https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97387
--- Comment #7 from fdlbxtqi <euloanty at live dot com> ---
(In reply to Jakub Jelinek from comment #6)
> Trying 10, 17 -> 18:
> 10: r88:QI=ltu(flags:CCC,0)
> REG_DEAD flags:CCC
> 17: {flags:CCC=cmp(r88:QI-0x1,r88:QI);clobber scratch;}
> REG_DEAD r88:QI
> 18:
> {flags:CCC=cmp(zero_extend(ltu(flags:CCC,0)+r106:DI+r107:DI),
> zero_extend(r107:DI)+ltu(flags:CCC,0));r109:DI=ltu(flags:CCC,0)+r106:DI+r107:
> DI
> ;}
> REG_DEAD r107:DI
> REG_DEAD r106:DI
> Can't combine i1 into i3
BTW.
clang does not remove the
movl $0, %esi
before
sbbq %rsi, %rsi
sbbq itself does not matter what the value itself is.
https://godbolt.org/z/szYb55
I do not know whether GCC would remove this after patch. If you can optimize
this away, I would thank you.
