https://gcc.gnu.org/g:4d341923e93d6d55b4cdc36db7a8e52f03973c19
commit r17-1953-g4d341923e93d6d55b4cdc36db7a8e52f03973c19 Author: Kael Andrew Alonzo Franco <[email protected]> Date: Tue Jun 23 14:34:29 2026 -0400 match: X % Y < Y -> Y >= 0 and X % Y >= Y -> Y < 0 [PR125737] We had a pattern for `X % Y < Y` when X and Y where non-negative but this can be generalized for all values. And also we can handle `>=` too. Bootstrapped and tested on x86_64-pc-linux-gnu PR tree-optimization/125737 gcc: * match.pd: Optimize X % Y < Y -> Y >= 0 and X % Y >= Y -> Y < 0 gcc/testsuite: * gcc.dg/pr125737.c: Move test to pr125737-1.c. * gcc.dg/pr125737-1.c: Add test for (a % b) >= b when a and b are nonnegative. * gcc.dg/pr125737-2.c: New test for (a % b) {<,>=} b. Signed-off-by: Kael Franco <[email protected]> Diff: --- gcc/match.pd | 10 ++++++---- gcc/testsuite/gcc.dg/{pr125737.c => pr125737-1.c} | 10 +++++++++- gcc/testsuite/gcc.dg/pr125737-2.c | 14 ++++++++++++++ 3 files changed, 29 insertions(+), 5 deletions(-) diff --git a/gcc/match.pd b/gcc/match.pd index 5d589989bd1e..ddf3b61638ce 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -1746,11 +1746,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) wi::max_value (TYPE_PRECISION (TREE_TYPE (@0)), SIGNED))) (resop @2 { build_zero_cst (TREE_TYPE (@2)); })))) -/* X % Y is smaller than Y. */ -(for cmp (lt ge) +/* X % Y < Y -> Y >= 0 + X % Y >= Y -> Y < 0 */ +(for ltge (lt ge) + gelt (ge lt) (simplify - (cmp:c (trunc_mod tree_expr_nonnegative_p@0 tree_expr_nonnegative_p@1) @1) - { constant_boolean_node (cmp == LT_EXPR, type); })) + (ltge:c (trunc_mod @0 @1) @1) + (gelt @1 { build_zero_cst (TREE_TYPE (@1)); }))) /* x | ~0 -> ~0 */ (simplify diff --git a/gcc/testsuite/gcc.dg/pr125737.c b/gcc/testsuite/gcc.dg/pr125737-1.c similarity index 51% rename from gcc/testsuite/gcc.dg/pr125737.c rename to gcc/testsuite/gcc.dg/pr125737-1.c index 93d0fcd215af..85347a63c7f2 100644 --- a/gcc/testsuite/gcc.dg/pr125737.c +++ b/gcc/testsuite/gcc.dg/pr125737-1.c @@ -9,4 +9,12 @@ f (unsigned short a, unsigned short b) { return c < bb; } -/* { dg-final { scan-tree-dump-times "return 1;" 1 "optimized" } } */ +int +g (unsigned short a, unsigned short b) { + int aa = a; + int bb = b; + int c = aa % bb; + return (c >= bb) == 0; +} + +/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */ diff --git a/gcc/testsuite/gcc.dg/pr125737-2.c b/gcc/testsuite/gcc.dg/pr125737-2.c new file mode 100644 index 000000000000..0090fa04ca8c --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr125737-2.c @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ + +_Bool +a_mod_b_lt_b (int a, int b) { + return ((a % b) < b) == (b >= 0); +} + +_Bool +a_mod_b_ge_b (int a, int b) { + return ((a % b) >= b) == (b < 0); +} + +/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */
