[pushed] match.pd: Add new abs pattern [PR94920]
Commit Message
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.
---
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(+)
create mode 100644 gcc/testsuite/g++.dg/pr94920-1.C
create mode 100644 gcc/testsuite/g++.dg/pr94920.C
create mode 100644 gcc/testsuite/gcc.dg/pr94920-2.c
base-commit: 28be481cf47d52af8b11972d2394226bbaf87867
Comments
On Thu, Jul 21, 2022 at 05:28:34PM -0400, Sam Feifer via Gcc-patches wrote:
> 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.
To clarify, this patch has been approved by Richi in an earlier
thread, so...
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
...this line isn't really asking for a review.
> PR tree-optimization/94920
>
> gcc/ChangeLog:
>
> * match.pd (x >= 0 ? x : 0) + (x <= 0 ? -x : 0): New simplification.
> (x <= 0 ? -x : 0): New simplification.
The second line ought to be formatted 8 spaces to the left, so that
it's aligned with '* match.pd'.
Marek
@@ -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)
new file mode 100644
@@ -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;
+}
new file mode 100644
@@ -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" } } */
new file mode 100644
@@ -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" } } */