https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38592
Thomas Koenig <tkoenig at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed|2017-08-15 00:00:00 |2020-11-11 --- Comment #10 from Thomas Koenig <tkoenig at gcc dot gnu.org> --- For the C test case, we now get yes: .LFB0: .cfi_startproc movl $25977, %eax movb $115, -1(%rsp) movw %ax, -3(%rsp) movzbl -2(%rsp), %eax subl $101, %eax jne .L1 movzbl -1(%rsp), %eax subl $115, %eax .L1: ret So, optimized further, but not folded. clang 7 folds this completely: yes: # @yes .cfi_startproc # %bb.0: xorl %eax, %eax retq .Lfunc_end0: