https://llvm.org/bugs/show_bug.cgi?id=27141
Bug ID: 27141
Summary: [x86, AVX] vbroadcast not used to splat constant
Product: libraries
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: spatel+l...@rotateright.com
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
This was noticed in the output of http://reviews.llvm.org/D18566 (bug 27100):
define void @hoo(<4 x i32>* %x, i8 %c) {
%ins = insertelement <4 x i32> undef, i32 42, i32 0
%splat = shufflevector <4 x i32> %ins, <4 x i32> undef, <4 x i32>
zeroinitializer
store <4 x i32> %splat, <4 x i32>* %x
ret void
}
$ ./llc -o - memset.ll -mattr=avx
...
vmovaps LCPI0_0(%rip), %xmm0 ## xmm0 = [42,42,42,42]
vmovaps %xmm0, (%rdi)
$ ./llc -o - memset.ll -mattr=avx2
...
vbroadcastss LCPI0_0(%rip), %xmm0
vmovaps %xmm0, (%rdi)
vbroadcastss from memory is available with AVX, so these should produce
identical asm.
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