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* [gcc r13-1916] match.pd: Add new division pattern [PR104992]
@ 2022-08-01 13:24 Sam Feifer
0 siblings, 0 replies; only message in thread
From: Sam Feifer @ 2022-08-01 13:24 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:388fbbd895e72669909173c3003ae65c6483a3c2
commit r13-1916-g388fbbd895e72669909173c3003ae65c6483a3c2
Author: Sam Feifer <sfeifer@redhat.com>
Date: Fri Jul 29 09:44:48 2022 -0400
match.pd: Add new division pattern [PR104992]
This patch fixes a missed optimization in match.pd. It takes the pattern,
x / y * y == x, and optimizes it to x % y == 0. This produces fewer
instructions. This simplification does not happen for complex types.
This patch also adds tests for the optimization rule.
Bootstrapped/regtested on x86_64-pc-linux-gnu.
PR tree-optimization/104992
gcc/ChangeLog:
* match.pd (x / y * y == x): New simplification.
gcc/testsuite/ChangeLog:
* g++.dg/pr104992-1.C: New test.
* gcc.dg/pr104992.c: New test.
Diff:
---
gcc/match.pd | 6 +++++
gcc/testsuite/g++.dg/pr104992-1.C | 30 +++++++++++++++++++++
gcc/testsuite/gcc.dg/pr104992.c | 57 +++++++++++++++++++++++++++++++++++++++
3 files changed, 93 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 330c1db0c8e..562138a8034 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3982,6 +3982,12 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(plus:c (mult:c (div @0 @1) @1) (mod @0 @1))
@0))
+/* x / y * y == x -> x % y == 0. */
+(simplify
+ (eq:c (mult:c (trunc_div:s @0 @1) @1) @0)
+ (if (TREE_CODE (TREE_TYPE (@0)) != COMPLEX_TYPE)
+ (eq (trunc_mod @0 @1) { build_zero_cst (TREE_TYPE (@0)); })))
+
/* ((X /[ex] A) +- B) * A --> X +- A * B. */
(for op (plus minus)
(simplify
diff --git a/gcc/testsuite/g++.dg/pr104992-1.C b/gcc/testsuite/g++.dg/pr104992-1.C
new file mode 100644
index 00000000000..f5696b245ac
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr104992-1.C
@@ -0,0 +1,30 @@
+/* PR tree-optimization/104992 */
+/* { dg-do run } */
+/* { dg-options "-O2"} */
+
+#include "../gcc.dg/pr104992.c"
+
+int main () {
+
+ /* Should be true. */
+ if (!foo(6, 3)
+ || !bar(12, 2)
+ || !baz(34, 17)
+ || !qux(50, 10)
+ || !fred(16, 8)
+ || !baz(-9, 3)
+ || !baz(9, -3)
+ || !baz(-9, -3)
+ ) {
+ __builtin_abort();
+ }
+
+ /* Should be false. */
+ if (foo(5, 30)
+ || bar(72, 27)
+ || baz(42, 15)) {
+ __builtin_abort();
+ }
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/pr104992.c b/gcc/testsuite/gcc.dg/pr104992.c
new file mode 100644
index 00000000000..b9d91a13ad8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr104992.c
@@ -0,0 +1,57 @@
+/* PR tree-optimization/104992 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+#define vector __attribute__((vector_size(4*sizeof(int))))
+
+/* Form from PR. */
+__attribute__((noipa)) unsigned foo(unsigned x, unsigned y)
+{
+ return x / y * y == x;
+}
+
+__attribute__((noipa)) unsigned bar(unsigned x, unsigned y) {
+ return x == x / y * y;
+}
+
+/* Signed test case. */
+__attribute__((noipa)) unsigned baz (int x, int y) {
+ return x / y * y == x;
+}
+
+/* Changed order. */
+__attribute__((noipa)) unsigned qux (unsigned x, unsigned y) {
+ return y * (x / y) == x;
+}
+
+/* Test for forward propogation. */
+__attribute__((noipa)) unsigned corge(unsigned x, unsigned y) {
+ int z = x / y;
+ int q = z * y;
+ return q == x;
+}
+
+/* Test vector case. */
+__attribute__((noipa)) vector int thud(vector int x, vector int y) {
+ return x / y * y == x;
+}
+
+/* Complex type should not simplify because mod is different. */
+__attribute__((noipa)) int goo(_Complex int x, _Complex int y)
+{
+ _Complex int z = x / y;
+ _Complex int q = z * y;
+ return q == x;
+}
+
+/* Wrong order. */
+__attribute__((noipa)) unsigned fred (unsigned x, unsigned y) {
+ return y * x / y == x;
+}
+
+/* Wrong pattern. */
+__attribute__((noipa)) unsigned waldo (unsigned x, unsigned y, unsigned z) {
+ return x / y * z == x;
+}
+
+/* { dg-final {scan-tree-dump-times " % " 9 "optimized" } } */
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