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[Bug c++/42633] hinting gcc that restricted pointer dont alias with members of structs
- From: "torbenh at gmx dot de" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 6 Jan 2010 13:19:48 -0000
- Subject: [Bug c++/42633] hinting gcc that restricted pointer dont alias with members of structs
- References: <bug-42633-18637@http.gcc.gnu.org/bugzilla/>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Comment #2 from torbenh at gmx dot de 2010-01-06 13:19 -------
the generated x86_64 asm: _Z11fill_bufferPfm: .LFB3: testq %rsi, %rsi
je .L4 xorl %eax, %eax movss .LC0(%rip), %xmm2
.p2align 4,,10 .p2align 3 .L3: movss ramp(%rip), %xmm1 movaps
%xmm1, %xmm0 addss %xmm2, %xmm0 movss %xmm0, ramp(%rip) movss
%xmm1, (%rdi,%rax,4) addq $1, %rax cmpq %rax, %rsi ja
.L3 .L4: rep ret while gcc patched with -fnoalias generates:
_Z11fill_bufferPfm: .LFB1: .cfi_startproc .cfi_personality
0x3,__gxx_personality_v0 testq %rsi, %rsi je .L4 movss
ramp(%rip), %xmm0 xorl %eax, %eax movss .LC0(%rip), %xmm1
.p2align 4,,10 .p2align 3 .L3: movss %xmm0, (%rdi,%rax,4) addq
$1, %rax addss %xmm1, %xmm0 cmpq %rax, %rsi ja .L3
movss %xmm0, ramp(%rip) .L4: rep ret
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42633