https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33717
--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
GCC does better now since GCC 10:
.L2:
movl (%ebx,%ecx,4), %eax
xorl %edx, %edx
addl $-1, %eax
adcl $0, %edx
addl %eax, %esi
adcl %edx, %edi
movl %esi, -424(%ebp,%ecx,4)
addl $1, %ecx
movl %edi, %esi
xorl %edi, %edi
cmpl $100, %ecx
jne .L2
But still not as good as ICC:
..B1.4: # Preds ..B1.4 ..B1.3
# Execution count [5.00e+01]
addl 32(%esp,%eax,8), %ebx #25.5
movl %esi, %edx #25.5
adcl $0, %edx #25.5
addl 432(%esp,%eax,8), %ebx #25.37
movl %ebx, 832(%esp,%eax,8) #26.5
movl %esi, %ebx #25.5
adcl $0, %edx #25.37
addl 36(%esp,%eax,8), %edx #25.5
adcl $0, %ebx #25.5
addl 436(%esp,%eax,8), %edx #25.37
movl %edx, 836(%esp,%eax,8) #26.5
adcl $0, %ebx #25.37
incl %eax #24.3
cmpl $50, %eax #24.3
jb ..B1.4 # Prob 98%
LLVM just falls over:
.LBB0_1: # =>This Inner Loop Header: Depth=1
xorl %ebx, %ebx
addl 808(%esp,%edx,4), %eax
setb %bl
addl 408(%esp,%edx,4), %eax
adcl $0, %ebx
movl %eax, 8(%esp,%edx,4)
cmpl $100, %edx
je .LBB0_3
# %bb.2: # in Loop: Header=BB0_1 Depth=1
xorl %eax, %eax
addl 812(%esp,%edx,4), %ebx
setb %al
addl 412(%esp,%edx,4), %ebx
adcl $0, %eax
movl %ebx, 12(%esp,%edx,4)
addl $2, %edx
jmp .LBB0_1
.LBB0_3:
