On Thu, Jul 14, 2022 at 1:24 PM Andrew Pinski <pins...@gmail.com> wrote:
> 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 for the help. I'm still having trouble with the vector test, though.
When I try to compile, I get an error saying "used vector type where scalar
is required", referring to the max expressions. How do I use the max
expression with two vectors as the inputs?
Thanks
-Sam
>
> >
> > 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
> >> >
> >>
>
>
