https://gcc.gnu.org/g:579de8f5295b05573d05f6e4102f1428f35c9f17
commit r16-4331-g579de8f5295b05573d05f6e4102f1428f35c9f17 Author: Jakub Jelinek <[email protected]> Date: Thu Oct 9 18:06:39 2025 +0200 gimplify: Fix up side-effect handling in 2nd __builtin_c[lt]zg argument [PR122188] The patch from yesterday made me think about side-effects in the second argument of __builtin_c[lt]zg. When we change __builtin_c[lt]zg (x, y) when y is not INTEGER_CST into x ? __builtin_c[lt]zg (x) : y with evaluating x only once, we omit the side-effects in y unless x is not 0. That looks undesirable, we should evaluate side-effects in y unconditionally. 2025-10-09 Jakub Jelinek <[email protected]> PR c/122188 * c-gimplify.cc (c_gimplify_expr): Also gimplify the second operand before the COND_EXPR and use in COND_EXPR result of gimplification. * gcc.dg/torture/pr122188.c: New test. Diff: --- gcc/c-family/c-gimplify.cc | 6 +++++- gcc/testsuite/gcc.dg/torture/pr122188.c | 33 +++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+), 1 deletion(-) diff --git a/gcc/c-family/c-gimplify.cc b/gcc/c-family/c-gimplify.cc index 6fcd45830562..2249c101cf56 100644 --- a/gcc/c-family/c-gimplify.cc +++ b/gcc/c-family/c-gimplify.cc @@ -1040,6 +1040,10 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED, if (gimplify_expr (&a, pre_p, post_p, is_gimple_val, fb_rvalue) == GS_ERROR) return GS_ERROR; + tree b = CALL_EXPR_ARG (*expr_p, 1); + if (gimplify_expr (&b, pre_p, post_p, is_gimple_val, fb_rvalue) + == GS_ERROR) + return GS_ERROR; tree c = build_call_expr_loc (EXPR_LOCATION (*expr_p), fndecl, 1, a); *expr_p = build3_loc (EXPR_LOCATION (*expr_p), COND_EXPR, @@ -1047,7 +1051,7 @@ c_gimplify_expr (tree *expr_p, gimple_seq *pre_p ATTRIBUTE_UNUSED, build2_loc (EXPR_LOCATION (*expr_p), NE_EXPR, boolean_type_node, a, build_zero_cst (TREE_TYPE (a))), - c, CALL_EXPR_ARG (*expr_p, 1)); + c, b); return GS_OK; } break; diff --git a/gcc/testsuite/gcc.dg/torture/pr122188.c b/gcc/testsuite/gcc.dg/torture/pr122188.c new file mode 100644 index 000000000000..2c549630f9de --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr122188.c @@ -0,0 +1,33 @@ +/* PR c/122188 */ +/* { dg-do run } */ + +int +foo (unsigned x, int y) +{ + unsigned a = x; + int b = y; + int ret = __builtin_ctzg (x++, y++); + if (x != a + 1 || y != b + 1) + __builtin_abort (); + return ret; +} + +int +bar (unsigned x, int y) +{ + unsigned a = x; + int b = y; + int ret = __builtin_clzg (x++, y++); + if (x != a + 1 || y != b + 1) + __builtin_abort (); + return ret; +} + +int +main () +{ + if (foo (0, 42) != 42 || foo (1, 5) != 0 || foo (4, 17) != 2) + __builtin_abort (); + if (bar (0, 42) != 42 || bar (~0U, 5) != 0 || bar (~0U >> 4, 17) != 4) + __builtin_abort (); +}
