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Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/tree-tailcall.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/gcc/tree-tailcall.c | 1049 |
1 files changed, 0 insertions, 1049 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/tree-tailcall.c b/gcc-4.2.1-5666.3/gcc/tree-tailcall.c deleted file mode 100644 index e45f0be35..000000000 --- a/gcc-4.2.1-5666.3/gcc/tree-tailcall.c +++ /dev/null @@ -1,1049 +0,0 @@ -/* Tail call optimization on trees. - Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc. - -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 "tree.h" -#include "rtl.h" -#include "tm_p.h" -#include "hard-reg-set.h" -#include "basic-block.h" -#include "function.h" -#include "tree-flow.h" -#include "tree-dump.h" -#include "diagnostic.h" -#include "except.h" -#include "tree-pass.h" -#include "flags.h" -#include "langhooks.h" - -/* The file implements the tail recursion elimination. It is also used to - analyze the tail calls in general, passing the results to the rtl level - where they are used for sibcall optimization. - - In addition to the standard tail recursion elimination, we handle the most - trivial cases of making the call tail recursive by creating accumulators. - For example the following function - - int sum (int n) - { - if (n > 0) - return n + sum (n - 1); - else - return 0; - } - - is transformed into - - int sum (int n) - { - int acc = 0; - - while (n > 0) - acc += n--; - - return acc; - } - - To do this, we maintain two accumulators (a_acc and m_acc) that indicate - when we reach the return x statement, we should return a_acc + x * m_acc - instead. They are initially initialized to 0 and 1, respectively, - so the semantics of the function is obviously preserved. If we are - guaranteed that the value of the accumulator never change, we - omit the accumulator. - - There are three cases how the function may exit. The first one is - handled in adjust_return_value, the other two in adjust_accumulator_values - (the second case is actually a special case of the third one and we - present it separately just for clarity): - - 1) Just return x, where x is not in any of the remaining special shapes. - We rewrite this to a gimple equivalent of return m_acc * x + a_acc. - - 2) return f (...), where f is the current function, is rewritten in a - classical tail-recursion elimination way, into assignment of arguments - and jump to the start of the function. Values of the accumulators - are unchanged. - - 3) return a + m * f(...), where a and m do not depend on call to f. - To preserve the semantics described before we want this to be rewritten - in such a way that we finally return - - a_acc + (a + m * f(...)) * m_acc = (a_acc + a * m_acc) + (m * m_acc) * f(...). - - I.e. we increase a_acc by a * m_acc, multiply m_acc by m and - eliminate the tail call to f. Special cases when the value is just - added or just multiplied are obtained by setting a = 0 or m = 1. - - TODO -- it is possible to do similar tricks for other operations. */ - -/* A structure that describes the tailcall. */ - -struct tailcall -{ - /* The block in that the call occur. */ - basic_block call_block; - - /* The iterator pointing to the call statement. */ - block_stmt_iterator call_bsi; - - /* True if it is a call to the current function. */ - bool tail_recursion; - - /* The return value of the caller is mult * f + add, where f is the return - value of the call. */ - tree mult, add; - - /* Next tailcall in the chain. */ - struct tailcall *next; -}; - -/* The variables holding the value of multiplicative and additive - accumulator. */ -static tree m_acc, a_acc; - -static bool suitable_for_tail_opt_p (void); -static bool optimize_tail_call (struct tailcall *, bool); -static void eliminate_tail_call (struct tailcall *); -static void find_tail_calls (basic_block, struct tailcall **); - -/* Returns false when the function is not suitable for tail call optimization - from some reason (e.g. if it takes variable number of arguments). */ - -static bool -suitable_for_tail_opt_p (void) -{ - referenced_var_iterator rvi; - tree var; - - if (current_function_stdarg) - return false; - - /* No local variable nor structure field should be call-clobbered. We - ignore any kind of memory tag, as these are not real variables. */ - - FOR_EACH_REFERENCED_VAR (var, rvi) - { - - if (!is_global_var (var) - && (!MTAG_P (var) || TREE_CODE (var) == STRUCT_FIELD_TAG) - && is_call_clobbered (var)) - return false; - } - - return true; -} -/* Returns false when the function is not suitable for tail call optimization - from some reason (e.g. if it takes variable number of arguments). - This test must pass in addition to suitable_for_tail_opt_p in order to make - tail call discovery happen. */ - -static bool -suitable_for_tail_call_opt_p (void) -{ - tree param; - - /* alloca (until we have stack slot life analysis) inhibits - sibling call optimizations, but not tail recursion. */ - if (current_function_calls_alloca) - return false; - - /* If we are using sjlj exceptions, we may need to add a call to - _Unwind_SjLj_Unregister at exit of the function. Which means - that we cannot do any sibcall transformations. */ - if (USING_SJLJ_EXCEPTIONS && current_function_has_exception_handlers ()) - return false; - - /* Any function that calls setjmp might have longjmp called from - any called function. ??? We really should represent this - properly in the CFG so that this needn't be special cased. */ - if (current_function_calls_setjmp) - return false; - - /* ??? It is OK if the argument of a function is taken in some cases, - but not in all cases. See PR15387 and PR19616. Revisit for 4.1. */ - for (param = DECL_ARGUMENTS (current_function_decl); - param; - param = TREE_CHAIN (param)) - if (TREE_ADDRESSABLE (param)) - return false; - - return true; -} - -/* Checks whether the expression EXPR in stmt AT is independent of the - statement pointed to by BSI (in a sense that we already know EXPR's value - at BSI). We use the fact that we are only called from the chain of - basic blocks that have only single successor. Returns the expression - containing the value of EXPR at BSI. */ - -static tree -independent_of_stmt_p (tree expr, tree at, block_stmt_iterator bsi) -{ - basic_block bb, call_bb, at_bb; - edge e; - edge_iterator ei; - - if (is_gimple_min_invariant (expr)) - return expr; - - if (TREE_CODE (expr) != SSA_NAME) - return NULL_TREE; - - /* Mark the blocks in the chain leading to the end. */ - at_bb = bb_for_stmt (at); - call_bb = bb_for_stmt (bsi_stmt (bsi)); - for (bb = call_bb; bb != at_bb; bb = single_succ (bb)) - bb->aux = &bb->aux; - bb->aux = &bb->aux; - - while (1) - { - at = SSA_NAME_DEF_STMT (expr); - bb = bb_for_stmt (at); - - /* The default definition or defined before the chain. */ - if (!bb || !bb->aux) - break; - - if (bb == call_bb) - { - for (; !bsi_end_p (bsi); bsi_next (&bsi)) - if (bsi_stmt (bsi) == at) - break; - - if (!bsi_end_p (bsi)) - expr = NULL_TREE; - break; - } - - if (TREE_CODE (at) != PHI_NODE) - { - expr = NULL_TREE; - break; - } - - FOR_EACH_EDGE (e, ei, bb->preds) - if (e->src->aux) - break; - gcc_assert (e); - - expr = PHI_ARG_DEF_FROM_EDGE (at, e); - if (TREE_CODE (expr) != SSA_NAME) - { - /* The value is a constant. */ - break; - } - } - - /* Unmark the blocks. */ - for (bb = call_bb; bb != at_bb; bb = single_succ (bb)) - bb->aux = NULL; - bb->aux = NULL; - - return expr; -} - -/* Simulates the effect of an assignment of ASS in STMT on the return value - of the tail recursive CALL passed in ASS_VAR. M and A are the - multiplicative and the additive factor for the real return value. */ - -static bool -process_assignment (tree ass, tree stmt, block_stmt_iterator call, tree *m, - tree *a, tree *ass_var) -{ - tree op0, op1, non_ass_var; - tree dest = TREE_OPERAND (ass, 0); - tree src = TREE_OPERAND (ass, 1); - enum tree_code code = TREE_CODE (src); - tree src_var = src; - - /* See if this is a simple copy operation of an SSA name to the function - result. In that case we may have a simple tail call. Ignore type - conversions that can never produce extra code between the function - call and the function return. */ - STRIP_NOPS (src_var); - if (TREE_CODE (src_var) == SSA_NAME) - { - if (src_var != *ass_var) - return false; - - *ass_var = dest; - return true; - } - - if (TREE_CODE_CLASS (code) != tcc_binary) - return false; - - /* Accumulator optimizations will reverse the order of operations. - We can only do that for floating-point types if we're assuming - that addition and multiplication are associative. */ - if (!flag_unsafe_math_optimizations) - if (FLOAT_TYPE_P (TREE_TYPE (DECL_RESULT (current_function_decl)))) - return false; - - /* We only handle the code like - - x = call (); - y = m * x; - z = y + a; - return z; - - TODO -- Extend it for cases where the linear transformation of the output - is expressed in a more complicated way. */ - - op0 = TREE_OPERAND (src, 0); - op1 = TREE_OPERAND (src, 1); - - if (op0 == *ass_var - && (non_ass_var = independent_of_stmt_p (op1, stmt, call))) - ; - else if (op1 == *ass_var - && (non_ass_var = independent_of_stmt_p (op0, stmt, call))) - ; - else - return false; - - switch (code) - { - case PLUS_EXPR: - /* There should be no previous addition. TODO -- it should be fairly - straightforward to lift this restriction -- just allow storing - more complicated expressions in *A, and gimplify it in - adjust_accumulator_values. */ - if (*a) - return false; - *a = non_ass_var; - *ass_var = dest; - return true; - - case MULT_EXPR: - /* Similar remark applies here. Handling multiplication after addition - is just slightly more complicated -- we need to multiply both *A and - *M. */ - if (*a || *m) - return false; - *m = non_ass_var; - *ass_var = dest; - return true; - - /* TODO -- Handle other codes (NEGATE_EXPR, MINUS_EXPR). */ - - default: - return false; - } -} - -/* Propagate VAR through phis on edge E. */ - -static tree -propagate_through_phis (tree var, edge e) -{ - basic_block dest = e->dest; - tree phi; - - for (phi = phi_nodes (dest); phi; phi = PHI_CHAIN (phi)) - if (PHI_ARG_DEF_FROM_EDGE (phi, e) == var) - return PHI_RESULT (phi); - - return var; -} - -/* Finds tailcalls falling into basic block BB. The list of found tailcalls is - added to the start of RET. */ - -static void -find_tail_calls (basic_block bb, struct tailcall **ret) -{ - tree ass_var, ret_var, stmt, func, param, args, call = NULL_TREE; - block_stmt_iterator bsi, absi; - bool tail_recursion; - struct tailcall *nw; - edge e; - tree m, a; - basic_block abb; - stmt_ann_t ann; - - if (!single_succ_p (bb)) - return; - - for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_prev (&bsi)) - { - stmt = bsi_stmt (bsi); - - /* Ignore labels. */ - if (TREE_CODE (stmt) == LABEL_EXPR) - continue; - - /* Check for a call. */ - if (TREE_CODE (stmt) == MODIFY_EXPR) - { - ass_var = TREE_OPERAND (stmt, 0); - call = TREE_OPERAND (stmt, 1); - if (TREE_CODE (call) == WITH_SIZE_EXPR) - call = TREE_OPERAND (call, 0); - } - else - { - ass_var = NULL_TREE; - call = stmt; - } - - if (TREE_CODE (call) == CALL_EXPR) - break; - - /* If the statement has virtual or volatile operands, fail. */ - ann = stmt_ann (stmt); - if (!ZERO_SSA_OPERANDS (stmt, (SSA_OP_VUSE | SSA_OP_VIRTUAL_DEFS)) - || ann->has_volatile_ops) - return; - } - - if (bsi_end_p (bsi)) - { - edge_iterator ei; - /* Recurse to the predecessors. */ - FOR_EACH_EDGE (e, ei, bb->preds) - find_tail_calls (e->src, ret); - - return; - } - - /* We found the call, check whether it is suitable. */ - tail_recursion = false; - func = get_callee_fndecl (call); - if (func == current_function_decl) - { - for (param = DECL_ARGUMENTS (func), args = TREE_OPERAND (call, 1); - param && args; - param = TREE_CHAIN (param), args = TREE_CHAIN (args)) - { - tree arg = TREE_VALUE (args); - if (param != arg) - { - /* Make sure there are no problems with copying. The parameter - have a copyable type and the two arguments must have reasonably - equivalent types. The latter requirement could be relaxed if - we emitted a suitable type conversion statement. */ - if (!is_gimple_reg_type (TREE_TYPE (param)) - || !lang_hooks.types_compatible_p (TREE_TYPE (param), - TREE_TYPE (arg))) - break; - - /* The parameter should be a real operand, so that phi node - created for it at the start of the function has the meaning - of copying the value. This test implies is_gimple_reg_type - from the previous condition, however this one could be - relaxed by being more careful with copying the new value - of the parameter (emitting appropriate MODIFY_EXPR and - updating the virtual operands). */ - if (!is_gimple_reg (param)) - break; - } - } - if (!args && !param) - tail_recursion = true; - } - - /* Now check the statements after the call. None of them has virtual - operands, so they may only depend on the call through its return - value. The return value should also be dependent on each of them, - since we are running after dce. */ - m = NULL_TREE; - a = NULL_TREE; - - abb = bb; - absi = bsi; - while (1) - { - bsi_next (&absi); - - while (bsi_end_p (absi)) - { - ass_var = propagate_through_phis (ass_var, single_succ_edge (abb)); - abb = single_succ (abb); - absi = bsi_start (abb); - } - - stmt = bsi_stmt (absi); - - if (TREE_CODE (stmt) == LABEL_EXPR) - continue; - - if (TREE_CODE (stmt) == RETURN_EXPR) - break; - - if (TREE_CODE (stmt) != MODIFY_EXPR) - return; - - if (!process_assignment (stmt, stmt, bsi, &m, &a, &ass_var)) - return; - } - - /* See if this is a tail call we can handle. */ - ret_var = TREE_OPERAND (stmt, 0); - if (ret_var - && TREE_CODE (ret_var) == MODIFY_EXPR) - { - tree ret_op = TREE_OPERAND (ret_var, 1); - STRIP_NOPS (ret_op); - if (!tail_recursion - && TREE_CODE (ret_op) != SSA_NAME) - return; - - if (!process_assignment (ret_var, stmt, bsi, &m, &a, &ass_var)) - return; - ret_var = TREE_OPERAND (ret_var, 0); - } - - /* We may proceed if there either is no return value, or the return value - is identical to the call's return. */ - if (ret_var - && (ret_var != ass_var)) - return; - - /* If this is not a tail recursive call, we cannot handle addends or - multiplicands. */ - if (!tail_recursion && (m || a)) - return; - - nw = XNEW (struct tailcall); - - nw->call_block = bb; - nw->call_bsi = bsi; - - nw->tail_recursion = tail_recursion; - - nw->mult = m; - nw->add = a; - - nw->next = *ret; - *ret = nw; -} - -/* Adjust the accumulator values according to A and M after BSI, and update - the phi nodes on edge BACK. */ - -static void -adjust_accumulator_values (block_stmt_iterator bsi, tree m, tree a, edge back) -{ - tree stmt, var, phi, tmp; - tree ret_type = TREE_TYPE (DECL_RESULT (current_function_decl)); - tree a_acc_arg = a_acc, m_acc_arg = m_acc; - - if (a) - { - if (m_acc) - { - if (integer_onep (a)) - var = m_acc; - else - { - stmt = build2 (MODIFY_EXPR, ret_type, NULL_TREE, - build2 (MULT_EXPR, ret_type, m_acc, a)); - - tmp = create_tmp_var (ret_type, "acc_tmp"); - add_referenced_var (tmp); - - var = make_ssa_name (tmp, stmt); - TREE_OPERAND (stmt, 0) = var; - bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); - } - } - else - var = a; - - stmt = build2 (MODIFY_EXPR, ret_type, NULL_TREE, - build2 (PLUS_EXPR, ret_type, a_acc, var)); - var = make_ssa_name (SSA_NAME_VAR (a_acc), stmt); - TREE_OPERAND (stmt, 0) = var; - bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); - a_acc_arg = var; - } - - if (m) - { - stmt = build2 (MODIFY_EXPR, ret_type, NULL_TREE, - build2 (MULT_EXPR, ret_type, m_acc, m)); - var = make_ssa_name (SSA_NAME_VAR (m_acc), stmt); - TREE_OPERAND (stmt, 0) = var; - bsi_insert_after (&bsi, stmt, BSI_NEW_STMT); - m_acc_arg = var; - } - - if (a_acc) - { - for (phi = phi_nodes (back->dest); phi; phi = PHI_CHAIN (phi)) - if (PHI_RESULT (phi) == a_acc) - break; - - add_phi_arg (phi, a_acc_arg, back); - } - - if (m_acc) - { - for (phi = phi_nodes (back->dest); phi; phi = PHI_CHAIN (phi)) - if (PHI_RESULT (phi) == m_acc) - break; - - add_phi_arg (phi, m_acc_arg, back); - } -} - -/* Adjust value of the return at the end of BB according to M and A - accumulators. */ - -static void -adjust_return_value (basic_block bb, tree m, tree a) -{ - tree ret_stmt = last_stmt (bb), ret_var, var, stmt, tmp; - tree ret_type = TREE_TYPE (DECL_RESULT (current_function_decl)); - block_stmt_iterator bsi = bsi_last (bb); - - gcc_assert (TREE_CODE (ret_stmt) == RETURN_EXPR); - - ret_var = TREE_OPERAND (ret_stmt, 0); - if (!ret_var) - return; - - if (TREE_CODE (ret_var) == MODIFY_EXPR) - { - ret_var->common.ann = (tree_ann_t) stmt_ann (ret_stmt); - bsi_replace (&bsi, ret_var, true); - SSA_NAME_DEF_STMT (TREE_OPERAND (ret_var, 0)) = ret_var; - ret_var = TREE_OPERAND (ret_var, 0); - ret_stmt = build1 (RETURN_EXPR, TREE_TYPE (ret_stmt), ret_var); - bsi_insert_after (&bsi, ret_stmt, BSI_NEW_STMT); - } - - if (m) - { - stmt = build2 (MODIFY_EXPR, ret_type, NULL_TREE, - build2 (MULT_EXPR, ret_type, m_acc, ret_var)); - - tmp = create_tmp_var (ret_type, "acc_tmp"); - add_referenced_var (tmp); - - var = make_ssa_name (tmp, stmt); - TREE_OPERAND (stmt, 0) = var; - bsi_insert_before (&bsi, stmt, BSI_SAME_STMT); - } - else - var = ret_var; - - if (a) - { - stmt = build2 (MODIFY_EXPR, ret_type, NULL_TREE, - build2 (PLUS_EXPR, ret_type, a_acc, var)); - - tmp = create_tmp_var (ret_type, "acc_tmp"); - add_referenced_var (tmp); - - var = make_ssa_name (tmp, stmt); - TREE_OPERAND (stmt, 0) = var; - bsi_insert_before (&bsi, stmt, BSI_SAME_STMT); - } - - TREE_OPERAND (ret_stmt, 0) = var; - update_stmt (ret_stmt); -} - -/* Subtract COUNT and FREQUENCY from the basic block and it's - outgoing edge. */ -static void -decrease_profile (basic_block bb, gcov_type count, int frequency) -{ - edge e; - bb->count -= count; - if (bb->count < 0) - bb->count = 0; - bb->frequency -= frequency; - if (bb->frequency < 0) - bb->frequency = 0; - if (!single_succ_p (bb)) - { - gcc_assert (!EDGE_COUNT (bb->succs)); - return; - } - e = single_succ_edge (bb); - e->count -= count; - if (e->count < 0) - e->count = 0; -} - -/* Returns true if argument PARAM of the tail recursive call needs to be copied - when the call is eliminated. */ - -static bool -arg_needs_copy_p (tree param) -{ - tree def; - - if (!is_gimple_reg (param) || !var_ann (param)) - return false; - - /* Parameters that are only defined but never used need not be copied. */ - def = default_def (param); - if (!def) - return false; - - return true; -} - -/* Eliminates tail call described by T. TMP_VARS is a list of - temporary variables used to copy the function arguments. */ - -static void -eliminate_tail_call (struct tailcall *t) -{ - tree param, stmt, args, rslt, call; - basic_block bb, first; - edge e; - tree phi; - block_stmt_iterator bsi; - tree orig_stmt; - - stmt = orig_stmt = bsi_stmt (t->call_bsi); - bb = t->call_block; - - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "Eliminated tail recursion in bb %d : ", - bb->index); - print_generic_stmt (dump_file, stmt, TDF_SLIM); - fprintf (dump_file, "\n"); - } - - if (TREE_CODE (stmt) == MODIFY_EXPR) - stmt = TREE_OPERAND (stmt, 1); - - first = single_succ (ENTRY_BLOCK_PTR); - - /* Remove the code after call_bsi that will become unreachable. The - possibly unreachable code in other blocks is removed later in - cfg cleanup. */ - bsi = t->call_bsi; - bsi_next (&bsi); - while (!bsi_end_p (bsi)) - { - tree t = bsi_stmt (bsi); - /* Do not remove the return statement, so that redirect_edge_and_branch - sees how the block ends. */ - if (TREE_CODE (t) == RETURN_EXPR) - break; - - bsi_remove (&bsi, true); - release_defs (t); - } - - /* Number of executions of function has reduced by the tailcall. */ - e = single_succ_edge (t->call_block); - decrease_profile (EXIT_BLOCK_PTR, e->count, EDGE_FREQUENCY (e)); - decrease_profile (ENTRY_BLOCK_PTR, e->count, EDGE_FREQUENCY (e)); - if (e->dest != EXIT_BLOCK_PTR) - decrease_profile (e->dest, e->count, EDGE_FREQUENCY (e)); - - /* Replace the call by a jump to the start of function. */ - e = redirect_edge_and_branch (single_succ_edge (t->call_block), first); - gcc_assert (e); - PENDING_STMT (e) = NULL_TREE; - - /* Add phi node entries for arguments. The ordering of the phi nodes should - be the same as the ordering of the arguments. */ - for (param = DECL_ARGUMENTS (current_function_decl), - args = TREE_OPERAND (stmt, 1), - phi = phi_nodes (first); - param; - param = TREE_CHAIN (param), - args = TREE_CHAIN (args)) - { - if (!arg_needs_copy_p (param)) - continue; - gcc_assert (param == SSA_NAME_VAR (PHI_RESULT (phi))); - - add_phi_arg (phi, TREE_VALUE (args), e); - phi = PHI_CHAIN (phi); - } - - /* Update the values of accumulators. */ - adjust_accumulator_values (t->call_bsi, t->mult, t->add, e); - - call = bsi_stmt (t->call_bsi); - if (TREE_CODE (call) == MODIFY_EXPR) - { - rslt = TREE_OPERAND (call, 0); - - /* Result of the call will no longer be defined. So adjust the - SSA_NAME_DEF_STMT accordingly. */ - SSA_NAME_DEF_STMT (rslt) = build_empty_stmt (); - } - - bsi_remove (&t->call_bsi, true); - release_defs (call); -} - -/* Add phi nodes for the virtual operands defined in the function to the - header of the loop created by tail recursion elimination. - - Originally, we used to add phi nodes only for call clobbered variables, - as the value of the non-call clobbered ones obviously cannot be used - or changed within the recursive call. However, the local variables - from multiple calls now share the same location, so the virtual ssa form - requires us to say that the location dies on further iterations of the loop, - which requires adding phi nodes. -*/ -static void -add_virtual_phis (void) -{ - referenced_var_iterator rvi; - tree var; - - /* The problematic part is that there is no way how to know what - to put into phi nodes (there in fact does not have to be such - ssa name available). A solution would be to have an artificial - use/kill for all virtual operands in EXIT node. Unless we have - this, we cannot do much better than to rebuild the ssa form for - possibly affected virtual ssa names from scratch. */ - - FOR_EACH_REFERENCED_VAR (var, rvi) - { - if (!is_gimple_reg (var) && default_def (var) != NULL_TREE) - mark_sym_for_renaming (var); - } - - update_ssa (TODO_update_ssa_only_virtuals); -} - -/* Optimizes the tailcall described by T. If OPT_TAILCALLS is true, also - mark the tailcalls for the sibcall optimization. */ - -static bool -optimize_tail_call (struct tailcall *t, bool opt_tailcalls) -{ - if (t->tail_recursion) - { - eliminate_tail_call (t); - return true; - } - - if (opt_tailcalls) - { - tree stmt = bsi_stmt (t->call_bsi); - - stmt = get_call_expr_in (stmt); - CALL_EXPR_TAILCALL (stmt) = 1; - if (dump_file && (dump_flags & TDF_DETAILS)) - { - fprintf (dump_file, "Found tail call "); - print_generic_expr (dump_file, stmt, dump_flags); - fprintf (dump_file, " in bb %i\n", t->call_block->index); - } - } - - return false; -} - -/* Optimizes tail calls in the function, turning the tail recursion - into iteration. */ - -static void -tree_optimize_tail_calls_1 (bool opt_tailcalls) -{ - edge e; - bool phis_constructed = false; - struct tailcall *tailcalls = NULL, *act, *next; - bool changed = false; - basic_block first = single_succ (ENTRY_BLOCK_PTR); - tree stmt, param, ret_type, tmp, phi; - edge_iterator