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[Statepoint] Use early return to reduce nesting and clarify comments [NFC]

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This commit is contained in:
Philip Reames 2020-07-07 15:50:50 -07:00
parent b000637153
commit 8b0004cdf7
1 changed files with 29 additions and 27 deletions
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56
lib/CodeGen/SelectionDAG/StatepointLowering.cpp
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@ -913,36 +913,38 @@ SelectionDAGBuilder::LowerStatepoint(const GCStatepointInst &I,
// Export the result value if needed
const GCResultInst *GCResult = I.getGCResult();
Type *RetTy = I.getActualReturnType();
if (!RetTy->isVoidTy() && GCResult) {
if (GCResult->getParent() != I.getParent()) {
// Result value will be used in a different basic block so we need to
// export it now. Default exporting mechanism will not work here because
// statepoint call has a different type than the actual call. It means
// that by default llvm will create export register of the wrong type
// (always i32 in our case). So instead we need to create export register
// with correct type manually.
// TODO: To eliminate this problem we can remove gc.result intrinsics
// completely and make statepoint call to return a tuple.
unsigned Reg = FuncInfo.CreateRegs(RetTy);
RegsForValue RFV(*DAG.getContext(), DAG.getTargetLoweringInfo(),
DAG.getDataLayout(), Reg, RetTy,
I.getCallingConv());
SDValue Chain = DAG.getEntryNode();
RFV.getCopyToRegs(ReturnValue, DAG, getCurSDLoc(), Chain, nullptr);
PendingExports.push_back(Chain);
FuncInfo.ValueMap[&I] = Reg;
} else {
// Result value will be used in a same basic block. Don't export it or
// perform any explicit register copies.
// We'll replace the actuall call node shortly. gc_result will grab
// this value.
setValue(&I, ReturnValue);
}
} else {
// The token value is never used from here on, just generate a poison value
if (RetTy->isVoidTy() || !GCResult) {
// The return value is not needed, just generate a poison value.
setValue(&I, DAG.getIntPtrConstant(-1, getCurSDLoc()));
return;
}
if (GCResult->getParent() == I.getParent()) {
// Result value will be used in a same basic block. Don't export it or
// perform any explicit register copies. The gc_result will simply grab
// this value.
setValue(&I, ReturnValue);
return;
}
// Result value will be used in a different basic block so we need to export
// it now. Default exporting mechanism will not work here because statepoint
// call has a different type than the actual call. It means that by default
// llvm will create export register of the wrong type (always i32 in our
// case). So instead we need to create export register with correct type
// manually.
// TODO: To eliminate this problem we can remove gc.result intrinsics
// completely and make statepoint call to return a tuple.
unsigned Reg = FuncInfo.CreateRegs(RetTy);
RegsForValue RFV(*DAG.getContext(), DAG.getTargetLoweringInfo(),
DAG.getDataLayout(), Reg, RetTy,
I.getCallingConv());
SDValue Chain = DAG.getEntryNode();
RFV.getCopyToRegs(ReturnValue, DAG, getCurSDLoc(), Chain, nullptr);
PendingExports.push_back(Chain);
FuncInfo.ValueMap[&I] = Reg;
}
void SelectionDAGBuilder::LowerCallSiteWithDeoptBundleImpl(