Re: [PATCH] match.pd: Add new division pattern [PR104992]

[Sam Feifer <sfeifer@redhat.com>]

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> _Complex int are strange beasts, I'd simply avoid the transform for them.
>
>
I added to the match.pd rule to not simplify if the operands are complex.
There is now a test case for complex types to make sure they do not
simplify. I had to move the "dg-do run" test to g++.dg to accommodate the
complex type function that is included (even though there isn't a runtime
test for complex types).

Can you please move the pattern next to the existing div/mod patterns,
> like after the related
>
>
done :)

/* Simplify (A / B) * B + (A % B) -> A.  */
> (for div (trunc_div ceil_div floor_div round_div)
>      mod (trunc_mod ceil_mod floor_mod round_mod)
>   (simplify
>    (plus:c (mult:c (div @0 @1) @1) (mod @0 @1))
>    @0))
>
> pattern?
>
> +/* x / y * y == x -> x % y == 0.  */
> +(simplify
> +  (eq (mult (trunc_div @0 @1) @1) @0)
> +  (eq (trunc_mod @0 @1) { build_zero_cst TREE_TYPE(@0); }))
>
> there are parens missing around the TREE_TYPE (@0), how did you test
> the patch?  You probably want :s on the trunc_div and as Andrew said
> :c on the eq and the mult.
>

I made those changes to the rule. The rule worked without the parentheses,
which is probably why I didn't notice they were missing. Attached is an
updated patch file.

Thanks
-Sam


> Richard.
>
> > Thanks
> > -Sam
> >
> >
> > > For vector try (which works for both the C and C++ front-end):
> > > #define vector __attribute__((vector_size(4*sizeof(int)) ))
> > > vector int f(vector int x, vector int y)
> > > {
> > >   return x == x / y * y;
> > > }
> > >
> > > That is for the vector case, == still returns a vector type.
> > >
> > > Thanks,
> > > Andrew Pinski
> > >
> > > >
> > > > Thanks
> > > > -Sam
> > > >
> > > >> Thanks,
> > > >> Andrew Pinski
> > > >>
> > > >> > diff --git a/gcc/testsuite/gcc.dg/pr104992-1.c
> > > b/gcc/testsuite/gcc.dg/pr104992-1.c
> > > >> > new file mode 100644
> > > >> > index 00000000000..a80e5e180ce
> > > >> > --- /dev/null
> > > >> > +++ b/gcc/testsuite/gcc.dg/pr104992-1.c
> > > >> > @@ -0,0 +1,30 @@
> > > >> > +/* PR tree-optimization/104992 */
> > > >> > +/* { dg-do run } */
> > > >> > +/* { dg-options "-O2"} */
> > > >> > +
> > > >> > +#include "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..b4b0ca53118
> > > >> > --- /dev/null
> > > >> > +++ b/gcc/testsuite/gcc.dg/pr104992.c
> > > >> > @@ -0,0 +1,35 @@
> > > >> > +/* PR tree-optimization/104992 */
> > > >> > +/* { dg-do compile } */
> > > >> > +/* { dg-options "-O2 -fdump-tree-optimized" } */
> > > >> > +
> > > >> > +/* 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;
> > > >> > +}
> > > >> > +
> > > >> > +/* 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 " % " 4 "optimized" } } */
> > > >> >
> > > >> > base-commit: 633e9920589ddfaf2d6da1c24ce99b18a2638db4
> > > >> > --
> > > >> > 2.31.1
> > > >> >
> > > >>
> > >
> > >
>
>

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From bdcfd7b85e95ec9a649c8083c4fbc1bfb88cea88 Mon Sep 17 00:00:00 2001
From: Sam Feifer <sfeifer@redhat.com>
Date: Wed, 27 Jul 2022 15:37:39 -0400
Subject: [PATCH] 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.

There are also tests for the optimizations to be added to the test suite.

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

	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.
---
 gcc/match.pd                      |  7 ++++
 gcc/testsuite/g++.dg/pr104992-1.C | 30 ++++++++++++++++
 gcc/testsuite/gcc.dg/pr104992.c   | 57 +++++++++++++++++++++++++++++++
 3 files changed, 94 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/pr104992-1.C
 create mode 100644 gcc/testsuite/gcc.dg/pr104992.c

diff --git a/gcc/match.pd b/gcc/match.pd
index 9736393061a..1442e4cf8dc 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -3981,6 +3981,13 @@ 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
+       && TREE_CODE (TREE_TYPE (@1)) != 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" } } */

base-commit: 633e9920589ddfaf2d6da1c24ce99b18a2638db4
-- 
2.31.1