https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114038
--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:853cbcb7a74ecd95efcba25279b270f0a868d584 commit r14-9131-g853cbcb7a74ecd95efcba25279b270f0a868d584 Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Feb 22 10:14:00 2024 +0100 bitintlower: Fix .MUL_OVERFLOW overflow checking [PR114038] Currently, bitint_large_huge::lower_mul_overflow uses cnt 1 only if startlimb == endlimb and in that case doesn't use a loop and handles everything in a special if: unsigned cnt; bool use_loop = false; if (startlimb == endlimb) cnt = 1; else if (startlimb + 1 == endlimb) cnt = 2; else if ((end % limb_prec) == 0) { cnt = 2; use_loop = true; } else { cnt = 3; use_loop = startlimb + 2 < endlimb; } if (cnt == 1) { ... } else The loop handling for the loop exit condition wants to compare if the incremented index is equal to endlimb, but that is correct only if end is not divisible by limb_prec and there will be a straight line check after the loop as well for the most significant limb. The code used endlimb + (cnt == 1) for that, but cnt == 1 is never true here, because cnt is either 2 or 3, so the right check is (cnt == 2). 2024-02-22 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/114038 * gimple-lower-bitint.cc (bitint_large_huge::lower_mul_overflow): Fix loop exit condition if end is divisible by limb_prec. * gcc.dg/torture/bitint-59.c: New test.
