P (val) - && TREE_OVERFLOW (val) - && (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0) - || operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0))); -} - -/* If VAL is now an overflow infinity, return VAL. Otherwise, return - the same value with TREE_OVERFLOW clear. This can be used to avoid - confusing a regular value with an overflow value. */ - -static inline tree -avoid_overflow_infinity (tree val) -{ - if (!is_overflow_infinity (val)) - return val; - - if (operand_equal_p (val, TYPE_MAX_VALUE (TREE_TYPE (val)), 0)) - return TYPE_MAX_VALUE (TREE_TYPE (val)); - else - { -#ifdef ENABLE_CHECKING - gcc_assert (operand_equal_p (val, TYPE_MIN_VALUE (TREE_TYPE (val)), 0)); -#endif - return TYPE_MIN_VALUE (TREE_TYPE (val)); - } -} - - -/* Return whether VAL is equal to the maximum value of its type. This - will be true for a positive overflow infinity. We can't do a - simple equality comparison with TYPE_MAX_VALUE because C typedefs - and Ada subtypes can produce types whose TYPE_MAX_VALUE is not == - to the integer constant with the same value in the type. */ - -static inline bool -vrp_val_is_max (tree val) -{ - tree type_max = TYPE_MAX_VALUE (TREE_TYPE (val)); - - return (val == type_max - || (type_max != NULL_TREE - && operand_equal_p (val, type_max, 0))); -} - -/* Return whether VAL is equal to the minimum value of its type. This - will be true for a negative overflow infinity. */ - -static inline bool -vrp_val_is_min (tree val) -{ - tree type_min = TYPE_MIN_VALUE (TREE_TYPE (val)); - - return (val == type_min - || (type_min != NULL_TREE - && operand_equal_p (val, type_min, 0))); -} - - -/* Return true if ARG is marked with the nonnull attribute in the - current function signature. */ - -static bool -nonnull_arg_p (tree arg) -{ - tree t, attrs, fntype; - unsigned HOST_WIDE_INT arg_num; - - gcc_assert (TREE_CODE (arg) == PARM_DECL && POINTER_TYPE_P (TREE_TYPE (arg))); - - /* The static chain decl is always non null. */ - if (arg == cfun->static_chain_decl) - return true; - - fntype = TREE_TYPE (current_function_decl); - attrs = lookup_attribute ("nonnull", TYPE_ATTRIBUTES (fntype)); - - /* If "nonnull" wasn't specified, we know nothing about the argument. */ - if (attrs == NULL_TREE) - return false; - - /* If "nonnull" applies to all the arguments, then ARG is non-null. */ - if (TREE_VALUE (attrs) == NULL_TREE) - return true; - - /* Get the position number for ARG in the function signature. */ - for (arg_num = 1, t = DECL_ARGUMENTS (current_function_decl); - t; - t = TREE_CHAIN (t), arg_num++) - { - if (t == arg) - break; - } - - gcc_assert (t == arg); - - /* Now see if ARG_NUM is mentioned in the nonnull list. */ - for (t = TREE_VALUE (attrs); t; t = TREE_CHAIN (t)) - { - if (compare_tree_int (TREE_VALUE (t), arg_num) == 0) - return true; - } - - return false; -} - - -/* Set value range VR to {T, MIN, MAX, EQUIV}. */ - -static void -set_value_range (value_range_t *vr, enum value_range_type t, tree min, - tree max, bitmap equiv) -{ -#if defined ENABLE_CHECKING - /* Check the validity of the range. */ - if (t == VR_RANGE || t == VR_ANTI_RANGE) - { - int cmp; - - gcc_assert (min && max); - - if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE) - gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max)); - - cmp = compare_values (min, max); - gcc_assert (cmp == 0 || cmp == -1 || cmp == -2); - - if (needs_overflow_infinity (TREE_TYPE (min))) - gcc_assert (!is_overflow_infinity (min) - || !is_overflow_infinity (max)); - } - - if (t == VR_UNDEFINED || t == VR_VARYING) - gcc_assert (min == NULL_TREE && max == NULL_TREE); - - if (t == VR_UNDEFINED || t == VR_VARYING) - gcc_assert (equiv == NULL || bitmap_empty_p (equiv)); -#endif - - vr->type = t; - vr->min = min; - vr->max = max; - - /* Since updating the equivalence set involves deep copying the - bitmaps, only do it if absolutely necessary. */ - if (vr->equiv == NULL) - vr->equiv = BITMAP_ALLOC (NULL); - - if (equiv != vr->equiv) - { - if (equiv && !bitmap_empty_p (equiv)) - bitmap_copy (vr->equiv, equiv); - else - bitmap_clear (vr->equiv); - } -} - - -/* Copy value range FROM into value range TO. */ - -static inline void -copy_value_range (value_range_t *to, value_range_t *from) -{ - set_value_range (to, from->type, from->min, from->max, from->equiv); -} - - -/* Set value range VR to VR_VARYING. */ - -static inline void -set_value_range_to_varying (value_range_t *vr) -{ - vr->type = VR_VARYING; - vr->min = vr->max = NULL_TREE; - if (vr->equiv) - bitmap_clear (vr->equiv); -} - -/* Set value range VR to a single value. This function is only called - with values we get from statements, and exists to clear the - TREE_OVERFLOW flag so that we don't think we have an overflow - infinity when we shouldn't. */ - -static inline void -set_value_range_to_value (value_range_t *vr, tree val, bitmap equiv) -{ - gcc_assert (is_gimple_min_invariant (val)); - val = avoid_overflow_infinity (val); - set_value_range (vr, VR_RANGE, val, val, equiv); -} - -/* Set value range VR to a non-negative range of type TYPE. - OVERFLOW_INFINITY indicates whether to use a overflow infinity - rather than TYPE_MAX_VALUE; this should be true if we determine - that the range is nonnegative based on the assumption that signed - overflow does not occur. */ - -static inline void -set_value_range_to_nonnegative (value_range_t *vr, tree type, - bool overflow_infinity) -{ - tree zero; - - if (overflow_infinity && !supports_overflow_infinity (type)) - { - set_value_range_to_varying (vr); - return; - } - - zero = build_int_cst (type, 0); - set_value_range (vr, VR_RANGE, zero, - (overflow_infinity - ? positive_overflow_infinity (type) - : TYPE_MAX_VALUE (type)), - vr->equiv); -} - -/* Set value range VR to a non-NULL range of type TYPE. */ - -static inline void -set_value_range_to_nonnull (value_range_t *vr, tree type) -{ - tree zero = build_int_cst (type, 0); - set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv); -} - - -/* Set value range VR to a NULL range of type TYPE. */ - -static inline void -set_value_range_to_null (value_range_t *vr, tree type) -{ - set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv); -} - - -/* Set value range VR to VR_UNDEFINED. */ - -static inline void -set_value_range_to_undefined (value_range_t *vr) -{ - vr->type = VR_UNDEFINED; - vr->min = vr->max = NULL_TREE; - if (vr->equiv) - bitmap_clear (vr->equiv); -} - - -/* Return value range information for VAR. - - If we have no values ranges recorded (ie, VRP is not running), then - return NULL. Otherwise create an empty range if none existed for VAR. */ - -static value_range_t * -get_value_range (tree var) -{ - value_range_t *vr; - tree sym; - unsigned ver = SSA_NAME_VERSION (var); - - /* If we have no recorded ranges, then return NULL. */ - if (! vr_value) - return NULL; - - vr = vr_value[ver]; - if (vr) - return vr; - - /* Create a default value range. */ - vr_value[ver] = vr = XNEW (value_range_t); - memset (vr, 0, sizeof (*vr)); - - /* Allocate an equivalence set. */ - vr->equiv = BITMAP_ALLOC (NULL); - - /* If VAR is a default definition, the variable can take any value - in VAR's type. */ - sym = SSA_NAME_VAR (var); - if (var == default_def (sym)) - { - /* Try to use the "nonnull" attribute to create ~[0, 0] - anti-ranges for pointers. Note that this is only valid with - default definitions of PARM_DECLs. */ - if (TREE_CODE (sym) == PARM_DECL - && POINTER_TYPE_P (TREE_TYPE (sym)) - && nonnull_arg_p (sym)) - set_value_range_to_nonnull (vr, TREE_TYPE (sym)); - else - set_value_range_to_varying (vr); - } - - return vr; -} - -/* Return true, if VAL1 and VAL2 are equal values for VRP purposes. */ - -static inline bool -vrp_operand_equal_p (tree val1, tree val2) -{ - if (val1 == val2) - return true; - if (!val1 || !val2 || !operand_equal_p (val1, val2, 0)) - return false; - if (is_overflow_infinity (val1)) - return is_overflow_infinity (val2); - return true; -} - -/* Return true, if the bitmaps B1 and B2 are equal. */ - -static inline bool -vrp_bitmap_equal_p (bitmap b1, bitmap b2) -{ - return (b1 == b2 - || (b1 && b2 - && bitmap_equal_p (b1, b2))); -} - -/* Update the value range and equivalence set for variable VAR to - NEW_VR. Return true if NEW_VR is different from VAR's previous - value. - - NOTE: This function assumes that NEW_VR is a temporary value range - object created for the sole purpose of updating VAR's range. The - storage used by the equivalence set from NEW_VR will be freed by - this function. Do not call update_value_range when NEW_VR - is the range object associated with another SSA name. */ - -static inline bool -update_value_range (tree var, value_range_t *new_vr) -{ - value_range_t *old_vr; - bool is_new; - - /* Update the value range, if necessary. */ - old_vr = get_value_range (var); - is_new = old_vr->type != new_vr->type - || !vrp_operand_equal_p (old_vr->min, new_vr->min) - || !vrp_operand_equal_p (old_vr->max, new_vr->max) - || !vrp_bitmap_equal_p (old_vr->equiv, new_vr->equiv); - - if (is_new) - set_value_range (old_vr, new_vr->type, new_vr->min, new_vr->max, - new_vr->equiv); - - BITMAP_FREE (new_vr->equiv); - new_vr->equiv = NULL; - - return is_new; -} - - -/* Add VAR and VAR's equivalence set to EQUIV. */ - -static void -add_equivalence (bitmap equiv, tree var) -{ - unsigned ver = SSA_NAME_VERSION (var); - value_range_t *vr = vr_value[ver]; - - bitmap_set_bit (equiv, ver); - if (vr && vr->equiv) - bitmap_ior_into (equiv, vr->equiv); -} - - -/* Return true if VR is ~[0, 0]. */ - -static inline bool -range_is_nonnull (value_range_t *vr) -{ - return vr->type == VR_ANTI_RANGE - && integer_zerop (vr->min) - && integer_zerop (vr->max); -} - - -/* Return true if VR is [0, 0]. */ - -static inline bool -range_is_null (value_range_t *vr) -{ - return vr->type == VR_RANGE - && integer_zerop (vr->min) - && integer_zerop (vr->max); -} - - -/* Return true if value range VR involves at least one symbol. */ - -static inline bool -symbolic_range_p (value_range_t *vr) -{ - return (!is_gimple_min_invariant (vr->min) - || !is_gimple_min_invariant (vr->max)); -} - -/* Return true if value range VR uses a overflow infinity. */ - -static inline bool -overflow_infinity_range_p (value_range_t *vr) -{ - return (vr->type == VR_RANGE - && (is_overflow_infinity (vr->min) - || is_overflow_infinity (vr->max))); -} - -/* Return false if we can not make a valid comparison based on VR; - this will be the case if it uses an overflow infinity and overflow - is not undefined (i.e., -fno-strict-overflow is in effect). - Otherwise return true, and set *STRICT_OVERFLOW_P to true if VR - uses an overflow infinity. */ - -static bool -usable_range_p (value_range_t *vr, bool *strict_overflow_p) -{ - gcc_assert (vr->type == VR_RANGE); - if (is_overflow_infinity (vr->min)) - { - *strict_overflow_p = true; - if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->min))) - return false; - } - if (is_overflow_infinity (vr->max)) - { - *strict_overflow_p = true; - if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (vr->max))) - return false; - } - return true; -} - - -/* Like tree_expr_nonnegative_warnv_p, but this function uses value - ranges obtained so far. */ - -static bool -vrp_expr_computes_nonnegative (tree expr, bool *strict_overflow_p) -{ - return tree_expr_nonnegative_warnv_p (expr, strict_overflow_p); -} - -/* Like tree_expr_nonzero_warnv_p, but this function uses value ranges - obtained so far. */ - -static bool -vrp_expr_computes_nonzero (tree expr, bool *strict_overflow_p) -{ - if (tree_expr_nonzero_warnv_p (expr, strict_overflow_p)) - return true; - - /* If we have an expression of the form &X->a, then the expression - is nonnull if X is nonnull. */ - if (TREE_CODE (expr) == ADDR_EXPR) - { - tree base = get_base_address (TREE_OPERAND (expr, 0)); - - if (base != NULL_TREE - && TREE_CODE (base) == INDIRECT_REF - && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME) - { - value_range_t *vr = get_value_range (TREE_OPERAND (base, 0)); - if (range_is_nonnull (vr)) - return true; - } - } - - return false; -} - -/* Returns true if EXPR is a valid value (as expected by compare_values) -- - a gimple invariant, or SSA_NAME +- CST. */ - -static bool -valid_value_p (tree expr) -{ - if (TREE_CODE (expr) == SSA_NAME) - return true; - - if (TREE_CODE (expr) == PLUS_EXPR - || TREE_CODE (expr) == MINUS_EXPR) - return (TREE_CODE (TREE_OPERAND (expr, 0)) == SSA_NAME - && TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST); - - return is_gimple_min_invariant (expr); -} - -/* Compare two values VAL1 and VAL2. Return - - -2 if VAL1 and VAL2 cannot be compared at compile-time, - -1 if VAL1 < VAL2, - 0 if VAL1 == VAL2, - +1 if VAL1 > VAL2, and - +2 if VAL1 != VAL2 - - This is similar to tree_int_cst_compare but supports pointer values - and values that cannot be compared at compile time. - - If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to - true if the return value is only valid if we assume that signed - overflow is undefined. */ - -static int -compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p) -{ - if (val1 == val2) - return 0; - - /* Below we rely on the fact that VAL1 and VAL2 are both pointers or - both integers. */ - gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1)) - == POINTER_TYPE_P (TREE_TYPE (val2))); - - if ((TREE_CODE (val1) == SSA_NAME - || TREE_CODE (val1) == PLUS_EXPR - || TREE_CODE (val1) == MINUS_EXPR) - && (TREE_CODE (val2) == SSA_NAME - || TREE_CODE (val2) == PLUS_EXPR - || TREE_CODE (val2) == MINUS_EXPR)) - { - tree n1, c1, n2, c2; - enum tree_code code1, code2; - - /* If VAL1 and VAL2 are of the form 'NAME [+-] CST' or 'NAME', - return -1 or +1 accordingly. If VAL1 and VAL2 don't use the - same name, return -2. */ - if (TREE_CODE (val1) == SSA_NAME) - { - code1 = SSA_NAME; - n1 = val1; - c1 = NULL_TREE; - } - else - { - code1 = TREE_CODE (val1); - n1 = TREE_OPERAND (val1, 0); - c1 = TREE_OPERAND (val1, 1); - if (tree_int_cst_sgn (c1) == -1) - { - if (is_negative_overflow_infinity (c1)) - return -2; - c1 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c1), c1); - if (!c1) - return -2; - code1 = code1 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; - } - } - - if (TREE_CODE (val2) == SSA_NAME) - { - code2 = SSA_NAME; - n2 = val2; - c2 = NULL_TREE; - } - else - { - code2 = TREE_CODE (val2); - n2 = TREE_OPERAND (val2, 0); - c2 = TREE_OPERAND (val2, 1); - if (tree_int_cst_sgn (c2) == -1) - { - if (is_negative_overflow_infinity (c2)) - return -2; - c2 = fold_unary_to_constant (NEGATE_EXPR, TREE_TYPE (c2), c2); - if (!c2) - return -2; - code2 = code2 == MINUS_EXPR ? PLUS_EXPR : MINUS_EXPR; - } - } - - /* Both values must use the same name. */ - if (n1 != n2) - return -2; - - if (code1 == SSA_NAME - && code2 == SSA_NAME) - /* NAME == NAME */ - return 0; - - /* If overflow is defined we cannot simplify more. */ - if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1))) - return -2; - - if (strict_overflow_p != NULL - && (code1 == SSA_NAME || !TREE_NO_WARNING (val1)) - && (code2 == SSA_NAME || !TREE_NO_WARNING (val2))) - *strict_overflow_p = true; - - if (code1 == SSA_NAME) - { - if (code2 == PLUS_EXPR) - /* NAME < NAME + CST */ - return -1; - else if (code2 == MINUS_EXPR) - /* NAME > NAME - CST */ - return 1; - } - else if (code1 == PLUS_EXPR) - { - if (code2 == SSA_NAME) - /* NAME + CST > NAME */ - return 1; - else if (code2 == PLUS_EXPR) - /* NAME + CST1 > NAME + CST2, if CST1 > CST2 */ - return compare_values_warnv (c1, c2, strict_overflow_p); - else if (code2 == MINUS_EXPR) - /* NAME + CST1 > NAME - CST2 */ - return 1; - } - else if (code1 == MINUS_EXPR) - { - if (code2 == SSA_NAME) - /* NAME - CST < NAME */ - return -1; - else if (code2 == PLUS_EXPR) - /* NAME - CST1 < NAME + CST2 */ - return -1; - else if (code2 == MINUS_EXPR) - /* NAME - CST1 > NAME - CST2, if CST1 < CST2. Notice that - C1 and C2 are swapped in the call to compare_values. */ - return compare_values_warnv (c2, c1, strict_overflow_p); - } - - gcc_unreachable (); - } - - /* We cannot compare non-constants. */ - if (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2)) - return -2; - - if (!POINTER_TYPE_P (TREE_TYPE (val1))) - { - /* We cannot compare overflowed values, except for overflow - infinities. */ - if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2)) - { - if (strict_overflow_p != NULL) - *strict_overflow_p = true; - if (is_negative_overflow_infinity (val1)) - return is_negative_overflow_infinity (val2) ? 0 : -1; - else if (is_negative_overflow_infinity (val2)) - return 1; - else if (is_positive_overflow_infinity (val1)) - return is_positive_overflow_infinity (val2) ? 