This patch adds a simplification to match.pd that was discussed on the thread for pr106243. It simplifies the pattern, abs(x) & 1, to x & 1.
There are also tests for the simplification in this patch. I couldn't figure out how to get abs to work with vectors. If a test for that is necessary, could I get some guidance on using abs with vector types? Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? PR tree-optimization/106243 gcc/ChangeLog: * match.pd (abs(x) & 1): New simplification. gcc/testsuite/ChangeLog: * gcc.dg/pr106243-2.c: New test. * gcc.dg/pr106243-3.c: New test. --- gcc/match.pd | 5 +++++ gcc/testsuite/gcc.dg/pr106243-2.c | 31 +++++++++++++++++++++++++++++++ gcc/testsuite/gcc.dg/pr106243-3.c | 18 ++++++++++++++++++ 3 files changed, 54 insertions(+) create mode 100644 gcc/testsuite/gcc.dg/pr106243-2.c create mode 100644 gcc/testsuite/gcc.dg/pr106243-3.c diff --git a/gcc/match.pd b/gcc/match.pd index f82f94ad1fe..c04e70f34c1 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -8071,3 +8071,8 @@ and, (simplify (bit_and (negate @0) integer_onep@1) (bit_and @0 @1)) + +/* abs(x) & 1 -> x & 1. */ +(simplify + (bit_and (abs @0) integer_onep@1) + (bit_and @0 @1)) diff --git a/gcc/testsuite/gcc.dg/pr106243-2.c b/gcc/testsuite/gcc.dg/pr106243-2.c new file mode 100644 index 00000000000..27e66f59160 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr106243-2.c @@ -0,0 +1,31 @@ +/* PR tree-optimization/106243 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +#include <stdlib.h> + +__attribute__((noipa)) int foo (int x) { + return abs(x) & 1; +} + +__attribute__((noipa)) int bar (int x) { + return (0 - abs(x)) & 1; +} + +/* Commutative property. */ +__attribute__((noipa)) int baz (int x) { + return 1 & abs(x); +} + +/* Forward propogation. */ +__attribute__((noipa)) int qux (int x) { + int y = abs(x); + return y & 1; +} + +/* Should not simplify. */ +__attribute__((noipa)) int thud (int x) { + return abs(x) & -1; +} + +/* { dg-final {scan-tree-dump-times " ABS_EXPR " 1 "optimized" } } */ diff --git a/gcc/testsuite/gcc.dg/pr106243-3.c b/gcc/testsuite/gcc.dg/pr106243-3.c new file mode 100644 index 00000000000..68800868751 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr106243-3.c @@ -0,0 +1,18 @@ +/* PR tree-optimization/106243 */ +/* { dg-do run } */ +/* { dg-options "-O2" } */ + +#include "pr106243-2.c" + +int main () { + + if (foo(6) != 0 + || bar(-3) != 1 + || baz(32) != 0 + || qux(-128) != 0 + || foo (127) != 1) { + __builtin_abort(); + } + + return 0; +} base-commit: be58bf98e98bb431ed26ca8be84586075fe8be82 -- 2.31.1