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

[Richard Biener <richard.guenther@gmail.com>]

On Wed, Jul 27, 2022 at 9:57 PM Sam Feifer <sfeifer@redhat.com> wrote:
>
>
>> _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.

+/* 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)

Testing this only for @0 is enough, we don't allow mixed types for
trunc_div or mult.

+    (eq (trunc_mod @0 @1) { build_zero_cst (TREE_TYPE(@0)); })))

space before (@0) in 'TREE_TYPE(@0)'

OK with those changes.

Thanks,
Richard.



> 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
>> > > >> >
>> > > >>
>> > >
>> > >
>>