0 : 1; - else if (is_positive_overflow_infinity (val2)) - return -1; - return -2; - } - - return tree_int_cst_compare (val1, val2); - } - else - { - tree t; - - /* First see if VAL1 and VAL2 are not the same. */ - if (val1 == val2 || operand_equal_p (val1, val2, 0)) - return 0; - - /* If VAL1 is a lower address than VAL2, return -1. */ - t = fold_binary (LT_EXPR, boolean_type_node, val1, val2); - if (t == boolean_true_node) - return -1; - - /* If VAL1 is a higher address than VAL2, return +1. */ - t = fold_binary (GT_EXPR, boolean_type_node, val1, val2); - if (t == boolean_true_node) - return 1; - - /* If VAL1 is different than VAL2, return +2. */ - t = fold_binary (NE_EXPR, boolean_type_node, val1, val2); - if (t == boolean_true_node) - return 2; - - return -2; - } -} - -/* Compare values like compare_values_warnv, but treat comparisons of - nonconstants which rely on undefined overflow as incomparable. */ - -static int -compare_values (tree val1, tree val2) -{ - bool sop; - int ret; - - sop = false; - ret = compare_values_warnv (val1, val2, &sop); - if (sop - && (!is_gimple_min_invariant (val1) || !is_gimple_min_invariant (val2))) - ret = -2; - return ret; -} - - -/* Return 1 if VAL is inside value range VR (VR->MIN <= VAL <= VR->MAX), - 0 if VAL is not inside VR, - -2 if we cannot tell either way. - - FIXME, the current semantics of this functions are a bit quirky - when taken in the context of VRP. In here we do not care - about VR's type. If VR is the anti-range ~[3, 5] the call - value_inside_range (4, VR) will return 1. - - This is counter-intuitive in a strict sense, but the callers - currently expect this. They are calling the function - merely to determine whether VR->MIN <= VAL <= VR->MAX. The - callers are applying the VR_RANGE/VR_ANTI_RANGE semantics - themselves. - - This also applies to value_ranges_intersect_p and - range_includes_zero_p. The semantics of VR_RANGE and - VR_ANTI_RANGE should be encoded here, but that also means - adapting the users of these functions to the new semantics. */ - -static inline int -value_inside_range (tree val, value_range_t *vr) -{ - tree cmp1, cmp2; - - fold_defer_overflow_warnings (); - - cmp1 = fold_binary_to_constant (GE_EXPR, boolean_type_node, val, vr->min); - if (!cmp1) - { - fold_undefer_and_ignore_overflow_warnings (); - return -2; - } - - cmp2 = fold_binary_to_constant (LE_EXPR, boolean_type_node, val, vr->max); - - fold_undefer_and_ignore_overflow_warnings (); - - if (!cmp2) - return -2; - - /* APPLE LOCAL begin 5562718 rewritten on mainline */ - /* Insure cmp1 and cmp2 are constants. */ - if ((cmp1 != boolean_true_node && cmp1 != boolean_false_node) - || (cmp2 != boolean_true_node && cmp2 != boolean_false_node)) - return -2; - /* APPLE LOCAL end 5562718 rewritten on mainline */ - - return cmp1 == boolean_true_node && cmp2 == boolean_true_node; -} - - -/* Return true if value ranges VR0 and VR1 have a non-empty - intersection. */ - -static inline bool -value_ranges_intersect_p (value_range_t *vr0, value_range_t *vr1) -{ - return (value_inside_range (vr1->min, vr0) == 1 - || value_inside_range (vr1->max, vr0) == 1 - || value_inside_range (vr0->min, vr1) == 1 - || value_inside_range (vr0->max, vr1) == 1); -} - - -/* Return true if VR includes the value zero, false otherwise. FIXME, - currently this will return false for an anti-range like ~[-4, 3]. - This will be wrong when the semantics of value_inside_range are - modified (currently the users of this function expect these - semantics). */ - -static inline bool -range_includes_zero_p (value_range_t *vr) -{ - tree zero; - - gcc_assert (vr->type != VR_UNDEFINED - && vr->type != VR_VARYING - && !symbolic_range_p (vr)); - - zero = build_int_cst (TREE_TYPE (vr->min), 0); - /* APPLE LOCAL begin 5562718 rewritten on mainline */ - switch (value_inside_range (zero, vr)) - { - case 1: /* Range includes zero. */ - case -2: /* Can't tell if range includes zero. */ - return TRUE; - default: /* Range does not include zero. */ - return FALSE; - } - /* APPLE LOCAL end 5562718 rewritten on mainline */ -} - -/* Return true if T, an SSA_NAME, is known to be nonnegative. Return - false otherwise or if no value range information is available. */ - -bool -ssa_name_nonnegative_p (tree t) -{ - value_range_t *vr = get_value_range (t); - - if (!vr) - return false; - - /* Testing for VR_ANTI_RANGE is not useful here as any anti-range - which would return a useful value should be encoded as a VR_RANGE. */ - if (vr->type == VR_RANGE) - { - int result = compare_values (vr->min, integer_zero_node); - - return (result == 0 || result == 1); - } - return false; -} - -/* Return true if T, an SSA_NAME, is known to be nonzero. Return - false otherwise or if no value range information is available. */ - -bool -ssa_name_nonzero_p (tree t) -{ - value_range_t *vr = get_value_range (t); - - if (!vr) - return false; - - /* A VR_RANGE which does not include zero is a nonzero value. */ - if (vr->type == VR_RANGE && !symbolic_range_p (vr)) - return ! range_includes_zero_p (vr); - - /* A VR_ANTI_RANGE which does include zero is a nonzero value. */ - if (vr->type == VR_ANTI_RANGE && !symbolic_range_p (vr)) - return range_includes_zero_p (vr); - - return false; -} - - -/* Extract value range information from an ASSERT_EXPR EXPR and store - it in *VR_P. */ - -static void -extract_range_from_assert (value_range_t *vr_p, tree expr) -{ - tree var, cond, limit, min, max, type; - value_range_t *var_vr, *limit_vr; - enum tree_code cond_code; - - var = ASSERT_EXPR_VAR (expr); - cond = ASSERT_EXPR_COND (expr); - - gcc_assert (COMPARISON_CLASS_P (cond)); - - /* Find VAR in the ASSERT_EXPR conditional. */ - if (var == TREE_OPERAND (cond, 0)) - { - /* If the predicate is of the form VAR COMP LIMIT, then we just - take LIMIT from the RHS and use the same comparison code. */ - limit = TREE_OPERAND (cond, 1); - cond_code = TREE_CODE (cond); - } - else - { - /* If the predicate is of the form LIMIT COMP VAR, then we need - to flip around the comparison code to create the proper range - for VAR. */ - limit = TREE_OPERAND (cond, 0); - cond_code = swap_tree_comparison (TREE_CODE (cond)); - } - - limit = avoid_overflow_infinity (limit); - - type = TREE_TYPE (limit); - gcc_assert (limit != var); - - /* For pointer arithmetic, we only keep track of pointer equality - and inequality. */ - if (POINTER_TYPE_P (type) && cond_code != NE_EXPR && cond_code != EQ_EXPR) - { - set_value_range_to_varying (vr_p); - return; - } - - /* If LIMIT is another SSA name and LIMIT has a range of its own, - try to use LIMIT's range to avoid creating symbolic ranges - unnecessarily. */ - limit_vr = (TREE_CODE (limit) == SSA_NAME) ? get_value_range (limit) : NULL; - - /* LIMIT's range is only interesting if it has any useful information. */ - if (limit_vr - && (limit_vr->type == VR_UNDEFINED - || limit_vr->type == VR_VARYING - || symbolic_range_p (limit_vr))) - limit_vr = NULL; - - /* Initially, the new range has the same set of equivalences of - VAR's range. This will be revised before returning the final - value. Since assertions may be chained via mutually exclusive - predicates, we will need to trim the set of equivalences before - we are done. */ - gcc_assert (vr_p->equiv == NULL); - vr_p->equiv = BITMAP_ALLOC (NULL); - add_equivalence (vr_p->equiv, var); - - /* Extract a new range based on the asserted comparison for VAR and - LIMIT's value range. Notice that if LIMIT has an anti-range, we - will only use it for equality comparisons (EQ_EXPR). For any - other kind of assertion, we cannot derive a range from LIMIT's - anti-range that can be used to describe the new range. For - instance, ASSERT_EXPR <x_2, x_2 <= b_4>. If b_4 is ~[2, 10], - then b_4 takes on the ranges [-INF, 1] and [11, +INF]. There is - no single range for x_2 that could describe LE_EXPR, so we might - as well build the range [b_4, +INF] for it. */ - if (cond_code == EQ_EXPR) - { - enum value_range_type range_type; - - if (limit_vr) - { - range_type = limit_vr->type; - min = limit_vr->min; - max = limit_vr->max; - } - else - { - range_type = VR_RANGE; - min = limit; - max = limit; - } - - set_value_range (vr_p, range_type, min, max, vr_p->equiv); - - /* When asserting the equality VAR == LIMIT and LIMIT is another - SSA name, the new range will also inherit the equivalence set - from LIMIT. */ - if (TREE_CODE (limit) == SSA_NAME) - add_equivalence (vr_p->equiv, limit); - } - else if (cond_code == NE_EXPR) - { - /* As described above, when LIMIT's range is an anti-range and - this assertion is an inequality (NE_EXPR), then we cannot - derive anything from the anti-range. For instance, if - LIMIT's range was ~[0, 0], the assertion 'VAR != LIMIT' does - not imply that VAR's range is [0, 0]. So, in the case of - anti-ranges, we just assert the inequality using LIMIT and - not its anti-range. - - If LIMIT_VR is a range, we can only use it to build a new - anti-range if LIMIT_VR is a single-valued range. For - instance, if LIMIT_VR is [0, 1], the predicate - VAR != [0, 1] does not mean that VAR's range is ~[0, 1]. - Rather, it means that for value 0 VAR should be ~[0, 0] - and for value 1, VAR should be ~[1, 1]. We cannot - represent these ranges. - - The only situation in which we can build a valid - anti-range is when LIMIT_VR is a single-valued range - (i.e., LIMIT_VR->MIN == LIMIT_VR->MAX). In that case, - build the anti-range ~[LIMIT_VR->MIN, LIMIT_VR->MAX]. */ - if (limit_vr - && limit_vr->type == VR_RANGE - && compare_values (limit_vr->min, limit_vr->max) == 0) - { - min = limit_vr->min; - max = limit_vr->max; - } - else - { - /* In any other case, we cannot use LIMIT's range to build a - valid anti-range. */ - min = max = limit; - } - - /* If MIN and MAX cover the whole range for their type, then - just use the original LIMIT. */ - if (INTEGRAL_TYPE_P (type) - && vrp_val_is_min (min) - && vrp_val_is_max (max)) - min = max = limit; - - set_value_range (vr_p, VR_ANTI_RANGE, min, max, vr_p->equiv); - } - else if (cond_code == LE_EXPR || cond_code == LT_EXPR) - { - min = TYPE_MIN_VALUE (type); - - if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) - max = limit; - else - { - /* If LIMIT_VR is of the form [N1, N2], we need to build the - range [MIN, N2] for LE_EXPR and [MIN, N2 - 1] for - LT_EXPR. */ - max = limit_vr->max; - } - - /* If the maximum value forces us to be out of bounds, simply punt. - It would be pointless to try and do anything more since this - all should be optimized away above us. */ - if ((cond_code == LT_EXPR - && compare_values (max, min) == 0) - || is_overflow_infinity (max)) - set_value_range_to_varying (vr_p); - else - { - /* For LT_EXPR, we create the range [MIN, MAX - 1]. */ - if (cond_code == LT_EXPR) - { - tree one = build_int_cst (type, 1); - max = fold_build2 (MINUS_EXPR, type, max, one); - if (EXPR_P (max)) - TREE_NO_WARNING (max) = 1; - } - - set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); - } - } - else if (cond_code == GE_EXPR || cond_code == GT_EXPR) - { - max = TYPE_MAX_VALUE (type); - - if (limit_vr == NULL || limit_vr->type == VR_ANTI_RANGE) - min = limit; - else - { - /* If LIMIT_VR is of the form [N1, N2], we need to build the - range [N1, MAX] for GE_EXPR and [N1 + 1, MAX] for - GT_EXPR. */ - min = limit_vr->min; - } - - /* If the minimum value forces us to be out of bounds, simply punt. - It would be pointless to try and do anything more since this - all should be optimized away above us. */ - if ((cond_code == GT_EXPR - && compare_values (min, max) == 0) - || is_overflow_infinity (min)) - set_value_range_to_varying (vr_p); - else - { - /* For GT_EXPR, we create the range [MIN + 1, MAX]. */ - if (cond_code == GT_EXPR) - { - tree one = build_int_cst (type, 1); - min = fold_build2 (PLUS_EXPR, type, min, one); - if (EXPR_P (min)) - TREE_NO_WARNING (min) = 1; - } - - set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); - } - } - else - gcc_unreachable (); - - /* If VAR already had a known range, it may happen that the new - range we have computed and VAR's range are not compatible. For - instance, - - if (p_5 == NULL) - p_6 = ASSERT_EXPR <p_5, p_5 == NULL>; - x_7 = p_6->fld; - p_8 = ASSERT_EXPR <p_6, p_6 != NULL>; - - While the above comes from a faulty program, it will cause an ICE - later because p_8 and p_6 will have incompatible ranges and at - the same time will be considered equivalent. A similar situation - would arise from - - if (i_5 > 10) - i_6 = ASSERT_EXPR <i_5, i_5 > 10>; - if (i_5 < 5) - i_7 = ASSERT_EXPR <i_6, i_6 < 5>; - - Again i_6 and i_7 will have incompatible ranges. It would be - pointless to try and do anything with i_7's range because - anything dominated by 'if (i_5 < 5)' will be optimized away. - Note, due to the wa in which simulation proceeds, the statement - i_7 = ASSERT_EXPR <...> we would never be visited because the - conditional 'if (i_5 < 5)' always evaluates to false. However, - this extra check does not hurt and may protect against future - changes to VRP that may get into a situation similar to the - NULL pointer dereference example. - - Note that these compatibility tests are only needed when dealing - with ranges or a mix of range and anti-range. If VAR_VR and VR_P - are both anti-ranges, they will always be compatible, because two - anti-ranges will always have a non-empty intersection. */ - - var_vr = get_value_range (var); - - /* We may need to make adjustments when VR_P and VAR_VR are numeric - ranges or anti-ranges. */ - if (vr_p->type == VR_VARYING - || vr_p->type == VR_UNDEFINED - || var_vr->type == VR_VARYING - || var_vr->type == VR_UNDEFINED - || symbolic_range_p (vr_p) - || symbolic_range_p (var_vr)) - return; - - if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE) - { - /* If the two ranges have a non-empty intersection, we can - refine the resulting range. Since the assert expression - creates an equivalency and at the same time it asserts a - predicate, we can take the intersection of the two ranges to - get better precision. */ - if (value_ranges_intersect_p (var_vr, vr_p)) - { - /* Use the larger of the two minimums. */ - if (compare_values (vr_p->min, var_vr->min) == -1) - min = var_vr->min; - else - min = vr_p->min; - - /* Use the smaller of the two maximums. */ - if (compare_values (vr_p->max, var_vr->max) == 1) - max = var_vr->max; - else - max = vr_p->max; - - set_value_range (vr_p, vr_p->type, min, max, vr_p->equiv); - } - else - { - /* The two ranges do not intersect, set the new range to - VARYING, because we will not be able to do anything - meaningful with it. */ - set_value_range_to_varying (vr_p); - } - } - else if ((var_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE) - || (var_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE)) - { - /* A range and an anti-range will cancel each other only if - their ends are the same. For instance, in the example above, - p_8's range ~[0, 0] and p_6's range [0, 0] are incompatible, - so VR_P should be set to VR_VARYING. */ - if (compare_values (var_vr->min, vr_p->min) == 0 - && compare_values (var_vr->max, vr_p->max) == 0) - set_value_range_to_varying (vr_p); - else - { - tree min, max, anti_min, anti_max, real_min, real_max; - - /* We want to compute the logical AND of the two ranges; - there are three cases to consider. - - - 1. The VR_ANTI_RANGE range is completely within the - VR_RANGE and the endpoints of the ranges are - different. In that case the resulting range - should be whichever range is more precise. - Typically that will be the VR_RANGE. - - 2. The VR_ANTI_RANGE is completely disjoint from - the VR_RANGE. In this case the resulting range - should be the VR_RANGE. - - 3. There is some overlap between the VR_ANTI_RANGE - and the VR_RANGE. - - 3a. If the high limit of the VR_ANTI_RANGE resides - within the VR_RANGE, then the result is a new - VR_RANGE starting at the high limit of the - the VR_ANTI_RANGE + 1 and extending to the - high limit of the original VR_RANGE. - - 3b. If the low limit of the VR_ANTI_RANGE resides - within the VR_RANGE, then the result is a new - VR_RANGE starting at the low limit of the original - VR_RANGE and extending to the low limit of the - VR_ANTI_RANGE - 1. */ - if (vr_p->type == VR_ANTI_RANGE) - { - anti_min = vr_p->min; - anti_max = vr_p->max; - real_min = var_vr->min; - real_max = var_vr->max; - } - else - { - anti_min = var_vr->min; - anti_max = var_vr->max; - real_min = vr_p->min; - real_max = vr_p->max; - } - - - /* Case 1, VR_ANTI_RANGE completely within VR_RANGE, - not including any endpoints. */ - if (compare_values (anti_max, real_max) == -1 - && compare_values (anti_min, real_min) == 1) - { - set_value_range (vr_p, VR_RANGE, real_min, - real_max, vr_p->equiv); - } - /* Case 2, VR_ANTI_RANGE completely disjoint from - VR_RANGE. */ - else if (compare_values (anti_min, real_max) == 1 - || compare_values (anti_max, real_min) == -1) - { - set_value_range (vr_p, VR_RANGE, real_min, - real_max, vr_p->equiv); - } - /* Case 3a, the anti-range extends into the low - part of the real range. Thus creating a new - low for the real range. */ - else if ((compare_values (anti_max, real_min) == 1 - || compare_values (anti_max, real_min) == 0) - && compare_values (anti_max, real_max) == -1) - { - gcc_assert (!is_positive_overflow_infinity (anti_max)); - if (needs_overflow_infinity (TREE_TYPE (anti_max)) - && vrp_val_is_max (anti_max)) - { - if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) - { - set_value_range_to_varying (vr_p); - return; - } - min = positive_overflow_infinity (TREE_TYPE (var_vr->min)); - } - else - min = fold_build2 (PLUS_EXPR, TREE_TYPE (var_vr->min), - anti_max, - build_int_cst (TREE_TYPE (var_vr->min), 1)); - max = real_max; - set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); - } - /* Case 3b, the anti-range extends into the high - part of the real range. Thus creating a new - higher for the real range. */ - else if (compare_values (anti_min, real_min) == 1 - && (compare_values (anti_min, real_max) == -1 - || compare_values (anti_min, real_max) == 0)) - { - gcc_assert (!is_negative_overflow_infinity (anti_min)); - if (needs_overflow_infinity (TREE_TYPE (anti_min)) - && vrp_val_is_min (anti_min)) - { - if (!supports_overflow_infinity (TREE_TYPE (var_vr->min))) - { - set_value_range_to_varying (vr_p); - return; - } - max = negative_overflow_infinity (TREE_TYPE (var_vr->min)); - } - else - max = fold_build2 (MINUS_EXPR, TREE_TYPE (var_vr->min), - anti_min, - build_int_cst (TREE_TYPE (var_vr->min), 1)); - min = real_min; - set_value_range (vr_p, VR_RANGE, min, max, vr_p->equiv); - } - } - } -} - - -/* Extract range information from SSA name VAR and store it in VR. If - VAR has an interesting range, use it. Otherwise, create the - range [VAR, VAR] and return it. This is useful in situations where - we may have conditionals testing values of VARYING names. For - instance, - - x_3 = y_5; - if (x_3 > y_5) - ... - - Even if y_5 is deemed VARYING, we can determine that x_3 > y_5 is - always false. */ - -static void -extract_range_from_ssa_name (value_range_t *vr, tree var) -{ - value_range_t *var_vr = get_value_range (var); - - if (var_vr->type != VR_UNDEFINED && var_vr->type != VR_VARYING) - copy_value_range (vr, var_vr); - else - set_value_range (vr, VR_RANGE, var, var, NULL); - - add_equivalence (vr->equiv, var); -} - - -/* Wrapper around int_const_binop. If the operation overflows and we - are not using wrapping arithmetic, then adjust the result to be - -INF or +INF depending on CODE, VAL1 and VAL2. This can return - NULL_TREE if we need to use an overflow infinity representation but - the type does not support it. */ - -static tree -vrp_int_const_binop (enum tree_code code, tree val1, tree val2) -{ - tree res; - - res = int_const_binop (code, val1, val2, 0); - - /* If we are not using wrapping arithmetic, operate symbolically - on -INF and +INF. */ - if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (val1))) - { - int checkz = compare_values (res, val1); - bool overflow = false; - - /* Ensure that res = val1 [+*] val2 >= val1 - or that res = val1 - val2 <= val1. */ - if ((code == PLUS_EXPR - && !(checkz == 1 || checkz == 0)) - || (code == MINUS_EXPR - && !