https://bugs.llvm.org/show_bug.cgi?id=39812
Bug ID: 39812
Summary: [x86] Cost model for v2i32 masked load/store looks
incorrect
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: unassignedb...@nondot.org
Reporter: craig.top...@gmail.com
CC: craig.top...@gmail.com, llvm-bugs@lists.llvm.org,
llvm-...@redking.me.uk, spatel+l...@rotateright.com
The code model for masked load/store contains this code
if (VT.isSimple() && LT.second != VT.getSimpleVT() &&
LT.second.getVectorNumElements() == NumElem)
// Promotion requires expand/truncate for data and a shuffle for mask.
Cost += getShuffleCost(TTI::SK_Select, SrcVTy, 0, nullptr) +
getShuffleCost(TTI::SK_Select, MaskTy, 0, nullptr);
But SK_Select does not describe an expand/truncate action. This code said
SK_Alternate when it was originally written, but was renamed to SK_Select in
r334513. I'm not sure if SK_Alternate was the same as select and was
confusingly named before?
The mask legalization cost also seems weird on AVX512 targets. We don't need to
expand/truncate it there as it would be an i1 type.
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