/* Reassociation for trees.
- Copyright (C) 2005 Free Software Foundation, Inc.
+ Copyright (C) 2005, 2007 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)
+the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
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. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
#include "config.h"
#include "system.h"
#include "tree-gimple.h"
#include "tree-dump.h"
#include "timevar.h"
-#include "hashtab.h"
#include "tree-iterator.h"
#include "tree-pass.h"
+#include "alloc-pool.h"
+#include "vec.h"
+#include "langhooks.h"
+#include "pointer-set.h"
+#include "cfgloop.h"
+#include "flags.h"
-/* This is a simple global reassociation pass that uses a combination
- of heuristics and a hashtable to try to expose more operations to
- CSE.
+/* 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).
- The basic idea behind the heuristic is to rank expressions by
- depth of the computation tree and loop depth, and try to produce
- expressions consisting of small rank operations, as they are more
- likely to reoccur. In addition, we use a hashtable to try to see
- if we can transpose an operation into something we have seen
- before.
+ It consists of five steps:
- Note that the way the hashtable is structured will sometimes find
- matches that will not expose additional redundancies, since it is
- not unwound as we traverse back up one branch of the dominator
- tree and down another. However, the cost of improving this is
- probably not worth the additional benefits it will bring. */
+ 1. Breaking up subtract operations into addition + negate, where
+ it would promote the reassociation of adds.
-/* Statistics */
-static struct
-{
- int reassociated_by_rank;
- int reassociated_by_match;
-} reassociate_stats;
+ 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.
-/* Seen binary operator hashtable. */
-static htab_t seen_binops;
+ 5. Repropagate negates, as nothing else will clean it up ATM.
-/* Binary operator struct. */
+ 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:
-typedef struct seen_binop_d
-{
- tree op1;
- tree op2;
-} *seen_binop_t;
-
-/* Return a SEEN_BINOP_T if we have seen an associative binary
- operator with OP1 and OP2 in it. */
+ We could do this much nicer theoretically, but don't (for reasons
+ explained after how to do it theoretically nice :P).
-static seen_binop_t
-find_seen_binop (tree op1, tree op2)
-{
- void **slot;
- struct seen_binop_d sbd;
- sbd.op1 = op1;
- sbd.op2 = op2;
- slot = htab_find_slot (seen_binops, &sbd, NO_INSERT);
- if (!slot)
- return NULL;
- return ((seen_binop_t) *slot);
-}
+ 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.
-/* Insert a binary operator consisting of OP1 and OP2 into the
- SEEN_BINOP table. */
+ 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.
-static void
-insert_seen_binop (tree op1, tree op2)
-{
- void **slot;
- seen_binop_t new_pair = xmalloc (sizeof (*new_pair));
- new_pair->op1 = op1;
- new_pair->op2 = op2;
- slot = htab_find_slot (seen_binops, new_pair, INSERT);
- if (*slot != NULL)
- free (*slot);
- *slot = new_pair;
-}
+ IE if you have to rewrite the following set of operands (listed with
+ rank in parentheses), with opcode PLUS_EXPR:
-/* Return the hash value for a seen binop structure pointed to by P.
- Because all the binops we consider are associative, we just add the
- hash value for op1 and op2. */
+ a (1), b (1), c (1), d (2), e (2)
-static hashval_t
-seen_binop_hash (const void *p)
-{
- const seen_binop_t sb = (seen_binop_t) p;
- return iterative_hash_expr (sb->op1, 0) + iterative_hash_expr (sb->op2, 0);
-}
-/* Return true if two seen binop structures pointed to by P1 and P2 are equal.
- We have to check the operators both ways because we don't know what
- order they appear in the table. */
+ We start with our merge worklist empty, and the ops list with all of
+ those on it.
-static int
-seen_binop_eq (const void *p1, const void *p2)
-{
- const seen_binop_t sb1 = (seen_binop_t) p1;
- const seen_binop_t sb2 = (seen_binop_t) p2;
- return (sb1->op1 == sb2->op1 && sb1->op2 == sb2->op2)
- || (sb1->op2 == sb2->op1 && sb1->op1 == sb2->op2);
-}
+ You want to first merge all leaves of the same rank, as much as
+ possible.