(checkz == 0 || checkz == -1))) - { - overflow = true; - } - /* Checking for multiplication overflow is done by dividing the - output of the multiplication by the first input of the - multiplication. If the result of that division operation is - not equal to the second input of the multiplication, then the - multiplication overflowed. */ - else if (code == MULT_EXPR && !integer_zerop (val1)) - { - tree tmp = int_const_binop (TRUNC_DIV_EXPR, - res, - val1, 0); - int check = compare_values (tmp, val2); - - if (check != 0) - overflow = true; - } - - if (overflow) - { - res = copy_node (res); - TREE_OVERFLOW (res) = 1; - } - - } - else if ((TREE_OVERFLOW (res) - && !TREE_OVERFLOW (val1) - && !TREE_OVERFLOW (val2)) - || is_overflow_infinity (val1) - || is_overflow_infinity (val2)) - { - /* If the operation overflowed but neither VAL1 nor VAL2 are - overflown, return -INF or +INF depending on the operation - and the combination of signs of the operands. */ - int sgn1 = tree_int_cst_sgn (val1); - int sgn2 = tree_int_cst_sgn (val2); - - if (needs_overflow_infinity (TREE_TYPE (res)) - && !supports_overflow_infinity (TREE_TYPE (res))) - return NULL_TREE; - - /* We have to punt on adding infinities of different signs, - since we can't tell what the sign of the result should be. - Likewise for subtracting infinities of the same sign. */ - if (((code == PLUS_EXPR && sgn1 != sgn2) - || (code == MINUS_EXPR && sgn1 == sgn2)) - && is_overflow_infinity (val1) - && is_overflow_infinity (val2)) - return NULL_TREE; - - /* Don't try to handle division or shifting of infinities. */ - if ((code == TRUNC_DIV_EXPR - || code == FLOOR_DIV_EXPR - || code == CEIL_DIV_EXPR - || code == EXACT_DIV_EXPR - || code == ROUND_DIV_EXPR - || code == RSHIFT_EXPR) - && (is_overflow_infinity (val1) - || is_overflow_infinity (val2))) - return NULL_TREE; - - /* Notice that we only need to handle the restricted set of - operations handled by extract_range_from_binary_expr. - Among them, only multiplication, addition and subtraction - can yield overflow without overflown operands because we - are working with integral types only... except in the - case VAL1 = -INF and VAL2 = -1 which overflows to +INF - for division too. */ - - /* For multiplication, the sign of the overflow is given - by the comparison of the signs of the operands. */ - if ((code == MULT_EXPR && sgn1 == sgn2) - /* For addition, the operands must be of the same sign - to yield an overflow. Its sign is therefore that - of one of the operands, for example the first. For - infinite operands X + -INF is negative, not positive. */ - || (code == PLUS_EXPR - && (sgn1 >= 0 - ? !is_negative_overflow_infinity (val2) - : is_positive_overflow_infinity (val2))) - /* For subtraction, non-infinite operands must be of - different signs to yield an overflow. Its sign is - therefore that of the first operand or the opposite of - that of the second operand. A first operand of 0 counts - as positive here, for the corner case 0 - (-INF), which - overflows, but must yield +INF. For infinite operands 0 - - INF is negative, not positive. */ - || (code == MINUS_EXPR - && (sgn1 >= 0 - ? !is_positive_overflow_infinity (val2) - : is_negative_overflow_infinity (val2))) - /* For division, the only case is -INF / -1 = +INF. */ - || code == TRUNC_DIV_EXPR - || code == FLOOR_DIV_EXPR - || code == CEIL_DIV_EXPR - || code == EXACT_DIV_EXPR - || code == ROUND_DIV_EXPR) - return (needs_overflow_infinity (TREE_TYPE (res)) - ? positive_overflow_infinity (TREE_TYPE (res)) - : TYPE_MAX_VALUE (TREE_TYPE (res))); - else - return (needs_overflow_infinity (TREE_TYPE (res)) - ? negative_overflow_infinity (TREE_TYPE (res)) - : TYPE_MIN_VALUE (TREE_TYPE (res))); - } - - return res; -} - - -/* Extract range information from a binary expression EXPR based on - the ranges of each of its operands and the expression code. */ - -static void -extract_range_from_binary_expr (value_range_t *vr, tree expr) -{ - enum tree_code code = TREE_CODE (expr); - enum value_range_type type; - tree op0, op1, min, max; - int cmp; - value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; - value_range_t vr1 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; - - /* Not all binary expressions can be applied to ranges in a - meaningful way. Handle only arithmetic operations. */ - if (code != PLUS_EXPR - && code != MINUS_EXPR - && code != MULT_EXPR - && code != TRUNC_DIV_EXPR - && code != FLOOR_DIV_EXPR - && code != CEIL_DIV_EXPR - && code != EXACT_DIV_EXPR - && code != ROUND_DIV_EXPR - && code != MIN_EXPR - && code != MAX_EXPR - && code != BIT_AND_EXPR - && code != TRUTH_ANDIF_EXPR - && code != TRUTH_ORIF_EXPR - && code != TRUTH_AND_EXPR - && code != TRUTH_OR_EXPR) - { - set_value_range_to_varying (vr); - return; - } - - /* Get value ranges for each operand. For constant operands, create - a new value range with the operand to simplify processing. */ - op0 = TREE_OPERAND (expr, 0); - if (TREE_CODE (op0) == SSA_NAME) - vr0 = *(get_value_range (op0)); - else if (is_gimple_min_invariant (op0)) - set_value_range_to_value (&vr0, op0, NULL); - else - set_value_range_to_varying (&vr0); - - op1 = TREE_OPERAND (expr, 1); - if (TREE_CODE (op1) == SSA_NAME) - vr1 = *(get_value_range (op1)); - else if (is_gimple_min_invariant (op1)) - set_value_range_to_value (&vr1, op1, NULL); - else - set_value_range_to_varying (&vr1); - - /* If either range is UNDEFINED, so is the result. */ - if (vr0.type == VR_UNDEFINED || vr1.type == VR_UNDEFINED) - { - set_value_range_to_undefined (vr); - return; - } - - /* The type of the resulting value range defaults to VR0.TYPE. */ - type = vr0.type; - - /* Refuse to operate on VARYING ranges, ranges of different kinds - and symbolic ranges. As an exception, we allow BIT_AND_EXPR - because we may be able to derive a useful range even if one of - the operands is VR_VARYING or symbolic range. TODO, we may be - able to derive anti-ranges in some cases. */ - if (code != BIT_AND_EXPR - && code != TRUTH_AND_EXPR - && code != TRUTH_OR_EXPR - && (vr0.type == VR_VARYING - || vr1.type == VR_VARYING - || vr0.type != vr1.type - || symbolic_range_p (&vr0) - || symbolic_range_p (&vr1))) - { - set_value_range_to_varying (vr); - return; - } - - /* Now evaluate the expression to determine the new range. */ - if (POINTER_TYPE_P (TREE_TYPE (expr)) - || POINTER_TYPE_P (TREE_TYPE (op0)) - || POINTER_TYPE_P (TREE_TYPE (op1))) - { - /* For pointer types, we are really only interested in asserting - whether the expression evaluates to non-NULL. FIXME, we used - to gcc_assert (code == PLUS_EXPR || code == MINUS_EXPR), but - ivopts is generating expressions with pointer multiplication - in them. */ - if (code == PLUS_EXPR) - { - if (range_is_nonnull (&vr0) || range_is_nonnull (&vr1)) - set_value_range_to_nonnull (vr, TREE_TYPE (expr)); - else if (range_is_null (&vr0) && range_is_null (&vr1)) - set_value_range_to_null (vr, TREE_TYPE (expr)); - else - set_value_range_to_varying (vr); - } - else - { - /* Subtracting from a pointer, may yield 0, so just drop the - resulting range to varying. */ - set_value_range_to_varying (vr); - } - - return; - } - - /* For integer ranges, apply the operation to each end of the - range and see what we end up with. */ - if (code == TRUTH_ANDIF_EXPR - || code == TRUTH_ORIF_EXPR - || code == TRUTH_AND_EXPR - || code == TRUTH_OR_EXPR) - { - /* If one of the operands is zero, we know that the whole - expression evaluates zero. */ - if (code == TRUTH_AND_EXPR - && ((vr0.type == VR_RANGE - && integer_zerop (vr0.min) - && integer_zerop (vr0.max)) - || (vr1.type == VR_RANGE - && integer_zerop (vr1.min) - && integer_zerop (vr1.max)))) - { - type = VR_RANGE; - min = max = build_int_cst (TREE_TYPE (expr), 0); - } - /* If one of the operands is one, we know that the whole - expression evaluates one. */ - else if (code == TRUTH_OR_EXPR - && ((vr0.type == VR_RANGE - && integer_onep (vr0.min) - && integer_onep (vr0.max)) - || (vr1.type == VR_RANGE - && integer_onep (vr1.min) - && integer_onep (vr1.max)))) - { - type = VR_RANGE; - min = max = build_int_cst (TREE_TYPE (expr), 1); - } - else if (vr0.type != VR_VARYING - && vr1.type != VR_VARYING - && vr0.type == vr1.type - && !symbolic_range_p (&vr0) - && !overflow_infinity_range_p (&vr0) - && !symbolic_range_p (&vr1) - && !overflow_infinity_range_p (&vr1)) - { - /* Boolean expressions cannot be folded with int_const_binop. */ - min = fold_binary (code, TREE_TYPE (expr), vr0.min, vr1.min); - max = fold_binary (code, TREE_TYPE (expr), vr0.max, vr1.max); - } - else - { - set_value_range_to_varying (vr); - return; - } - } - else if (code == PLUS_EXPR - || code == MIN_EXPR - || code == MAX_EXPR) - { - /* If we have a PLUS_EXPR with two VR_ANTI_RANGEs, drop to - VR_VARYING. It would take more effort to compute a precise - range for such a case. For example, if we have op0 == 1 and - op1 == -1 with their ranges both being ~[0,0], we would have - op0 + op1 == 0, so we cannot claim that the sum is in ~[0,0]. - Note that we are guaranteed to have vr0.type == vr1.type at - this point. */ - if (code == PLUS_EXPR && vr0.type == VR_ANTI_RANGE) - { - set_value_range_to_varying (vr); - return; - } - - /* For operations that make the resulting range directly - proportional to the original ranges, apply the operation to - the same end of each range. */ - min = vrp_int_const_binop (code, vr0.min, vr1.min); - max = vrp_int_const_binop (code, vr0.max, vr1.max); - } - else if (code == MULT_EXPR - || code == TRUNC_DIV_EXPR - || code == FLOOR_DIV_EXPR - || code == CEIL_DIV_EXPR - || code == EXACT_DIV_EXPR - || code == ROUND_DIV_EXPR) - { - tree val[4]; - size_t i; - bool sop; - - /* If we have an unsigned MULT_EXPR with two VR_ANTI_RANGEs, - drop to VR_VARYING. It would take more effort to compute a - precise range for such a case. For example, if we have - op0 == 65536 and op1 == 65536 with their ranges both being - ~[0,0] on a 32-bit machine, we would have op0 * op1 == 0, so - we cannot claim that the product is in ~[0,0]. Note that we - are guaranteed to have vr0.type == vr1.type at this - point. */ - if (code == MULT_EXPR - && vr0.type == VR_ANTI_RANGE - && !TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (op0))) - { - set_value_range_to_varying (vr); - return; - } - - /* Multiplications and divisions are a bit tricky to handle, - depending on the mix of signs we have in the two ranges, we - need to operate on different values to get the minimum and - maximum values for the new range. One approach is to figure - out all the variations of range combinations and do the - operations. - - However, this involves several calls to compare_values and it - is pretty convoluted. It's simpler to do the 4 operations - (MIN0 OP MIN1, MIN0 OP MAX1, MAX0 OP MIN1 and MAX0 OP MAX0 OP - MAX1) and then figure the smallest and largest values to form - the new range. */ - - /* Divisions by zero result in a VARYING value. */ - if (code != MULT_EXPR - && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1))) - { - set_value_range_to_varying (vr); - return; - } - - /* Compute the 4 cross operations. */ - sop = false; - val[0] = vrp_int_const_binop (code, vr0.min, vr1.min); - if (val[0] == NULL_TREE) - sop = true; - - if (vr1.max == vr1.min) - val[1] = NULL_TREE; - else - { - val[1] = vrp_int_const_binop (code, vr0.min, vr1.max); - if (val[1] == NULL_TREE) - sop = true; - } - - if (vr0.max == vr0.min) - val[2] = NULL_TREE; - else - { - val[2] = vrp_int_const_binop (code, vr0.max, vr1.min); - if (val[2] == NULL_TREE) - sop = true; - } - - if (vr0.min == vr0.max || vr1.min == vr1.max) - val[3] = NULL_TREE; - else - { - val[3] = vrp_int_const_binop (code, vr0.max, vr1.max); - if (val[3] == NULL_TREE) - sop = true; - } - - if (sop) - { - set_value_range_to_varying (vr); - return; - } - - /* Set MIN to the minimum of VAL[i] and MAX to the maximum - of VAL[i]. */ - min = val[0]; - max = val[0]; - for (i = 1; i < 4; i++) - { - if (!is_gimple_min_invariant (min) - || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) - || !is_gimple_min_invariant (max) - || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) - break; - - if (val[i]) - { - if (!is_gimple_min_invariant (val[i]) - || (TREE_OVERFLOW (val[i]) - && !is_overflow_infinity (val[i]))) - { - /* If we found an overflowed value, set MIN and MAX - to it so that we set the resulting range to - VARYING. */ - min = max = val[i]; - break; - } - - if (compare_values (val[i], min) == -1) - min = val[i]; - - if (compare_values (val[i], max) == 1) - max = val[i]; - } - } - } - else if (code == MINUS_EXPR) - { - /* If we have a MINUS_EXPR with two VR_ANTI_RANGEs, drop to - VR_VARYING. It would take more effort to compute a precise - range for such a case. For example, if we have op0 == 1 and - op1 == 1 with their ranges both being ~[0,0], we would have - op0 - op1 == 0, so we cannot claim that the difference is in - ~[0,0]. Note that we are guaranteed to have - vr0.type == vr1.type at this point. */ - if (vr0.type == VR_ANTI_RANGE) - { - set_value_range_to_varying (vr); - return; - } - - /* For MINUS_EXPR, apply the operation to the opposite ends of - each range. */ - min = vrp_int_const_binop (code, vr0.min, vr1.max); - max = vrp_int_const_binop (code, vr0.max, vr1.min); - } - else if (code == BIT_AND_EXPR) - { - if (vr0.type == VR_RANGE - && vr0.min == vr0.max - && TREE_CODE (vr0.max) == INTEGER_CST - && !TREE_OVERFLOW (vr0.max) - && tree_int_cst_sgn (vr0.max) >= 0) - { - min = build_int_cst (TREE_TYPE (expr), 0); - max = vr0.max; - } - else if (vr1.type == VR_RANGE - && vr1.min == vr1.max - && TREE_CODE (vr1.max) == INTEGER_CST - && !TREE_OVERFLOW (vr1.max) - && tree_int_cst_sgn (vr1.max) >= 0) - { - type = VR_RANGE; - min = build_int_cst (TREE_TYPE (expr), 0); - max = vr1.max; - } - else - { - set_value_range_to_varying (vr); - return; - } - } - else - gcc_unreachable (); - - /* If either MIN or MAX overflowed, then set the resulting range to - VARYING. But we do accept an overflow infinity - representation. */ - if (min == NULL_TREE - || !is_gimple_min_invariant (min) - || (TREE_OVERFLOW (min) && !is_overflow_infinity (min)) - || max == NULL_TREE - || !is_gimple_min_invariant (max) - || (TREE_OVERFLOW (max) && !is_overflow_infinity (max))) - { - set_value_range_to_varying (vr); - return; - } - - /* We punt if: - 1) [-INF, +INF] - 2) [-INF, +-INF(OVF)] - 3) [+-INF(OVF), +INF] - 4) [+-INF(OVF), +-INF(OVF)] - We learn nothing when we have INF and INF(OVF) on both sides. - Note that we do accept [-INF, -INF] and [+INF, +INF] without - overflow. */ - if ((vrp_val_is_min (min) || is_overflow_infinity (min)) - && (vrp_val_is_max (max) || is_overflow_infinity (max))) - { - set_value_range_to_varying (vr); - return; - } - - cmp = compare_values (min, max); - if (cmp == -2 || cmp == 1) - { - /* If the new range has its limits swapped around (MIN > MAX), - then the operation caused one of them to wrap around, mark - the new range VARYING. */ - set_value_range_to_varying (vr); - } - else - set_value_range (vr, type, min, max, NULL); -} - - -/* Extract range information from a unary expression EXPR based on - the range of its operand and the expression code. */ - -static void -extract_range_from_unary_expr (value_range_t *vr, tree expr) -{ - enum tree_code code = TREE_CODE (expr); - tree min, max, op0; - int cmp; - value_range_t vr0 = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; - - /* Refuse to operate on certain unary expressions for which we - cannot easily determine a resulting range. */ - if (code == FIX_TRUNC_EXPR - || code == FIX_CEIL_EXPR - || code == FIX_FLOOR_EXPR - || code == FIX_ROUND_EXPR - || code == FLOAT_EXPR - || code == BIT_NOT_EXPR - || code == NON_LVALUE_EXPR - || code == CONJ_EXPR) - { - set_value_range_to_varying (vr); - return; - } - - /* Get value ranges for the operand. For constant operands, create - a new value range with the operand to simplify processing. */ - op0 = TREE_OPERAND (expr, 0); - if (TREE_CODE (op0) == SSA_NAME) - vr0 = *(get_value_range (op0)); - else if (is_gimple_min_invariant (op0)) - set_value_range_to_value (&vr0, op0, NULL); - else - set_value_range_to_varying (&vr0); - - /* If VR0 is UNDEFINED, so is the result. */ - if (vr0.type == VR_UNDEFINED) - { - set_value_range_to_undefined (vr); - return; - } - - /* Refuse to operate on symbolic ranges, or if neither operand is - a pointer or integral type. */ - if ((!INTEGRAL_TYPE_P (TREE_TYPE (op0)) - && !POINTER_TYPE_P (TREE_TYPE (op0))) - || (vr0.type != VR_VARYING - && symbolic_range_p (&vr0))) - { - set_value_range_to_varying (vr); - return; - } - - /* If the expression involves pointers, we are only interested in - determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]). */ - if (POINTER_TYPE_P (TREE_TYPE (expr)) || POINTER_TYPE_P (TREE_TYPE (op0))) - { - bool sop; - - sop = false; - if (range_is_nonnull (&vr0) - || (tree_expr_nonzero_warnv_p (expr, &sop) - && !sop)) - set_value_range_to_nonnull (vr, TREE_TYPE (expr)); - else if (range_is_null (&vr0)) - set_value_range_to_null (vr, TREE_TYPE (expr)); - else - set_value_range_to_varying (vr); - - return; - } - - /* Handle unary expressions on integer ranges. */ - if (code == NOP_EXPR || code == CONVERT_EXPR) - { - tree inner_type = TREE_TYPE (op0); - tree outer_type = TREE_TYPE (expr); - - /* If VR0 represents a simple range, then try to convert - the min and max values for the range to the same type - as OUTER_TYPE. If the results compare equal to VR0's - min and max values and the new min is still less than - or equal to the new max, then we can safely use the newly - computed range for EXPR. This allows us to compute - accurate ranges through many casts. */ - if ((vr0.type == VR_RANGE - && !overflow_infinity_range_p (&vr0)) - || (vr0.type == VR_VARYING - && TYPE_PRECISION (outer_type) > TYPE_PRECISION (inner_type))) - { - tree new_min, new_max, orig_min, orig_max; - - /* Convert the input operand min/max to OUTER_TYPE. If - the input has no range information, then use the min/max - for the input's type. */ - if (vr0.type == VR_RANGE) - { - orig_min = vr0.min; - orig_max = vr0.max; - } - else - { - orig_min = TYPE_MIN_VALUE (inner_type); - orig_max = TYPE_MAX_VALUE (inner_type); - } - - new_min = fold_convert (outer_type, orig_min); - new_max = fold_convert (outer_type, orig_max); - - /* Verify the new min/max values are gimple values and - that they compare equal to the original input's - min/max values. */ - if (is_gimple_val (new_min) - && is_gimple_val (new_max) - && tree_int_cst_equal (new_min, orig_min) - && tree_int_cst_equal (new_max, orig_max) - && (!is_overflow_infinity (new_min) - || !is_overflow_infinity (new_max)) - && compare_values (new_min, new_max) <= 0 - && compare_values (new_min, new_max) >= -1) - { - set_value_range (vr, VR_RANGE, new_min, new_max, vr->equiv); - return; - } - } - - /* When converting types of different sizes, set the result to - VARYING. Things like sign extensions and precision loss may - change the range. For instance, if x_3 is of type 'long long - int' and 'y_5 = (unsigned short) x_3', if x_3 is ~[0, 0], it - is impossible to know at compile time whether y_5 will be - ~[0, 0]. */ - if (TYPE_SIZE (inner_type) != TYPE_SIZE (outer_type) - || TYPE_PRECISION (inner_type) != TYPE_PRECISION (outer_type)) - { - set_value_range_to_varying (vr); - return; - } - } - - /* Conversion of a VR_VARYING value to a wider type can result - in a usable range. So wait until after we've handled conversions - before dropping the result to VR_VARYING if we had a source - operand that is VR_VARYING. */ - if (vr0.type == VR_VARYING) - { - set_value_range_to_varying (vr); - return; - } - - /* Apply the operation to each end of the range and see what we end - up with. */ - if (code == NEGATE_EXPR - && !TYPE_UNSIGNED (TREE_TYPE (expr))) - { - /* NEGATE_EXPR flips the range around. We need to treat - TYPE_MIN_VALUE specially. */ - if (is_positive_overflow_infinity (vr0.max)) - min = negative_overflow_infinity (TREE_TYPE (expr)); - else if (is_negative_overflow_infinity (vr0.max)) - min = positive_overflow_infinity (TREE_TYPE (expr)); - else if (!vrp_val_is_min (vr0.max)) - min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); - else if (needs_overflow_infinity (TREE_TYPE (expr))) - { - if (supports_overflow_infinity (TREE_TYPE (expr)) - && !is_overflow_infinity (vr0.min) - && !vrp_val_is_min (vr0.min)) - min = positive_overflow_infinity (TREE_TYPE (expr)); - else - { - set_value_range_to_varying (vr); - return; - } - } - else - min = TYPE_MIN_VALUE (TREE_TYPE (expr)); - - if (is_positive_overflow_infinity (vr0.min)) - max = negative_overflow_infinity (TREE_TYPE (expr)); - else if (is_negative_overflow_infinity (vr0.min)) - max = positive_overflow_infinity (TREE_TYPE (expr)); - else