diff options
Diffstat (limited to 'gcc-4.2.1-5666.3/gcc/tree-ssa-reassoc.c')
| -rw-r--r-- | gcc-4.2.1-5666.3/gcc/tree-ssa-reassoc.c | 1521 |
1 files changed, 1521 insertions, 0 deletions
diff --git a/gcc-4.2.1-5666.3/gcc/tree-ssa-reassoc.c b/gcc-4.2.1-5666.3/gcc/tree-ssa-reassoc.c new file mode 100644 index 000000000..d93f44d0a --- /dev/null +++ b/gcc-4.2.1-5666.3/gcc/tree-ssa-reassoc.c @@ -0,0 +1,1521 @@ +/* Reassociation for trees. + Copyright (C) 2005 Free Software Foundation, Inc. + Contributed by Daniel Berlin <dan@dberlin.org> + +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 "errors.h" +#include "ggc.h" +#include "tree.h" +#include "basic-block.h" +#include "diagnostic.h" +#include "tree-inline.h" +#include "tree-flow.h" +#include "tree-gimple.h" +#include "tree-dump.h" +#include "timevar.h" +#include "tree-iterator.h" +#include "tree-pass.h" +#include "alloc-pool.h" +#include "vec.h" +#include "langhooks.h" + +/* This is a simple global reassociation pass. It is, in part, based + on the LLVM pass of the same name (They do some things more/less + than we do, in different orders, etc). + + It consists of five steps: + + 1. Breaking up subtract operations into addition + negate, where + it would promote the reassociation of adds. + + 2. Left linearization of the expression trees, so that (A+B)+(C+D) + becomes (((A+B)+C)+D), which is easier for us to rewrite later. + During linearization, we place the operands of the binary + expressions into a vector of operand_entry_t + + 3. Optimization of the operand lists, eliminating things like a + + -a, a & a, etc. + + 4. Rewrite the expression trees we linearized and optimized so + they are in proper rank order. + + 5. Repropagate negates, as nothing else will clean it up ATM. + + A bit of theory on #4, since nobody seems to write anything down + about why it makes sense to do it the way they do it: + + We could do this much nicer theoretically, but don't (for reasons + explained after how to do it theoretically nice :P). + + In order to promote the most redundancy elimination, you want + binary expressions whose operands are the same rank (or + preferably, the same value) exposed to the redundancy eliminator, + for possible elimination. + + So the way to do this if we really cared, is to build the new op + tree from the leaves to the roots, merging as you go, and putting the + new op on the end of the worklist, until you are left with one + thing on the worklist. + + IE if you have to rewrite the following set of operands (listed with + rank in parentheses), with opcode PLUS_EXPR: + + a (1), b (1), c (1), d (2), e (2) + + + We start with our merge worklist empty, and the ops list with all of + those on it. + + You want to first merge all leaves of the same rank, as much as + possible. + + So first build a binary op of + + mergetmp = a + b, and put "mergetmp" on the merge worklist. + + Because there is no three operand form of PLUS_EXPR, c is not going to + be exposed to redundancy elimination as a rank 1 operand. + + So you might as well throw it on the merge worklist (you could also + consider it to now be a rank two operand, and merge it with d and e, + but in this case, you then have evicted e from a binary op. So at + least in this situation, you can't win.) + + Then build a binary op of d + e + mergetmp2 = d + e + + and put mergetmp2 on the merge worklist. + + so merge worklist = {mergetmp, c, mergetmp2} + + Continue building binary ops of these operations until you have only + one operation left on the worklist. + + So we have + + build binary op + mergetmp3 = mergetmp + c + + worklist = {mergetmp2, mergetmp3} + + mergetmp4 = mergetmp2 + mergetmp3 + + worklist = {mergetmp4} + + because we have one operation left, we can now just set the original + statement equal to the result of that operation. + + This will at least expose a + b and d + e to redundancy elimination + as binary operations. + + For extra points, you can reuse the old statements to build the + mergetmps, since you shouldn't run out. + + So why don't we do this? + + Because it's expensive, and rarely will help. Most trees we are + reassociating have 3 or less ops. If they have 2 ops, they already + will be written into a nice single binary op. If you have 3 ops, a + single simple check suffices to tell you whether the first two are of the + same rank. If so, you know to order it + + mergetmp = op1 + op2 + newstmt = mergetmp + op3 + + instead of + mergetmp = op2 + op3 + newstmt = mergetmp + op1 + + If all three are of the same rank, you can't expose them all in a + single binary operator anyway, so the above is *still* the best you + can do. + + Thus, this is what we do. When we have three ops left, we check to see + what order to put them in, and call it a day. As a nod to vector sum + reduction, we check if any of ops are a really a phi node that is a + destructive update for the associating op, and keep the destructive + update together for vector sum reduction recognition. */ + + +/* Statistics */ +static struct +{ + int linearized; + int