https://llvm.org/bugs/show_bug.cgi?id=30596
Bug ID: 30596
Summary: [X86][AVX] Broadcast loads don't respect dependencies
Product: libraries
Version: 3.9
Hardware: PC
OS: Windows NT
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: llvm-...@redking.me.uk
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
As detailed in https://reviews.llvm.org/D25039:
declare void @gfunc(<4 x float>*)
declare void @llvm.lifetime.start(i64, i8*)
declare void @llvm.lifetime.end(i64, i8*)
define float @broadcast_lifetime() nounwind {
%1 = alloca <4 x float>, align 16
%2 = alloca <4 x float>, align 16
%3 = bitcast <4 x float>* %1 to i8*
%4 = bitcast <4 x float>* %2 to i8*
call void @llvm.lifetime.start(i64 16, i8* %3)
call void @gfunc(<4 x float>* %1)
%5 = load <4 x float>, <4 x float>* %1, align 16
call void @llvm.lifetime.end(i64 16, i8* %3)
call void @llvm.lifetime.start(i64 16, i8* %4)
call void @gfunc(<4 x float>* %2)
%6 = load <4 x float>, <4 x float>* %2, align 16
call void @llvm.lifetime.end(i64 16, i8* %4)
%7 = extractelement <4 x float> %5, i32 1
%8 = extractelement <4 x float> %6, i32 1
%9 = fsub float %8, %7
ret float %9
}
broadcast_lifetime:
subq $24, %rsp
movq %rsp, %rdi
callq gfunc
movq %rsp, %rdi
callq gfunc
vbroadcastss 4(%rsp), %xmm0 ## <-- 1st gfunc result
vbroadcastss 4(%rsp), %xmm1 ## <-- 2nd gfunc result
vsubss %xmm0, %xmm1, %xmm0
addq $24, %rsp
retq
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