if (!vrp_val_is_min (vr0.min)) - max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); - else if (needs_overflow_infinity (TREE_TYPE (expr))) - { - if (supports_overflow_infinity (TREE_TYPE (expr))) - max = positive_overflow_infinity (TREE_TYPE (expr)); - else - { - set_value_range_to_varying (vr); - return; - } - } - else - max = TYPE_MIN_VALUE (TREE_TYPE (expr)); - } - else if (code == NEGATE_EXPR - && TYPE_UNSIGNED (TREE_TYPE (expr))) - { - if (!range_includes_zero_p (&vr0)) - { - max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); - min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); - } - else - { - if (range_is_null (&vr0)) - set_value_range_to_null (vr, TREE_TYPE (expr)); - else - set_value_range_to_varying (vr); - return; - } - } - else if (code == ABS_EXPR - && !TYPE_UNSIGNED (TREE_TYPE (expr))) - { - /* -TYPE_MIN_VALUE = TYPE_MIN_VALUE with flag_wrapv so we can't get a - useful range. */ - if (!TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (expr)) - && ((vr0.type == VR_RANGE - && vrp_val_is_min (vr0.min)) - || (vr0.type == VR_ANTI_RANGE - && !vrp_val_is_min (vr0.min) - && !range_includes_zero_p (&vr0)))) - { - set_value_range_to_varying (vr); - return; - } - - /* ABS_EXPR may flip the range around, if the original range - included negative values. */ - if (is_overflow_infinity (vr0.min)) - min = positive_overflow_infinity (TREE_TYPE (expr)); - else if (!vrp_val_is_min (vr0.min)) - min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); - else if (!needs_overflow_infinity (TREE_TYPE (expr))) - min = TYPE_MAX_VALUE (TREE_TYPE (expr)); - else if (supports_overflow_infinity (TREE_TYPE (expr))) - min = positive_overflow_infinity (TREE_TYPE (expr)); - else - { - set_value_range_to_varying (vr); - return; - } - - if (is_overflow_infinity (vr0.max)) - max = positive_overflow_infinity (TREE_TYPE (expr)); - else if (!vrp_val_is_min (vr0.max)) - max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); - else if (!needs_overflow_infinity (TREE_TYPE (expr))) - max = TYPE_MAX_VALUE (TREE_TYPE (expr)); - else if (supports_overflow_infinity (TREE_TYPE (expr))) - max = positive_overflow_infinity (TREE_TYPE (expr)); - else - { - set_value_range_to_varying (vr); - return; - } - - cmp = compare_values (min, max); - - /* If a VR_ANTI_RANGEs contains zero, then we have - ~[-INF, min(MIN, MAX)]. */ - if (vr0.type == VR_ANTI_RANGE) - { - if (range_includes_zero_p (&vr0)) - { - /* Take the lower of the two values. */ - if (cmp != 1) - max = min; - - /* Create ~[-INF, min (abs(MIN), abs(MAX))] - or ~[-INF + 1, min (abs(MIN), abs(MAX))] when - flag_wrapv is set and the original anti-range doesn't include - TYPE_MIN_VALUE, remember -TYPE_MIN_VALUE = TYPE_MIN_VALUE. */ - if (TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr))) - { - tree type_min_value = TYPE_MIN_VALUE (TREE_TYPE (expr)); - - min = (vr0.min != type_min_value - ? int_const_binop (PLUS_EXPR, type_min_value, - integer_one_node, 0) - : type_min_value); - } - else - { - if (overflow_infinity_range_p (&vr0)) - min = negative_overflow_infinity (TREE_TYPE (expr)); - else - min = TYPE_MIN_VALUE (TREE_TYPE (expr)); - } - } - else - { - /* All else has failed, so create the range [0, INF], even for - flag_wrapv since TYPE_MIN_VALUE is in the original - anti-range. */ - vr0.type = VR_RANGE; - min = build_int_cst (TREE_TYPE (expr), 0); - if (needs_overflow_infinity (TREE_TYPE (expr))) - { - if (supports_overflow_infinity (TREE_TYPE (expr))) - max = positive_overflow_infinity (TREE_TYPE (expr)); - else - { - set_value_range_to_varying (vr); - return; - } - } - else - max = TYPE_MAX_VALUE (TREE_TYPE (expr)); - } - } - - /* If the range contains zero then we know that the minimum value in the - range will be zero. */ - else if (range_includes_zero_p (&vr0)) - { - if (cmp == 1) - max = min; - min = build_int_cst (TREE_TYPE (expr), 0); - } - else - { - /* If the range was reversed, swap MIN and MAX. */ - if (cmp == 1) - { - tree t = min; - min = max; - max = t; - } - } - } - else - { - /* Otherwise, operate on each end of the range. */ - min = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.min); - max = fold_unary_to_constant (code, TREE_TYPE (expr), vr0.max); - - if (needs_overflow_infinity (TREE_TYPE (expr))) - { - gcc_assert (code != NEGATE_EXPR && code != ABS_EXPR); - - /* If both sides have overflowed, we don't know - anything. */ - if ((is_overflow_infinity (vr0.min) - || TREE_OVERFLOW (min)) - && (is_overflow_infinity (vr0.max) - || TREE_OVERFLOW (max))) - { - set_value_range_to_varying (vr); - return; - } - - if (is_overflow_infinity (vr0.min)) - min = vr0.min; - else if (TREE_OVERFLOW (min)) - { - if (supports_overflow_infinity (TREE_TYPE (expr))) - min = (tree_int_cst_sgn (min) >= 0 - ? positive_overflow_infinity (TREE_TYPE (min)) - : negative_overflow_infinity (TREE_TYPE (min))); - else - { - set_value_range_to_varying (vr); - return; - } - } - - if (is_overflow_infinity (vr0.max)) - max = vr0.max; - else if (TREE_OVERFLOW (max)) - { - if (supports_overflow_infinity (TREE_TYPE (expr))) - max = (tree_int_cst_sgn (max) >= 0 - ? positive_overflow_infinity (TREE_TYPE (max)) - : negative_overflow_infinity (TREE_TYPE (max))); - else - { - set_value_range_to_varying (vr); - return; - } - } - } - } - - cmp = compare_values (min, max); - if (cmp == -2 || cmp == 1) - { - /* If the new range has its limits swapped around (MIN > MAX), - then the operation caused one of them to wrap around, mark - the new range VARYING. */ - set_value_range_to_varying (vr); - } - else - set_value_range (vr, vr0.type, min, max, NULL); -} - - -/* Extract range information from a comparison expression EXPR based - on the range of its operand and the expression code. */ - -static void -extract_range_from_comparison (value_range_t *vr, tree expr) -{ - bool sop = false; - tree val = vrp_evaluate_conditional_warnv (expr, false, &sop); - - /* A disadvantage of using a special infinity as an overflow - representation is that we lose the ability to record overflow - when we don't have an infinity. So we have to ignore a result - which relies on overflow. */ - - if (val && !is_overflow_infinity (val) && !sop) - { - /* Since this expression was found on the RHS of an assignment, - its type may be different from _Bool. Convert VAL to EXPR's - type. */ - val = fold_convert (TREE_TYPE (expr), val); - if (is_gimple_min_invariant (val)) - set_value_range_to_value (vr, val, vr->equiv); - else - set_value_range (vr, VR_RANGE, val, val, vr->equiv); - } - else - set_value_range_to_varying (vr); -} - - -/* Try to compute a useful range out of expression EXPR and store it - in *VR. */ - -static void -extract_range_from_expr (value_range_t *vr, tree expr) -{ - enum tree_code code = TREE_CODE (expr); - - if (code == ASSERT_EXPR) - extract_range_from_assert (vr, expr); - else if (code == SSA_NAME) - extract_range_from_ssa_name (vr, expr); - else if (TREE_CODE_CLASS (code) == tcc_binary - || code == TRUTH_ANDIF_EXPR - || code == TRUTH_ORIF_EXPR - || code == TRUTH_AND_EXPR - || code == TRUTH_OR_EXPR - || code == TRUTH_XOR_EXPR) - extract_range_from_binary_expr (vr, expr); - else if (TREE_CODE_CLASS (code) == tcc_unary) - extract_range_from_unary_expr (vr, expr); - else if (TREE_CODE_CLASS (code) == tcc_comparison) - extract_range_from_comparison (vr, expr); - else if (is_gimple_min_invariant (expr)) - set_value_range_to_value (vr, expr, NULL); - else - set_value_range_to_varying (vr); - - /* If we got a varying range from the tests above, try a final - time to derive a nonnegative or nonzero range. This time - relying primarily on generic routines in fold in conjunction - with range data. */ - if (vr->type == VR_VARYING) - { - bool sop = false; - - if (INTEGRAL_TYPE_P (TREE_TYPE (expr)) - && vrp_expr_computes_nonnegative (expr, &sop)) - set_value_range_to_nonnegative (vr, TREE_TYPE (expr), - sop || is_overflow_infinity (expr)); - else if (vrp_expr_computes_nonzero (expr, &sop) - && !sop) - set_value_range_to_nonnull (vr, TREE_TYPE (expr)); - } -} - -/* Given a range VR, a LOOP and a variable VAR, determine whether it - would be profitable to adjust VR using scalar evolution information - for VAR. If so, update VR with the new limits. */ - -static void -adjust_range_with_scev (value_range_t *vr, struct loop *loop, tree stmt, - tree var) -{ - tree init, step, chrec, tmin, tmax, min, max, type; - enum ev_direction dir; - - /* TODO. Don't adjust anti-ranges. An anti-range may provide - better opportunities than a regular range, but I'm not sure. */ - if (vr->type == VR_ANTI_RANGE) - return; - - chrec = instantiate_parameters (loop, analyze_scalar_evolution (loop, var)); - if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) - return; - - init = initial_condition_in_loop_num (chrec, loop->num); - step = evolution_part_in_loop_num (chrec, loop->num); - - /* If STEP is symbolic, we can't know whether INIT will be the - minimum or maximum value in the range. Also, unless INIT is - a simple expression, compare_values and possibly other functions - in tree-vrp won't be able to handle it. */ - if (step == NULL_TREE - || !is_gimple_min_invariant (step) - || !valid_value_p (init)) - return; - - dir = scev_direction (chrec); - if (/* Do not adjust ranges if we do not know whether the iv increases - or decreases, ... */ - dir == EV_DIR_UNKNOWN - /* ... or if it may wrap. */ - || scev_probably_wraps_p (init, step, stmt, - current_loops->parray[CHREC_VARIABLE (chrec)], - true)) - return; - - /* We use TYPE_MIN_VALUE and TYPE_MAX_VALUE here instead of - negative_overflow_infinity and positive_overflow_infinity, - because we have concluded that the loop probably does not - wrap. */ - - type = TREE_TYPE (var); - if (POINTER_TYPE_P (type) || !TYPE_MIN_VALUE (type)) - tmin = lower_bound_in_type (type, type); - else - tmin = TYPE_MIN_VALUE (type); - if (POINTER_TYPE_P (type) || !TYPE_MAX_VALUE (type)) - tmax = upper_bound_in_type (type, type); - else - tmax = TYPE_MAX_VALUE (type); - - if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) - { - min = tmin; - max = tmax; - - /* For VARYING or UNDEFINED ranges, just about anything we get - from scalar evolutions should be better. */ - - if (dir == EV_DIR_DECREASES) - max = init; - else - min = init; - - /* If we would create an invalid range, then just assume we - know absolutely nothing. This may be over-conservative, - but it's clearly safe, and should happen only in unreachable - parts of code, or for invalid programs. */ - if (compare_values (min, max) == 1) - return; - - set_value_range (vr, VR_RANGE, min, max, vr->equiv); - } - else if (vr->type == VR_RANGE) - { - min = vr->min; - max = vr->max; - - if (dir == EV_DIR_DECREASES) - { - /* INIT is the maximum value. If INIT is lower than VR->MAX - but no smaller than VR->MIN, set VR->MAX to INIT. */ - if (compare_values (init, max) == -1) - { - max = init; - - /* If we just created an invalid range with the minimum - greater than the maximum, we fail conservatively. - This should happen only in unreachable - parts of code, or for invalid programs. */ - if (compare_values (min, max) == 1) - return; - } - - /* According to the loop information, the variable does not - overflow. If we think it does, probably because of an - overflow due to arithmetic on a different INF value, - reset now. */ - if (is_negative_overflow_infinity (min)) - min = tmin; - } - else - { - /* If INIT is bigger than VR->MIN, set VR->MIN to INIT. */ - if (compare_values (init, min) == 1) - { - min = init; - - /* Again, avoid creating invalid range by failing. */ - if (compare_values (min, max) == 1) - return; - } - - if (is_positive_overflow_infinity (max)) - max = tmax; - } - - set_value_range (vr, VR_RANGE, min, max, vr->equiv); - } -} - -/* Return true if VAR may overflow at STMT. This checks any available - loop information to see if we can determine that VAR does not - overflow. */ - -static bool -vrp_var_may_overflow (tree var, tree stmt) -{ - struct loop *l; - tree chrec, init, step; - - if (current_loops == NULL) - return true; - - l = loop_containing_stmt (stmt); - if (l == NULL) - return true; - - chrec = instantiate_parameters (l, analyze_scalar_evolution (l, var)); - if (TREE_CODE (chrec) != POLYNOMIAL_CHREC) - return true; - - init = initial_condition_in_loop_num (chrec, l->num); - step = evolution_part_in_loop_num (chrec, l->num); - - if (step == NULL_TREE - || !is_gimple_min_invariant (step) - || !valid_value_p (init)) - return true; - - /* If we get here, we know something useful about VAR based on the - loop information. If it wraps, it may overflow. */ - - if (scev_probably_wraps_p (init, step, stmt, - current_loops->parray[CHREC_VARIABLE (chrec)], - true)) - return true; - - if (dump_file && (dump_flags & TDF_DETAILS) != 0) - { - print_generic_expr (dump_file, var, 0); - fprintf (dump_file, ": loop information indicates does not overflow\n"); - } - - return false; -} - - -/* Given two numeric value ranges VR0, VR1 and a comparison code COMP: - - - Return BOOLEAN_TRUE_NODE if VR0 COMP VR1 always returns true for - all the values in the ranges. - - - Return BOOLEAN_FALSE_NODE if the comparison always returns false. - - - Return NULL_TREE if it is not always possible to determine the - value of the comparison. - - Also set *STRICT_OVERFLOW_P to indicate whether a range with an - overflow infinity was used in the test. */ - - -static tree -compare_ranges (enum tree_code comp, value_range_t *vr0, value_range_t *vr1, - bool *strict_overflow_p) -{ - /* VARYING or UNDEFINED ranges cannot be compared. */ - if (vr0->type == VR_VARYING - || vr0->type == VR_UNDEFINED - || vr1->type == VR_VARYING - || vr1->type == VR_UNDEFINED) - return NULL_TREE; - - /* Anti-ranges need to be handled separately. */ - if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) - { - /* If both are anti-ranges, then we cannot compute any - comparison. */ - if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) - return NULL_TREE; - - /* These comparisons are never statically computable. */ - if (comp == GT_EXPR - || comp == GE_EXPR - || comp == LT_EXPR - || comp == LE_EXPR) - return NULL_TREE; - - /* Equality can be computed only between a range and an - anti-range. ~[VAL1, VAL2] == [VAL1, VAL2] is always false. */ - if (vr0->type == VR_RANGE) - { - /* To simplify processing, make VR0 the anti-range. */ - value_range_t *tmp = vr0; - vr0 = vr1; - vr1 = tmp; - } - - gcc_assert (comp == NE_EXPR || comp == EQ_EXPR); - - if (compare_values_warnv (vr0->min, vr1->min, strict_overflow_p) == 0 - && compare_values_warnv (vr0->max, vr1->max, strict_overflow_p) == 0) - return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; - - return NULL_TREE; - } - - if (!usable_range_p (vr0, strict_overflow_p) - || !usable_range_p (vr1, strict_overflow_p)) - return NULL_TREE; - - /* Simplify processing. If COMP is GT_EXPR or GE_EXPR, switch the - operands around and change the comparison code. */ - if (comp == GT_EXPR || comp == GE_EXPR) - { - value_range_t *tmp; - comp = (comp == GT_EXPR) ? LT_EXPR : LE_EXPR; - tmp = vr0; - vr0 = vr1; - vr1 = tmp; - } - - if (comp == EQ_EXPR) - { - /* Equality may only be computed if both ranges represent - exactly one value. */ - if (compare_values_warnv (vr0->min, vr0->max, strict_overflow_p) == 0 - && compare_values_warnv (vr1->min, vr1->max, strict_overflow_p) == 0) - { - int cmp_min = compare_values_warnv (vr0->min, vr1->min, - strict_overflow_p); - int cmp_max = compare_values_warnv (vr0->max, vr1->max, - strict_overflow_p); - if (cmp_min == 0 && cmp_max == 0) - return boolean_true_node; - else if (cmp_min != -2 && cmp_max != -2) - return boolean_false_node; - } - /* If [V0_MIN, V1_MAX] < [V1_MIN, V1_MAX] then V0 != V1. */ - else if (compare_values_warnv (vr0->min, vr1->max, - strict_overflow_p) == 1 - || compare_values_warnv (vr1->min, vr0->max, - strict_overflow_p) == 1) - return boolean_false_node; - - return NULL_TREE; - } - else if (comp == NE_EXPR) - { - int cmp1, cmp2; - - /* If VR0 is completely to the left or completely to the right - of VR1, they are always different. Notice that we need to - make sure that both comparisons yield similar results to - avoid comparing values that cannot be compared at - compile-time. */ - cmp1 = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); - cmp2 = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); - if ((cmp1 == -1 && cmp2 == -1) || (cmp1 == 1 && cmp2 == 1)) - return boolean_true_node; - - /* If VR0 and VR1 represent a single value and are identical, - return false. */ - else if (compare_values_warnv (vr0->min, vr0->max, - strict_overflow_p) == 0 - && compare_values_warnv (vr1->min, vr1->max, - strict_overflow_p) == 0 - && compare_values_warnv (vr0->min, vr1->min, - strict_overflow_p) == 0 - && compare_values_warnv (vr0->max, vr1->max, - strict_overflow_p) == 0) - return boolean_false_node; - - /* Otherwise, they may or may not be different. */ - else - return NULL_TREE; - } - else if (comp == LT_EXPR || comp == LE_EXPR) - { - int tst; - - /* If VR0 is to the left of VR1, return true. */ - tst = compare_values_warnv (vr0->max, vr1->min, strict_overflow_p); - if ((comp == LT_EXPR && tst == -1) - || (comp == LE_EXPR && (tst == -1 || tst == 0))) - { - if (overflow_infinity_range_p (vr0) - || overflow_infinity_range_p (vr1)) - *strict_overflow_p = true; - return boolean_true_node; - } - - /* If VR0 is to the right of VR1, return false. */ - tst = compare_values_warnv (vr0->min, vr1->max, strict_overflow_p); - if ((comp == LT_EXPR && (tst == 0 || tst == 1)) - || (comp == LE_EXPR && tst == 1)) - { - if (overflow_infinity_range_p (vr0) - || overflow_infinity_range_p (vr1)) - *strict_overflow_p = true; - return boolean_false_node; - } - - /* Otherwise, we don't know. */ - return NULL_TREE; - } - - gcc_unreachable (); -} - - -/* Given a value range VR, a value VAL and a comparison code COMP, return - BOOLEAN_TRUE_NODE if VR COMP VAL always returns true for all the - values in VR. Return BOOLEAN_FALSE_NODE if the comparison - always returns false. Return NULL_TREE if it is not always - possible to determine the value of the comparison. Also set - *STRICT_OVERFLOW_P to indicate whether a range with an overflow - infinity was used in the test. */ - -static tree -compare_range_with_value (enum tree_code comp, value_range_t *vr, tree val, - bool *strict_overflow_p) -{ - if (vr->type == VR_VARYING || vr->type == VR_UNDEFINED) - return NULL_TREE; - - /* Anti-ranges need to be handled separately. */ - if (vr->type == VR_ANTI_RANGE) - { - /* For anti-ranges, the only predicates that we can compute at - compile time are equality and inequality. */ - if (comp == GT_EXPR - || comp == GE_EXPR - || comp == LT_EXPR - || comp == LE_EXPR) - return NULL_TREE; - - /* ~[VAL_1, VAL_2] OP VAL is known if VAL_1 <= VAL <= VAL_2. */ - if (value_inside_range (val, vr) == 1) - return (comp == NE_EXPR) ? boolean_true_node : boolean_false_node; - - return NULL_TREE; - } - - if (!usable_range_p (vr, strict_overflow_p)) - return NULL_TREE; - - if (comp == EQ_EXPR) - { - /* EQ_EXPR may only be computed if VR represents exactly - one value. */ - if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0) - { - int