From d3b588965daf43d5fd13c7bf6603c9f8017a041c Mon Sep 17 00:00:00 2001 From: Craig Topper Date: Tue, 17 Jan 2012 09:09:48 +0000 Subject: [PATCH] Teach DAG combiner to turn a BUILD_VECTOR of UNDEFs into an UNDEF of vector type. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148297 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index b9099277cf8..769fc726249 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -7142,11 +7142,13 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) { // optimizations. We do not handle sign-extend because we can't fill the sign // using shuffles. EVT SourceType = MVT::Other; - bool allAnyExt = true; - for (unsigned i = 0; i < NumInScalars; ++i) { + bool AllAnyExt = true; + bool AllUndef = true; + for (unsigned i = 0; i != NumInScalars; ++i) { SDValue In = N->getOperand(i); // Ignore undef inputs. if (In.getOpcode() == ISD::UNDEF) continue; + AllUndef = false; bool AnyExt = In.getOpcode() == ISD::ANY_EXTEND; bool ZeroExt = In.getOpcode() == ISD::ZERO_EXTEND; @@ -7171,9 +7173,11 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) { } // Check if all of the extends are ANY_EXTENDs. - allAnyExt &= AnyExt; + AllAnyExt &= AnyExt; } + if (AllUndef) + return DAG.getUNDEF(VT); // In order to have valid types, all of the inputs must be extended from the // same source type and all of the inputs must be any or zero extend. @@ -7193,7 +7197,7 @@ SDValue DAGCombiner::visitBUILD_VECTOR(SDNode *N) { bool isLE = TLI.isLittleEndian(); unsigned ElemRatio = OutScalarTy.getSizeInBits()/SourceType.getSizeInBits(); assert(ElemRatio > 1 && "Invalid element size ratio"); - SDValue Filler = allAnyExt ? DAG.getUNDEF(SourceType): + SDValue Filler = AllAnyExt ? DAG.getUNDEF(SourceType): DAG.getConstant(0, SourceType); unsigned NewBVElems = ElemRatio * N->getValueType(0).getVectorNumElements();