https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67438
Bug ID: 67438
Summary: [6 Regression] ~X op ~Y pattern relocation causes loop
performance degradation
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: afomin.mailbox at gmail dot com
CC: izamyatin at gmail dot com, rguenth at gcc dot gnu.org,
ysrumyan at gmail dot com
Target Milestone: ---
Target: i686
For the loop in the attached test compiled with -O3 -m32 -march=slm
-ftree-loop-if-convert (in fact, -march=slm can be omitted resulting in a
greater number of insns) after r225249 we generate 28 insns instead of 23 insns
for r225248. That revision moves some simplification patterns from fold-const.c
to match.pd, and I've noticed that relocating back ~X op ~Y -> Y op X from
match.pd to fold-const.c fixes the problem.
r225248:
movzbl (%ebx),%ecx
add $0x3,%ebx
movzbl -0x2(%ebx),%edx
not %ecx
movzbl -0x1(%ebx),%eax
not %edx
mov %cl,(%esi)
mov %dl,0x1(%esi)
not %eax
cmp %al,%cl
mov %eax,%edi
mov %al,0x2(%esi)
mov %eax,%ebp
cmovle %ecx,%edi
cmp %al,%dl
cmovle %edx,%ebp
add $0x4,%esi
cmp %dl,%cl
mov %ebp,%eax
cmovl %edi,%eax
cmp (%esp),%ebx
mov %al,-0x1(%esi)
jne 30 <foo+0x30>
r225249:
movzbl (%edi),%eax
add $0x3,%edi
movzbl -0x2(%edi),%edx
mov %al,0x2(%esp)
mov %eax,%ebx
movzbl -0x1(%edi),%eax
not %ebx
mov %dl,0x3(%esp)
mov %edx,%ecx
mov %bl,0x0(%ebp)
not %ecx
mov %cl,0x1(%ebp)
not %eax
cmp %al,%bl
mov %eax,%esi
mov %al,0x2(%ebp)
cmovle %ebx,%esi
cmp %al,%cl
mov %esi,%edx
mov %eax,%esi
cmovle %ecx,%esi
add $0x4,%ebp
movzbl 0x3(%esp),%ecx
cmp %cl,0x2(%esp)
cmovle %esi,%edx
cmp 0x4(%esp),%edi
mov %dl,-0x1(%ebp)
jne 30 <foo+0x30>