-/* Value rank structure. */
+ So first build a binary op of
-typedef struct valrank_d
-{
- tree e;
- unsigned int rank;
-} *valrank_t;
+ mergetmp = a + b, and put "mergetmp" on the merge worklist.
-/* 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;
+ 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.
-/* Value rank hashtable. */
-static htab_t value_rank;
+ 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
-/* Look up the value rank structure for expression 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.
-static valrank_t
-find_value_rank (tree e)
-{
- void **slot;
- struct valrank_d vrd;
- vrd.e = e;
- slot = htab_find_slot (value_rank, &vrd, NO_INSERT);
- if (!slot)
- return NULL;
- return ((valrank_t) *slot);
-}
+ 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. */
-/* Insert {E,RANK} into the value rank hashtable. */
-static void
-insert_value_rank (tree e, unsigned int rank)
+/* Statistics */
+static struct
{
- void **slot;
- valrank_t new_pair = xmalloc (sizeof (*new_pair));
- new_pair->e = e;
- new_pair->rank = rank;
- slot = htab_find_slot (value_rank, new_pair, INSERT);
- gcc_assert (*slot == NULL);
- *slot = new_pair;
-
-}
-
-
-/* Return the hash value for a value rank structure */
+ int linearized;
+ int constants_eliminated;
+ int ops_eliminated;
+ int rewritten;
+} reassociate_stats;
-static hashval_t
-valrank_hash (const void *p)
+/* Operator, rank pair. */
+typedef struct operand_entry
{
- const valrank_t vr = (valrank_t) p;
- return iterative_hash_expr (vr->e, 0);
-}
+ unsigned int rank;
+ tree op;
+} *operand_entry_t;
-/* Return true if two value rank structures are equal. */
+static alloc_pool operand_entry_pool;
-static int
-valrank_eq (const void *p1, const void *p2)
-{
- const valrank_t vr1 = (valrank_t) p1;
- const valrank_t vr2 = (valrank_t) p2;
- return vr1->e == vr2->e;
-}
+/* 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 long *bb_rank;
-/* Initialize the reassociation pass. */
+/* Operand->rank hashtable. */
+static struct pointer_map_t *operand_rank;
-static void
-init_reassoc (void)
-{
- int i;
- unsigned int rank = 2;
-
- tree param;
- int *bbs = xmalloc ((last_basic_block + 1) * sizeof (int));
-
- memset (&reassociate_stats, 0, sizeof (reassociate_stats));
- /* Reverse RPO (Reverse Post Order) will give us something where
- deeper loops come later. */
- flow_reverse_top_sort_order_compute (bbs);
- bb_rank = xcalloc (last_basic_block + 1, sizeof (unsigned int));
- value_rank = htab_create (511, valrank_hash,
- valrank_eq, free);
- seen_binops = htab_create (511, seen_binop_hash,
- seen_binop_eq, free);
-
- /* 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_value_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_value_rank (def, ++rank);
- }
-
- /* Set up rank for each BB */
- for (i = 0; i < n_basic_blocks; i++)
- bb_rank[bbs[i]] = ++rank << 16;
-
- free (bbs);
- calculate_dominance_info (CDI_DOMINATORS);
+/* Look up the operand rank structure for expression E. */
+static inline long
+find_operand_rank (tree e)
+{
+ void **slot = pointer_map_contains (operand_rank, e);
+ return slot ? (long) *slot : -1;
}
-/* Cleanup after the reassociation pass, and print stats if
- requested. */
+/* Insert {E,RANK} into the operand rank hashtable. */
-static void
-fini_reassoc (void)
+static inline void
+insert_operand_rank (tree e, long rank)
{
-
- if (dump_file && (dump_flags & TDF_STATS))
- {
- fprintf (dump_file, "Reassociation stats:\n");
- fprintf (dump_file, "Reassociated by rank: %d\n", reassociate_stats.reassociated_by_rank);
- fprintf (dump_file, "Reassociated by match: %d\n", reassociate_stats.reassociated_by_match);
- }
- htab_delete (value_rank);
- htab_delete (seen_binops);
- free (bb_rank);
+ void **slot;
+ gcc_assert (rank > 0);
+ slot = pointer_map_insert (operand_rank, e);
+ gcc_assert (!*slot);
+ *slot = (void *) rank;
}
/* Given an expression E, return the rank of the expression. */
-static unsigned int
+static long
get_rank (tree e)
{
- valrank_t vr;
-
- /* Constants have rank 0. */
+ /* 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.
