On Wed, Aug 3, 2022 at 9:11 PM Sam Feifer via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> This patch adds a new optimization to match.pd. The pattern, -x & 1,
> now gets simplified to x & 1, reducing the number of instructions
> produced.
>
> This patch also adds tests for the optimization rule.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
>
> PR tree-optimization/106243
>
> gcc/ChangeLog:
>
> * match.pd (-x & 1): New simplification.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/pr106243-1.c: New test.
> * gcc.dg/pr106243.c: New test.
> ---
> gcc/match.pd | 5 ++++
> gcc/testsuite/gcc.dg/pr106243-1.c | 18 +++++++++++++
> gcc/testsuite/gcc.dg/pr106243.c | 43 +++++++++++++++++++++++++++++++
> 3 files changed, 66 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/pr106243-1.c
> create mode 100644 gcc/testsuite/gcc.dg/pr106243.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 562138a8034..78b32567836 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -8061,3 +8061,8 @@ and,
> (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
> (bit_and @0 @1)
> (cond (le @0 @1) @0 (bit_and @0 @1))))))
> +
> +/* -x & 1 -> x & 1. */
> +(simplify
> + (bit_and:c (negate @0) integer_onep@1)
Note the bit_and doesn't need :c because constant operands are always
canonicalized second.
OK with that change.
Thanks,
Richard.
> + (bit_and @0 @1))
> diff --git a/gcc/testsuite/gcc.dg/pr106243-1.c
> b/gcc/testsuite/gcc.dg/pr106243-1.c
> new file mode 100644
> index 00000000000..b1dbe5cbe44
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr106243-1.c
> @@ -0,0 +1,18 @@
> +/* PR tree-optimization/106243 */
> +/* { dg-do run } */
> +/* { dg-options "-O2" } */
> +
> +#include "pr106243.c"
> +
> +int main () {
> +
> + if (foo(3) != 1
> + || bar(-6) != 0
> + || baz(17) != 1
> + || qux(-128) != 0
> + || foo(127) != 1) {
> + __builtin_abort();
> + }
> +
> + return 0;
> +}
> diff --git a/gcc/testsuite/gcc.dg/pr106243.c b/gcc/testsuite/gcc.dg/pr106243.c
> new file mode 100644
> index 00000000000..ee2706f2bf9
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/pr106243.c
> @@ -0,0 +1,43 @@
> +/* PR tree-optimization/106243 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +#define vector __attribute__((vector_size(4*sizeof(int))))
> +
> +/* Test from PR. */
> +__attribute__((noipa)) int foo (int x) {
> + return -x & 1;
> +}
> +
> +/* Other test from PR. */
> +__attribute__((noipa)) int bar (int x) {
> + return (0 - x) & 1;
> +}
> +
> +/* Forward propogation. */
> +__attribute__((noipa)) int baz (int x) {
> + x = -x;
> + return x & 1;
> +}
> +
> +/* Commutative property. */
> +__attribute__((noipa)) int qux (int x) {
> + return 1 & -x;
> +}
> +
> +/* Vector test case. */
> +__attribute__((noipa)) vector int waldo (vector int x) {
> + return -x & 1;
> +}
> +
> +/* Should not simplify. */
> +__attribute__((noipa)) int thud (int x) {
> + return -x & 2;
> +}
> +
> +/* Should not simplify. */
> +__attribute__((noipa)) int corge (int x) {
> + return -x & -1;
> +}
> +
> +/* { dg-final {scan-tree-dump-times "-" 2 "optimized" } } */
>
> base-commit: 388fbbd895e72669909173c3003ae65c6483a3c2
> --
> 2.31.1
>
