#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"
-/* 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;
+ We could do this much nicer theoretically, but don't (for reasons
+ explained after how to do it theoretically nice :P).
-/* Return a SEEN_BINOP_T if we have seen an associative binary
- operator with OP1 and OP2 in it. */
+ 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.
-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);
-}
+ 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.
-/* Insert a binary operator consisting of OP1 and OP2 into the
- SEEN_BINOP table. */
+ IE if you have to rewrite the following set of operands (listed with
+ rank in parentheses), with opcode PLUS_EXPR:
-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;
-}
+ a (1), b (1), c (1), d (2), e (2)
-/* 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. */
-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);
-}
+ We start with our merge worklist empty, and the ops list with all of
+ those on it.
-/* 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. */
+ 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. */
-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);
-}
-/* Value rank structure. */
+/* Statistics */
+static struct
+{
+ int linearized;
+ int constants_eliminated;
+ int ops_eliminated;
+ int rewritten;
+} reassociate_stats;
-typedef struct valrank_d
+/* Operator, rank pair. */
+typedef struct operand_entry
{
- tree e;
- unsigned int rank;
-} *valrank_t;
+ 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;
-/* Value rank hashtable. */
-static htab_t value_rank;
+/* Operand->rank hashtable. */
+static htab_t operand_rank;
-/* Look up the value rank structure for expression E. */
+/* Look up the operand rank structure for expression E. */
-static valrank_t
-find_value_rank (tree e)
+static operand_entry_t
+find_operand_rank (tree e)
{
void **slot;
- struct valrank_d vrd;
- vrd.e = e;
- slot = htab_find_slot (value_rank, &vrd, NO_INSERT);
+ struct operand_entry vrd;
+
+ vrd.op = e;
+ slot = htab_find_slot (operand_rank, &vrd, NO_INSERT);
if (!slot)
return NULL;
- return ((valrank_t) *slot);
+ return ((operand_entry_t) *slot);
}
-/* Insert {E,RANK} into the value rank hashtable. */
+/* Insert {E,RANK} into the operand rank hashtable. */
static void
-insert_value_rank (tree e, unsigned int rank)
+insert_operand_rank (tree e, unsigned int rank)
{
void **slot;
- valrank_t new_pair = xmalloc (sizeof (*new_pair));
- new_pair->e = e;
+ operand_entry_t new_pair = pool_alloc (operand_entry_pool);
+
+ new_pair->op = e;
new_pair->rank = rank;
- slot = htab_find_slot (value_rank, new_pair, INSERT);
+ slot = htab_find_slot (operand_rank, new_pair, INSERT);
gcc_assert (*slot == NULL);
*slot = new_pair;
-
}
-
-/* Return the hash value for a value rank structure */
+/* Return the hash value for a operand rank structure */
static hashval_t
-valrank_hash (const void *p)
+operand_entry_hash (const void *p)
{
- const valrank_t vr = (valrank_t) p;
- return iterative_hash_expr (vr->e, 0);
+ const operand_entry_t vr = (operand_entry_t) p;
+ return iterative_hash_expr (vr->op, 0);
}
-/* Return true if two value rank structures are equal. */
+/* Return true if two operand rank structures are equal. */
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;
-}
-
-
-/* Initialize the reassociation pass. */
-
-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);
-
-}
-
-/* Cleanup after the reassociation pass, and print stats if
- requested. */
-
-static void
-fini_reassoc (void)
+operand_entry_eq (const void *p1, const void *p2)
{
-
- 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);
+ 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)
{
- valrank_t vr;
+ operand_entry_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;
+ 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_value_rank (e)->rank;
-
+ 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_value_rank (e);
+ vr = find_operand_rank (e);
if (vr)
return vr->rank;
rhs = TREE_OPERAND (stmt, 1);
if (TREE_CODE_LENGTH (TREE_CODE (rhs)) == 0)
rank = MAX (rank, get_rank (rhs));
- else
+ else
{
- for (i = 0;
- i < TREE_CODE_LENGTH (TREE_CODE (rhs))
+ for (i = 0;
+ i < TREE_CODE_LENGTH (TREE_CODE (rhs))
&& 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));
}
-
+
/* 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;
+}
+
+/* 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);
+}
-/* 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. */
+/* Return true if STMT is reassociable operation containing a binary
+ operation with tree code CODE. */
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)
- {
- lowrankop = 1;
- highrankop = 0;
- *takeop = 0;
- highrank = lowrank;
- lowrank = temp;
- }
-
- /* 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)
+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. */
- /* 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_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 & or |, 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)
{
- 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;
- }
-
+ switch (opcode)
+ {
+ 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, " [&|] ");
+ 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;
}
-/* 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 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
-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-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))
+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;
-
- /* 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)
+
+ 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 temp;
- unsigned int temp1;
- temp = lhs;
- lhs = rhs;
- rhs = temp;
- temp1 = lhsrank;
- lhsrank = rhsrank;
- rhsrank = temp1;
+ 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;
+ }
}
- /* 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;
+}
+
+/* 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++)
{
- lhsdef = SSA_NAME_DEF_STMT (lhs);
- if (TREE_CODE (lhsdef) == MODIFY_EXPR)
+ if (oe->op == notop)
{
- lhsi = TREE_OPERAND (lhsdef, 1);
- if (TREE_CODE (lhsi) == TREE_CODE (bexpr))
+ if (dump_file && (dump_flags & TDF_DETAILS))
{
- use_operand_p use;
- tree usestmt;
- if (single_imm_use (lhs, &use, &usestmt))
- {
- 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;
- }
- }
+ 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 changed;
+
+ return false;
}
-/* Reassociate expressions in basic block BB and its dominator as
- children , return true if any
- expressions changed. */
+/* 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 bool
-reassociate_bb (basic_block bb)
+static void
+eliminate_using_constants (enum tree_code opcode,
+ VEC(operand_entry_t, heap) **ops)
{
- bool changed = false;
- block_stmt_iterator bsi;
- basic_block son;
+ operand_entry_t oelast = VEC_last (operand_entry_t, *ops);
- for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
+ if (oelast->rank == 0 && INTEGRAL_TYPE_P (TREE_TYPE (oelast->op)))
{
- tree stmt = bsi_stmt (bsi);
-
- if (TREE_CODE (stmt) == MODIFY_EXPR)
+ switch (opcode)
{
- tree rhs = TREE_OPERAND (stmt, 1);
- if (associative_tree_code (TREE_CODE (rhs)))
+ 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 (reassociate_expr (rhs, &bsi))
+ if (VEC_length (operand_entry_t, *ops) != 1)
{
- changed = true;
- update_stmt (stmt);
+ 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;
}
- insert_seen_binop (TREE_OPERAND (rhs, 0),
- TREE_OPERAND (rhs, 1));
}
+ break;
+ default:
+ break;
}
}
- for (son = first_dom_son (CDI_DOMINATORS, bb);
- son;
- son = next_dom_son (CDI_DOMINATORS, son))
- {
- changed |= reassociate_bb (son);
- }
- return changed;
}
-
-static bool
-do_reassoc (void)
-{
- bool changed = false;
-
- changed = reassociate_bb (ENTRY_BLOCK_PTR);
+/* 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. */
- return changed;
-}
+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;
-/* Gate and execute functions for Reassociation. */
+ 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 ();
-static void
-execute_reassoc (void)
-{
- init_reassoc ();
- do_reassoc ();
fini_reassoc ();
+ return 0;
}
struct tree_opt_pass pass_reassoc =
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 */
};
OSDN Git Service
