[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();
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.h b/llvm/lib/Target/ARM/ARMISelLowering.h
index 6348edb..5255d82 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.h
+++ b/llvm/lib/Target/ARM/ARMISelLowering.h
@@ -431,6 +431,10 @@
bool shouldConvertConstantLoadToIntImm(const APInt &Imm,
Type *Ty) const override;
+ /// Return true if EXTRACT_SUBVECTOR is cheap for this result type
+ /// with this index.
+ bool isExtractSubvectorCheap(EVT ResVT, unsigned Index) const override;
+
/// \brief Returns true if an argument of type Ty needs to be passed in a
/// contiguous block of registers in calling convention CallConv.
bool functionArgumentNeedsConsecutiveRegisters(