constants_eliminated; + int ops_eliminated; + int rewritten; +} reassociate_stats; + +/* Operator, rank pair. */ +typedef struct operand_entry +{ + unsigned int rank; + tree op; +} *operand_entry_t; + +static alloc_pool operand_entry_pool; + + +/* Starting rank number for a given basic block, so that we can rank + operations using unmovable instructions in that BB based on the bb + depth. */ +static unsigned int *bb_rank; + +/* Operand->rank hashtable. */ +static htab_t operand_rank; + + +/* Look up the operand rank structure for expression E. */ + +static operand_entry_t +find_operand_rank (tree e) +{ + void **slot; + struct operand_entry vrd; + + vrd.op = e; + slot = htab_find_slot (operand_rank, &vrd, NO_INSERT); + if (!slot) + return NULL; + return ((operand_entry_t) *slot); +} + +/* Insert {E,RANK} into the operand rank hashtable. */ + +static void +insert_operand_rank (tree e, unsigned int rank) +{ + void **slot; + operand_entry_t new_pair = pool_alloc (operand_entry_pool); + + new_pair->op = e; + new_pair->rank = rank; + slot = htab_find_slot (operand_rank, new_pair, INSERT); + gcc_assert (*slot == NULL); + *slot = new_pair; +} + +/* Return the hash value for a operand rank structure */ + +static hashval_t +operand_entry_hash (const void *p) +{ + const operand_entry_t vr = (operand_entry_t) p; + return iterative_hash_expr (vr->op, 0); +} + +/* Return true if two operand rank structures are equal. */ + +static int +operand_entry_eq (const void *p1, const void *p2) +{ + const operand_entry_t vr1 = (operand_entry_t) p1; + const operand_entry_t vr2 = (operand_entry_t) p2; + return vr1->op == vr2->op; +} + +/* Given an expression E, return the rank of the expression. */ + +static unsigned int +get_rank (tree e) +{ + operand_entry_t vr; + + /* Constants have rank 0. */ + if (is_gimple_min_invariant (e)) + return 0; + + /* SSA_NAME's have the rank of the expression they are the result + of. + For globals and uninitialized values, the rank is 0. + For function arguments, use the pre-setup rank. + For PHI nodes, stores, asm statements, etc, we use the rank of + the BB. + For simple operations, the rank is the maximum rank of any of + its operands, or the bb_rank, whichever is less. + I make no claims that this is optimal, however, it gives good + results. */ + + if (TREE_CODE (e) == SSA_NAME) + { + tree stmt; + tree rhs; + unsigned int rank, maxrank; + int i; + + if (TREE_CODE (SSA_NAME_VAR (e)) == PARM_DECL + && e == default_def (SSA_NAME_VAR (e))) + return find_operand_rank (e)->rank; + + stmt = SSA_NAME_DEF_STMT (e); + if (bb_for_stmt (stmt) == NULL) + return 0; + + if (TREE_CODE (stmt) != MODIFY_EXPR + || !ZERO_SSA_OPERANDS (stmt, SSA_OP_VIRTUAL_DEFS)) + return bb_rank[bb_for_stmt (stmt)->index]; + + /* If we already have a rank for this expression, use that. */ + vr = find_operand_rank (e); + if (vr) + return vr->rank; + + /* Otherwise, find the maximum rank for the operands, or the bb + rank, whichever is less. */ + rank = 0; + maxrank = bb_rank[bb_for_stmt(stmt)->index]; + rhs = TREE_OPERAND (stmt, 1); + if (TREE_CODE_LENGTH (TREE_CODE (rhs)) == 0) + rank = MAX (rank, get_rank (rhs)); + else + { + for (i = 0; + i < TREE_CODE_LENGTH (TREE_CODE (rhs)) + && TREE_OPERAND (rhs, i) + && rank != maxrank; + i++) + rank = MAX(rank, get_rank (TREE_OPERAND (rhs, i))); + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Rank for "); + print_generic_expr (dump_file, e, 0); + fprintf (dump_file, " is %d\n", (rank + 1)); + } + + /* Note the rank in the hashtable so we don't recompute it. */ + insert_operand_rank (e, (rank + 1)); + return (rank + 1); + } + + /* Globals, etc, are rank 0 */ + return 0; +} + +DEF_VEC_P(operand_entry_t); +DEF_VEC_ALLOC_P(operand_entry_t, heap); + +/* We want integer ones to end up last no matter what, since they are + the ones we can do the most with. */ +#define INTEGER_CONST_TYPE 1 << 3 +#define FLOAT_CONST_TYPE 1 << 2 +#define OTHER_CONST_TYPE 1 << 1 + +/* Classify an invariant tree into integer, float, or other, so that + we can sort them to be near other constants of the same type. */ +static inline int +constant_type (tree t) +{ + if (INTEGRAL_TYPE_P (TREE_TYPE (t))) + return INTEGER_CONST_TYPE; + else if (SCALAR_FLOAT_TYPE_P (TREE_TYPE (t))) + return FLOAT_CONST_TYPE; + else + return OTHER_CONST_TYPE; +} + +/* qsort comparison function to sort operand entries PA and PB by rank + so that the sorted array is ordered by rank in decreasing order. */ +static int +sort_by_operand_rank (const void *pa, const void *pb) +{ + const operand_entry_t oea = *(const operand_entry_t *)pa; + const operand_entry_t oeb = *(const operand_entry_t *)pb; + + /* It's nicer for optimize_expression if constants that are likely + to fold when added/multiplied//whatever are put next to each + other. Since all constants have rank 0, order them by type. */ + if (oeb->rank == 0 && oea->rank == 0) + return constant_type (oeb->op) - constant_type (oea->op); + + /* Lastly, make sure the versions that are the same go next to each + other. We use SSA_NAME_VERSION because it's stable. */ + if ((oeb->rank - oea->rank == 0) + && TREE_CODE (oea->op) == SSA_NAME + && TREE_CODE (oeb->op) == SSA_NAME) + return SSA_NAME_VERSION (oeb->op) - SSA_NAME_VERSION (oea->op); + + return oeb->rank - oea->rank; +} + +/* Add an operand entry to *OPS for the tree operand OP. */ + +static void +add_to_ops_vec (VEC(operand_entry_t, heap) **ops, tree op) +{ + operand_entry_t oe = pool_alloc (operand_entry_pool); + + oe->op = op; + oe->rank = get_rank (op); + VEC_safe_push (operand_entry_t, heap, *ops, oe); +} + +/* Return true if STMT is reassociable operation containing a binary + operation with tree code CODE. */ + +static bool +is_reassociable_op (tree stmt, enum tree_code code) +{ + if (!IS_EMPTY_STMT (stmt) + && TREE_CODE (stmt) == MODIFY_EXPR + && TREE_CODE (TREE_OPERAND (stmt, 1)) == code + && has_single_use (TREE_OPERAND (stmt, 0))) + return true; + return false; +} + + +/* Given NAME, if NAME is defined by a unary operation OPCODE, return the + operand of the negate operation. Otherwise, return NULL. */ + +static tree +get_unary_op (tree name, enum tree_code opcode) +{ + tree stmt = SSA_NAME_DEF_STMT (name); + tree rhs; + + if (TREE_CODE (stmt) != MODIFY_EXPR) + return NULL_TREE; + + rhs = TREE_OPERAND (stmt, 1); + if (TREE_CODE (rhs) == opcode) + return TREE_OPERAND (rhs, 0); + return NULL_TREE; +} + +/* If CURR and LAST are a pair of ops that OPCODE allows us to + eliminate through equivalences, do so, remove them from OPS, and + return true. Otherwise, return false. */ + +static bool +eliminate_duplicate_pair (enum tree_code opcode, + VEC (operand_entry_t, heap) **ops, + bool *all_done, + unsigned int i, + operand_entry_t curr, + operand_entry_t last) +{ + + /* If we have two of the same op, and the opcode is & |, min, or max, + we can eliminate one of them. + If we have two of the same op, and the opcode is ^, we can + eliminate both of them. */ + + if (last && last->op == curr->op) + { + switch (opcode) + { + case MAX_EXPR: + case MIN_EXPR: + case BIT_IOR_EXPR: + case BIT_AND_EXPR: + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Equivalence: "); + print_generic_expr (dump_file, curr->op, 0); + fprintf (dump_file, " [&|minmax] "); + print_generic_expr (dump_file, last->op, 0); + fprintf (dump_file, " -> "); + print_generic_stmt (dump_file, last->op, 0); + } + + VEC_ordered_remove (operand_entry_t, *ops, i); + reassociate_stats.ops_eliminated ++; + + return true; + + case BIT_XOR_EXPR: + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Equivalence: "); + print_generic_expr (dump_file, curr->op, 0); + fprintf (dump_file, " ^ "); + print_generic_expr (dump_file, last->op, 0); + fprintf (dump_file, " -> nothing\n"); + } + + reassociate_stats.ops_eliminated += 2; + + if (VEC_length (operand_entry_t, *ops) == 2) + { + VEC_free (operand_entry_t, heap, *ops); + *ops = NULL; + add_to_ops_vec (ops, fold_convert (TREE_TYPE (last->op), + integer_zero_node)); + *all_done = true; + } + else + { + VEC_ordered_remove (operand_entry_t, *ops, i-1); + VEC_ordered_remove (operand_entry_t, *ops, i-1); + } + + return true; + + default: + break; + } + } + return false; +} + +/* If OPCODE is PLUS_EXPR, CURR->OP is really a negate expression, + look in OPS for a corresponding positive operation to cancel it + out. If we find one, remove the other from OPS, replace + OPS[CURRINDEX] with 0, and return true. Otherwise, return + false. */ + +static bool +eliminate_plus_minus_pair (enum tree_code opcode, + VEC (operand_entry_t, heap) **ops, + unsigned int currindex, + operand_entry_t curr) +{ + tree negateop; + unsigned int i; + operand_entry_t oe; + + if (opcode != PLUS_EXPR || TREE_CODE (curr->op) != SSA_NAME) + return false; + + negateop = get_unary_op (curr->op, NEGATE_EXPR); + if (negateop == NULL_TREE) + return false; + + /* Any non-negated version will have a rank that is one less than + the current rank. So once we hit those ranks, if we don't find + one, we can stop. */ + + for (i = currindex + 1; + VEC_iterate (operand_entry_t, *ops, i, oe) + && oe->rank >= curr->rank - 1 ; + i++) + { + if (oe->op == negateop) + { + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Equivalence: "); + print_generic_expr (dump_file, negateop, 0); + fprintf (dump_file, " + -"); + print_generic_expr (dump_file, oe->op, 0); + fprintf (dump_file, " -> 0\n"); + } + + VEC_ordered_remove (operand_entry_t, *ops, i); + add_to_ops_vec (ops, fold_convert(TREE_TYPE (oe->op), + integer_zero_node)); + VEC_ordered_remove (operand_entry_t, *ops, currindex); + reassociate_stats.ops_eliminated ++; + + return true; + } + } + + return false; +} + +/* If OPCODE is BIT_IOR_EXPR, BIT_AND_EXPR, and, CURR->OP is really a + bitwise not expression, look in OPS for a corresponding operand to + cancel it out. If we find one, remove the other from OPS, replace + OPS[CURRINDEX] with 0, and return true. Otherwise, return + false. */ + +static bool +eliminate_not_pairs (enum tree_code opcode, + VEC (operand_entry_t, heap) **ops, + unsigned int currindex, + operand_entry_t curr) +{ + tree notop; + unsigned int i; + operand_entry_t