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[SelectionDAG][X86] Fix the assertion failure in Release build after #91747 #93434

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Merged
merged 3 commits into from
May 27, 2024
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[SelectionDAG][X86] Fix the assertion failure in Release build after #91747 #93434

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[SelectionDAG][X86] Fix the assertion failure in Release build after …
KanRobert May 27, 2024
0c0e2e8
format code
KanRobert May 27, 2024
a217c8a
address review comments
KanRobert May 27, 2024
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5 changes: 4 additions & 1 deletion llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1801,8 +1801,11 @@ void DAGCombiner::Run(CombineLevel AtLevel) {

if (N->getNumValues() == RV->getNumValues())
DAG.ReplaceAllUsesWith(N, RV.getNode());
else
else {
assert(N->getValueType(0) == RV.getValueType() &&
N->getNumValues() == 1 && "Type mismatch");
DAG.ReplaceAllUsesWith(N, &RV);
}

// Push the new node and any users onto the worklist. Omit this if the
// new node is the EntryToken (e.g. if a store managed to get optimized
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6 changes: 4 additions & 2 deletions llvm/lib/Target/X86/X86ISelLowering.cpp
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Expand Up @@ -49253,8 +49253,10 @@ static SDValue combineX86SubCmpForFlags(SDNode *N, SDValue Flag,
return SDValue();

SDValue X = SetCC.getOperand(1);
// Replace API is called manually here b/c the number of results may change.
DAG.ReplaceAllUsesOfValueWith(Flag, X);
// sub has two results while X only have one. DAG combine assumes the value
// type matches.
if (N->getOpcode() == X86ISD::SUB)
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Doesn't N always have 2 results?

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N can be a X86ISD::CMP or X86ISD::SUB. When N is CMP, it only has one result.

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How about if (N->getOpcode() == X86ISD::SUB) for clarity?

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Good suggestion, done

X = DAG.getMergeValues({N->getOperand(0), X}, SDLoc(N));

SDValue CCN = SetCC.getOperand(0);
X86::CondCode CC =
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