https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120434
--- Comment #14 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:54da199f28da07166a44eae7d53acb9e3abe1306 commit r16-1399-g54da199f28da07166a44eae7d53acb9e3abe1306 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Jun 10 20:07:06 2025 +0200 i386: Handle ZERO_EXTEND like SIGN_EXTEND in bsr patterns [PR120434] The just posted second PR120434 patch causes +FAIL: gcc.target/i386/pr78103-3.c scan-assembler \\\\m(leaq|addq|incq)\\\\M +FAIL: gcc.target/i386/pr78103-3.c scan-assembler-not \\\\mmovl\\\\M+ +FAIL: gcc.target/i386/pr78103-3.c scan-assembler-not \\\\msubq\\\\M +FAIL: gcc.target/i386/pr78103-3.c scan-assembler-not \\\\mxor[lq]\\\\M While the patch generally improves code generation by often using ZERO_EXTEND instead of SIGN_EXTEND, where the former is often for free on x86_64 while the latter requires an extra instruction or larger instruction than one with just zero extend, the PR78103 combine patterns and splitters were written only with SIGN_EXTEND in mind. As CLZ is UB on 0 and otherwise returns just [0,63] and is xored with 63, ZERO_EXTEND does the same thing there as SIGN_EXTEND. 2025-06-10 Jakub Jelinek <ja...@redhat.com> PR middle-end/120434 * config/i386/i386.md (*bsr_rex64_2): Rename to ... (*bsr_rex64<u>_2): ... this. Use any_extend instead of sign_extend. (*bsr_2): Rename to ... (*bsr<u>_2): ... this. Use any_extend instead of sign_extend. (bsr splitters after those): Use any_extend instead of sign_extend.