ei; - - if (!suitable_for_tail_opt_p ()) - return; - if (opt_tailcalls) - opt_tailcalls = suitable_for_tail_call_opt_p (); - - FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) - { - /* Only traverse the normal exits, i.e. those that end with return - statement. */ - stmt = last_stmt (e->src); - - if (stmt - && TREE_CODE (stmt) == RETURN_EXPR) - find_tail_calls (e->src, &tailcalls); - } - - /* Construct the phi nodes and accumulators if necessary. */ - a_acc = m_acc = NULL_TREE; - for (act = tailcalls; act; act = act->next) - { - if (!act->tail_recursion) - continue; - - if (!phis_constructed) - { - /* Ensure that there is only one predecessor of the block. */ - if (!single_pred_p (first)) - first = split_edge (single_succ_edge (ENTRY_BLOCK_PTR)); - - /* Copy the args if needed. */ - for (param = DECL_ARGUMENTS (current_function_decl); - param; - param = TREE_CHAIN (param)) - if (arg_needs_copy_p (param)) - { - tree name = default_def (param); - tree new_name = make_ssa_name (param, SSA_NAME_DEF_STMT (name)); - tree phi; - - set_default_def (param, new_name); - phi = create_phi_node (name, first); - SSA_NAME_DEF_STMT (name) = phi; - add_phi_arg (phi, new_name, single_pred_edge (first)); - } - phis_constructed = true; - } - - if (act->add && !a_acc) - { - ret_type = TREE_TYPE (DECL_RESULT (current_function_decl)); - - tmp = create_tmp_var (ret_type, "add_acc"); - add_referenced_var (tmp); - - phi = create_phi_node (tmp, first); - add_phi_arg (phi, - /* RET_TYPE can be a float when -ffast-maths is - enabled. */ - fold_convert (ret_type, integer_zero_node), - single_pred_edge (first)); - a_acc = PHI_RESULT (phi); - } - - if (act->mult && !m_acc) - { - ret_type = TREE_TYPE (DECL_RESULT (current_function_decl)); - - tmp = create_tmp_var (ret_type, "mult_acc"); - add_referenced_var (tmp); - - phi = create_phi_node (tmp, first); - add_phi_arg (phi, - /* RET_TYPE can be a float when -ffast-maths is - enabled. */ - fold_convert (ret_type, integer_one_node), - single_pred_edge (first)); - m_acc = PHI_RESULT (phi); - } - } - - - if (phis_constructed) - { - /* Reverse the order of the phi nodes, so that it matches the order - of operands of the function, as assumed by eliminate_tail_call. */ - set_phi_nodes (first, phi_reverse (phi_nodes (first))); - } - - for (; tailcalls; tailcalls = next) - { - next = tailcalls->next; - changed |= optimize_tail_call (tailcalls, opt_tailcalls); - free (tailcalls); - } - - if (a_acc || m_acc) - { - /* Modify the remaining return statements. */ - FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds) - { - stmt = last_stmt (e->src); - - if (stmt - && TREE_CODE (stmt) == RETURN_EXPR) - adjust_return_value (e->src, m_acc, a_acc); - } - } - - if (changed) - { - free_dominance_info (CDI_DOMINATORS); - cleanup_tree_cfg (); - } - - if (phis_constructed) - add_virtual_phis (); -} - -static unsigned int -execute_tail_recursion (void) -{ - tree_optimize_tail_calls_1 (false); - return 0; -} - -static bool -gate_tail_calls (void) -{ - return flag_optimize_sibling_calls != 0; -} - -static unsigned int -execute_tail_calls (void) -{ - tree_optimize_tail_calls_1 (true); - return 0; -} - -struct tree_opt_pass pass_tail_recursion = -{ - "tailr", /* name */ - gate_tail_calls, /* gate */ - execute_tail_recursion, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - 0, /* tv_id */ - PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */ - 0 /* letter */ -}; - -struct tree_opt_pass pass_tail_calls = -{ - "tailc", /* name */ - gate_tail_calls, /* gate */ - execute_tail_calls, /* execute */ - NULL, /* sub */ - NULL, /* next */ - 0, /* static_pass_number */ - 0, /* tv_id */ - PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ - 0, /* properties_provided */ - 0, /* properties_destroyed */ - 0, /* todo_flags_start */ - TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */ - 0 /* letter */ -}; |