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[DAGCombiner] Don't create truncate nodes in (aext (zextload x)) -> (zextload x) and similar folds. NFCI 

The truncate is being used to replace other users of of the load, but we checked that the load only has one use so there are no other uses to replace.

llvm-svn: 324567
This commit is contained in:
Craig Topper 2018-02-08 06:04:18 +00:00
parent a217e505c3
commit 9b9d527427
1 changed files with 5 additions and 15 deletions
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20
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -7592,10 +7592,7 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
LN0->getBasePtr(), MemVT,
LN0->getMemOperand());
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(),
DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
@ -7964,10 +7961,7 @@ SDValue DAGCombiner::visitZERO_EXTEND(SDNode *N) {
LN0->getBasePtr(), MemVT,
LN0->getMemOperand());
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(),
DAG.getNode(ISD::TRUNCATE, SDLoc(N0), N0.getValueType(),
ExtLoad),
ExtLoad.getValue(1));
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}
@ -8134,9 +8128,8 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
// fold (aext (zextload x)) -> (aext (truncate (zextload x)))
// fold (aext (sextload x)) -> (aext (truncate (sextload x)))
// fold (aext ( extload x)) -> (aext (truncate (extload x)))
if (N0.getOpcode() == ISD::LOAD &&
!ISD::isNON_EXTLoad(N0.getNode()) && ISD::isUNINDEXEDLoad(N0.getNode()) &&
N0.hasOneUse()) {
if (N0.getOpcode() == ISD::LOAD && !ISD::isNON_EXTLoad(N0.getNode()) &&
ISD::isUNINDEXEDLoad(N0.getNode()) && N0.hasOneUse()) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
ISD::LoadExtType ExtType = LN0->getExtensionType();
EVT MemVT = LN0->getMemoryVT();
@ -8145,10 +8138,7 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
VT, LN0->getChain(), LN0->getBasePtr(),
MemVT, LN0->getMemOperand());
CombineTo(N, ExtLoad);
CombineTo(N0.getNode(),
DAG.getNode(ISD::TRUNCATE, SDLoc(N0),
N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
DAG.ReplaceAllUsesOfValueWith(SDValue(LN0, 1), ExtLoad.getValue(1));
return SDValue(N, 0); // Return N so it doesn't get rechecked!
}
}