https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127326
--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> ---
Hm, patched compiler produces quite unoptimal code:
movl .LC0, %esi
movl .LC0+4, %ebx
movl .LC0+8, %ecx
movl .LC0+12, %edx
movl 48(%esp), %eax
movl %esi, 16(%esp)
movl %ebx, 20(%esp)
movl %ecx, 24(%esp)
movl %edx, 28(%esp)
<--- **asm is here**
movl 16(%esp), %esi
movl 20(%esp), %ebx
movl 24(%esp), %ecx
movl 28(%esp), %edx
movl %esi, (%esp) <-- dead store
movl %esi, (%eax)
movl %ebx, 4(%esp) <-- dead store
movl %ecx, 8(%esp) <-- dead store
movl %edx, 12(%esp) <-- dead store
movl %ebx, 4(%eax)
movl %ecx, 8(%eax)
movl %edx, 12(%eax)
.LC0:
.long 10
.long 0
.long 0
.long 809369600
.reload pass creates:
25: [sp:SI]=0xa
26: [sp:SI+0x4]=0
27: [sp:SI+0x8]=0
28: [sp:SI+0xc]=0x303e0000 <--- the constant is already on stack
31: si:SI=[`*.LC0']
48: [sp:SI+0x10]=si:SI
32: bx:SI=[const(`*.LC0'+0x4)]
47: [sp:SI+0x14]=bx:SI
33: cx:SI=[const(`*.LC0'+0x8)]
46: [sp:SI+0x18]=cx:SI
34: dx:SI=[const(`*.LC0'+0xc)]
45: [sp:SI+0x1c]=dx:SI <--- another copy of the constant on stack
11: {[sp:SI+0x10]=asm_operands;clobber flags:CC;}
44: si:SI=[sp:SI+0x10]
36: [sp:SI]=si:SI
43: bx:SI=[sp:SI+0x14]
37: [sp:SI+0x4]=bx:SI
42: cx:SI=[sp:SI+0x18]
38: [sp:SI+0x8]=cx:SI
41: dx:SI=[sp:SI+0x1c]
39: [sp:SI+0xc]=dx:SI <--- copies from temporary to the original loc
6: si:SI=[sp:SI]
7: bx:SI=[sp:SI+0x4]
8: cx:SI=[sp:SI+0x8]
9: dx:SI=[sp:SI+0xc] <--- and from the original loc ...
12: [ax:SI]=si:SI
13: [ax:SI+0x4]=bx:SI
14: [ax:SI+0x8]=cx:SI
15: [ax:SI+0xc]=dx:SI <--- ... to the result ptr
20: use ax:SI
