https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87421
Bug ID: 87421
Summary: GCC generates unaligned movdqa
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: yshuiv7 at gmail dot com
Target Milestone: ---
C++ Test case:
struct A {
unsigned int a1;
long a5;
unsigned int a6;
};
int fun(A *res);
int fun2(A *desc)
{
A resource;
fun(&resource);
*desc = resource;
return 0;
}
Target: amd64
Compiler flags:
g++ test.cc -c -O2 -fno-omit-frame-pointer -std=gnu++11
Compiles to:
0000000000000000 <_Z4fun2P1A>:
// Assuming 16 bytes stack alignment
0: 55 push %rbp // rsp now aligns to
16 bytes + 8 bytes
1: 48 89 e5 mov %rsp,%rbp // rbp also aligns to
16 + 8
4: 53 push %rbx
5: 48 89 fb mov %rdi,%rbx
8: 48 8d 7d d0 lea -0x30(%rbp),%rdi
c: 48 83 ec 28 sub $0x28,%rsp
10: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
17: 00 00
19: 48 89 45 e8 mov %rax,-0x18(%rbp)
1d: 31 c0 xor %eax,%eax
1f: e8 00 00 00 00 callq 24 <_Z4fun2P1A+0x24>
24: 48 8b 45 e0 mov -0x20(%rbp),%rax
28: 66 0f 6f 45 d0 movdqa -0x30(%rbp),%xmm0 // rbp-0x30 is not
aligned to 16 bytes
2d: 48 89 43 10 mov %rax,0x10(%rbx)
31: 0f 11 03 movups %xmm0,(%rbx)
34: 48 8b 55 e8 mov -0x18(%rbp),%rdx
38: 64 48 33 14 25 28 00 xor %fs:0x28,%rdx
3f: 00 00
41: 75 09 jne 4c <_Z4fun2P1A+0x4c>
43: 48 83 c4 28 add $0x28,%rsp
47: 31 c0 xor %eax,%eax
49: 5b pop %rbx
4a: 5d pop %rbp
4b: c3 retq
4c: e8 00 00 00 00 callq 51 <_Z4fun2P1A+0x51>