oe; + + if ((opcode != BIT_IOR_EXPR && opcode != BIT_AND_EXPR) + || TREE_CODE (curr->op) != SSA_NAME) + return false; + + notop = get_unary_op (curr->op, BIT_NOT_EXPR); + if (notop == NULL_TREE) + return false; + + /* Any non-not version will have a rank that is one less than + the current rank. So once we hit those ranks, if we don't find + one, we can stop. */ + + for (i = currindex + 1; + VEC_iterate (operand_entry_t, *ops, i, oe) + && oe->rank >= curr->rank - 1; + i++) + { + if (oe->op == notop) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Equivalence: "); + print_generic_expr (dump_file, notop, 0); + if (opcode == BIT_AND_EXPR) + fprintf (dump_file, " & ~"); + else if (opcode == BIT_IOR_EXPR) + fprintf (dump_file, " | ~"); + print_generic_expr (dump_file, oe->op, 0); + if (opcode == BIT_AND_EXPR) + fprintf (dump_file, " -> 0\n"); + else if (opcode == BIT_IOR_EXPR) + fprintf (dump_file, " -> -1\n"); + } + + if (opcode == BIT_AND_EXPR) + oe->op = fold_convert (TREE_TYPE (oe->op), integer_zero_node); + else if (opcode == BIT_IOR_EXPR) + oe->op = build_low_bits_mask (TREE_TYPE (oe->op), + TYPE_PRECISION (TREE_TYPE (oe->op))); + + reassociate_stats.ops_eliminated + += VEC_length (operand_entry_t, *ops) - 1; + VEC_free (operand_entry_t, heap, *ops); + *ops = NULL; + VEC_safe_push (operand_entry_t, heap, *ops, oe); + return true; + } + } + + return false; +} + +/* Use constant value that may be present in OPS to try to eliminate + operands. Note that this function is only really used when we've + eliminated ops for other reasons, or merged constants. Across + single statements, fold already does all of this, plus more. There + is little point in duplicating logic, so I've only included the + identities that I could ever construct testcases to trigger. */ + +static void +eliminate_using_constants (enum tree_code opcode, + VEC(operand_entry_t, heap) **ops) +{ + operand_entry_t oelast = VEC_last (operand_entry_t, *ops); + + if (oelast->rank == 0 && INTEGRAL_TYPE_P (TREE_TYPE (oelast->op))) + { + switch (opcode) + { + case BIT_AND_EXPR: + if (integer_zerop (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found & 0, removing all other ops\n"); + + reassociate_stats.ops_eliminated + += VEC_length (operand_entry_t, *ops) - 1; + + VEC_free (operand_entry_t, heap, *ops); + *ops = NULL; + VEC_safe_push (operand_entry_t, heap, *ops, oelast); + return; + } + } + else if (integer_all_onesp (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found & -1, removing\n"); + VEC_pop (operand_entry_t, *ops); + reassociate_stats.ops_eliminated++; + } + } + break; + case BIT_IOR_EXPR: + if (integer_all_onesp (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found | -1, removing all other ops\n"); + + reassociate_stats.ops_eliminated + += VEC_length (operand_entry_t, *ops) - 1; + + VEC_free (operand_entry_t, heap, *ops); + *ops = NULL; + VEC_safe_push (operand_entry_t, heap, *ops, oelast); + return; + } + } + else if (integer_zerop (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found | 0, removing\n"); + VEC_pop (operand_entry_t, *ops); + reassociate_stats.ops_eliminated++; + } + } + break; + case MULT_EXPR: + if (integer_zerop (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found * 0, removing all other ops\n"); + + reassociate_stats.ops_eliminated + += VEC_length (operand_entry_t, *ops) - 1; + VEC_free (operand_entry_t, heap, *ops); + *ops = NULL; + VEC_safe_push (operand_entry_t, heap, *ops, oelast); + return; + } + } + else if (integer_onep (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found * 1, removing\n"); + VEC_pop (operand_entry_t, *ops); + reassociate_stats.ops_eliminated++; + return; + } + } + break; + case BIT_XOR_EXPR: + case PLUS_EXPR: + case MINUS_EXPR: + if (integer_zerop (oelast->op)) + { + if (VEC_length (operand_entry_t, *ops) != 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Found [|^+] 0, removing\n"); + VEC_pop (operand_entry_t, *ops); + reassociate_stats.ops_eliminated++; + return; + } + } + break; + default: + break; + } + } +} + +/* Perform various identities and other optimizations on the list of + operand entries, stored in OPS. The tree code for the binary + operation between all the operands is OPCODE. */ + +static void +optimize_ops_list (enum tree_code opcode, + VEC (operand_entry_t, heap) **ops) +{ + unsigned int length = VEC_length (operand_entry_t, *ops); + unsigned int i; + operand_entry_t oe; + operand_entry_t oelast = NULL; + bool iterate = false; + + if (length == 1) + return; + + oelast = VEC_last (operand_entry_t, *ops); + + /* If the last two are constants, pop the constants off, merge them + and try the next two. */ + if (oelast->rank == 0 && is_gimple_min_invariant (oelast->op)) + { + operand_entry_t oelm1 = VEC_index (operand_entry_t, *ops, length - 2); + + if (oelm1->rank == 0 + && is_gimple_min_invariant (oelm1->op) + && lang_hooks.types_compatible_p (TREE_TYPE (oelm1->op), + TREE_TYPE (oelast->op))) + { + tree folded = fold_binary (opcode, TREE_TYPE (oelm1->op), + oelm1->op, oelast->op); + + if (folded && is_gimple_min_invariant (folded)) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Merging constants\n"); + + VEC_pop (operand_entry_t, *ops); + VEC_pop (operand_entry_t, *ops); + + add_to_ops_vec (ops, folded); + reassociate_stats.constants_eliminated++; + + optimize_ops_list (opcode, ops); + return; + } + } + } + + eliminate_using_constants (opcode, ops); + oelast = NULL; + + for (i = 0; VEC_iterate (operand_entry_t, *ops, i, oe);) + { + bool done = false; + + if (eliminate_not_pairs (opcode, ops, i, oe)) + return; + if (eliminate_duplicate_pair (opcode, ops, &done, i, oe, oelast) + || (!done && eliminate_plus_minus_pair (opcode, ops, i, oe))) + { + if (done) + return; + iterate = true; + oelast = NULL; + continue; + } + oelast = oe; + i++; + } + + length = VEC_length (operand_entry_t, *ops); + oelast = VEC_last (operand_entry_t, *ops); + + if (iterate) + optimize_ops_list (opcode, ops); +} + +/* Return true if OPERAND is defined by a PHI node which uses the LHS + of STMT in it's operands. This is also known as a "destructive + update" operation. */ + +static bool +is_phi_for_stmt (tree stmt, tree operand) +{ + tree def_stmt; + tree lhs = TREE_OPERAND (stmt, 0); + use_operand_p arg_p; + ssa_op_iter i; + + if (TREE_CODE (operand) != SSA_NAME) + return false; + + def_stmt = SSA_NAME_DEF_STMT (operand); + if (TREE_CODE (def_stmt) != PHI_NODE) + return false; + + FOR_EACH_PHI_ARG (arg_p, def_stmt, i, SSA_OP_USE) + if (lhs == USE_FROM_PTR (arg_p)) + return true; + return false; +} + +/* Recursively rewrite our linearized statements so that the operators + match those in OPS[OPINDEX], putting the computation in rank + order. */ + +static void +rewrite_expr_tree (tree stmt, unsigned int opindex, + VEC(operand_entry_t, heap) * ops) +{ + tree rhs = TREE_OPERAND (stmt, 1); + operand_entry_t oe; + + /* If we have three operands left, then we want to make sure the one + that gets the double binary op are the ones with the same rank. + + The alternative we try is to see if this is a destructive + update style statement, which is like: + b = phi (a, ...) + a = c + b; + In that case, we want to use the destructive update form to + expose the possible vectorizer sum reduction opportunity. + In that case, the third operand will be the phi node. + + We could, of course, try to be better as noted above, and do a + lot of work to try to find these opportunities in >3 operand + cases, but it is unlikely to be worth it. */ + if (opindex + 3 == VEC_length (operand_entry_t, ops)) + { + operand_entry_t oe1, oe2, oe3; + + oe1 = VEC_index (operand_entry_t, ops, opindex); + oe2 = VEC_index (operand_entry_t, ops, opindex + 1); + oe3 = VEC_index (operand_entry_t, ops, opindex + 2); + + if ((oe1->rank == oe2->rank + && oe2->rank != oe3->rank) + || (is_phi_for_stmt (stmt, oe3->op) + && !is_phi_for_stmt (stmt, oe1->op) + && !is_phi_for_stmt (stmt, oe2->op))) + { + struct operand_entry temp = *oe3; + oe3->op = oe1->op; + oe3->rank = oe1->rank; + oe1->op = temp.op; + oe1->rank= temp.rank; + } + } + + /* The final recursion case for this function is that you have + exactly two operations left. + If we had one exactly one op in the entire list to start with, we + would have never called this function, and the tail recursion + rewrites them one at a time. */ + if (opindex + 2 == VEC_length (operand_entry_t, ops)) + { + operand_entry_t oe1, oe2; + + oe1 = VEC_index (operand_entry_t, ops, opindex); + oe2 = VEC_index (operand_entry_t, ops, opindex + 1); + + if (TREE_OPERAND (rhs, 0) != oe1->op + || TREE_OPERAND (rhs, 1) != oe2->op) + { + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Transforming "); + print_generic_expr (dump_file, rhs, 0); + } + + TREE_OPERAND (rhs, 0) = oe1->op; + TREE_OPERAND (rhs, 1) = oe2->op; + update_stmt (stmt); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " into "); + print_generic_stmt (dump_file, rhs, 0); + } + + } + return; + } + + /* If we hit here, we should have 3 or more ops left. */ + gcc_assert (opindex + 2 < VEC_length (operand_entry_t, ops)); + + /* Rewrite the next operator. */ + oe = VEC_index (operand_entry_t, ops, opindex); + + if (oe->op != TREE_OPERAND (rhs, 1)) + { + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Transforming "); + print_generic_expr (dump_file, rhs, 0); + } + + TREE_OPERAND (rhs, 1) = oe->op; + update_stmt (stmt); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " into "); + print_generic_stmt (dump_file, rhs, 0); + } + } + /* Recurse on the LHS of the binary operator, which is guaranteed to + be the non-leaf side. */ + rewrite_expr_tree (SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0)), + opindex + 1, ops); +} + +/* Transform STMT, which is really (A +B) + (C + D) into the left + linear form, ((A+B)+C)+D. + Recurse on D if necessary. */ + +static void +linearize_expr (tree stmt) +{ + block_stmt_iterator bsinow, bsirhs; + tree rhs = TREE_OPERAND (stmt, 1); + enum tree_code rhscode = TREE_CODE (rhs); + tree binrhs = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 1)); + tree binlhs = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0)); + tree newbinrhs = NULL_TREE; + + gcc_assert (is_reassociable_op (binlhs, TREE_CODE (rhs)) + && is_reassociable_op (binrhs, TREE_CODE (rhs))); + + bsinow = bsi_for_stmt (stmt); + bsirhs = bsi_for_stmt (binrhs); + bsi_move_before (&bsirhs, &bsinow); + + TREE_OPERAND (rhs, 1) = TREE_OPERAND (TREE_OPERAND (binrhs, 1), 0); + if (TREE_CODE (TREE_OPERAND (rhs, 1)) == SSA_NAME) + newbinrhs = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 1)); + TREE_OPERAND (TREE_OPERAND (binrhs, 1), 0) = TREE_OPERAND (binlhs, 0); + TREE_OPERAND (rhs, 0) = TREE_OPERAND (binrhs, 0); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Linearized: "); + print_generic_stmt (dump_file, rhs, 0); + } + + reassociate_stats.linearized++; + update_stmt (binrhs); + update_stmt (binlhs); + update_stmt (stmt); + TREE_VISITED (binrhs) = 1; + TREE_VISITED (binlhs) = 1; + TREE_VISITED (stmt) = 1; + + /* Tail recurse on the new rhs if it still needs reassociation. */ + if (newbinrhs && is_reassociable_op (newbinrhs, rhscode)) + linearize_expr (stmt); + +} + +/* If LHS has a single immediate use that is a MODIFY_EXPR, return + it. Otherwise, return NULL. */ + +static tree +get_single_immediate_use (tree lhs) +{ + use_operand_p immuse; + tree immusestmt; + + if (TREE_CODE (lhs) == SSA_NAME + && single_imm_use (lhs, &immuse, &immusestmt)) + { + if (TREE_CODE (immusestmt) == RETURN_EXPR) + immusestmt = TREE_OPERAND (immusestmt, 0); + if (TREE_CODE (immusestmt) == MODIFY_EXPR) + return immusestmt; + } + return NULL_TREE; +} +static VEC(tree, heap) *broken_up_subtracts; + + +/* Recursively negate the value of TONEGATE, and return the SSA_NAME + representing the negated value. Insertions of any necessary + instructions go before BSI. + This function is recursive in that, if you hand it "a_5" as the + value to negate, and a_5 is defined by "a_5 = b_3 + b_4", it will + transform b_3 + b_4 into a_5 = -b_3 + -b_4. */ + +static tree +negate_value (tree tonegate, block_stmt_iterator *bsi) +{ + tree negatedef = tonegate; + tree resultofnegate; + + if (TREE_CODE (tonegate) == SSA_NAME) + negatedef = SSA_NAME_DEF_STMT (tonegate); + + /* If we are trying to negate a name, defined by an add, negate the + add operands instead. */ + if (TREE_CODE (tonegate) == SSA_NAME + && TREE_CODE (negatedef) == MODIFY_EXPR + && TREE_CODE (TREE_OPERAND (negatedef, 0)) == SSA_NAME + && has_single_use (TREE_OPERAND (negatedef, 0)) + && TREE_CODE (TREE_OPERAND (negatedef, 1)) == PLUS_EXPR) + { + block_stmt_iterator bsi; + tree binop = TREE_OPERAND (negatedef, 1); + + bsi = bsi_for_stmt (negatedef); + TREE_OPERAND (binop, 0) = negate_value (TREE_OPERAND (binop, 0), + &bsi); + bsi = bsi_for_stmt (negatedef); + TREE_OPERAND (binop, 1) = negate_value (TREE_OPERAND (binop, 1), + &bsi); + update_stmt (negatedef); + return TREE_OPERAND (negatedef, 0); + } + + tonegate = fold_build1 (NEGATE_EXPR, TREE_TYPE (tonegate), tonegate); + resultofnegate = force_gimple_operand_bsi (bsi, tonegate, true, + NULL_TREE); + VEC_safe_push (tree, heap, broken_up_subtracts, resultofnegate); + return resultofnegate; + +} + +/* Return true if we should break up the subtract in STMT into an add + with negate. This is true when we the subtract operands are really + adds, or the subtract itself is used in an add expression. In + either case, breaking up the subtract into an add with negate + exposes the adds to reassociation. */ + +static bool +should_break_up_subtract (tree stmt) +{ + + tree lhs = TREE_OPERAND (stmt, 0); + tree rhs = TREE_OPERAND (stmt, 1); + tree binlhs = TREE_OPERAND (rhs, 0); + tree binrhs = TREE_OPERAND (rhs, 1); + tree immusestmt; + + if (TREE_CODE (binlhs) == SSA_NAME + && is_reassociable_op (SSA_NAME_DEF_STMT (binlhs), PLUS_EXPR)) + return true; + + if (TREE_CODE (binrhs) == SSA_NAME + && is_reassociable_op (SSA_NAME_DEF_STMT (binrhs), PLUS_EXPR)) + return true; + + if (TREE_CODE (lhs) == SSA_NAME + && (immusestmt = get_single_immediate_use (lhs)) + && TREE_CODE (TREE_OPERAND (immusestmt, 1)) == PLUS_EXPR) + return true; + return false; + +} + +/* Transform STMT from A - B into A + -B. */ + +static void +break_up_subtract (tree stmt, block_stmt_iterator *bsi) +{ + tree rhs = TREE_OPERAND (stmt, 1); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Breaking up subtract "); + print_generic_stmt (dump_file, stmt, 0); + } + + TREE_SET_CODE (TREE_OPERAND (stmt, 1), PLUS_EXPR); + TREE_OPERAND (rhs, 1) = negate_value (TREE_OPERAND (rhs, 1), bsi); + + update_stmt (stmt); +} + +/* Recursively linearize a binary expression that is the RHS of STMT. + Place the operands of the expression tree in the vector named OPS. */ + +static void +linearize_expr_tree (VEC(operand_entry_t, heap) **ops, tree stmt) +{ + block_stmt_iterator bsinow, bsilhs; + tree rhs = TREE_OPERAND (stmt, 1); + tree binrhs = TREE_OPERAND (rhs, 1); + tree binlhs = TREE_OPERAND (rhs, 0); + tree binlhsdef, binrhsdef; + bool binlhsisreassoc = false; + bool binrhsisreassoc = false; + enum tree_code rhscode = TREE_CODE (rhs); + + TREE_VISITED (stmt) = 1; + + if (TREE_CODE (binlhs) == SSA_NAME) + { + binlhsdef = SSA_NAME_DEF_STMT (binlhs); + binlhsisreassoc = is_reassociable_op (binlhsdef, rhscode); + } + + if (TREE_CODE (binrhs) == SSA_NAME) + { + binrhsdef = SSA_NAME_DEF_STMT (binrhs); + binrhsisreassoc = is_reassociable_op (binrhsdef, rhscode); + } + + /* If the LHS is not reassociable, but the RHS is, we need to swap + them. If neither is reassociable, there is nothing we can do, so + just put them in the ops vector. If the LHS is reassociable, + linearize it. If both are reassociable, then linearize the RHS + and the LHS. */ + + if (!binlhsisreassoc) + { + tree temp; + + if (!binrhsisreassoc) + { + add_to_ops_vec (ops, binrhs); + add_to_ops_vec (ops, binlhs); + return; + } + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "swapping operands of "); + print_generic_expr (dump_file, stmt, 0); + } + + swap_tree_operands (stmt, &TREE_OPERAND (rhs, 0), + &TREE_OPERAND (rhs, 1)); + update_stmt (stmt); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " is now "); + print_generic_stmt (dump_file, stmt, 0); + } + + /* We want to make it so the lhs is always the reassociative op, + so swap. */ + temp = binlhs; + binlhs = binrhs; + binrhs = temp; + } + else if (binrhsisreassoc) + { + linearize_expr (stmt); + gcc_assert (rhs == TREE_OPERAND (stmt, 1)); + binlhs = TREE_OPERAND (rhs, 0); + binrhs = TREE_OPERAND (rhs, 1); + } + + gcc_assert (TREE_CODE (binrhs) != SSA_NAME + || !is_reassociable_op (SSA_NAME_DEF_STMT (binrhs), rhscode)); + bsinow = bsi_for_stmt (stmt); + bsilhs = bsi_for_stmt (SSA_NAME_DEF_STMT (binlhs)); + bsi_move_before (&bsilhs, &bsinow); + linearize_expr_tree (ops, SSA_NAME_DEF_STMT (binlhs)); + add_to_ops_vec (ops, binrhs); +} + +/* Repropagate the negates back into subtracts, since no other pass + currently does it. */ + +static void +repropagate_negates (void) +{ + unsigned int i = 0; + tree negate; + + for (i = 0; VEC_iterate (tree, broken_up_subtracts, i, negate); i++) + { + tree user = get_single_immediate_use (negate); + + /* The negate operand can be either operand of a PLUS_EXPR + (it can be the LHS if the RHS is a constant for example). + + Force the negate operand to the RHS of the PLUS_EXPR, then + transform the PLUS_EXPR into a MINUS_EXPR. */ + if (user + && TREE_CODE (user) == MODIFY_EXPR + && TREE_CODE (TREE_OPERAND (user, 1)) == PLUS_EXPR) + { + tree rhs = TREE_OPERAND (user, 1); + + /* If the negated operand appears on the LHS of the + PLUS_EXPR, exchange the operands of the PLUS_EXPR + to force the negated operand to the RHS of the PLUS_EXPR. */ + if (TREE_OPERAND (TREE_OPERAND (user, 1), 0) == negate) + { + tree temp = TREE_OPERAND (rhs, 0); + TREE_OPERAND (rhs, 0) = TREE_OPERAND (rhs, 1); + TREE_OPERAND (rhs, 1) = temp; + } + + /* Now transform the PLUS_EXPR into a MINUS_EXPR and replace + the RHS of the PLUS_EXPR with the operand of the NEGATE_EXPR. */ + if (TREE_OPERAND (TREE_OPERAND (user, 1), 1) == negate) + { + TREE_SET_CODE (rhs, MINUS_EXPR); + TREE_OPERAND (rhs, 1) = get_unary_op (negate, NEGATE_EXPR); + update_stmt (user); + } + } + } +} + +/* Break up subtract operations in block BB. + + We do this top down because we don't know whether the subtract is + part of a possible chain of reassociation except at the top. + + IE given + d = f + g + c = a + e + b = c - d + q = b - r + k = t - q + + we want to break up k = t - q, but we won't until we've transformed q + = b - r, which won't be broken up until we transform b = c - d. */ + +static void +break_up_subtract_bb (basic_block bb) +{ + block_stmt_iterator bsi; + basic_block son; + + for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) + { + tree stmt = bsi_stmt (bsi); + + if (TREE_CODE (stmt) == MODIFY_EXPR) + { + tree lhs = TREE_OPERAND (stmt, 0); + tree rhs = TREE_OPERAND (stmt, 1); + + TREE_VISITED (stmt) = 0; + /* If unsafe math optimizations we can do reassociation for + non-integral types. */ + if ((!INTEGRAL_TYPE_P (TREE_TYPE (lhs)) + || !INTEGRAL_TYPE_P (TREE_TYPE (rhs))) + && (!SCALAR_FLOAT_TYPE_P (TREE_TYPE (rhs)) + || !SCALAR_FLOAT_TYPE_P (TREE_TYPE(lhs)) + || !flag_unsafe_math_optimizations)) + continue; + + /* Check for a subtract used only in an addition. If this + is the case, transform it into add of a negate for better + reassociation. IE transform C = A-B into C = A + -B if C + is only used in an addition. */ + if (TREE_CODE (rhs) == MINUS_EXPR) + if (should_break_up_subtract (stmt)) + break_up_subtract (stmt, &bsi); + } + } + for (son = first_dom_son (CDI_DOMINATORS, bb); + son; + son = next_dom_son (CDI_DOMINATORS, son)) + break_up_subtract_bb (son); +} + +/* Reassociate expressions in basic block BB and its post-dominator as + children. */ + +static void +reassociate_bb (basic_block bb) +{ + block_stmt_iterator bsi; + basic_block son; + + for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_prev (&bsi)) + { + tree stmt = bsi_stmt (bsi); + + if (TREE_CODE (stmt) == MODIFY_EXPR) + { + tree lhs = TREE_OPERAND (stmt, 0); + tree rhs = TREE_OPERAND (stmt, 1); + + /* If this was part of an already processed tree, we