if (TREE_CODE (e) == SSA_NAME)
{
tree stmt;
- tree rhs;
- unsigned int rank, maxrank;
+ tree rhs;
+ long rank, maxrank;
int i;
-
+ int n;
+
if (TREE_CODE (SSA_NAME_VAR (e)) == PARM_DECL
- && e == default_def (SSA_NAME_VAR (e)))
- return find_value_rank (e)->rank;
-
+ && SSA_NAME_IS_DEFAULT_DEF (e))
+ return find_operand_rank (e);
+
stmt = SSA_NAME_DEF_STMT (e);
if (bb_for_stmt (stmt) == NULL)
return 0;
-
- if (TREE_CODE (stmt) != MODIFY_EXPR
+
+ if (TREE_CODE (stmt) != GIMPLE_MODIFY_STMT
|| !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_value_rank (e);
- if (vr)
- return vr->rank;
+ rank = find_operand_rank (e);
+ if (rank != -1)
+ return 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)
+ rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ n = TREE_OPERAND_LENGTH (rhs);
+ if (n == 0)
rank = MAX (rank, get_rank (rhs));
- else
+ else
{
- for (i = 0;
- i < TREE_CODE_LENGTH (TREE_CODE (rhs))
+ for (i = 0;
+ i < n
&& TREE_OPERAND (rhs, i)
- && rank != maxrank; 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));
+ fprintf (dump_file, " is %ld\n", (rank + 1));
}
-
+
/* Note the rank in the hashtable so we don't recompute it. */
- insert_value_rank (e, (rank + 1));
+ insert_operand_rank (e, (rank + 1));
return (rank + 1);
}
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;
+}
-/* Decide whether we should transpose RHS and some operand of
- LHSDEFOP.
- If yes, then return true and set TAKEOP to the operand number of LHSDEFOP to
- switch RHS for.
- Otherwise, return false. */
+/* 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 = (operand_entry_t) 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, and is inside LOOP. */
static bool
-should_transpose (tree rhs ATTRIBUTE_UNUSED,
- unsigned int rhsrank,
- tree lhsdefop, unsigned int *takeop)
-{
- /* Attempt to expose the low ranked
- arguments to CSE if we have something like:
- a = <rank 2> + c (rank 1)
- b = a (rank 3) + d (rank 1)
- We want to transform this into:
- a = c + d
- b = <rank 2> + <rank 3>
-
- The op finding part wouldn't be necessary if
- we could swap the operands above and not have
- update_stmt change them back on us.
- */
- unsigned int lowrankop;
- unsigned int lowrank;
- unsigned int highrank;
- unsigned int highrankop;
- unsigned int temp;
-
- lowrankop = 0;
- *takeop = 1;
- lowrank = get_rank (TREE_OPERAND (lhsdefop, 0));
- temp = get_rank (TREE_OPERAND (lhsdefop, 1));
- highrank = temp;
- highrankop = 1;
- if (temp < lowrank)
+is_reassociable_op (tree stmt, enum tree_code code, struct loop *loop)
+{
+ basic_block bb;
+
+ if (IS_EMPTY_STMT (stmt))
+ return false;
+
+ bb = bb_for_stmt (stmt);
+ if (!flow_bb_inside_loop_p (loop, bb))
+ return false;
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (stmt, 1)) == code
+ && has_single_use (GIMPLE_STMT_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) != GIMPLE_MODIFY_STMT)
+ return NULL_TREE;
+
+ rhs = GIMPLE_STMT_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)
{
- lowrankop = 1;
- highrankop = 0;
- *takeop = 0;
- highrank = lowrank;
- lowrank = temp;
+ 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;
+ }
}
-
- /* If highrank == lowrank, then we had something
- like:
- a = <rank 1> + <rank 1>
- already, so there is no guarantee that
- swapping our argument in is going to be
- better.