cmp = compare_values_warnv (vr->min, val, strict_overflow_p); - if (cmp == 0) - return boolean_true_node; - else if (cmp == -1 || cmp == 1 || cmp == 2) - return boolean_false_node; - } - else if (compare_values_warnv (val, vr->min, strict_overflow_p) == -1 - || compare_values_warnv (vr->max, val, strict_overflow_p) == -1) - return boolean_false_node; - - return NULL_TREE; - } - else if (comp == NE_EXPR) - { - /* If VAL is not inside VR, then they are always different. */ - if (compare_values_warnv (vr->max, val, strict_overflow_p) == -1 - || compare_values_warnv (vr->min, val, strict_overflow_p) == 1) - return boolean_true_node; - - /* If VR represents exactly one value equal to VAL, then return - false. */ - if (compare_values_warnv (vr->min, vr->max, strict_overflow_p) == 0 - && compare_values_warnv (vr->min, val, strict_overflow_p) == 0) - return boolean_false_node; - - /* Otherwise, they may or may not be different. */ - return NULL_TREE; - } - else if (comp == LT_EXPR || comp == LE_EXPR) - { - int tst; - - /* If VR is to the left of VAL, return true. */ - tst = compare_values_warnv (vr->max, val, strict_overflow_p); - if ((comp == LT_EXPR && tst == -1) - || (comp == LE_EXPR && (tst == -1 || tst == 0))) - { - if (overflow_infinity_range_p (vr)) - *strict_overflow_p = true; - return boolean_true_node; - } - - /* If VR is to the right of VAL, return false. */ - tst = compare_values_warnv (vr->min, val, strict_overflow_p); - if ((comp == LT_EXPR && (tst == 0 || tst == 1)) - || (comp == LE_EXPR && tst == 1)) - { - if (overflow_infinity_range_p (vr)) - *strict_overflow_p = true; - return boolean_false_node; - } - - /* Otherwise, we don't know. */ - return NULL_TREE; - } - else if (comp == GT_EXPR || comp == GE_EXPR) - { - int tst; - - /* If VR is to the right of VAL, return true. */ - tst = compare_values_warnv (vr->min, val, strict_overflow_p); - if ((comp == GT_EXPR && tst == 1) - || (comp == GE_EXPR && (tst == 0 || tst == 1))) - { - if (overflow_infinity_range_p (vr)) - *strict_overflow_p = true; - return boolean_true_node; - } - - /* If VR is to the left of VAL, return false. */ - tst = compare_values_warnv (vr->max, val, strict_overflow_p); - if ((comp == GT_EXPR && (tst == -1 || tst == 0)) - || (comp == GE_EXPR && tst == -1)) - { - if (overflow_infinity_range_p (vr)) - *strict_overflow_p = true; - return boolean_false_node; - } - - /* Otherwise, we don't know. */ - return NULL_TREE; - } - - gcc_unreachable (); -} - - -/* Debugging dumps. */ - -void dump_value_range (FILE *, value_range_t *); -void debug_value_range (value_range_t *); -void dump_all_value_ranges (FILE *); -void debug_all_value_ranges (void); -void dump_vr_equiv (FILE *, bitmap); -void debug_vr_equiv (bitmap); - - -/* Dump value range VR to FILE. */ - -void -dump_value_range (FILE *file, value_range_t *vr) -{ - if (vr == NULL) - fprintf (file, "[]"); - else if (vr->type == VR_UNDEFINED) - fprintf (file, "UNDEFINED"); - else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE) - { - tree type = TREE_TYPE (vr->min); - - fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : ""); - - if (is_negative_overflow_infinity (vr->min)) - fprintf (file, "-INF(OVF)"); - else if (INTEGRAL_TYPE_P (type) - && !TYPE_UNSIGNED (type) - && vrp_val_is_min (vr->min)) - fprintf (file, "-INF"); - else - print_generic_expr (file, vr->min, 0); - - fprintf (file, ", "); - - if (is_positive_overflow_infinity (vr->max)) - fprintf (file, "+INF(OVF)"); - else if (INTEGRAL_TYPE_P (type) - && vrp_val_is_max (vr->max)) - fprintf (file, "+INF"); - else - print_generic_expr (file, vr->max, 0); - - fprintf (file, "]"); - - if (vr->equiv) - { - bitmap_iterator bi; - unsigned i, c = 0; - - fprintf (file, " EQUIVALENCES: { "); - - EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi) - { - print_generic_expr (file, ssa_name (i), 0); - fprintf (file, " "); - c++; - } - - fprintf (file, "} (%u elements)", c); - } - } - else if (vr->type == VR_VARYING) - fprintf (file, "VARYING"); - else - fprintf (file, "INVALID RANGE"); -} - - -/* Dump value range VR to stderr. */ - -void -debug_value_range (value_range_t *vr) -{ - dump_value_range (stderr, vr); - fprintf (stderr, "\n"); -} - - -/* Dump value ranges of all SSA_NAMEs to FILE. */ - -void -dump_all_value_ranges (FILE *file) -{ - size_t i; - - for (i = 0; i < num_ssa_names; i++) - { - if (vr_value[i]) - { - print_generic_expr (file, ssa_name (i), 0); - fprintf (file, ": "); - dump_value_range (file, vr_value[i]); - fprintf (file, "\n"); - } - } - - fprintf (file, "\n"); -} - - -/* Dump all value ranges to stderr. */ - -void -debug_all_value_ranges (void) -{ - dump_all_value_ranges (stderr); -} - - -/* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V, - create a new SSA name N and return the assertion assignment - 'V = ASSERT_EXPR <V, V OP W>'. */ - -static tree -build_assert_expr_for (tree cond, tree v) -{ - tree n, assertion; - - gcc_assert (TREE_CODE (v) == SSA_NAME); - n = duplicate_ssa_name (v, NULL_TREE); - - if (COMPARISON_CLASS_P (cond)) - { - tree a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond); - assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, a); - } - else if (TREE_CODE (cond) == TRUTH_NOT_EXPR) - { - /* Given !V, build the assignment N = false. */ - tree op0 = TREE_OPERAND (cond, 0); - gcc_assert (op0 == v); - assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_false_node); - } - else if (TREE_CODE (cond) == SSA_NAME) - { - /* Given V, build the assignment N = true. */ - gcc_assert (v == cond); - assertion = build2 (MODIFY_EXPR, TREE_TYPE (v), n, boolean_true_node); - } - else - gcc_unreachable (); - - SSA_NAME_DEF_STMT (n) = assertion; - - /* The new ASSERT_EXPR, creates a new SSA name that replaces the - operand of the ASSERT_EXPR. Register the new name and the old one - in the replacement table so that we can fix the SSA web after - adding all the ASSERT_EXPRs. */ - register_new_name_mapping (n, v); - - return assertion; -} - - -/* Return false if EXPR is a predicate expression involving floating - point values. */ - -static inline bool -fp_predicate (tree expr) -{ - return (COMPARISON_CLASS_P (expr) - && FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)))); -} - - -/* If the range of values taken by OP can be inferred after STMT executes, - return the comparison code (COMP_CODE_P) and value (VAL_P) that - describes the inferred range. Return true if a range could be - inferred. */ - -static bool -infer_value_range (tree stmt, tree op, enum tree_code *comp_code_p, tree *val_p) -{ - *val_p = NULL_TREE; - *comp_code_p = ERROR_MARK; - - /* Do not attempt to infer anything in names that flow through - abnormal edges. */ - if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op)) - return false; - - /* Similarly, don't infer anything from statements that may throw - exceptions. */ - if (tree_could_throw_p (stmt)) - return false; - - /* If STMT is the last statement of a basic block with no - successors, there is no point inferring anything about any of its - operands. We would not be able to find a proper insertion point - for the assertion, anyway. */ - if (stmt_ends_bb_p (stmt) && EDGE_COUNT (bb_for_stmt (stmt)->succs) == 0) - return false; - - /* We can only assume that a pointer dereference will yield - non-NULL if -fdelete-null-pointer-checks is enabled. */ - if (flag_delete_null_pointer_checks && POINTER_TYPE_P (TREE_TYPE (op))) - { - bool is_store; - unsigned num_uses, num_derefs; - - count_uses_and_derefs (op, stmt, &num_uses, &num_derefs, &is_store); - if (num_derefs > 0) - { - *val_p = build_int_cst (TREE_TYPE (op), 0); - *comp_code_p = NE_EXPR; - return true; - } - } - - return false; -} - - -void dump_asserts_for (FILE *, tree); -void debug_asserts_for (tree); -void dump_all_asserts (FILE *); -void debug_all_asserts (void); - -/* Dump all the registered assertions for NAME to FILE. */ - -void -dump_asserts_for (FILE *file, tree name) -{ - assert_locus_t loc; - - fprintf (file, "Assertions to be inserted for "); - print_generic_expr (file, name, 0); - fprintf (file, "\n"); - - loc = asserts_for[SSA_NAME_VERSION (name)]; - while (loc) - { - fprintf (file, "\t"); - print_generic_expr (file, bsi_stmt (loc->si), 0); - fprintf (file, "\n\tBB #%d", loc->bb->index); - if (loc->e) - { - fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index, - loc->e->dest->index); - dump_edge_info (file, loc->e, 0); - } - fprintf (file, "\n\tPREDICATE: "); - print_generic_expr (file, name, 0); - fprintf (file, " %s ", tree_code_name[(int)loc->comp_code]); - print_generic_expr (file, loc->val, 0); - fprintf (file, "\n\n"); - loc = loc->next; - } - - fprintf (file, "\n"); -} - - -/* Dump all the registered assertions for NAME to stderr. */ - -void -debug_asserts_for (tree name) -{ - dump_asserts_for (stderr, name); -} - - -/* Dump all the registered assertions for all the names to FILE. */ - -void -dump_all_asserts (FILE *file) -{ - unsigned i; - bitmap_iterator bi; - - fprintf (file, "\nASSERT_EXPRs to be inserted\n\n"); - EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) - dump_asserts_for (file, ssa_name (i)); - fprintf (file, "\n"); -} - - -/* Dump all the registered assertions for all the names to stderr. */ - -void -debug_all_asserts (void) -{ - dump_all_asserts (stderr); -} - - -/* If NAME doesn't have an ASSERT_EXPR registered for asserting - 'NAME COMP_CODE VAL' at a location that dominates block BB or - E->DEST, then register this location as a possible insertion point - for ASSERT_EXPR <NAME, NAME COMP_CODE VAL>. - - BB, E and SI provide the exact insertion point for the new - ASSERT_EXPR. If BB is NULL, then the ASSERT_EXPR is to be inserted - on edge E. Otherwise, if E is NULL, the ASSERT_EXPR is inserted on - BB. If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E - must not be NULL. */ - -static void -register_new_assert_for (tree name, - enum tree_code comp_code, - tree val, - basic_block bb, - edge e, - block_stmt_iterator si) -{ - assert_locus_t n, loc, last_loc; - bool found; - basic_block dest_bb; - -#if defined ENABLE_CHECKING - gcc_assert (bb == NULL || e == NULL); - - if (e == NULL) - gcc_assert (TREE_CODE (bsi_stmt (si)) != COND_EXPR - && TREE_CODE (bsi_stmt (si)) != SWITCH_EXPR); -#endif - - /* The new assertion A will be inserted at BB or E. We need to - determine if the new location is dominated by a previously - registered location for A. If we are doing an edge insertion, - assume that A will be inserted at E->DEST. Note that this is not - necessarily true. - - If E is a critical edge, it will be split. But even if E is - split, the new block will dominate the same set of blocks that - E->DEST dominates. - - The reverse, however, is not true, blocks dominated by E->DEST - will not be dominated by the new block created to split E. So, - if the insertion location is on a critical edge, we will not use - the new location to move another assertion previously registered - at a block dominated by E->DEST. */ - dest_bb = (bb) ? bb : e->dest; - - /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and - VAL at a block dominating DEST_BB, then we don't need to insert a new - one. Similarly, if the same assertion already exists at a block - dominated by DEST_BB and the new location is not on a critical - edge, then update the existing location for the assertion (i.e., - move the assertion up in the dominance tree). - - Note, this is implemented as a simple linked list because there - should not be more than a handful of assertions registered per - name. If this becomes a performance problem, a table hashed by - COMP_CODE and VAL could be implemented. */ - loc = asserts_for[SSA_NAME_VERSION (name)]; - last_loc = loc; - found = false; - while (loc) - { - if (loc->comp_code == comp_code - && (loc->val == val - || operand_equal_p (loc->val, val, 0))) - { - /* If the assertion NAME COMP_CODE VAL has already been - registered at a basic block that dominates DEST_BB, then - we don't need to insert the same assertion again. Note - that we don't check strict dominance here to avoid - replicating the same assertion inside the same basic - block more than once (e.g., when a pointer is - dereferenced several times inside a block). - - An exception to this rule are edge insertions. If the - new assertion is to be inserted on edge E, then it will - dominate all the other insertions that we may want to - insert in DEST_BB. So, if we are doing an edge - insertion, don't do this dominance check. */ - if (e == NULL - && dominated_by_p (CDI_DOMINATORS, dest_bb, loc->bb)) - return; - - /* Otherwise, if E is not a critical edge and DEST_BB - dominates the existing location for the assertion, move - the assertion up in the dominance tree by updating its - location information. */ - if ((e == NULL || !EDGE_CRITICAL_P (e)) - && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb)) - { - loc->bb = dest_bb; - loc->e = e; - loc->si = si; - return; - } - } - - /* Update the last node of the list and move to the next one. */ - last_loc = loc; - loc = loc->next; - } - - /* If we didn't find an assertion already registered for - NAME COMP_CODE VAL, add a new one at the end of the list of - assertions associated with NAME. */ - n = XNEW (struct assert_locus_d); - n->bb = dest_bb; - n->e = e; - n->si = si; - n->comp_code = comp_code; - n->val = val; - n->next = NULL; - - if (last_loc) - last_loc->next = n; - else - asserts_for[SSA_NAME_VERSION (name)] = n; - - bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name)); -} - - -/* Try to register an edge assertion for SSA name NAME on edge E for - the conditional jump pointed to by SI. Return true if an assertion - for NAME could be registered. */ - -static bool -register_edge_assert_for (tree name, edge e, block_stmt_iterator si) -{ - tree val, stmt; - enum tree_code comp_code; - - stmt = bsi_stmt (si); - - /* Do not attempt to infer anything in names that flow through - abnormal edges. */ - if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name)) - return false; - - /* If NAME was not found in the sub-graph reachable from E, then - there's nothing to do. */ - if (!TEST_BIT (found_in_subgraph, SSA_NAME_VERSION (name))) - return false; - - /* We found a use of NAME in the sub-graph rooted at E->DEST. - Register an assertion for NAME according to the value that NAME - takes on edge E. */ - if (TREE_CODE (stmt) == COND_EXPR) - { - /* If BB ends in a COND_EXPR then NAME then we should insert - the original predicate on EDGE_TRUE_VALUE and the - opposite predicate on EDGE_FALSE_VALUE. */ - tree cond = COND_EXPR_COND (stmt); - bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0; - - /* Predicates may be a single SSA name or NAME OP VAL. */ - if (cond == name) - { - /* If the predicate is a name, it must be NAME, in which - case we create the predicate NAME == true or - NAME == false accordingly. */ - comp_code = EQ_EXPR; - val = (is_else_edge) ? boolean_false_node : boolean_true_node; - } - else - { - /* Otherwise, we have a comparison of the form NAME COMP VAL - or VAL COMP NAME. */ - if (name == TREE_OPERAND (cond, 1)) - { - /* If the predicate is of the form VAL COMP NAME, flip - COMP around because we need to register NAME as the - first operand in the predicate. */ - comp_code = swap_tree_comparison (TREE_CODE (cond)); - val = TREE_OPERAND (cond, 0); - } - else - { - /* The comparison is of the form NAME COMP VAL, so the - comparison code remains unchanged. */ - comp_code = TREE_CODE (cond); - val = TREE_OPERAND (cond, 1); - } - - /* If we are inserting the assertion on the ELSE edge, we - need to invert the sign comparison. */ - if (is_else_edge) - comp_code = invert_tree_comparison (comp_code, 0); - - /* Do not register always-false predicates. FIXME, this - works around a limitation in fold() when dealing with - enumerations. Given 'enum { N1, N2 } x;', fold will not - fold 'if (x > N2)' to 'if (0)'. */ - if ((comp_code == GT_EXPR || comp_code == LT_EXPR) - && (INTEGRAL_TYPE_P (TREE_TYPE (val)) - || SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)))) - { - tree min = TYPE_MIN_VALUE (TREE_TYPE (val)); - tree max = TYPE_MAX_VALUE (TREE_TYPE (val)); - - if (comp_code == GT_EXPR && compare_values (val, max) == 0) - return false; - - if (comp_code == LT_EXPR && compare_values (val, min) == 0) - return false; - } - } - } - else - { - /* FIXME. Handle SWITCH_EXPR. */ - gcc_unreachable (); - } - - register_new_assert_for (name, comp_code, val, NULL, e, si); - return true; -} - - -static bool find_assert_locations (basic_block bb); - -/* Determine whether the outgoing edges of BB should receive an - ASSERT_EXPR for each of the operands of BB's last statement. The - last statement of BB must be a COND_EXPR or a SWITCH_EXPR. - - If any of the sub-graphs rooted at BB have an interesting use of - the predicate operands, an assert location node is added to the - list of assertions for the corresponding operands. */ - -static bool -find_conditional_asserts (basic_block bb) -{ - bool need_assert; - block_stmt_iterator last_si; - tree op, last; - edge_iterator ei; - edge e; - ssa_op_iter iter; - - need_assert = false; - last_si = bsi_last (bb); - last = bsi_stmt (last_si); - - /* Look for uses of the operands in each of the sub-graphs - rooted at BB. We need to check each of the outgoing edges - separately, so that we know what kind of ASSERT_EXPR to - insert. */ - FOR_EACH_EDGE (e, ei, bb->succs) - { - if (e->dest == bb) - continue; - - /* Remove the COND_EXPR operands from the FOUND_IN_SUBGRAPH bitmap. - Otherwise, when we finish traversing each of the sub-graphs, we - won't know whether the variables were found in the sub-graphs or - if they had been found in a block upstream from BB. - - This is actually a bad idea is some cases, particularly jump - threading. Consider a CFG like the following: - - 0 - /| - 1 | - \| - 2 - / \ - 3 4 - - Assume that one or more operands in the conditional at the - end of block 0 are used in a conditional in block 2, but not - anywhere in block 1. In this case we will not insert any - assert statements in block 1, which may cause us to miss - opportunities to optimize, particularly for jump threading. */ - FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) - RESET_BIT (found_in_subgraph, SSA_NAME_VERSION (op)); - - /* Traverse the strictly dominated sub-graph rooted at E->DEST - to determine if any of the operands in the conditional - predicate are used. */ - if (e->dest != bb) - need_assert |= find_assert_locations (e->dest); - - /* Register the necessary assertions for each operand in the - conditional predicate. */ - FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) - need_assert |= register_edge_assert_for (op, e, last_si); - } - - /* Finally, indicate that we have found the operands in the - conditional. */ - FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE) - SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op)); - - return need_assert; -} - - -/* Traverse all the statements in block BB looking for statements that - may generate useful assertions for the SSA names in their operand. - If a statement produces a useful assertion A for name N_i, then the - list of assertions already generated