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tree-optimization/95393 - fold MIN/MAX_EXPR generated by phiopt

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This makes sure to fold generated stmts so they do not survive
until RTL expansion and cause awkward code generation.

2020-05-29  Richard Biener <rguenther@suse.de>

	PR tree-optimization/95393
	* tree-ssa-phiopt.c (minmax_replacement): Use gimple_build
	to build the min/max expression so we simplify cases like
	MAX(0, s) immediately.

	* gcc.dg/tree-ssa/phi-opt-21.c: New testcase.
	* g++.dg/vect/slp-pr87105.cc: Adjust.
This commit is contained in:
Richard Biener 2020-05-29 09:25:53 +02:00
parent 6802b5ba82
commit 07852a81f5
3 changed files with 29 additions and 13 deletions
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2
gcc/testsuite/g++.dg/vect/slp-pr87105.cc
View file

@ -102,4 +102,4 @@ void quadBoundingBoxA(const Point bez[3], Box& bBox) noexcept {
// { dg-final { scan-tree-dump-times "basic block part vectorized" 1 "slp2" { xfail { { ! vect_element_align } && { ! vect_hw_misalign } } } } }
// It's a bit awkward to detect that all stores were vectorized but the
// following more or less does the trick
// { dg-final { scan-tree-dump "vect_iftmp\[^\r\m\]* = MIN" "slp2" { xfail { { ! vect_element_align } && { ! vect_hw_misalign } } } } }
// { dg-final { scan-tree-dump "vect_\[^\r\m\]* = MIN" "slp2" { xfail { { ! vect_element_align } && { ! vect_hw_misalign } } } } }

15
gcc/testsuite/gcc.dg/tree-ssa/phi-opt-21.c Normal file
View file

@ -0,0 +1,15 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-phiopt4-details" } */
int f(unsigned s)
{
int i;
for (i = 0; i < s; ++i)
;
return i;
}
/* { dg-final { scan-tree-dump "converted to straightline code" "phiopt4" } } */
/* Make sure we fold the detected MAX<s, 0>. */
/* { dg-final { scan-tree-dump-not "MAX" "phiopt4" } } */

25
gcc/tree-ssa-phiopt.c
View file

@ -46,6 +46,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree-inline.h"
#include "case-cfn-macros.h"
#include "tree-eh.h"
#include "gimple-fold.h"
static unsigned int tree_ssa_phiopt_worker (bool, bool, bool);
static bool two_value_replacement (basic_block, basic_block, edge, gphi *,
@ -1364,7 +1365,6 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb,
{
tree result, type, rhs;
gcond *cond;
gassign *new_stmt;
edge true_edge, false_edge;
enum tree_code cmp, minmax, ass_code;
tree smaller, alt_smaller, larger, alt_larger, arg_true, arg_false;
@ -1688,19 +1688,20 @@ minmax_replacement (basic_block cond_bb, basic_block middle_bb,
gsi_move_before (&gsi_from, &gsi);
}
/* Create an SSA var to hold the min/max result. If we're the only
things setting the target PHI, then we can clone the PHI
variable. Otherwise we must create a new one. */
result = PHI_RESULT (phi);
if (EDGE_COUNT (gimple_bb (phi)->preds) == 2)
result = duplicate_ssa_name (result, NULL);
else
result = make_ssa_name (TREE_TYPE (result));
/* Emit the statement to compute min/max. */
new_stmt = gimple_build_assign (result, minmax, arg0, arg1);
gimple_seq stmts = NULL;
tree phi_result = PHI_RESULT (phi);
result = gimple_build (&stmts, minmax, TREE_TYPE (phi_result), arg0, arg1);
/* Duplicate range info if we're the only things setting the target PHI. */
if (!gimple_seq_empty_p (stmts)
&& EDGE_COUNT (gimple_bb (phi)->preds) == 2
&& !POINTER_TYPE_P (TREE_TYPE (phi_result))
&& SSA_NAME_RANGE_INFO (phi_result))
duplicate_ssa_name_range_info (result, SSA_NAME_RANGE_TYPE (phi_result),
SSA_NAME_RANGE_INFO (phi_result));
gsi = gsi_last_bb (cond_bb);
gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
gsi_insert_seq_before (&gsi, stmts, GSI_NEW_STMT);
replace_phi_edge_with_variable (cond_bb, e1, phi, result);