[ARM] Implement isExtractSubvectorCheap.
See https://reviews.llvm.org/D6678 for the history of
isExtractSubvectorCheap. Essentially the same considerations apply
to ARM.
This temporarily breaks the formation of vpadd/vpaddl in certain cases;
AddCombineToVPADDL essentially assumes that we won't form VUZP shuffles.
See https://reviews.llvm.org/D27779 for followup fix.
Differential Revision: https://reviews.llvm.org/D27774
llvm-svn: 290198
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 2c88c75..5895cad 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -12921,6 +12921,14 @@
return true;
}
+bool ARMTargetLowering::isExtractSubvectorCheap(EVT ResVT,
+ unsigned Index) const {
+ if (!isOperationLegalOrCustom(ISD::EXTRACT_SUBVECTOR, ResVT))
+ return false;
+
+ return (Index == 0 || Index == ResVT.getVectorNumElements());
+}
+
Instruction* ARMTargetLowering::makeDMB(IRBuilder<> &Builder,
ARM_MB::MemBOpt Domain) const {
Module *M = Builder.GetInsertBlock()->getParent()->getParent();