https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111107
--- Comment #19 from LIU Hao <lh_mouse at 126 dot com> ---
test.c:
```
void foo(int* p);
int bar(int x, int y) {
_Alignas(16) int t[4] = { x, y, x, y };
foo(t);
return 42;
}
```
With SSE (not default):
```
E:\lh_mouse\Desktop>gcc test.c -O2 -c -msse && objdump -drw -Mintel test.o
test.o: file format pe-i386
Disassembly of section .text:
00000000 <_bar>:
0: 55 push ebp
1: 89 e5 mov ebp,esp
3: 83 e4 f0 and esp,0xfffffff0
6: 8d 64 24 e0 lea esp,[esp-0x20]
a: 66 0f 6e 45 08 movd xmm0,DWORD PTR [ebp+0x8]
f: 8d 44 24 10 lea eax,[esp+0x10]
13: 66 0f 3a 22 45 0c 01 pinsrd xmm0,DWORD PTR [ebp+0xc],0x1
1a: 89 04 24 mov DWORD PTR [esp],eax
1d: 66 0f 6c c0 punpcklqdq xmm0,xmm0
21: f3 0f 7f 44 24 10 movdqu XMMWORD PTR [esp+0x10],xmm0
27: e8 00 00 00 00 call 2c <_bar+0x2c> 28: DISP32 _foo
2c: 89 ec mov esp,ebp
2e: b8 2a 00 00 00 mov eax,0x2a
33: 5d pop ebp
34: c3 ret
```
Without SSE (default):
```
E:\lh_mouse\Desktop>gcc test.c -O2 -c -mno-sse && objdump -drw -Mintel test.o
test.o: file format pe-i386
Disassembly of section .text:
00000000 <_bar>:
0: 8d 64 24 d4 lea esp,[esp-0x2c]
4: 8b 44 24 34 mov eax,DWORD PTR [esp+0x34]
8: 8b 54 24 30 mov edx,DWORD PTR [esp+0x30]
c: 89 44 24 14 mov DWORD PTR [esp+0x14],eax
10: 89 44 24 1c mov DWORD PTR [esp+0x1c],eax
14: 8d 44 24 10 lea eax,[esp+0x10]
18: 89 04 24 mov DWORD PTR [esp],eax
1b: 89 54 24 10 mov DWORD PTR [esp+0x10],edx
1f: 89 54 24 18 mov DWORD PTR [esp+0x18],edx
23: e8 00 00 00 00 call 28 <_bar+0x28> 24: DISP32 _foo
28: b8 2a 00 00 00 mov eax,0x2a
2d: 8d 64 24 2c lea esp,[esp+0x2c]
31: c3 ret
```
So it looks like enabling SSE somehow forces realigning ESP. But in this case
we declare a variable that requires the realignment, which is the bug.. ?
