DAG combine incorrectly optimize (i32 vextract (v4i16 load $addr), c) to
(i16 load $addr+c*sizeof(i16)) and replace uses of (i32 vextract) with the
i16 load. It should issue an extload instead: (i32 extload $addr+c*sizeof(i16)).
rdar://11035895
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152675 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index d93af72..66c04b4 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -7202,6 +7202,11 @@
EVT ExtVT = VT.getVectorElementType();
EVT LVT = ExtVT;
+ // If the result of load has to be truncated, then it's not necessarily
+ // profitable.
+ if (NVT.bitsLT(LVT))
+ return SDValue();
+
if (InVec.getOpcode() == ISD::BITCAST) {
// Don't duplicate a load with other uses.
if (!InVec.hasOneUse())
@@ -7302,10 +7307,20 @@
// Note that this replacement assumes that the extractvalue is the only
// use of the load; that's okay because we don't want to perform this
// transformation in other cases anyway.
- SDValue Load = DAG.getLoad(LVT, N->getDebugLoc(), LN0->getChain(), NewPtr,
- LN0->getPointerInfo().getWithOffset(PtrOff),
- LN0->isVolatile(), LN0->isNonTemporal(),
- LN0->isInvariant(), Align);
+ SDValue Load;
+ if (NVT.bitsGT(LVT)) {
+ // If the result type of vextract is wider than the load, then issue an
+ // extending load instead.
+ ISD::LoadExtType ExtType = TLI.isLoadExtLegal(ISD::ZEXTLOAD, LVT)
+ ? ISD::ZEXTLOAD : ISD::EXTLOAD;
+ Load = DAG.getExtLoad(ExtType, N->getDebugLoc(), NVT, LN0->getChain(),
+ NewPtr, LN0->getPointerInfo().getWithOffset(PtrOff),
+ LVT, LN0->isVolatile(), LN0->isNonTemporal(),Align);
+ } else
+ Load = DAG.getLoad(LVT, N->getDebugLoc(), LN0->getChain(), NewPtr,
+ LN0->getPointerInfo().getWithOffset(PtrOff),
+ LN0->isVolatile(), LN0->isNonTemporal(),
+ LN0->isInvariant(), Align);
WorkListRemover DeadNodes(*this);
SDValue From[] = { SDValue(N, 0), SDValue(LN0,1) };
SDValue To[] = { Load.getValue(0), Load.getValue(1) };