- If we run reassoc twice, we could probably
- have a flag that switches this behavior on,
- so that we try once without it, and once with
- it, so that redundancy elimination sees it
- both ways.
- */
-
- if (lowrank == rhsrank && highrank != lowrank)
- return true;
+ 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. */
- /* Also, see if the LHS's high ranked op should be switched with our
- RHS simply because it is greater in rank than our current RHS. */
- if (TREE_CODE (TREE_OPERAND (lhsdefop, highrankop)) == SSA_NAME)
+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++)
{
- tree iop = SSA_NAME_DEF_STMT (TREE_OPERAND (lhsdefop, highrankop));
- if (TREE_CODE (iop) == MODIFY_EXPR)
- iop = TREE_OPERAND (iop, 1);
- if (TREE_CODE (iop) == TREE_CODE (lhsdefop))
- *takeop = 1;
- if (rhsrank < get_rank (TREE_OPERAND (lhsdefop, *takeop)))
- return true;
- }
-
+ 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;
}
-/* Attempt to reassociate the associative binary operator BEXPR, which
- is in the statement pointed to by CURRBSI. Return true if we
- changed the statement. */
+/* 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
-reassociate_expr (tree bexpr, block_stmt_iterator *currbsi)
-{
- tree lhs = TREE_OPERAND (bexpr, 0);
- tree rhs = TREE_OPERAND (bexpr, 1);
- tree lhsdef;
- tree lhsi;
- bool changed = false;
- unsigned int lhsrank = get_rank (lhs);
- unsigned int rhsrank = get_rank (rhs);
-
- /* If unsafe math optimizations we can do reassociation for non integal
- 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))
+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;
-
- /* We want the greater ranked operand to be our "LHS" for simplicity
- sake. There is no point in actually modifying the expression, as
- update_stmt will simply resort the operands anyway. */
- if (lhsrank < rhsrank)
+
+ 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++)
{
- tree temp;
- unsigned int temp1;
- temp = lhs;
- lhs = rhs;
- rhs = temp;
- temp1 = lhsrank;
- lhsrank = rhsrank;
- rhsrank = temp1;
+ 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;
+ }
}
- /* If the high ranked operand is an SSA_NAME, and the binary
- operator is not something we've already seen somewhere else
- (i.e., it may be redundant), attempt to reassociate it.
-
- We can't reassociate expressions unless the expression we are
- going to reassociate with is only used in our current expression,
- or else we may screw up other computations, like so:
-
- a = b + c
- e = a + d
-
- g = a + f
-
- We cannot reassociate and rewrite the "a = ..." ,
- because that would change the value of the computation of
- "g = a + f". */
- if (TREE_CODE (lhs) == SSA_NAME && !find_seen_binop (lhs, rhs))
+ 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);
+ tree type = TREE_TYPE (oelast->op);
+
+ if (oelast->rank == 0
+ && (INTEGRAL_TYPE_P (type) || FLOAT_TYPE_P (type)))
{
- lhsdef = SSA_NAME_DEF_STMT (lhs);
- if (TREE_CODE (lhsdef) == MODIFY_EXPR)
+ switch (opcode)
{
- lhsi = TREE_OPERAND (lhsdef, 1);
- if (TREE_CODE (lhsi) == TREE_CODE (bexpr))
+ case BIT_AND_EXPR:
+ if (integer_zerop (oelast->op))
{
- use_operand_p use;
- tree usestmt;
- if (single_imm_use (lhs, &use, &usestmt))
+ if (VEC_length (operand_entry_t, *ops) != 1)
{
- unsigned int takeop = 0;
- unsigned int otherop = 1;
- bool foundmatch = false;
- bool foundrank = false;
-
- /* If we can easily transpose this into an operation
- we've already seen, let's do that.
