https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109086
--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Xi Ruoyao <xry...@gcc.gnu.org>: https://gcc.gnu.org/g:45641f3a99281bb0a429649741a29c2aace4c63e commit r13-6690-g45641f3a99281bb0a429649741a29c2aace4c63e Author: Xi Ruoyao <xry...@xry111.site> Date: Wed Mar 15 15:34:52 2023 +0800 builtins: Move the character difference into result instead of reassigning result [PR109086] expand_simple_binop() is allowed to allocate a new pseudo-register and return it, instead of forcing the result into the provided pseudo-register. This can cause a problem when we expand the unrolled loop for __builtin_strcmp: the compiler always generates code for all n iterations of the loop, so "result" will be an alias of the pseudo-register allocated and used in the last iteration; but at runtime the loop can break early, causing this pseudo-register uninitialized. Emit a move instruction in the iteration to force the difference into one register which has been allocated before the loop, to avoid this issue. gcc/ChangeLog: PR other/109086 * builtins.cc (inline_string_cmp): Force the character difference into "result" pseudo-register, instead of reassign the pseudo-register.
