On Thu, Jul 14, 2022 at 7:09 AM Sam Feifer <sfei...@redhat.com> wrote:
>
>
> On Wed, Jul 13, 2022 at 3:36 PM Andrew Pinski <pins...@gmail.com> wrote:
>>
>> On Wed, Jul 13, 2022 at 12:26 PM Sam Feifer via Gcc-patches
>> <gcc-patches@gcc.gnu.org> 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). I had to
>> > write a second simplification in match.pd to handle the commutative
>> > property as the match was not ocurring otherwise. Additionally, the
>> > pattern (x <= 0 ? -x : 0) now gets optimized to max(-x, 0), which helps
>> > with the other simplification rule.
>>
>> You could use :c for the commutative property instead and that should
>> simplify things.
>> That is:
>>
>> (simplify
>> (plus:c (max @0 integer_zerop) (max (negate @0) integer_zerop))
>> (abs @0))
>>
>> Also since integer_zerop works on vectors, it seems like you should
>> add a testcase or two for the vector case.
>> Also would be useful if you write a testcase that uses different
>> statements rather than one big one so it gets exercised in the
>> forwprop case.
>> Note also if either of the max are used more than just in this
>> simplification, it could increase the lifetime of @0, maybe you need
>> to add :s to the max expressions.
>>
>
> Thanks for the feedback. I'm not quite sure what a vector test case would
> look like for this. Could I get some guidance on that?
Yes this should produce the pattern at forwprop1 time (with the C++
front-end, the C front-end does not support vector selects):
typedef int __attribute__((vector_size(4*sizeof(int)))) vint;
vint foo(vint x) {
vint t = (x >= 0 ? x : 0) ;
vint xx = -x;
vint t1 = (xx >= 0 ? xx : 0);
return t + t1;
}
int foo(int x) {
int t = (x >= 0 ? x : 0) ;
int xx = -x;
int t1 = (xx >= 0 ? xx : 0);
return t + t1;
}
Thanks,
Andrew Pinski
>
> Thanks
> -Sam
>
>>
>> Thanks,
>> Andrew
>>
>> >
>> > Tests are also included to be added to the testsuite.
>> >
>> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>> >
>> > PR tree-optimization/94290
>> >
>> > gcc/ChangeLog:
>> >
>> > * match.pd (x >= 0 ? x : 0) + (x <= 0 ? -x : 0): New
>> > simplification.
>> > * match.pd (x <= 0 ? -x : 0): New Simplification.
>> >
>> > gcc/testsuite/ChangeLog:
>> >
>> > * gcc.c-torture/execute/pr94290-1.c: New test.
>> > * gcc.dg/pr94290-2.c: New test.
>> > * gcc.dg/pr94290.c: New test.
>> > ---
>> > gcc/match.pd | 15 ++++++
>> > .../gcc.c-torture/execute/pr94290-1.c | 16 +++++++
>> > gcc/testsuite/gcc.dg/pr94290-2.c | 15 ++++++
>> > gcc/testsuite/gcc.dg/pr94290.c | 46 +++++++++++++++++++
>> > 4 files changed, 92 insertions(+)
>> > create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr94290-1.c
>> > create mode 100644 gcc/testsuite/gcc.dg/pr94290-2.c
>> > create mode 100644 gcc/testsuite/gcc.dg/pr94290.c
>> >
>> > diff --git a/gcc/match.pd b/gcc/match.pd
>> > index 45aefd96688..55ca79d7ac9 100644
>> > --- a/gcc/match.pd
>> > +++ b/gcc/match.pd
>> > @@ -7848,3 +7848,18 @@ and,
>> > (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
>> > (bit_and @0 @1)
>> > (cond (le @0 @1) @0 (bit_and @0 @1))))))
>> > +
>> > +/* (x >= 0 ? x : 0) + (x <= 0 ? -x : 0) -> abs x. */
>> > +(simplify
>> > + (plus (max @0 integer_zerop) (max (negate @0) integer_zerop))
>> > + (abs @0))
>> > +
>> > +/* (x <= 0 ? -x : 0) + (x >= 0 ? x : 0) -> abs x. */
>> > +(simplify
>> > + (plus (max (negate @0) integer_zerop) (max @0 integer_zerop) )
>> > + (abs @0))
>> > +
>> > +/* (x <= 0 ? -x : 0) -> max(-x, 0). */
>> > +(simplify
>> > + (cond (le @0 integer_zerop@1) (negate @0) integer_zerop@1)
>> > + (max (negate @0) @1))
>> > diff --git a/gcc/testsuite/gcc.c-torture/execute/pr94290-1.c
>> > b/gcc/testsuite/gcc.c-torture/execute/pr94290-1.c
>> > new file mode 100644
>> > index 00000000000..93b80d569aa
>> > --- /dev/null
>> > +++ b/gcc/testsuite/gcc.c-torture/execute/pr94290-1.c
>> > @@ -0,0 +1,16 @@
>> > +/* PR tree-optimization/94290 */
>> > +
>> > +#include "../../gcc.dg/pr94290.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/gcc.dg/pr94290-2.c
>> > b/gcc/testsuite/gcc.dg/pr94290-2.c
>> > new file mode 100644
>> > index 00000000000..ea6e55755f5
>> > --- /dev/null
>> > +++ b/gcc/testsuite/gcc.dg/pr94290-2.c
>> > @@ -0,0 +1,15 @@
>> > +/* PR tree-optimization/94290 */
>> > +/* { 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" } } */
>> > diff --git a/gcc/testsuite/gcc.dg/pr94290.c
>> > b/gcc/testsuite/gcc.dg/pr94290.c
>> > new file mode 100644
>> > index 00000000000..47617c36c02
>> > --- /dev/null
>> > +++ b/gcc/testsuite/gcc.dg/pr94290.c
>> > @@ -0,0 +1,46 @@
>> > +/* PR tree-optimization/94290 */
>> > +/* { dg-do compile } */
>> > +/* { dg-options "-O2 -fdump-tree-optimized" } */
>> > +
>> > +
>> > +/* Same form as PR. */
>> > +__attribute__((noipa)) unsigned int foo(int x) {
>> > + return (x >= 0 ? x : 0) + (x <= 0 ? -x : 0);
>> > +}
>> > +
>> > +/* 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 " 4 "optimized" } } */
>> >
>> > base-commit: 6af530f914801f5e561057da55c41480f28751f7
>> > --
>> > 2.31.1
>> >
>>