don't + need to touch it again. */ + if (TREE_VISITED (stmt)) + continue; + + /* If unsafe math optimizations we can do reassociation for + non-integral types. */ + if ((!INTEGRAL_TYPE_P (TREE_TYPE (lhs)) + || !INTEGRAL_TYPE_P (TREE_TYPE (rhs))) + && (!SCALAR_FLOAT_TYPE_P (TREE_TYPE (rhs)) + || !SCALAR_FLOAT_TYPE_P (TREE_TYPE(lhs)) + || !flag_unsafe_math_optimizations)) + continue; + + if (associative_tree_code (TREE_CODE (rhs))) + { + VEC(operand_entry_t, heap) *ops = NULL; + + /* There may be no immediate uses left by the time we + get here because we may have eliminated them all. */ + if (TREE_CODE (lhs) == SSA_NAME && has_zero_uses (lhs)) + continue; + + TREE_VISITED (stmt) = 1; + linearize_expr_tree (&ops, stmt); + qsort (VEC_address (operand_entry_t, ops), + VEC_length (operand_entry_t, ops), + sizeof (operand_entry_t), + sort_by_operand_rank); + optimize_ops_list (TREE_CODE (rhs), &ops); + + if (VEC_length (operand_entry_t, ops) == 1) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Transforming "); + print_generic_expr (dump_file, rhs, 0); + } + TREE_OPERAND (stmt, 1) = VEC_last (operand_entry_t, ops)->op; + update_stmt (stmt); + + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, " into "); + print_generic_stmt (dump_file, + TREE_OPERAND (stmt, 1), 0); + } + } + else + { + rewrite_expr_tree (stmt, 0, ops); + } + + VEC_free (operand_entry_t, heap, ops); + } + } + } + for (son = first_dom_son (CDI_POST_DOMINATORS, bb); + son; + son = next_dom_son (CDI_POST_DOMINATORS, son)) + reassociate_bb (son); +} + +void dump_ops_vector (FILE *file, VEC (operand_entry_t, heap) *ops); +void debug_ops_vector (VEC (operand_entry_t, heap) *ops); + +/* Dump the operand entry vector OPS to FILE. */ + +void +dump_ops_vector (FILE *file, VEC (operand_entry_t, heap) *ops) +{ + operand_entry_t oe; + unsigned int i; + + for (i = 0; VEC_iterate (operand_entry_t, ops, i, oe); i++) + { + fprintf (file, "Op %d -> rank: %d, tree: ", i, oe->rank); + print_generic_stmt (file, oe->op, 0); + } +} + +/* Dump the operand entry vector OPS to STDERR. */ + +void +debug_ops_vector (VEC (operand_entry_t, heap) *ops) +{ + dump_ops_vector (stderr, ops); +} + +static void +do_reassoc (void) +{ + break_up_subtract_bb (ENTRY_BLOCK_PTR); + reassociate_bb (EXIT_BLOCK_PTR); +} + +/* Initialize the reassociation pass. */ + +static void +init_reassoc (void) +{ + int i; + unsigned int rank = 2; + tree param; + int *bbs = XNEWVEC (int, last_basic_block + 1); + + memset (&reassociate_stats, 0, sizeof (reassociate_stats)); + + operand_entry_pool = create_alloc_pool ("operand entry pool", + sizeof (struct operand_entry), 30); + + /* Reverse RPO (Reverse Post Order) will give us something where + deeper loops come later. */ + pre_and_rev_post_order_compute (NULL, bbs, false); + bb_rank = XCNEWVEC (unsigned int, last_basic_block + 1); + + operand_rank = htab_create (511, operand_entry_hash, + operand_entry_eq, 0); + + /* Give each argument a distinct rank. */ + for (param = DECL_ARGUMENTS (current_function_decl); + param; + param = TREE_CHAIN (param)) + { + if (default_def (param) != NULL) + { + tree def = default_def (param); + insert_operand_rank (def, ++rank); + } + } + + /* Give the chain decl a distinct rank. */ + if (cfun->static_chain_decl != NULL) + { + tree def = default_def (cfun->static_chain_decl); + if (def != NULL) + insert_operand_rank (def, ++rank); + } + + /* Set up rank for each BB */ + for (i = 0; i < n_basic_blocks - NUM_FIXED_BLOCKS; i++) + bb_rank[bbs[i]] = ++rank << 16; + + free (bbs); + calculate_dominance_info (CDI_DOMINATORS); + calculate_dominance_info (CDI_POST_DOMINATORS); + broken_up_subtracts = NULL; +} + +/* Cleanup after the reassociation pass, and print stats if + requested. */ + +static void +fini_reassoc (void) +{ + + if (dump_file && (dump_flags & TDF_STATS)) + { + fprintf (dump_file, "Reassociation stats:\n"); + fprintf (dump_file, "Linearized: %d\n", + reassociate_stats.linearized); + fprintf (dump_file, "Constants eliminated: %d\n", + reassociate_stats.constants_eliminated); + fprintf (dump_file, "Ops eliminated: %d\n", + reassociate_stats.ops_eliminated); + fprintf (dump_file, "Statements rewritten: %d\n", + reassociate_stats.rewritten); + } + htab_delete (operand_rank); + + free_alloc_pool (operand_entry_pool); + free (bb_rank); + VEC_free (tree, heap, broken_up_subtracts); + free_dominance_info (CDI_POST_DOMINATORS); +} + +/* Gate and execute functions for Reassociation. */ + +static unsigned int +execute_reassoc (void) +{ + init_reassoc (); + + do_reassoc (); + repropagate_negates (); + + fini_reassoc (); + return 0; +} + +struct tree_opt_pass pass_reassoc = +{ + "reassoc", /* name */ + NULL, /* gate */ + execute_reassoc, /* execute */ + NULL, /* sub */ + NULL, /* next */ + 0, /* static_pass_number */ + TV_TREE_REASSOC, /* tv_id */ + PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ + 0, /* properties_provided */ + 0, /* properties_destroyed */ + 0, /* todo_flags_start */ + TODO_dump_func | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */ + 0 /* letter */ +}; |