From 5b0b023a6414064a944808499f0718372def98a8 Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Tue, 8 Jul 2014 07:44:15 +0000 Subject: [PATCH] [SDAG] Actually check for a non-constant splat and clarify comments around the handling of UNDEF lanes in boolean vector content analysis. The code before my changes here also failed to check for non-constant splats in a buildvector. I have no idea how to trigger this, I just spotted by inspection when trying to understand the code. It seems extremely unlikely to be worth the trouble to teach the only caller of this code (DAG combining setcc patterns) how to cleverly handle undef lanes, so I've just commented more thoroughly that we're giving up there. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212515 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/TargetLowering.cpp | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp index 74de034777d..9aee3894b64 100644 --- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -1160,8 +1160,10 @@ bool TargetLowering::isConstTrueVal(const SDNode *N) const { IsVec = true; bool HasUndefElements; CN = BV->getConstantSplatNode(HasUndefElements); - if (HasUndefElements) - return false; // Can't blindly collapse the undef values. + // Only interested in constant splats, and we don't try to handle undef + // elements in identifying boolean constants. + if (!CN || HasUndefElements) + return false; } switch (getBooleanContents(IsVec)) { @@ -1190,8 +1192,10 @@ bool TargetLowering::isConstFalseVal(const SDNode *N) const { IsVec = true; bool HasUndefElements; CN = BV->getConstantSplatNode(HasUndefElements); - if (HasUndefElements) - return false; // Can't blindly collapse the undef values. + // Only interested in constant splats, and we don't try to handle undef + // elements in identifying boolean constants. + if (!CN || HasUndefElements) + return false; } if (getBooleanContents(IsVec) == UndefinedBooleanContent) -- 2.50.0