https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82682
--- Comment #9 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The effect of the patch on the testcase is:
.L3:
movzbl (%edx), %esi
addl $2, %edx
movzbl -1(%edx), %eax
addl $1, %ecx
- movl %esi, %ebx
imull $38470, %eax, %eax
- movzbl %bl, %esi
imull $19595, %esi, %esi
addl %esi, %eax
sarl $16, %eax
movb %al, -1(%ecx)
cmpl %edi, %edx
where the useless movl %esi, %ebx isn't removed by the REE pass itself, but by
rtl_dce later on. In any case, no extra copy insn is generated in this case,
we just keep around the QI %ebx = QI %esi insn in case the register is used
later on.
