https://gcc.gnu.org/g:65936041dbffdc735bed4dbf831462ff3922d28f
commit 65936041dbffdc735bed4dbf831462ff3922d28f
Author: Andrew Pinski <quic_apin...@quicinc.com>
Date: Thu Jul 25 17:43:07 2024 -0700
isel: Don't duplicate comparisons for -O0 nor -fno-tree-ter [PR116101]
While doing cleanups on this code I noticed that we do the duplicate
of comparisons at -O0. For C and C++ code this makes no difference as
the gimplifier never produces COND_EXPR. But it could make a difference
for other front-ends.
Oh and for -fno-tree-ter, duplicating the comparison is just a waste
as it is never used for expand.
I also decided to add a few testcases so this is checked in the future.
Even added one for the duplication itself.
Bootstrapped and tested on x86_64-linux-gnu with no regressions.
PR tree-optimization/116101
gcc/ChangeLog:
* gimple-isel.cc (maybe_duplicate_comparison): Don't
do anything for -O0 or -fno-tree-ter.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/dup_compare_cond-1.c: New test.
* gcc.dg/tree-ssa/dup_compare_cond-2.c: New test.
* gcc.dg/tree-ssa/dup_compare_cond-3.c: New test.
Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
Diff:
---
gcc/gimple-isel.cc | 5 +++++
gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c | 19 +++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c | 19 +++++++++++++++++++
gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c | 19 +++++++++++++++++++
4 files changed, 62 insertions(+)
diff --git a/gcc/gimple-isel.cc b/gcc/gimple-isel.cc
index 99bfc937bd55..2817ab659af1 100644
--- a/gcc/gimple-isel.cc
+++ b/gcc/gimple-isel.cc
@@ -407,6 +407,11 @@ maybe_duplicate_comparison (gassign *stmt, basic_block bb)
tree lhs = gimple_assign_lhs (stmt);
unsigned cnt = 0;
+ /* This is should not be used for -O0 nor it is not useful
+ when ter is turned off. */
+ if (!optimize || !flag_tree_ter)
+ return;
+
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, lhs)
{
if (is_gimple_debug (USE_STMT (use_p)))
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
new file mode 100644
index 000000000000..0321a60b34f8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-1.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple -O0 -fdump-tree-optimized " } */
+/* PR tree-optimization/116101 */
+
+int __GIMPLE() f(int a, int b, int c, int d, int e)
+{
+ _Bool t;
+ int ff;
+ int gg;
+ int res;
+ t = a == b;
+ ff = t ? a : e;
+ gg = t ? d : b;
+ res = ff+gg;
+ return res;
+}
+
+/* At -O0 we should not duplicate the comparison. */
+/* { dg-final { scan-tree-dump-times " == " 1 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
new file mode 100644
index 000000000000..07e2175c612e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-2.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple -O2 -fdump-tree-optimized " } */
+/* PR middle-end/105715 */
+
+int __GIMPLE() f(int a, int b, int c, int d, int e)
+{
+ _Bool t;
+ int ff;
+ int gg;
+ int res;
+ t = a == b;
+ ff = t ? a : e;
+ gg = t ? d : b;
+ res = ff+gg;
+ return res;
+}
+
+/* At -O2 we should have duplicate the comparison. */
+/* { dg-final { scan-tree-dump-times " == " 2 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
new file mode 100644
index 000000000000..88bf19795e04
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/dup_compare_cond-3.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-fgimple -O2 -fno-tree-ter -fdump-tree-optimized " } */
+/* PR tree-optimization/116101 */
+
+int __GIMPLE() f(int a, int b, int c, int d, int e)
+{
+ _Bool t;
+ int ff;
+ int gg;
+ int res;
+ t = a == b;
+ ff = t ? a : e;
+ gg = t ? d : b;
+ res = ff+gg;
+ return res;
+}
+
+/* With -fno-tree-ter it is not useful to duplicate the comparison. */
+/* { dg-final { scan-tree-dump-times " == " 1 "optimized" } } */
