https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106231
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Roger Sayle <sa...@gcc.gnu.org>: https://gcc.gnu.org/g:2907bfc3412dd8aef6c6acc17f2152a4e0ac4979 commit r13-1726-g2907bfc3412dd8aef6c6acc17f2152a4e0ac4979 Author: Roger Sayle <ro...@nextmovesoftware.com> Date: Mon Jul 18 07:44:38 2022 +0100 PR target/106231: Optimize (any_extend:DI (ctz:SI ...)) on x86_64. This patch resolves PR target/106231 by providing insns that recognize (zero_extend:DI (ctz:SI ...)) and (sign_extend:DI (ctz:SI ...)). The result of ctz:SI is always between 0 and 32 (or undefined), so sign_extension is the same as zero_extension, and the result is already extended in the destination register. Things are a little complicated, because the existing implementation of *ctzsi2 handles multiple cases, including false dependencies, which we continue to support in this patch. 2022-07-18 Roger Sayle <ro...@nextmovesoftware.com> gcc/ChangeLog PR target/106231 * config/i386/i386.md (*ctzsidi2_<s>ext): New insn_and_split to recognize any_extend:DI of ctz:SI which is implicitly extended. (*ctzsidi2_<s>ext_falsedep): New define_insn to model a DImode extended ctz:SI that has preceding xor to break false dependency. gcc/testsuite/ChangeLog PR target/106231 * gcc.target/i386/pr106231-1.c: New test case. * gcc.target/i386/pr106231-2.c: New test case.