for N_i is scanned to - determine if A is actually needed. - - If N_i already had the assertion A at a location dominating the - current location, then nothing needs to be done. Otherwise, the - new location for A is recorded instead. - - 1- For every statement S in BB, all the variables used by S are - added to bitmap FOUND_IN_SUBGRAPH. - - 2- If statement S uses an operand N in a way that exposes a known - value range for N, then if N was not already generated by an - ASSERT_EXPR, create a new assert location for N. For instance, - if N is a pointer and the statement dereferences it, we can - assume that N is not NULL. - - 3- COND_EXPRs are a special case of #2. We can derive range - information from the predicate but need to insert different - ASSERT_EXPRs for each of the sub-graphs rooted at the - conditional block. If the last statement of BB is a conditional - expression of the form 'X op Y', then - - a) Remove X and Y from the set FOUND_IN_SUBGRAPH. - - b) If the conditional is the only entry point to the sub-graph - corresponding to the THEN_CLAUSE, recurse into it. On - return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then - an ASSERT_EXPR is added for the corresponding variable. - - c) Repeat step (b) on the ELSE_CLAUSE. - - d) Mark X and Y in FOUND_IN_SUBGRAPH. - - For instance, - - if (a == 9) - b = a; - else - b = c + 1; - - In this case, an assertion on the THEN clause is useful to - determine that 'a' is always 9 on that edge. However, an assertion - on the ELSE clause would be unnecessary. - - 4- If BB does not end in a conditional expression, then we recurse - into BB's dominator children. - - At the end of the recursive traversal, every SSA name will have a - list of locations where ASSERT_EXPRs should be added. When a new - location for name N is found, it is registered by calling - register_new_assert_for. That function keeps track of all the - registered assertions to prevent adding unnecessary assertions. - For instance, if a pointer P_4 is dereferenced more than once in a - dominator tree, only the location dominating all the dereference of - P_4 will receive an ASSERT_EXPR. - - If this function returns true, then it means that there are names - for which we need to generate ASSERT_EXPRs. Those assertions are - inserted by process_assert_insertions. - - TODO. Handle SWITCH_EXPR. */ - -static bool -find_assert_locations (basic_block bb) -{ - block_stmt_iterator si; - tree last, phi; - bool need_assert; - basic_block son; - - if (TEST_BIT (blocks_visited, bb->index)) - return false; - - SET_BIT (blocks_visited, bb->index); - - need_assert = false; - - /* Traverse all PHI nodes in BB marking used operands. */ - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - { - use_operand_p arg_p; - ssa_op_iter i; - - FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE) - { - tree arg = USE_FROM_PTR (arg_p); - if (TREE_CODE (arg) == SSA_NAME) - { - gcc_assert (is_gimple_reg (PHI_RESULT (phi))); - SET_BIT (found_in_subgraph, SSA_NAME_VERSION (arg)); - } - } - } - - /* Traverse all the statements in BB marking used names and looking - for statements that may infer assertions for their used operands. */ - last = NULL_TREE; - for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) - { - tree stmt, op; - ssa_op_iter i; - - stmt = bsi_stmt (si); - - /* See if we can derive an assertion for any of STMT's operands. */ - FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE) - { - tree value; - enum tree_code comp_code; - - /* Mark OP in bitmap FOUND_IN_SUBGRAPH. If STMT is inside - the sub-graph of a conditional block, when we return from - this recursive walk, our parent will use the - FOUND_IN_SUBGRAPH bitset to determine if one of the - operands it was looking for was present in the sub-graph. */ - SET_BIT (found_in_subgraph, SSA_NAME_VERSION (op)); - - /* If OP is used in such a way that we can infer a value - range for it, and we don't find a previous assertion for - it, create a new assertion location node for OP. */ - if (infer_value_range (stmt, op, &comp_code, &value)) - { - /* If we are able to infer a nonzero value range for OP, - then walk backwards through the use-def chain to see if OP - was set via a typecast. - - If so, then we can also infer a nonzero value range - for the operand of the NOP_EXPR. */ - if (comp_code == NE_EXPR && integer_zerop (value)) - { - tree t = op; - tree def_stmt = SSA_NAME_DEF_STMT (t); - - while (TREE_CODE (def_stmt) == MODIFY_EXPR - && TREE_CODE (TREE_OPERAND (def_stmt, 1)) == NOP_EXPR - && TREE_CODE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0)) == SSA_NAME - && POINTER_TYPE_P (TREE_TYPE (TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0)))) - { - t = TREE_OPERAND (TREE_OPERAND (def_stmt, 1), 0); - def_stmt = SSA_NAME_DEF_STMT (t); - - /* Note we want to register the assert for the - operand of the NOP_EXPR after SI, not after the - conversion. */ - if (! has_single_use (t)) - { - register_new_assert_for (t, comp_code, value, - bb, NULL, si); - need_assert = true; - } - } - } - - /* If OP is used only once, namely in this STMT, don't - bother creating an ASSERT_EXPR for it. Such an - ASSERT_EXPR would do nothing but increase compile time. */ - if (!has_single_use (op)) - { - register_new_assert_for (op, comp_code, value, bb, NULL, si); - need_assert = true; - } - } - } - - /* Remember the last statement of the block. */ - last = stmt; - } - - /* If BB's last statement is a conditional expression - involving integer operands, recurse into each of the sub-graphs - rooted at BB to determine if we need to add ASSERT_EXPRs. */ - if (last - && TREE_CODE (last) == COND_EXPR - && !fp_predicate (COND_EXPR_COND (last)) - && !ZERO_SSA_OPERANDS (last, SSA_OP_USE)) - need_assert |= find_conditional_asserts (bb); - - /* Recurse into the dominator children of BB. */ - for (son = first_dom_son (CDI_DOMINATORS, bb); - son; - son = next_dom_son (CDI_DOMINATORS, son)) - need_assert |= find_assert_locations (son); - - return need_assert; -} - - -/* Create an ASSERT_EXPR for NAME and insert it in the location - indicated by LOC. Return true if we made any edge insertions. */ - -static bool -process_assert_insertions_for (tree name, assert_locus_t loc) -{ - /* Build the comparison expression NAME_i COMP_CODE VAL. */ - tree stmt, cond, assert_expr; - edge_iterator ei; - edge e; - - cond = build2 (loc->comp_code, boolean_type_node, name, loc->val); - assert_expr = build_assert_expr_for (cond, name); - - if (loc->e) - { - /* We have been asked to insert the assertion on an edge. This - is used only by COND_EXPR and SWITCH_EXPR assertions. */ -#if defined ENABLE_CHECKING - gcc_assert (TREE_CODE (bsi_stmt (loc->si)) == COND_EXPR - || TREE_CODE (bsi_stmt (loc->si)) == SWITCH_EXPR); -#endif - - bsi_insert_on_edge (loc->e, assert_expr); - return true; - } - - /* Otherwise, we can insert right after LOC->SI iff the - statement must not be the last statement in the block. */ - stmt = bsi_stmt (loc->si); - if (!stmt_ends_bb_p (stmt)) - { - bsi_insert_after (&loc->si, assert_expr, BSI_SAME_STMT); - return false; - } - - /* If STMT must be the last statement in BB, we can only insert new - assertions on the non-abnormal edge out of BB. Note that since - STMT is not control flow, there may only be one non-abnormal edge - out of BB. */ - FOR_EACH_EDGE (e, ei, loc->bb->succs) - if (!(e->flags & EDGE_ABNORMAL)) - { - bsi_insert_on_edge (e, assert_expr); - return true; - } - - gcc_unreachable (); -} - - -/* Process all the insertions registered for every name N_i registered - in NEED_ASSERT_FOR. The list of assertions to be inserted are - found in ASSERTS_FOR[i]. */ - -static void -process_assert_insertions (void) -{ - unsigned i; - bitmap_iterator bi; - bool update_edges_p = false; - int num_asserts = 0; - - if (dump_file && (dump_flags & TDF_DETAILS)) - dump_all_asserts (dump_file); - - EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi) - { - assert_locus_t loc = asserts_for[i]; - gcc_assert (loc); - - while (loc) - { - assert_locus_t next = loc->next; - update_edges_p |= process_assert_insertions_for (ssa_name (i), loc); - free (loc); - loc = next; - num_asserts++; - } - } - - if (update_edges_p) - bsi_commit_edge_inserts (); - - if (dump_file && (dump_flags & TDF_STATS)) - fprintf (dump_file, "\nNumber of ASSERT_EXPR expressions inserted: %d\n\n", - num_asserts); -} - - -/* Traverse the flowgraph looking for conditional jumps to insert range - expressions. These range expressions are meant to provide information - to optimizations that need to reason in terms of value ranges. They - will not be expanded into RTL. For instance, given: - - x = ... - y = ... - if (x < y) - y = x - 2; - else - x = y + 3; - - this pass will transform the code into: - - x = ... - y = ... - if (x < y) - { - x = ASSERT_EXPR <x, x < y> - y = x - 2 - } - else - { - y = ASSERT_EXPR <y, x <= y> - x = y + 3 - } - - The idea is that once copy and constant propagation have run, other - optimizations will be able to determine what ranges of values can 'x' - take in different paths of the code, simply by checking the reaching - definition of 'x'. */ - -static void -insert_range_assertions (void) -{ - edge e; - edge_iterator ei; - bool update_ssa_p; - - found_in_subgraph = sbitmap_alloc (num_ssa_names); - sbitmap_zero (found_in_subgraph); - - blocks_visited = sbitmap_alloc (last_basic_block); - sbitmap_zero (blocks_visited); - - need_assert_for = BITMAP_ALLOC (NULL); - asserts_for = XNEWVEC (assert_locus_t, num_ssa_names); - memset (asserts_for, 0, num_ssa_names * sizeof (assert_locus_t)); - - calculate_dominance_info (CDI_DOMINATORS); - - update_ssa_p = false; - FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs) - if (find_assert_locations (e->dest)) - update_ssa_p = true; - - if (update_ssa_p) - { - process_assert_insertions (); - update_ssa (TODO_update_ssa_no_phi); - } - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n"); - dump_function_to_file (current_function_decl, dump_file, dump_flags); - } - - sbitmap_free (found_in_subgraph); - free (asserts_for); - BITMAP_FREE (need_assert_for); -} - - -/* Convert range assertion expressions into the implied copies and - copy propagate away the copies. Doing the trivial copy propagation - here avoids the need to run the full copy propagation pass after - VRP. - - FIXME, this will eventually lead to copy propagation removing the - names that had useful range information attached to them. For - instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>, - then N_i will have the range [3, +INF]. - - However, by converting the assertion into the implied copy - operation N_i = N_j, we will then copy-propagate N_j into the uses - of N_i and lose the range information. We may want to hold on to - ASSERT_EXPRs a little while longer as the ranges could be used in - things like jump threading. - - The problem with keeping ASSERT_EXPRs around is that passes after - VRP need to handle them appropriately. - - Another approach would be to make the range information a first - class property of the SSA_NAME so that it can be queried from - any pass. This is made somewhat more complex by the need for - multiple ranges to be associated with one SSA_NAME. */ - -static void -remove_range_assertions (void) -{ - basic_block bb; - block_stmt_iterator si; - - /* Note that the BSI iterator bump happens at the bottom of the - loop and no bump is necessary if we're removing the statement - referenced by the current BSI. */ - FOR_EACH_BB (bb) - for (si = bsi_start (bb); !bsi_end_p (si);) - { - tree stmt = bsi_stmt (si); - tree use_stmt; - - if (TREE_CODE (stmt) == MODIFY_EXPR - && TREE_CODE (TREE_OPERAND (stmt, 1)) == ASSERT_EXPR) - { - tree rhs = TREE_OPERAND (stmt, 1), var; - tree cond = fold (ASSERT_EXPR_COND (rhs)); - use_operand_p use_p; - imm_use_iterator iter; - - gcc_assert (cond != boolean_false_node); - - /* Propagate the RHS into every use of the LHS. */ - var = ASSERT_EXPR_VAR (rhs); - FOR_EACH_IMM_USE_STMT (use_stmt, iter, TREE_OPERAND (stmt, 0)) - FOR_EACH_IMM_USE_ON_STMT (use_p, iter) - { - SET_USE (use_p, var); - gcc_assert (TREE_CODE (var) == SSA_NAME); - } - - /* And finally, remove the copy, it is not needed. */ - bsi_remove (&si, true); - } - else - bsi_next (&si); - } - - sbitmap_free (blocks_visited); -} - - -/* Return true if STMT is interesting for VRP. */ - -static bool -stmt_interesting_for_vrp (tree stmt) -{ - if (TREE_CODE (stmt) == PHI_NODE - && is_gimple_reg (PHI_RESULT (stmt)) - && (INTEGRAL_TYPE_P (TREE_TYPE (PHI_RESULT (stmt))) - || POINTER_TYPE_P (TREE_TYPE (PHI_RESULT (stmt))))) - return true; - else if (TREE_CODE (stmt) == MODIFY_EXPR) - { - tree lhs = TREE_OPERAND (stmt, 0); - tree rhs = TREE_OPERAND (stmt, 1); - - /* In general, assignments with virtual operands are not useful - for deriving ranges, with the obvious exception of calls to - builtin functions. */ - if (TREE_CODE (lhs) == SSA_NAME - && (INTEGRAL_TYPE_P (TREE_TYPE (lhs)) - || POINTER_TYPE_P (TREE_TYPE (lhs))) - && ((TREE_CODE (rhs) == CALL_EXPR - && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR - && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) - && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) - || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS))) - return true; - } - else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) - return true; - - return false; -} - - -/* Initialize local data structures for VRP. */ - -static void -vrp_initialize (void) -{ - basic_block bb; - - vr_value = XNEWVEC (value_range_t *, num_ssa_names); - memset (vr_value, 0, num_ssa_names * sizeof (value_range_t *)); - - FOR_EACH_BB (bb) - { - block_stmt_iterator si; - tree phi; - - for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi)) - { - if (!stmt_interesting_for_vrp (phi)) - { - tree lhs = PHI_RESULT (phi); - set_value_range_to_varying (get_value_range (lhs)); - DONT_SIMULATE_AGAIN (phi) = true; - } - else - DONT_SIMULATE_AGAIN (phi) = false; - } - - for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si)) - { - tree stmt = bsi_stmt (si); - - if (!stmt_interesting_for_vrp (stmt)) - { - ssa_op_iter i; - tree def; - FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_DEF) - set_value_range_to_varying (get_value_range (def)); - DONT_SIMULATE_AGAIN (stmt) = true; - } - else - { - DONT_SIMULATE_AGAIN (stmt) = false; - } - } - } -} - - -/* Visit assignment STMT. If it produces an interesting range, record - the SSA name in *OUTPUT_P. */ - -static enum ssa_prop_result -vrp_visit_assignment (tree stmt, tree *output_p) -{ - tree lhs, rhs, def; - ssa_op_iter iter; - - lhs = TREE_OPERAND (stmt, 0); - rhs = TREE_OPERAND (stmt, 1); - - /* We only keep track of ranges in integral and pointer types. */ - if (TREE_CODE (lhs) == SSA_NAME - && ((INTEGRAL_TYPE_P (TREE_TYPE (lhs)) - /* It is valid to have NULL MIN/MAX values on a type. See - build_range_type. */ - && TYPE_MIN_VALUE (TREE_TYPE (lhs)) - && TYPE_MAX_VALUE (TREE_TYPE (lhs))) - || POINTER_TYPE_P (TREE_TYPE (lhs)))) - { - struct loop *l; - value_range_t new_vr = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; - - extract_range_from_expr (&new_vr, rhs); - - /* If STMT is inside a loop, we may be able to know something - else about the range of LHS by examining scalar evolution - information. */ - if (current_loops && (l = loop_containing_stmt (stmt))) - adjust_range_with_scev (&new_vr, l, stmt, lhs); - - if (update_value_range (lhs, &new_vr)) - { - *output_p = lhs; - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "Found new range for "); - print_generic_expr (dump_file, lhs, 0); - fprintf (dump_file, ": "); - dump_value_range (dump_file, &new_vr); - fprintf (dump_file, "\n\n"); - } - - if (new_vr.type == VR_VARYING) - return SSA_PROP_VARYING; - - return SSA_PROP_INTERESTING; - } - - return SSA_PROP_NOT_INTERESTING; - } - - /* Every other statement produces no useful ranges. */ - FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) - set_value_range_to_varying (get_value_range (def)); - - return SSA_PROP_VARYING; -} - - -/* Compare all the value ranges for names equivalent to VAR with VAL - using comparison code COMP. Return the same value returned by - compare_range_with_value, including the setting of - *STRICT_OVERFLOW_P. */ - -static tree -compare_name_with_value (enum tree_code comp, tree var, tree val, - bool *strict_overflow_p) -{ - bitmap_iterator bi; - unsigned i; - bitmap e; - tree retval, t; - int used_strict_overflow; - - t = retval = NULL_TREE; - - /* Get the set of equivalences for VAR. */ - e = get_value_range (var)->equiv; - - /* Add VAR to its own set of equivalences so that VAR's value range - is processed by this loop (otherwise, we would have to replicate - the body of the loop just to check VAR's value range). */ - bitmap_set_bit (e, SSA_NAME_VERSION (var)); - - /* Start at -1. Set it to 0 if we do a comparison without relying - on overflow, or 1 if all comparisons rely on overflow. */ - used_strict_overflow = -1; - - EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi) - { - bool sop; - - value_range_t equiv_vr = *(vr_value[i]); - - /* If name N_i does not have a valid range, use N_i as its own - range. This allows us to compare against names that may - have N_i in their ranges. */ - if (equiv_vr.type == VR_VARYING || equiv_vr.type == VR_UNDEFINED) - { - equiv_vr.type = VR_RANGE; - equiv_vr.min = ssa_name (i); - equiv_vr.max = ssa_name (i); - } - - sop = false; - t = compare_range_with_value (comp, &equiv_vr, val, &sop); - if (t) - { - /* If we get different answers from different members - of the equivalence set this check must be in a dead - code region. Folding it to a trap representation - would be correct here. For now just return don't-know. */ - if (retval != NULL - && t != retval) - { - retval = NULL_TREE; - break; - } - retval = t; - - if (!sop) - used_strict_overflow = 0; - else if (used_strict_overflow < 0) - used_strict_overflow = 1; - } - } - - /* Remove VAR from its own equivalence set. */ - bitmap_clear_bit (e, SSA_NAME_VERSION (var)); - - if (retval) - { - if (used_strict_overflow > 0) - *strict_overflow_p = true; - return retval; - } - - /* We couldn't find a non-NULL value for the predicate. */ - return NULL_TREE; -} - - -/* Given a comparison code COMP and names N1 and N2, compare all the - ranges equivalent to N1 against all the ranges equivalent to N2 - to determine the value of N1 COMP N2. Return the same value - returned by compare_ranges. Set *STRICT_OVERFLOW_P to indicate - whether we relied on an overflow infinity in the comparison. */ - - -static tree -compare_names (enum tree_code comp, tree n1, tree n2, - bool *strict_overflow_p) -{ - tree t, retval; - bitmap e1, e2; - bitmap_iterator bi1, bi2; - unsigned i1, i2; - int used_strict_overflow; - - /* Compare the ranges of every name equivalent to N1 against the - ranges of every name equivalent to N2. */ - e1 = get_value_range (n1)->equiv; - e2 = get_value_range (n2)->equiv; - - /* Add N1 and N2 to their own set of equivalences to avoid - duplicating the body of the loop just to check N1 and N2 - ranges. */ - bitmap_set_bit (e1, SSA_NAME_VERSION (n1)); - bitmap_set_bit (e2, SSA_NAME_VERSION (n2)); - - /* If the equivalence sets have a common intersection, then the two - names can be compared without checking their ranges. */ - if (bitmap_intersect_p (e1, e2)) - { - bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); - bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); - - return (comp == EQ_EXPR || comp == GE_EXPR || comp == LE_EXPR) - ? boolean_true_node - : boolean_false_node; - } - - /* Start at -1. Set it to 0 if we do a comparison without relying - on overflow, or 1 if all comparisons rely on overflow. */ - used_strict_overflow = -1; - - /* Otherwise, compare all the equivalent ranges. First, add N1 and - N2 to their own set of equivalences to avoid duplicating the body - of the loop just to check N1 and N2 ranges. */ - EXECUTE_IF_SET_IN_BITMAP (e1, 0, i1, bi1) - { - value_range_t vr1 = *(vr_value[i1]); - - /* If the range is VARYING or UNDEFINED, use the name itself. */ - if (vr1.type == VR_VARYING || vr1.type == VR_UNDEFINED) - { - vr1.type = VR_RANGE; - vr1.min = ssa_name (i1); - vr1.max = ssa_name (i1); - } - - t = retval = NULL_TREE; - EXECUTE_IF_SET_IN_BITMAP (e2, 0, i2, bi2) - { - bool sop = false; - - value_range_t vr2 = *(vr_value[i2]); - - if (vr2.type == VR_VARYING || vr2.type == VR_UNDEFINED) - { - vr2.type = VR_RANGE; - vr2.min = ssa_name (i2); - vr2.max = ssa_name (i2); - } - - t = compare_ranges (comp, &vr1, &vr2, &sop); - if (t) - { - /* If we get different answers from different members - of the equivalence set this check must be in a dead - code region. Folding it to a trap representation - would be correct here. For now just return don't-know. */ - if (retval != NULL - && t != retval) - { - bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); - bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); - return NULL_TREE; - } - retval = t; - - if (!sop) - used_strict_overflow = 0; - else if (used_strict_overflow < 0) - used_strict_overflow = 1; - } - } - - if (retval) - { - bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); - bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); - if (used_strict_overflow > 0) - *strict_overflow_p = true; - return retval; - } - } - - /* None of the equivalent ranges are useful in computing this - comparison. */ - bitmap_clear_bit (e1, SSA_NAME_VERSION (n1)); - bitmap_clear_bit (e2, SSA_NAME_VERSION (n2)); - return NULL_TREE; -} - - -/* Given a conditional predicate COND, try to determine if COND yields - true or false based on the value ranges of its operands. Return - BOOLEAN_TRUE_NODE if the conditional always evaluates to true, - BOOLEAN_FALSE_NODE if the conditional always evaluates to false, and, - NULL if the conditional cannot be evaluated at compile time. - - If USE_EQUIV_P is true, the ranges of all the names equivalent with - the operands in COND are used when trying to compute its value. - This is only used during final substitution. During propagation, - we only check the range of each variable and not its equivalents. - - Set *STRICT_OVERFLOW_P to indicate whether we relied on an overflow - infinity to produce the result. */ - -static tree -vrp_evaluate_conditional_warnv (tree cond, bool use_equiv_p, - bool *strict_overflow_p) -{ - gcc_assert (TREE_CODE (cond) == SSA_NAME - || TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison); - - if (TREE_CODE (cond) == SSA_NAME) - { - value_range_t *vr; - tree retval; - - if (use_equiv_p) - retval = compare_name_with_value (NE_EXPR, cond, boolean_false_node, - strict_overflow_p); - else - { - value_range_t *vr = get_value_range (cond); - retval = compare_range_with_value (NE_EXPR, vr, boolean_false_node, - strict_overflow_p); - } - - /* If COND has a known boolean range, return it. */ - if (retval) - return retval; - - /* Otherwise, if COND has a symbolic range of exactly one value, - return it. */ - vr = get_value_range (cond); - if (vr->type == VR_RANGE && vr->min == vr->max) - return vr->min; - } - else - { - tree op0 = TREE_OPERAND (cond, 0); - tree op1 = TREE_OPERAND (cond, 1); - - /* We only deal with integral and pointer types. */ - if (!INTEGRAL_TYPE_P (TREE_TYPE (op0)) - && !POINTER_TYPE_P (TREE_TYPE (op0))) - return NULL_TREE; - - if (use_equiv_p) - { - if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME) - return compare_names (TREE_CODE (cond), op0, op1, - strict_overflow_p); - else if (TREE_CODE (op0) == SSA_NAME) - return compare_name_with_value (TREE_CODE (cond), op0, op1, - strict_overflow_p); - else if (TREE_CODE (op1) == SSA_NAME) - return (compare_name_with_value - (swap_tree_comparison (TREE_CODE (cond)), op1, op0, - strict_overflow_p)); - } - else - { - value_range_t *vr0, *vr1; - - vr0 = (TREE_CODE (op0) == SSA_NAME) ? get_value_range (op0) : NULL; - vr1 = (TREE_CODE (op1) == SSA_NAME) ? get_value_range (op1) : NULL; - - if (vr0 && vr1) - return compare_ranges (TREE_CODE (cond), vr0, vr1, - strict_overflow_p); - else if (vr0 && vr1 == NULL) - return compare_range_with_value (TREE_CODE (cond), vr0, op1, - strict_overflow_p); - else if (vr0 == NULL && vr1) - return (compare_range_with_value - (swap_tree_comparison (TREE_CODE (cond)), vr1, op0, - strict_overflow_p)); - } - } - - /* Anything else cannot be computed statically. */ - return NULL_TREE; -} - -/* Given COND within STMT, try to simplify it based on value range - information. Return NULL if the conditional can not be evaluated. - The ranges of all the names equivalent with the operands in COND - will be used when trying to compute the value. If the result is - based on undefined signed overflow, issue a warning if - appropriate. */ - -tree -vrp_evaluate_conditional (tree cond, tree stmt) -{ - bool sop; - tree ret; - - sop = false; - ret = vrp_evaluate_conditional_warnv (cond, true, &sop); - - if (ret && sop) - { - enum warn_strict_overflow_code wc; - const char* warnmsg; - - if (is_gimple_min_invariant (ret)) - { - wc = WARN_STRICT_OVERFLOW_CONDITIONAL; - warnmsg = G_("assuming signed overflow does not occur when " - "simplifying conditional to constant"); - } - else - { - wc = WARN_STRICT_OVERFLOW_COMPARISON; - warnmsg = G_("assuming signed overflow does not occur when " - "simplifying conditional"); - } - - if (issue_strict_overflow_warning (wc)) - { - location_t locus; - - if (!EXPR_HAS_LOCATION (stmt)) - locus = input_location; - else - locus = EXPR_LOCATION (stmt); - warning (OPT_Wstrict_overflow, "%H%s", &locus, warnmsg); - } - } - - return ret; -} - - -/* Visit conditional statement STMT. If we can determine which edge - will be taken out of STMT's basic block, record it in - *TAKEN_EDGE_P and return SSA_PROP_INTERESTING. Otherwise, return - SSA_PROP_VARYING. */ - -static enum ssa_prop_result -vrp_visit_cond_stmt (tree stmt, edge *taken_edge_p) -{ - tree cond, val; - bool sop; - - *taken_edge_p = NULL; - - /* FIXME. Handle SWITCH_EXPRs. But first, the assert pass needs to - add ASSERT_EXPRs for them. */ - if (TREE_CODE (stmt) == SWITCH_EXPR) - return SSA_PROP_VARYING; - - cond = COND_EXPR_COND (stmt); - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - tree use; - ssa_op_iter i; - - fprintf (dump_file, "\nVisiting conditional with predicate: "); - print_generic_expr (dump_file, cond, 0); - fprintf (dump_file, "\nWith known ranges\n"); - - FOR_EACH_SSA_TREE_OPERAND (use, stmt, i, SSA_OP_USE) - { - fprintf (dump_file, "\t"); - print_generic_expr (dump_file, use, 0); - fprintf (dump_file, ": "); - dump_value_range (dump_file, vr_value[SSA_NAME_VERSION (use)]); - } - - fprintf (dump_file, "\n"); - } - - /* Compute the value of the predicate COND by checking the known - ranges of each of its operands. - - Note that we cannot evaluate all the equivalent ranges here - because those ranges may not yet be final and with the current - propagation strategy, we cannot determine when the value ranges - of the names in the equivalence set have changed. - - For instance, given the following code fragment - - i_5 = PHI <8, i_13> - ... - i_14 = ASSERT_EXPR <i_5, i_5 != 0> - if (i_14 == 1) - ... - - Assume that on the first visit to i_14, i_5 has the temporary - range [8, 8] because the second argument to the PHI function is - not yet executable. We derive the range ~[0, 0] for i_14 and the - equivalence set { i_5 }. So, when we visit 'if (i_14 == 1)' for - the first time, since i_14 is equivalent to the range [8, 8], we - determine that the predicate is always false. - - On the next round of propagation, i_13 is determined to be - VARYING, which causes i_5 to drop down to VARYING. So, another - visit to i_14 is scheduled. In this second visit, we compute the - exact same range and equivalence set for i_14, namely ~[0, 0] and - { i_5 }. But we did not have the previous range for i_5 - registered, so vrp_visit_assignment thinks that the range for - i_14 has not changed. Therefore, the predicate 'if (i_14 == 1)' - is not visited again, which stops propagation from visiting - statements in the THEN clause of that if(). - - To properly fix this we would need to keep the previous range - value for the names in the equivalence set. This way we would've - discovered that from one visit to the other i_5 changed from - range [8, 8] to VR_VARYING. - - However, fixing this apparent limitation may not be worth the - additional checking. Testing on several code bases (GCC, DLV, - MICO, TRAMP3D and SPEC2000) showed that doing this results in - 4 more predicates folded in SPEC. */ - sop = false; - val = vrp_evaluate_conditional_warnv (cond, false, &sop); - if (val) - { - if (!sop) - *taken_edge_p = find_taken_edge (bb_for_stmt (stmt), val); - else - { - if (dump_file && (dump_flags & TDF_DETAILS)) - fprintf (dump_file, - "\nIgnoring predicate evaluation because " - "it assumes that signed overflow is undefined"); - val = NULL_TREE; - } - } - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\nPredicate evaluates to: "); - if (val == NULL_TREE) - fprintf (dump_file, "DON'T KNOW\n"); - else - print_generic_stmt (dump_file, val, 0); - } - - return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; -} - - -/* Evaluate statement STMT. If the statement produces a useful range, - return SSA_PROP_INTERESTING and record the SSA name with the - interesting range into *OUTPUT_P. - - If STMT is a conditional branch and we can determine its truth - value, the taken edge is recorded in *TAKEN_EDGE_P. - - If STMT produces a varying value, return SSA_PROP_VARYING. */ - -static enum ssa_prop_result -vrp_visit_stmt (tree stmt, edge *taken_edge_p, tree *output_p) -{ - tree def; - ssa_op_iter iter; - stmt_ann_t ann; - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\nVisiting statement:\n"); - print_generic_stmt (dump_file, stmt, dump_flags); - fprintf (dump_file, "\n"); - } - - ann = stmt_ann (stmt); - if (TREE_CODE (stmt) == MODIFY_EXPR) - { - tree rhs = TREE_OPERAND (stmt, 1); - - /* In general, assignments with virtual operands are not useful - for deriving ranges, with the obvious exception of calls to - builtin functions. */ - if ((TREE_CODE (rhs) == CALL_EXPR - && TREE_CODE (TREE_OPERAND (rhs, 0)) == ADDR_EXPR - && DECL_P (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0)) - && DECL_IS_BUILTIN (TREE_OPERAND (TREE_OPERAND (rhs, 0), 0))) - || ZERO_SSA_OPERANDS (stmt, SSA_OP_ALL_VIRTUALS)) - return vrp_visit_assignment (stmt, output_p); - } - else if (TREE_CODE (stmt) == COND_EXPR || TREE_CODE (stmt) == SWITCH_EXPR) - return vrp_visit_cond_stmt (stmt, taken_edge_p); - - /* All other statements produce nothing of interest for VRP, so mark - their outputs varying and prevent further simulation. */ - FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF) - set_value_range_to_varying (get_value_range (def)); - - return SSA_PROP_VARYING; -} - - -/* Meet operation for value ranges. Given two value ranges VR0 and - VR1, store in VR0 the result of meeting VR0 and VR1. - - The meeting rules are as follows: - - 1- If VR0 and VR1 have an empty intersection, set VR0 to VR_VARYING. - - 2- If VR0 and VR1 have a non-empty intersection, set VR0 to the - union of VR0 and VR1. */ - -static void -vrp_meet (value_range_t *vr0, value_range_t *vr1) -{ - if (vr0->type == VR_UNDEFINED) - { - copy_value_range (vr0, vr1); - return; - } - - if (vr1->type == VR_UNDEFINED) - { - /* Nothing to do. VR0 already has the resulting range. */ - return; - } - - if (vr0->type == VR_VARYING) - { - /* Nothing to do. VR0 already has the resulting range. */ - return; - } - - if (vr1->type == VR_VARYING) - { - set_value_range_to_varying (vr0); - return; - } - - if (vr0->type == VR_RANGE && vr1->type == VR_RANGE) - { - /* If VR0 and VR1 have a non-empty intersection, compute the - union of both ranges. */ - if (value_ranges_intersect_p (vr0, vr1)) - { - int cmp; - tree min, max; - - /* The lower limit of the new range is the minimum of the - two ranges. If they cannot be compared, the result is - VARYING. */ - cmp = compare_values (vr0->min, vr1->min); - if (cmp == 0 || cmp == 1) - min = vr1->min; - else if (cmp == -1) - min = vr0->min; - else - { - set_value_range_to_varying (vr0); - return; - } - - /* Similarly, the upper limit of the new range is the - maximum of the two ranges. If they cannot be compared, - the result is VARYING. */ - cmp = compare_values (vr0->max, vr1->max); - if (cmp == 0 || cmp == -1) - max = vr1->max; - else if (cmp == 1) - max = vr0->max; - else - { - set_value_range_to_varying (vr0); - return; - } - - /* Check for useless ranges. */ - if (INTEGRAL_TYPE_P (TREE_TYPE (min)) - && ((vrp_val_is_min (min) || is_overflow_infinity (min)) - && (vrp_val_is_max (max) || is_overflow_infinity (max)))) - { - set_value_range_to_varying (vr0); - return; - } - - /* The resulting set of equivalences is the intersection of - the two sets. */ - if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) - bitmap_and_into (vr0->equiv, vr1->equiv); - else if (vr0->equiv && !vr1->equiv) - bitmap_clear (vr0->equiv); - - set_value_range (vr0, vr0->type, min, max, vr0->equiv); - } - else - goto no_meet; - } - else if (vr0->type == VR_ANTI_RANGE && vr1->type == VR_ANTI_RANGE) - { - /* Two anti-ranges meet only if they are both identical. */ - if (compare_values (vr0->min, vr1->min) == 0 - && compare_values (vr0->max, vr1->max) == 0 - && compare_values (vr0->min, vr0->max) == 0) - { - /* The resulting set of equivalences is the intersection of - the two sets. */ - if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) - bitmap_and_into (vr0->equiv, vr1->equiv); - else if (vr0->equiv && !vr1->equiv) - bitmap_clear (vr0->equiv); - } - else - goto no_meet; - } - else if (vr0->type == VR_ANTI_RANGE || vr1->type == VR_ANTI_RANGE) - { - /* A numeric range [VAL1, VAL2] and an anti-range ~[VAL3, VAL4] - meet only if the ranges have an empty intersection. The - result of the meet operation is the anti-range. */ - if (!symbolic_range_p (vr0) - && !symbolic_range_p (vr1) - && !value_ranges_intersect_p (vr0, vr1)) - { - /* Copy most of VR1 into VR0. Don't copy VR1's equivalence - set. We need to compute the intersection of the two - equivalence sets. */ - if (vr1->type == VR_ANTI_RANGE) - set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv); - - /* The resulting set of equivalences is the intersection of - the two sets. */ - if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv) - bitmap_and_into (vr0->equiv, vr1->equiv); - else if (vr0->equiv && !vr1->equiv) - bitmap_clear (vr0->equiv); - } - else - goto no_meet; - } - else - gcc_unreachable (); - - return; - -no_meet: - /* The two range VR0 and VR1 do not meet. Before giving up and - setting the result to VARYING, see if we can at least derive a - useful anti-range. FIXME, all this nonsense about distinguishing - anti-ranges from ranges is necessary because of the odd - semantics of range_includes_zero_p and friends. */ - if (!symbolic_range_p (vr0) - && ((vr0->type == VR_RANGE && !range_includes_zero_p (vr0)) - || (vr0->type == VR_ANTI_RANGE && range_includes_zero_p (vr0))) - && !symbolic_range_p (vr1) - && ((vr1->type == VR_RANGE && !range_includes_zero_p (vr1)) - || (vr1->type == VR_ANTI_RANGE && range_includes_zero_p (vr1)))) - { - set_value_range_to_nonnull (vr0, TREE_TYPE (vr0->min)); - - /* Since this meet operation did not result from the meeting of - two equivalent names, VR0 cannot have any equivalences. */ - if (vr0->equiv) - bitmap_clear (vr0->equiv); - } - else - set_value_range_to_varying (vr0); -} - - -/* Visit all arguments for PHI node PHI that flow through executable - edges. If a valid value range can be derived from all the incoming - value ranges, set a new range for the LHS of PHI. */ - -static enum ssa_prop_result -vrp_visit_phi_node (tree phi) -{ - int i; - tree lhs = PHI_RESULT (phi); - value_range_t *lhs_vr = get_value_range (lhs); - value_range_t vr_result = { VR_UNDEFINED, NULL_TREE, NULL_TREE, NULL }; - - copy_value_range (&vr_result, lhs_vr); - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\nVisiting PHI node: "); - print_generic_expr (dump_file, phi, dump_flags); - } - - for (i = 0; i < PHI_NUM_ARGS (phi); i++) - { - edge e = PHI_ARG_EDGE (phi, i); - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, - "\n Argument #%d (%d -> %d %sexecutable)\n", - i, e->src->index, e->dest->index, - (e->flags & EDGE_EXECUTABLE) ? "" : "not "); - } - - if (e->flags & EDGE_EXECUTABLE) - { - tree arg = PHI_ARG_DEF (phi, i); - value_range_t vr_arg; - - if (TREE_CODE (arg) == SSA_NAME) - vr_arg = *(get_value_range (arg)); - else - { - if (is_overflow_infinity (arg)) - { - arg = copy_node (arg); - TREE_OVERFLOW (arg) = 0; - } - - vr_arg.type = VR_RANGE; - vr_arg.min = arg; - vr_arg.max = arg; - vr_arg.equiv = NULL; - } - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "\t"); - print_generic_expr (dump_file, arg, dump_flags); - fprintf (dump_file, "\n\tValue: "); - dump_value_range (dump_file, &vr_arg); - fprintf (dump_file, "\n"); - } - - vrp_meet (&vr_result, &vr_arg); - - if (vr_result.type == VR_VARYING) - break; - } - } - - if (vr_result.type == VR_VARYING) - goto varying; - - /* To prevent infinite iterations in the algorithm, derive ranges - when the new value is slightly bigger or smaller than the - previous one. */ - if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE) - { - if (!POINTER_TYPE_P (TREE_TYPE (lhs))) - { - int cmp_min = compare_values (lhs_vr->min, vr_result.min); - int cmp_max = compare_values (lhs_vr->max, vr_result.max); - - /* If the new minimum is smaller or larger than the previous - one, go all the way to -INF. In the first case, to avoid - iterating millions of times to reach -INF, and in the - other case to avoid infinite bouncing between different - minimums. */ - if (cmp_min > 0 || cmp_min < 0) - { - /* If we will end up with a (-INF, +INF) range, set it - to VARYING. */ - if (vrp_val_is_max (vr_result.max)) - goto varying; - - if (!needs_overflow_infinity (TREE_TYPE (vr_result.min)) - || !vrp_var_may_overflow (lhs, phi)) - vr_result.min = TYPE_MIN_VALUE (TREE_TYPE (vr_result.min)); - else if (supports_overflow_infinity (TREE_TYPE (vr_result.min))) - vr_result.min = - negative_overflow_infinity (TREE_TYPE (vr_result.min)); - else - goto varying; - } - - /* Similarly, if the new maximum is smaller or larger than - the previous one, go all the way to +INF. */ - if (cmp_max < 0 || cmp_max > 0) - { - /* If we will end up with a (-INF, +INF) range, set it - to VARYING. */ - if (vrp_val_is_min (vr_result.min)) - goto varying; - - if (!needs_overflow_infinity (TREE_TYPE (vr_result.max)) - || !vrp_var_may_overflow (lhs, phi)) - vr_result.max = TYPE_MAX_VALUE (TREE_TYPE (vr_result.max)); - else if (supports_overflow_infinity (TREE_TYPE (vr_result.max))) - vr_result.max = - positive_overflow_infinity (TREE_TYPE (vr_result.max)); - else - goto varying; - } - } - } - - /* If the new range is different than the previous value, keep - iterating. */ - if (update_value_range (lhs, &vr_result)) - return SSA_PROP_INTERESTING; - - /* Nothing changed, don't add outgoing edges. */ - return SSA_PROP_NOT_INTERESTING; - - /* No match found. Set the LHS to VARYING. */ -varying: - set_value_range_to_varying (lhs_vr); - return SSA_PROP_VARYING; -} - -/* Simplify a division or modulo operator to a right shift or - bitwise and if the first operand is unsigned or is greater - than zero and the second operand is an exact power of two. */ - -static void -simplify_div_or_mod_using_ranges (tree stmt, tree rhs, enum tree_code rhs_code) -{ - tree val = NULL; - tree op = TREE_OPERAND (rhs, 0); - value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0)); - - if (TYPE_UNSIGNED (TREE_TYPE (op))) - { - val = integer_one_node; - } - else - { - bool sop = false; - - val = compare_range_with_value (GT_EXPR, vr, integer_zero_node, &sop); - - if (val - && sop - && integer_onep (val) - && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) - { - location_t locus; - - if (!EXPR_HAS_LOCATION (stmt)) - locus = input_location; - else - locus = EXPR_LOCATION (stmt); - warning (OPT_Wstrict_overflow, - ("%Hassuming signed overflow does not occur when " - "simplifying / or %% to >> or &"), - &locus); - } - } - - if (val && integer_onep (val)) - { - tree t; - tree op0 = TREE_OPERAND (rhs, 0); - tree op1 = TREE_OPERAND (rhs, 1); - - if (rhs_code == TRUNC_DIV_EXPR) - { - t = build_int_cst (NULL_TREE, tree_log2 (op1)); - t = build2 (RSHIFT_EXPR, TREE_TYPE (op0), op0, t); - } - else - { - t = build_int_cst (TREE_TYPE (op1), 1); - t = int_const_binop (MINUS_EXPR, op1, t, 0); - t = fold_convert (TREE_TYPE (op0), t); - t = build2 (BIT_AND_EXPR, TREE_TYPE (op0), op0, t); - } - - TREE_OPERAND (stmt, 1) = t; - update_stmt (stmt); - } -} - -/* If the operand to an ABS_EXPR is >= 0, then eliminate the - ABS_EXPR. If the operand is <= 0, then simplify the - ABS_EXPR into a NEGATE_EXPR. */ - -static void -simplify_abs_using_ranges (tree stmt, tree rhs) -{ - tree val = NULL; - tree op = TREE_OPERAND (rhs, 0); - tree type = TREE_TYPE (op); - value_range_t *vr = get_value_range (TREE_OPERAND (rhs, 0)); - - if (TYPE_UNSIGNED (type)) - { - val = integer_zero_node; - } - else if (vr) - { - bool sop = false; - - val = compare_range_with_value (LE_EXPR, vr, integer_zero_node, &sop); - if (!val) - { - sop = false; - val = compare_range_with_value (GE_EXPR, vr, integer_zero_node, - &sop); - - if (val) - { - if (integer_zerop (val)) - val = integer_one_node; - else if (integer_onep (val)) - val = integer_zero_node; - } - } - - if (val - && (integer_onep (val) || integer_zerop (val))) - { - tree t; - - if (sop && issue_strict_overflow_warning (WARN_STRICT_OVERFLOW_MISC)) - { - location_t locus; - - if (!EXPR_HAS_LOCATION (stmt)) - locus = input_location; - else - locus = EXPR_LOCATION (stmt); - warning (OPT_Wstrict_overflow, - ("%Hassuming signed overflow does not occur when " - "simplifying abs (X) to X or -X"), - &locus); - } - - if (integer_onep (val)) - t = build1 (NEGATE_EXPR, TREE_TYPE (op), op); - else - t = op; - - TREE_OPERAND (stmt, 1) = t; - update_stmt (stmt); - } - } -} - -/* We are comparing trees OP0 and OP1 using COND_CODE. OP0 has - a known value range VR. - - If there is one and only one value which will satisfy the - conditional, then return that value. Else return NULL. */ - -static tree -test_for_singularity (enum tree_code cond_code, tree op0, - tree op1, value_range_t *vr) -{ - tree min = NULL; - tree max = NULL; - - /* Extract minimum/maximum values which satisfy the - the conditional as it was written. */ - if (cond_code == LE_EXPR || cond_code == LT_EXPR) - { - /* This should not be negative infinity; there is no overflow - here. */ - min = TYPE_MIN_VALUE (TREE_TYPE (op0)); - - max = op1; - if (cond_code == LT_EXPR && !is_overflow_infinity (max)) - { - tree one = build_int_cst (TREE_TYPE (op0), 1); - max = fold_build2 (MINUS_EXPR, TREE_TYPE (op0), max, one); - if (EXPR_P (max)) - TREE_NO_WARNING (max) = 1; - } - } - else if (cond_code == GE_EXPR || cond_code == GT_EXPR) - { - /* This should not be positive infinity; there is no overflow - here. */ - max = TYPE_MAX_VALUE (TREE_TYPE (op0)); - - min = op1; - if (cond_code == GT_EXPR && !is_overflow_infinity (min)) - { - tree one = build_int_cst (TREE_TYPE (op0), 1); - min = fold_build2 (PLUS_EXPR, TREE_TYPE (op0), min, one); - if (EXPR_P (min)) - TREE_NO_WARNING (min) = 1; - } - } - - /* Now refine the minimum and maximum values using any - value range information we have for op0. */ - if (min && max) - { - if (compare_values (vr->min, min) == -1) - min = min; - else - min = vr->min; - if (compare_values (vr->max, max) == 1) - max = max; - else - max = vr->max; - - /* If the new min/max values have converged to a single value, - then there is only one value which can satisfy the condition, - return that value. */ - if (operand_equal_p (min, max, 0) && is_gimple_min_invariant (min)) - return min; - } - return NULL; -} - -/* Simplify a conditional using a relational operator to an equality - test if the range information indicates only one value can satisfy - the original conditional. */ - -static void -simplify_cond_using_ranges (tree stmt) -{ - tree cond = COND_EXPR_COND (stmt); - tree op0 = TREE_OPERAND (cond, 0); - tree op1 = TREE_OPERAND (cond, 1); - enum tree_code cond_code = TREE_CODE (cond); - - if (cond_code != NE_EXPR - && cond_code != EQ_EXPR - && TREE_CODE (op0) == SSA_NAME - && INTEGRAL_TYPE_P (TREE_TYPE (op0)) - && is_gimple_min_invariant (op1)) - { - value_range_t *vr = get_value_range (op0); - - /* If we have range information for OP0, then we might be - able to simplify this conditional. */ - if (vr->type == VR_RANGE) - { - tree new = test_for_singularity (cond_code, op0, op1, vr); - - if (new) - { - if (dump_file) - { - fprintf (dump_file, "Simplified relational "); - print_generic_expr (dump_file, cond, 0); - fprintf (dump_file, " into "); - } - - COND_EXPR_COND (stmt) - = build2 (EQ_EXPR, boolean_type_node, op0, new); - update_stmt (stmt); - - if (dump_file) - { - print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0); - fprintf (dump_file, "\n"); - } - return; - - } - - /* Try again after inverting the condition. We only deal - with integral types here, so no need to worry about - issues with inverting FP comparisons. */ - cond_code = invert_tree_comparison (cond_code, false); - new = test_for_singularity (cond_code, op0, op1, vr); - - if (new) - { - if (dump_file) - { - fprintf (dump_file, "Simplified relational "); - print_generic_expr (dump_file, cond, 0); - fprintf (dump_file, " into "); - } - - COND_EXPR_COND (stmt) - = build2 (NE_EXPR, boolean_type_node, op0, new); - update_stmt (stmt); - - if (dump_file) - { - print_generic_expr (dump_file, COND_EXPR_COND (stmt), 0); - fprintf (dump_file, "\n"); - } - return; - - } - } - } -} - -/* Simplify STMT using ranges if possible. */ - -void -simplify_stmt_using_ranges (tree stmt) -{ - if (TREE_CODE (stmt) == MODIFY_EXPR) - { - tree rhs = TREE_OPERAND (stmt, 1); - enum tree_code rhs_code = TREE_CODE (rhs); - - /* Transform TRUNC_DIV_EXPR and TRUNC_MOD_EXPR into RSHIFT_EXPR - and BIT_AND_EXPR respectively if the first operand is greater - than zero and the second operand is an exact power of two. */ - if ((rhs_code == TRUNC_DIV_EXPR || rhs_code == TRUNC_MOD_EXPR) - && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0))) - && integer_pow2p (TREE_OPERAND (rhs, 1))) - simplify_div_or_mod_using_ranges (stmt, rhs, rhs_code); - - /* Transform ABS (X) into X or -X as appropriate. */ - if (rhs_code == ABS_EXPR - && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME - && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (rhs, 0)))) - simplify_abs_using_ranges (stmt, rhs); - } - else if (TREE_CODE (stmt) == COND_EXPR - && COMPARISON_CLASS_P (COND_EXPR_COND (stmt))) - { - simplify_cond_using_ranges (stmt); - } -} - -/* Stack of dest,src equivalency pairs that need to be restored after - each attempt to thread a block's incoming edge to an outgoing edge. - - A NULL entry is used to mark the end of pairs which need to be - restored. */ -static VEC(tree,heap) *stack; - -/* A trivial wrapper so that we can present the generic jump threading - code with a simple API for simplifying statements. STMT is the - statement we want to simplify, WITHIN_STMT provides the location - for any overflow warnings. */ - -static tree -simplify_stmt_for_jump_threading (tree stmt, tree within_stmt) -{ - /* We only use VRP information to simplify conditionals. This is - overly conservative, but it's unclear if doing more would be - worth the compile time cost. */ - if (TREE_CODE (stmt) != COND_EXPR) - return NULL; - - return vrp_evaluate_conditional (COND_EXPR_COND (stmt), within_stmt); -} - -/* Blocks which have more than one predecessor and more than - one successor present jump threading opportunities. ie, - when the block is reached from a specific predecessor, we - may be able to determine which of the outgoing edges will - be traversed. When this optimization applies, we are able - to avoid conditionals at runtime and we may expose secondary - optimization opportunities. - - This routine is effectively a driver for the generic jump - threading code. It basically just presents the generic code - with edges that may be suitable for jump threading. - - Unlike DOM, we do not iterate VRP if jump threading was successful. - While iterating may expose new opportunities for VRP, it is expected - those opportunities would be very limited and the compile time cost - to expose those opportunities would be significant. - - As jump threading opportunities are discovered, they are registered - for later realization. */ - -static void -identify_jump_threads (void) -{ - basic_block bb; - tree dummy; - - /* Ugh. When substituting values earlier in this pass we can - wipe the dominance information. So rebuild the dominator - information as we need it within the jump threading code. */ - calculate_dominance_info (CDI_DOMINATORS); - - /* We do not allow VRP information to be used for jump threading - across a back edge in the CFG. Otherwise it becomes too - difficult to avoid eliminating loop exit tests. Of course - EDGE_DFS_BACK is not accurate at this time so we have to - recompute it. */ - mark_dfs_back_edges (); - - /* Allocate our unwinder stack to unwind any temporary equivalences - that might be recorded. */ - stack = VEC_alloc (tree, heap, 20); - - /* To avoid lots of silly node creation, we create a single - conditional and just modify it in-place when attempting to - thread jumps. */ - dummy = build2 (EQ_EXPR, boolean_type_node, NULL, NULL); - dummy = build3 (COND_EXPR, void_type_node, dummy, NULL, NULL); - - /* Walk through all the blocks finding those which present a - potential jump threading opportunity. We could set this up - as a dominator walker and record data during the walk, but - I doubt it's worth the effort for the classes of jump - threading opportunities we are trying to identify at this - point in compilation. */ - FOR_EACH_BB (bb) - { - tree last, cond; - - /* If the generic jump threading code does not find this block - interesting, then there is nothing to do. */ - if (! potentially_threadable_block (bb)) - continue; - - /* We only care about blocks ending in a COND_EXPR. While there - may be some value in handling SWITCH_EXPR here, I doubt it's - terribly important. */ - last = bsi_stmt (bsi_last (bb)); - if (TREE_CODE (last) != COND_EXPR) - continue; - - /* We're basically looking for any kind of conditional with - integral type arguments. */ - cond = COND_EXPR_COND (last); - if ((TREE_CODE (cond) == SSA_NAME - && INTEGRAL_TYPE_P (TREE_TYPE (cond))) - || (COMPARISON_CLASS_P (cond) - && TREE_CODE (TREE_OPERAND (cond, 0)) == SSA_NAME - && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 0))) - && (TREE_CODE (TREE_OPERAND (cond, 1)) == SSA_NAME - || is_gimple_min_invariant (TREE_OPERAND (cond, 1))) - && INTEGRAL_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1))))) - { - edge_iterator ei; - edge e; - - /* We've got a block with multiple predecessors and multiple - successors which also ends in a suitable conditional. For - each predecessor, see if we can thread it to a specific - successor. */ - FOR_EACH_EDGE (e, ei, bb->preds) - { - /* Do not thread across back edges or abnormal edges - in the CFG. */ - if (e->flags & (EDGE_DFS_BACK | EDGE_COMPLEX)) - continue; - - thread_across_edge (dummy, e, true, - &stack, - simplify_stmt_for_jump_threading); - } - } - } - - /* We do not actually update the CFG or SSA graphs at this point as - ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet - handle ASSERT_EXPRs gracefully. */ -} - -/* We identified all the jump threading opportunities earlier, but could - not transform the CFG at that time. This routine transforms the - CFG and arranges for the dominator tree to be rebuilt if necessary. - - Note the SSA graph update will occur during the normal TODO - processing by the pass manager. */ -static void -finalize_jump_threads (void) -{ - bool cfg_altered = false; - cfg_altered = thread_through_all_blocks (); - - /* If we threaded jumps, then we need to recompute the dominance - information, to safely do that we must clean up the CFG first. */ - if (cfg_altered) - { - free_dominance_info (CDI_DOMINATORS); - cleanup_tree_cfg (); - calculate_dominance_info (CDI_DOMINATORS); - } - VEC_free (tree, heap, stack); -} - - -/* Traverse all the blocks folding conditionals with known ranges. */ - -static void -vrp_finalize (void) -{ - size_t i; - prop_value_t *single_val_range; - bool do_value_subst_p; - - if (dump_file) - { - fprintf (dump_file, "\nValue ranges after VRP:\n\n"); - dump_all_value_ranges (dump_file); - fprintf (dump_file, "\n"); - } - - /* We may have ended with ranges that have exactly one value. Those - values can be substituted as any other copy/const propagated - value using substitute_and_fold. */ - single_val_range = XNEWVEC (prop_value_t, num_ssa_names); - memset (single_val_range, 0, num_ssa_names * sizeof (*single_val_range)); - - do_value_subst_p = false; - for (i = 0; i < num_ssa_names; i++) - if (vr_value[i] - && vr_value[i]->type == VR_RANGE - && vr_value[i]->min == vr_value[i]->max) - { - single_val_range[i].value = vr_value[i]->min; - do_value_subst_p = true; - } - - if (!do_value_subst_p) - { - /* We found no single-valued ranges, don't waste time trying to - do single value substitution in substitute_and_fold. */ - free (single_val_range); - single_val_range = NULL; - } - - substitute_and_fold (single_val_range, true); - - /* We must identify jump threading opportunities before we release - the datastructures built by VRP. */ - identify_jump_threads (); - - /* Free allocated memory. */ - for (i = 0; i < num_ssa_names; i++) - if (vr_value[i]) - { - BITMAP_FREE (vr_value[i]->equiv); - free (vr_value[i]); - } - - free (single_val_range); - free (vr_value); - - /* So that we can distinguish between VRP data being available - and not available. */ - vr_value = NULL; -} - - -/* Main entry point to VRP (Value Range Propagation). This pass is - loosely based on J. R. C. Patterson, ``Accurate Static Branch - Prediction by Value Range Propagation,'' in SIGPLAN Conference on - Programming Language Design and Implementation, pp. 67-78, 1995. - Also available at http://citeseer.ist.psu.edu/patterson95accurate.html - - This is essentially an SSA-CCP pass modified to deal with ranges - instead of constants. - - While propagating ranges, we may find that two or more SSA name - have equivalent, though distinct ranges. For instance, - - 1 x_9 = p_3->a; - 2 p_4 = ASSERT_EXPR <p_3, p_3 != 0> - 3 if (p_4 == q_2) - 4 p_5 = ASSERT_EXPR <p_4, p_4 == q_2>; - 5 endif - 6 if (q_2) - - In the code above, pointer p_5 has range [q_2, q_2], but from the - code we can also determine that p_5 cannot be NULL and, if q_2 had - a non-varying range, p_5's range should also be compatible with it. - - These equivalences are created by two expressions: ASSERT_EXPR and - copy operations. Since p_5 is an assertion on p_4, and p_4 was the - result of another assertion, then we can use the fact that p_5 and - p_4 are equivalent when evaluating p_5's range. - - Together with value ranges, we also propagate these equivalences - between names so that we can take advantage of information from - multiple ranges when doing final replacement. Note that this - equivalency relation is transitive but not symmetric. - - In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we - cannot assert that q_2 is equivalent to p_5 because q_2 may be used - in contexts where that assertion does not hold (e.g., in line 6). - - TODO, the main difference between this pass and Patterson's is that - we do not propagate edge probabilities. We only compute whether - edges can be taken or not. That is, instead of having a spectrum - of jump probabilities between 0 and 1, we only deal with 0, 1 and - DON'T KNOW. In the future, it may be worthwhile to propagate - probabilities to aid branch prediction. */ - -static unsigned int -execute_vrp (void) -{ - insert_range_assertions (); - - current_loops = loop_optimizer_init (LOOPS_NORMAL); - if (current_loops) - scev_initialize (current_loops); - - vrp_initialize (); - ssa_propagate (vrp_visit_stmt, vrp_visit_phi_node); - vrp_finalize (); - - if (current_loops) - { - scev_finalize (); - loop_optimizer_finalize (current_loops); - current_loops = NULL; - } - - /* ASSERT_EXPRs must be removed before finalizing jump threads - as finalizing jump threads calls the CFG cleanup code which - does not properly handle ASSERT_EXPRs. */ - remove_range_assertions (); - - /* If we exposed any new variables, go ahead and put them into - SSA form now, before we handle jump threading. This simplifies - interactions between rewriting of _DECL nodes into SSA form - and rewriting SSA_NAME nodes into SSA form after block - duplication and CFG manipulation. */ - update_ssa (TODO_update_ssa); - - finalize_jump_threads (); - return 0; -} - -static bool -gate_vrp (void) -{ - return flag_tree_vrp != 0; -} - -struct tree_opt_pass pass_vrp = -{ - "vrp", /* name */ - gate_vrp, /* gate */ - execute_vrp, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - TV_TREE_VRP, /* tv_id */ - PROP_ssa | PROP_alias, /* properties_required */ - 0, /* properties_provided */ - PROP_smt_usage, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_cleanup_cfg - | TODO_ggc_collect - | TODO_verify_ssa - | TODO_dump_func - | TODO_update_ssa - | TODO_update_smt_usage, /* todo_flags_finish */ - 0 /* letter */ -}; |