- otherwise, let's try to expose low ranked ops to
- CSE. */
- if (find_seen_binop (TREE_OPERAND (lhsi, 1), rhs))
- {
- takeop = 0;
- otherop = 1;
- foundmatch = true;
- }
- else if (find_seen_binop (TREE_OPERAND (lhsi, 0),
- rhs))
- {
- takeop = 1;
- otherop = 0;
- foundmatch = true;
- }
- else if (should_transpose (rhs, rhsrank, lhsi,
- &takeop))
- {
- foundrank = true;
- }
- if (foundmatch || foundrank)
- {
- block_stmt_iterator lhsbsi = bsi_for_stmt (lhsdef);
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "Reassociating by %s\n",
- foundmatch ? "match" : "rank");
- fprintf (dump_file, "Before LHS:");
- print_generic_stmt (dump_file, lhsi, 0);
- fprintf (dump_file, "Before curr expr:");
- print_generic_stmt (dump_file, bexpr, 0);
- }
- TREE_OPERAND (bexpr, 0) = TREE_OPERAND (lhsi, takeop);
- TREE_OPERAND (lhsi, takeop) = rhs;
- TREE_OPERAND (bexpr, 1) = TREE_OPERAND (lhsdef, 0);
- if (dump_file && (dump_flags & TDF_DETAILS))
- {
- fprintf (dump_file, "After LHS:");
- print_generic_stmt (dump_file, lhsi, 0);
- fprintf (dump_file, "After curr expr:");
- print_generic_stmt (dump_file, bexpr, 0);
- }
- bsi_move_before (&lhsbsi, currbsi);
- update_stmt (lhsdef);
- update_stmt (bsi_stmt (*currbsi));
- lhsbsi = bsi_for_stmt (lhsdef);
- update_stmt (bsi_stmt (lhsbsi));
-
- /* If update_stmt didn't reorder our operands,
- we'd like to recurse on the expression we
- just reassociated and reassociate it
- top-down, exposing further opportunities.
- Unfortunately, update_stmt does reorder them,
- so we can't do this cheaply. */
- if (!foundmatch)
- reassociate_stats.reassociated_by_rank++;
- else
- reassociate_stats.reassociated_by_match++;
- return true;
- }
+ 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)
+ || (FLOAT_TYPE_P (type)
+ && !HONOR_NANS (TYPE_MODE (type))
+ && !HONOR_SIGNED_ZEROS (TYPE_MODE (type))
+ && real_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)
+ || (FLOAT_TYPE_P (type)
+ && !HONOR_SNANS (TYPE_MODE (type))
+ && real_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)
+ || (FLOAT_TYPE_P (type)
+ && (opcode == PLUS_EXPR || opcode == MINUS_EXPR)
+ && fold_real_zero_addition_p (type, oelast->op,
+ opcode == MINUS_EXPR)))
+ {
+ 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;
}
}
- return changed;
}
-/* Reassociate expressions in basic block BB and its dominator as
- children , return true if any
- expressions changed. */
+/* 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)
+ && useless_type_conversion_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
-reassociate_bb (basic_block bb)
+is_phi_for_stmt (tree stmt, tree operand)
+{
+ tree def_stmt;
+ tree lhs = GIMPLE_STMT_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 = GIMPLE_STMT_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;
+ }
+ else if ((oe1->rank == oe3->rank
+ && oe2->rank != oe3->rank)
+ || (is_phi_for_stmt (stmt, oe2->op)
+ && !is_phi_for_stmt (stmt, oe1->op)
+ && !is_phi_for_stmt (stmt, oe3->op)))
+ {
+ struct operand_entry temp = *oe2;
+ oe2->op = oe1->op;
+ oe2->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 = GIMPLE_STMT_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;
+ struct loop *loop = loop_containing_stmt (stmt);
+
+ gcc_assert (is_reassociable_op (binlhs, TREE_CODE (rhs), loop)
+ && is_reassociable_op (binrhs, TREE_CODE (rhs), loop));
+
+ bsinow = bsi_for_stmt (stmt);
+ bsirhs = bsi_for_stmt (binrhs);
+ bsi_move_before (&bsirhs, &bsinow);
+
+ TREE_OPERAND (rhs, 1) = TREE_OPERAND (GIMPLE_STMT_OPERAND (binrhs, 1), 0);
+ if (TREE_CODE (TREE_OPERAND (rhs, 1)) == SSA_NAME)
