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re PR tree-optimization/66502 (SCCVN can't handle PHIs optimistically optimally) 

2015-08-13  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/66502
	PR tree-optimization/67167
	* tree-ssa-sccvn.c (vn_phi_compute_hash): Do not include
	backedge arguments.
	(vn_phi_lookup): Adjust.
	(vn_phi_insert): Likewise.
	(visit_phi): Prefer to value-number to another PHI node
	over value-numbering to a PHI argument.
	(init_scc_vn): Mark DFS back edges.

	* gcc.dg/tree-ssa/ssa-fre-46.c: New testcase.

From-SVN: r226850
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Richard Biener 2015-08-13 07:06:10 +00:00 committed by Richard Biener
parent 003b40ae57
commit 9fe4f60adb
4 changed files with 73 additions and 25 deletions
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12
gcc/ChangeLog
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@ -1,3 +1,15 @@
2015-08-13 Richard Biener <rguenther@suse.de>
PR tree-optimization/66502
PR tree-optimization/67167
* tree-ssa-sccvn.c (vn_phi_compute_hash): Do not include
backedge arguments.
(vn_phi_lookup): Adjust.
(vn_phi_insert): Likewise.
(visit_phi): Prefer to value-number to another PHI node
over value-numbering to a PHI argument.
(init_scc_vn): Mark DFS back edges.
2015-08-13 Richard Biener <rguenther@suse.de>
* gimple.h (gcall::code_): New constant static member.

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2015-08-13 Richard Biener <rguenther@suse.de>
PR tree-optimization/66502
PR tree-optimization/67167
* gcc.dg/tree-ssa/ssa-fre-46.c: New testcase.
2015-08-12 Paolo Carlini <paolo.carlini@oracle.com>
PR c++/53330

21
gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-46.c Normal file
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@ -0,0 +1,21 @@
/* { dg-do compile } */
/* { dg-options "-O -fdump-tree-fre1-details" } */
int x[1024];
int foo (int a, int s, unsigned int k)
{
int i = a, j = a;
int sum = 0;
do
{
sum += x[i];
sum += x[j];
i += s;
j += s;
}
while (k--);
return sum;
}
/* We want to remove the redundant induction variable and thus its PHI node. */
/* { dg-final { scan-tree-dump "Removing dead stmt \[^\r\n\]*PHI" "fre1" } } */

59
gcc/tree-ssa-sccvn.c
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@ -2663,17 +2663,24 @@ static inline hashval_t
vn_phi_compute_hash (vn_phi_t vp1)
{
inchash::hash hstate (vp1->block->index);
int i;
tree phi1op;
tree type;
edge e;
edge_iterator ei;
/* If all PHI arguments are constants we need to distinguish
the PHI node via its type. */
type = vp1->type;
hstate.merge_hash (vn_hash_type (type));
FOR_EACH_VEC_ELT (vp1->phiargs, i, phi1op)
FOR_EACH_EDGE (e, ei, vp1->block->preds)
{
/* Don't hash backedge values they need to be handled as VN_TOP
for optimistic value-numbering. */
if (e->flags & EDGE_DFS_BACK)
continue;
phi1op = vp1->phiargs[e->dest_idx];
if (phi1op == VN_TOP)
continue;
inchash::add_expr (phi1op, hstate);
@ -2726,16 +2733,18 @@ vn_phi_lookup (gimple phi)
{
vn_phi_s **slot;
struct vn_phi_s vp1;
unsigned i;
edge e;
edge_iterator ei;
shared_lookup_phiargs.truncate (0);
shared_lookup_phiargs.safe_grow (gimple_phi_num_args (phi));
/* Canonicalize the SSA_NAME's to their value number. */
for (i = 0; i < gimple_phi_num_args (phi); i++)
FOR_EACH_EDGE (e, ei, gimple_bb (phi)->preds)
{
tree def = PHI_ARG_DEF (phi, i);
tree def = PHI_ARG_DEF_FROM_EDGE (phi, e);
def = TREE_CODE (def) == SSA_NAME ? SSA_VAL (def) : def;
shared_lookup_phiargs.safe_push (def);
shared_lookup_phiargs[e->dest_idx] = def;
}
vp1.type = TREE_TYPE (gimple_phi_result (phi));
vp1.phiargs = shared_lookup_phiargs;
@ -2759,15 +2768,18 @@ vn_phi_insert (gimple phi, tree result)
{
vn_phi_s **slot;
vn_phi_t vp1 = current_info->phis_pool->allocate ();
unsigned i;
vec<tree> args = vNULL;
edge e;
edge_iterator ei;
args.safe_grow (gimple_phi_num_args (phi));
/* Canonicalize the SSA_NAME's to their value number. */
for (i = 0; i < gimple_phi_num_args (phi); i++)
FOR_EACH_EDGE (e, ei, gimple_bb (phi)->preds)
{
tree def = PHI_ARG_DEF (phi, i);
tree def = PHI_ARG_DEF_FROM_EDGE (phi, e);
def = TREE_CODE (def) == SSA_NAME ? SSA_VAL (def) : def;
args.safe_push (def);
args[e->dest_idx] = def;
}
vp1->value_id = VN_INFO (result)->value_id;
vp1->type = TREE_TYPE (gimple_phi_result (phi));
@ -3252,28 +3264,23 @@ visit_phi (gimple phi)
if (def == VN_TOP)
continue;
if (sameval == VN_TOP)
sameval = def;
else if (!expressions_equal_p (def, sameval))
{
sameval = def;
}
else
{
if (!expressions_equal_p (def, sameval))
{
allsame = false;
break;
}
allsame = false;
break;
}
}
/* If all value numbered to the same value, the phi node has that
value. */
if (allsame)
return set_ssa_val_to (PHI_RESULT (phi), sameval);
/* Otherwise, see if it is equivalent to a phi node in this block. */
/* First see if it is equivalent to a phi node in this block. We prefer
this as it allows IV elimination - see PRs 66502 and 67167. */
result = vn_phi_lookup (phi);
if (result)
changed = set_ssa_val_to (PHI_RESULT (phi), result);
/* Otherwise all value numbered to the same value, the phi node has that
value. */
else if (allsame)
changed = set_ssa_val_to (PHI_RESULT (phi), sameval);
else
{
vn_phi_insert (phi, PHI_RESULT (phi));
@ -4163,6 +4170,8 @@ init_scc_vn (void)
int *rpo_numbers_temp;
calculate_dominance_info (CDI_DOMINATORS);
mark_dfs_back_edges ();
sccstack.create (0);
constant_to_value_id = new hash_table<vn_constant_hasher> (23);