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* [gcc r13-1785] match.pd: Add new abs pattern [PR94920]
@ 2022-07-21 21:27 Sam Feifer
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From: Sam Feifer @ 2022-07-21 21:27 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:633e9920589ddfaf2d6da1c24ce99b18a2638db4
commit r13-1785-g633e9920589ddfaf2d6da1c24ce99b18a2638db4
Author: Sam Feifer <sfeifer@redhat.com>
Date: Thu Jul 21 16:31:41 2022 -0400
match.pd: Add new abs pattern [PR94920]
This patch is intended to fix a missed optimization in match.pd. It optimizes (x >= 0 ? x : 0) + (x <= 0 ? -x : 0) to just abs(x). Additionally, the pattern (x <= 0 ? -x : 0) now gets optimized to max(-x, 0), which helps with the other simplification rule.
Tests are also included to be added to the testsuite.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
PR tree-optimization/94920
gcc/ChangeLog:
* match.pd (x >= 0 ? x : 0) + (x <= 0 ? -x : 0): New simplification.
(x <= 0 ? -x : 0): New simplification.
gcc/testsuite/ChangeLog:
* g++.dg/pr94920-1.C: New test.
* g++.dg/pr94920.C: New test.
* gcc.dg/pr94920-2.c: New test.
Diff:
---
gcc/match.pd | 10 +++++++
gcc/testsuite/g++.dg/pr94920-1.C | 17 +++++++++++
gcc/testsuite/g++.dg/pr94920.C | 63 ++++++++++++++++++++++++++++++++++++++++
gcc/testsuite/gcc.dg/pr94920-2.c | 15 ++++++++++
4 files changed, 105 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 88a1a5aa9cc..9736393061a 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -339,6 +339,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (REAL_VALUE_NEGATIVE (TREE_REAL_CST (@0)))
(COPYSIGN_ALL (negate @0) @1)))
+/* (x >= 0 ? x : 0) + (x <= 0 ? -x : 0) -> abs x. */
+(simplify
+ (plus:c (max @0 integer_zerop) (max (negate @0) integer_zerop))
+ (abs @0))
+
/* X * 1, X / 1 -> X. */
(for op (mult trunc_div ceil_div floor_div round_div exact_div)
(simplify
@@ -3425,6 +3430,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
&& (GIMPLE || !TREE_SIDE_EFFECTS (@1)))
(cond (convert:boolean_type_node @2) @1 @0)))
+/* (x <= 0 ? -x : 0) -> max(-x, 0). */
+(simplify
+ (cond (le @0 integer_zerop@1) (negate@2 @0) integer_zerop@1)
+ (max @2 @1))
+
/* Simplifications of shift and rotates. */
(for rotate (lrotate rrotate)
diff --git a/gcc/testsuite/g++.dg/pr94920-1.C b/gcc/testsuite/g++.dg/pr94920-1.C
new file mode 100644
index 00000000000..6c6483eab2d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr94920-1.C
@@ -0,0 +1,17 @@
+/* PR tree-optimization/94920 */
+/* { dg-do run } */
+
+#include "pr94920.C"
+
+int main() {
+
+ if (foo(0) != 0
+ || foo(-42) != 42
+ || foo(42) != 42
+ || baz(-10) != 10
+ || baz(-10) != 10) {
+ __builtin_abort();
+ }
+
+ return 0;
+}
diff --git a/gcc/testsuite/g++.dg/pr94920.C b/gcc/testsuite/g++.dg/pr94920.C
new file mode 100644
index 00000000000..925ec4f42f1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr94920.C
@@ -0,0 +1,63 @@
+/* PR tree-optimization/94920 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+typedef int __attribute__((vector_size(4*sizeof(int)))) vint;
+
+/* Same form as PR. */
+__attribute__((noipa)) unsigned int foo(int x) {
+ return (x >= 0 ? x : 0) + (x <= 0 ? -x : 0);
+}
+
+/* Test for forward propogation. */
+__attribute__((noipa)) unsigned int corge(int x) {
+ int w = (x >= 0 ? x : 0);
+ int y = -x;
+ int z = (y >= 0 ? y : 0);
+ return w + z;
+}
+
+/* Vector case. */
+__attribute__((noipa)) vint thud(vint x) {
+ vint t = (x >= 0 ? x : 0) ;
+ vint xx = -x;
+ vint t1 = (xx >= 0 ? xx : 0);
+ return t + t1;
+}
+
+/* Signed function. */
+__attribute__((noipa)) int bar(int x) {
+ return (x >= 0 ? x : 0) + (x <= 0 ? -x : 0);
+}
+
+/* Commutative property. */
+__attribute__((noipa)) unsigned int baz(int x) {
+ return (x <= 0 ? -x : 0) + (x >= 0 ? x : 0);
+}
+
+/* Flipped order for max expressions. */
+__attribute__((noipa)) unsigned int quux(int x) {
+ return (0 <= x ? x : 0) + (0 >= x ? -x : 0);
+}
+
+/* Not zero so should not optimize. */
+__attribute__((noipa)) unsigned int waldo(int x) {
+ return (x >= 4 ? x : 4) + (x <= 4 ? -x : 4);
+}
+
+/* Not zero so should not optimize. */
+__attribute__((noipa)) unsigned int fred(int x) {
+ return (x >= -4 ? x : -4) + (x <= -4 ? -x : -4);
+}
+
+/* Incorrect pattern. */
+__attribute__((noipa)) unsigned int goo(int x) {
+ return (x <= 0 ? x : 0) + (x >= 0 ? -x : 0);
+}
+
+/* Incorrect pattern. */
+__attribute__((noipa)) int qux(int x) {
+ return (x >= 0 ? x : 0) + (x >= 0 ? x : 0);
+}
+
+/* { dg-final {scan-tree-dump-times " ABS_EXPR " 6 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/pr94920-2.c b/gcc/testsuite/gcc.dg/pr94920-2.c
new file mode 100644
index 00000000000..a2d23324cfa
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94920-2.c
@@ -0,0 +1,15 @@
+/* PR tree-optimization/94920 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+/* Form from PR. */
+__attribute__((noipa)) unsigned int foo(int x) {
+ return x <= 0 ? -x : 0;
+}
+
+/* Changed order. */
+__attribute__((noipa)) unsigned int bar(int x) {
+ return 0 >= x ? -x : 0;
+}
+
+/* { dg-final {scan-tree-dump-times " MAX_EXPR " 2 "optimized" } } */
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