+ newbinrhs = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 1));
+ TREE_OPERAND (GIMPLE_STMT_OPERAND (binrhs, 1), 0)
+ = GIMPLE_STMT_OPERAND (binlhs, 0);
+ TREE_OPERAND (rhs, 0) = GIMPLE_STMT_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, loop))
+ linearize_expr (stmt);
+}
+
+/* If LHS has a single immediate use that is a GIMPLE_MODIFY_STMT, 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) == GIMPLE_MODIFY_STMT)
+ 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) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (negatedef, 0)) == SSA_NAME
+ && has_single_use (GIMPLE_STMT_OPERAND (negatedef, 0))
+ && TREE_CODE (GIMPLE_STMT_OPERAND (negatedef, 1)) == PLUS_EXPR)
+ {
+ block_stmt_iterator bsi;
+ tree binop = GIMPLE_STMT_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 GIMPLE_STMT_OPERAND (negatedef, 0);
+ }
+
+ tonegate = fold_build1 (NEGATE_EXPR, TREE_TYPE (tonegate), tonegate);
+ resultofnegate = force_gimple_operand_bsi (bsi, tonegate, true,
+ NULL_TREE, true, BSI_SAME_STMT);
+ 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 = GIMPLE_STMT_OPERAND (stmt, 0);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+ tree binlhs = TREE_OPERAND (rhs, 0);
+ tree binrhs = TREE_OPERAND (rhs, 1);
+ tree immusestmt;
+ struct loop *loop = loop_containing_stmt (stmt);
+
+ if (TREE_CODE (binlhs) == SSA_NAME
+ && is_reassociable_op (SSA_NAME_DEF_STMT (binlhs), PLUS_EXPR, loop))
+ return true;
+
+ if (TREE_CODE (binrhs) == SSA_NAME
+ && is_reassociable_op (SSA_NAME_DEF_STMT (binrhs), PLUS_EXPR, loop))
+ return true;
+
+ if (TREE_CODE (lhs) == SSA_NAME
+ && (immusestmt = get_single_immediate_use (lhs))
+ && TREE_CODE (GIMPLE_STMT_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 = GIMPLE_STMT_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 (GIMPLE_STMT_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 = GENERIC_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);
+ struct loop *loop = loop_containing_stmt (stmt);
+
+ TREE_VISITED (stmt) = 1;
+
+ if (TREE_CODE (binlhs) == SSA_NAME)
+ {
+ binlhsdef = SSA_NAME_DEF_STMT (binlhs);
+ binlhsisreassoc = is_reassociable_op (binlhsdef, rhscode, loop);
+ }
+
+ if (TREE_CODE (binrhs) == SSA_NAME)
+ {
+ binrhsdef = SSA_NAME_DEF_STMT (binrhs);
+ binrhsisreassoc = is_reassociable_op (binrhsdef, rhscode, loop);
+ }
+
+ /* 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 == GIMPLE_STMT_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, loop));
+ 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) == GIMPLE_MODIFY_STMT
+ && TREE_CODE (GIMPLE_STMT_OPERAND (user, 1)) == PLUS_EXPR)
+ {
+ tree rhs = GIMPLE_STMT_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 (GIMPLE_STMT_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 (GIMPLE_STMT_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)
{
- bool changed = false;
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)
+
+ if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT)
{
- tree rhs = TREE_OPERAND (stmt, 1);
+ tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ tree rhs = GIMPLE_STMT_OPERAND (stmt, 1);
+
+ TREE_VISITED (stmt) = 0;
+ /* If associative-math we can do reassociation for
+ non-integral types. Or, we can do reassociation for
+ non-saturating fixed-point 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_associative_math)
+ && (!NON_SAT_FIXED_POINT_TYPE_P (TREE_TYPE (rhs))
+ || !NON_SAT_FIXED_POINT_TYPE_P (TREE_TYPE(lhs))))
+ 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) == GIMPLE_MODIFY_STMT)
+ {
+ tree lhs = GIMPLE_STMT_OPERAND (stmt, 0);
