https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104054
--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> --- For some reason the pass does not detect usage of Register si in (insn 55): (debug_insn 55 54 56 6 (var_location:TI b (reg/v:TI 4 si [orig:86 b ] [86])) -1 (nil)) Register ax (1): Register dx (1): Register cx (1): Register si (1): Register di (1): 55 [ALL_REGS] Register r8 (1): 59 [GENERAL_REGS] 59 [GENERAL_REGS] 59 [GENERAL_REGS] Register r9 (1): Register r10 (1):