Add target hook to prevent folding some bitcasted loads.
This is to avoid this transformation in some cases:
fold (conv (load x)) -> (load (conv*)x)
On architectures that don't natively support some vector
loads efficiently casting the load to a smaller vector of
larger types and loading is more efficient.
Patch by Micah Villmow.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194783 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 90cd1d3..78543a4 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -5768,7 +5768,8 @@
if (ISD::isNormalLoad(N0.getNode()) && N0.hasOneUse() &&
// Do not change the width of a volatile load.
!cast<LoadSDNode>(N0)->isVolatile() &&
- (!LegalOperations || TLI.isOperationLegal(ISD::LOAD, VT))) {
+ (!LegalOperations || TLI.isOperationLegal(ISD::LOAD, VT)) &&
+ TLI.isLoadBitCastBeneficial(N0.getValueType(), VT)) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
unsigned Align = TLI.getDataLayout()->
getABITypeAlignment(VT.getTypeForEVT(*DAG.getContext()));
diff --git a/lib/Target/R600/AMDGPUISelLowering.cpp b/lib/Target/R600/AMDGPUISelLowering.cpp
index 51ad217..fdabea5 100644
--- a/lib/Target/R600/AMDGPUISelLowering.cpp
+++ b/lib/Target/R600/AMDGPUISelLowering.cpp
@@ -196,6 +196,18 @@
return MVT::i32;
}
+bool AMDGPUTargetLowering::isLoadBitCastBeneficial(EVT LoadTy,
+ EVT CastTy) const {
+ if (LoadTy.getSizeInBits() != CastTy.getSizeInBits())
+ return true;
+
+ unsigned LScalarSize = LoadTy.getScalarType().getSizeInBits();
+ unsigned CastScalarSize = CastTy.getScalarType().getSizeInBits();
+
+ return ((LScalarSize <= CastScalarSize) ||
+ (CastScalarSize >= 32) ||
+ (LScalarSize < 32));
+}
//===---------------------------------------------------------------------===//
// Target Properties
diff --git a/lib/Target/R600/AMDGPUISelLowering.h b/lib/Target/R600/AMDGPUISelLowering.h
index dacb086..2dfd3cf 100644
--- a/lib/Target/R600/AMDGPUISelLowering.h
+++ b/lib/Target/R600/AMDGPUISelLowering.h
@@ -77,6 +77,7 @@
virtual bool isFAbsFree(EVT VT) const;
virtual bool isFNegFree(EVT VT) const;
virtual MVT getVectorIdxTy() const;
+ virtual bool isLoadBitCastBeneficial(EVT, EVT) const LLVM_OVERRIDE;
virtual SDValue LowerReturn(SDValue Chain, CallingConv::ID CallConv,
bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,