https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111657
--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Uros Bizjak <u...@gcc.gnu.org>: https://gcc.gnu.org/g:69669180d29cc420b1b1ac86530a4f9573748d81 commit r16-285-g69669180d29cc420b1b1ac86530a4f9573748d81 Author: Uros Bizjak <ubiz...@gmail.com> Date: Tue Apr 29 18:08:05 2025 +0200 i386: Disable string insn from non-default AS for Pmode != word_mode [PR111657] 0x67 prefix is applied before segment register. That is in rep movsq %gs:(%esi), (%edi) the address is %gs + %esi. In case Pmode != word_mode (x32 with a default -maddress-mode=short) instructions should not allow segment override prefixes. Also, remove explicit addr32 prefix from asm templates because address mode can be determined from explicit instruction operands. Also note that Pmode != word_mode only with TARGET_64BIT, so the check in ix86_print_operand is not needed. PR target/111657 gcc/ChangeLog: * config/i386/i386-expand.cc (alg_usable_p): For Pmode != word_mode reject rep_prefix_{1,4,8}_byte algorithms with src_as in the non-default address space. * config/i386/i386-protos.h (ix86_check_movs): New prototype. * config/i386/i386.cc (ix86_check_movs): New function. (ix86_print_operand) [case '^']: Remove excess check for TARGET_64BIT. * config/i386/i386.md (strmov): For Pmode != word_mode expand with gen_strmov_single only when operands[3] (source) is in the default address space. (*strmovdi_rex_1) Use ix86_check_movs. Remove %^ from asm template. (*strmovsi_1): Ditto. (*strmovhi_1): DItto. (*strmovqi_1): Ditto. (*rep_movdi_rex64): Ditto. (*rep_movsi): Ditto. (*rep_movqi): Ditto. gcc/testsuite/ChangeLog: * gcc.target/i386/pr111657-1.c: Check that segment override is not generated for "rep movsq" for x32 target.
