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Split SETCC if VSELECT requires splitting too.

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This patch is a rewrite of the original patch commited in r194542. Instead of
relying on the type legalizer to do the splitting for us, we now peform the
splitting ourselves in the DAG combiner. This is necessary for the case where
the vector mask is a legal type after promotion and still wouldn't require
splitting.

Patch by: Juergen Ributzka

NOTE: This is a candidate for the 3.4 branch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195397 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Tom Stellard
2013-11-22 00:39:23 +00:00
parent 2d5d104c5b
commit b7bad852f4
3 changed files with 45 additions and 22 deletions
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56
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@@ -4327,6 +4327,23 @@ SDValue DAGCombiner::visitSELECT(SDNode *N) {
return SDValue();
}
static
std::pair<SDValue, SDValue> SplitVSETCC(const SDNode *N, SelectionDAG &DAG) {
SDLoc DL(N);
EVT LoVT, HiVT;
llvm::tie(LoVT, HiVT) = DAG.GetSplitDestVTs(N->getValueType(0));
// Split the inputs.
SDValue Lo, Hi, LL, LH, RL, RH;
llvm::tie(LL, LH) = DAG.SplitVectorOperand(N, 0);
llvm::tie(RL, RH) = DAG.SplitVectorOperand(N, 1);
Lo = DAG.getNode(N->getOpcode(), DL, LoVT, LL, RL, N->getOperand(2));
Hi = DAG.getNode(N->getOpcode(), DL, HiVT, LH, RH, N->getOperand(2));
return std::make_pair(Lo, Hi);
}
SDValue DAGCombiner::visitVSELECT(SDNode *N) {
SDValue N0 = N->getOperand(0);
SDValue N1 = N->getOperand(1);
@@ -4364,27 +4381,32 @@ SDValue DAGCombiner::visitVSELECT(SDNode *N) {
}
}
// Treat SETCC as a vector mask and promote the result type based on the
// targets expected SETCC result type. This will ensure that SETCC and VSELECT
// are both split by the type legalizer. This is done to prevent the type
// legalizer from unrolling SETCC into scalar comparions.
EVT SelectVT = N->getValueType(0);
EVT MaskVT = getSetCCResultType(SelectVT);
assert(MaskVT.isVector() && "Expected a vector type.");
if (N0.getOpcode() == ISD::SETCC && N0.getValueType() != MaskVT) {
SDLoc MaskDL(N0);
// If the VSELECT result requires splitting and the mask is provided by a
// SETCC, then split both nodes and its operands before legalization. This
// prevents the type legalizer from unrolling SETCC into scalar comparisons
// and enables future optimizations (e.g. min/max pattern matching on X86).
if (N0.getOpcode() == ISD::SETCC) {
EVT VT = N->getValueType(0);
// Extend the mask to the desired value type.
ISD::NodeType ExtendCode =
TargetLowering::getExtendForContent(TLI.getBooleanContents(true));
SDValue Mask = DAG.getNode(ExtendCode, MaskDL, MaskVT, N0);
// Check if any splitting is required.
if (TLI.getTypeAction(*DAG.getContext(), VT) !=
TargetLowering::TypeSplitVector)
return SDValue();
AddToWorkList(Mask.getNode());
SDValue Lo, Hi, CCLo, CCHi, LL, LH, RL, RH;
llvm::tie(CCLo, CCHi) = SplitVSETCC(N0.getNode(), DAG);
llvm::tie(LL, LH) = DAG.SplitVectorOperand(N, 1);
llvm::tie(RL, RH) = DAG.SplitVectorOperand(N, 2);
SDValue LHS = N->getOperand(1);
SDValue RHS = N->getOperand(2);
Lo = DAG.getNode(N->getOpcode(), DL, LL.getValueType(), CCLo, LL, RL);
Hi = DAG.getNode(N->getOpcode(), DL, LH.getValueType(), CCHi, LH, RH);
return DAG.getNode(ISD::VSELECT, DL, SelectVT, Mask, LHS, RHS);
// Add the new VSELECT nodes to the work list in case they need to be split
// again.
AddToWorkList(Lo.getNode());
AddToWorkList(Hi.getNode());
return DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, Lo, Hi);
}
return SDValue();