+ tree rhs = GIMPLE_STMT_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 associative-math we can do reassociation for
+ non-integral types. Or, we can do reassociation for
+ non-saturating fixed-point 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_associative_math)
+ && (!NON_SAT_FIXED_POINT_TYPE_P (TREE_TYPE (rhs))
+ || !NON_SAT_FIXED_POINT_TYPE_P (TREE_TYPE(lhs))))
+ continue;
+
if (associative_tree_code (TREE_CODE (rhs)))
{
- if (reassociate_expr (rhs, &bsi))
+ 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)
{
- changed = true;
- update_stmt (stmt);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Transforming ");
+ print_generic_expr (dump_file, rhs, 0);
+ }
+ GIMPLE_STMT_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,
+ GIMPLE_STMT_OPERAND (stmt, 1), 0);
+ }
+ }
+ else
+ {
+ rewrite_expr_tree (stmt, 0, ops);
}
- insert_seen_binop (TREE_OPERAND (rhs, 0),
- TREE_OPERAND (rhs, 1));
+
+ VEC_free (operand_entry_t, heap, ops);
}
}
}
- for (son = first_dom_son (CDI_DOMINATORS, bb);
+ for (son = first_dom_son (CDI_POST_DOMINATORS, bb);
son;
- son = next_dom_son (CDI_DOMINATORS, 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++)
{
- changed |= reassociate_bb (son);
+ fprintf (file, "Op %d -> rank: %d, tree: ", i, oe->rank);
+ print_generic_stmt (file, oe->op, 0);
}
- return changed;
}
-
-static bool
+/* 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)
-{
- bool changed = false;
-
- changed = reassociate_bb (ENTRY_BLOCK_PTR);
+{
+ break_up_subtract_bb (ENTRY_BLOCK_PTR);
+ reassociate_bb (EXIT_BLOCK_PTR);
+}
+
+/* Initialize the reassociation pass. */
+
+static void
+init_reassoc (void)
+{
+ int i;
+ long rank = 2;
+ tree param;
+ int *bbs = XNEWVEC (int, last_basic_block + 1);
+
+ /* Find the loops, so that we can prevent moving calculations in
+ them. */
+ loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
- return changed;
+ 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 (long, last_basic_block + 1);
+ operand_rank = pointer_map_create ();
+
+ /* Give each argument a distinct rank. */
+ for (param = DECL_ARGUMENTS (current_function_decl);
+ param;
+ param = TREE_CHAIN (param))
+ {
+ if (gimple_default_def (cfun, param) != NULL)
+ {
+ tree def = gimple_default_def (cfun, param);
+ insert_operand_rank (def, ++rank);
+ }
+ }
+
+ /* Give the chain decl a distinct rank. */
+ if (cfun->static_chain_decl != NULL)
+ {
+ tree def = gimple_default_def (cfun, 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_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);
+ }
+
+ pointer_map_destroy (operand_rank);
+ free_alloc_pool (operand_entry_pool);
+ free (bb_rank);
+ VEC_free (tree, heap, broken_up_subtracts);
+ free_dominance_info (CDI_POST_DOMINATORS);
+ loop_optimizer_finalize ();
+}
/* Gate and execute functions for Reassociation. */
-static void
+static unsigned int
execute_reassoc (void)
{
init_reassoc ();
+
do_reassoc ();
+ repropagate_negates ();
+
fini_reassoc ();
+ return 0;
+}
+
+static bool
+gate_tree_ssa_reassoc (void)
+{
+ return flag_tree_reassoc != 0;
}
struct tree_opt_pass pass_reassoc =
{
"reassoc", /* name */
- NULL, /* gate */
- execute_reassoc, /* execute */
+ gate_tree_ssa_reassoc, /* gate */
+ execute_reassoc, /* execute */
NULL, /* sub */
NULL, /* next */
0, /* static_pass_number */
- TV_TREE_REASSOC, /* tv_id */
+ TV_TREE_REASSOC, /* tv_id */
PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_update_ssa | TODO_dump_func
- | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */
+ TODO_dump_func | TODO_ggc_collect | TODO_verify_ssa, /* todo_flags_finish */
0 /* letter */
};