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[NFC ]Add a helper function isTailCall for getting libcall in SelectionDAG #155256

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[NFC ]Add a helper function isTailCall for getting libcall in SelectionDAG #155256

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955e081
add a helper function isTailCall
diggerlin Aug 25, 2025
1dbfb70
address comment
diggerlin Sep 2, 2025
18c8ba8
address comment
diggerlin Sep 8, 2025
3bb9426
address comment
diggerlin Sep 8, 2025
25e80f8
minor change
diggerlin Sep 8, 2025
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28 changes: 16 additions & 12 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9012,6 +9012,18 @@ static void checkAddrSpaceIsValidForLibcall(const TargetLowering *TLI,
}
}

static bool isInTailCallPositionWrapper(const CallInst *CI,
const SelectionDAG *SelDAG,
bool AllowReturnsFirstArg) {
if (!CI || !CI->isTailCall())
return false;
// TODO: Fix "returns-first-arg" determination so it doesn't depend on which
// helper symbol we lower to.
return isInTailCallPosition(*CI, SelDAG->getTarget(),
AllowReturnsFirstArg &&
funcReturnsFirstArgOfCall(*CI));
}

std::pair<SDValue, SDValue>
SelectionDAG::getMemcmp(SDValue Chain, const SDLoc &dl, SDValue Mem0,
SDValue Mem1, SDValue Size, const CallInst *CI) {
Expand All @@ -9033,10 +9045,8 @@ SelectionDAG::getMemcmp(SDValue Chain, const SDLoc &dl, SDValue Mem0,
GetEntry(getDataLayout().getIntPtrType(*getContext()), Size)};

TargetLowering::CallLoweringInfo CLI(*this);
bool IsTailCall = false;
bool ReturnsFirstArg = CI && funcReturnsFirstArgOfCall(*CI);
IsTailCall = CI && CI->isTailCall() &&
isInTailCallPosition(*CI, getTarget(), ReturnsFirstArg);
bool IsTailCall =
isInTailCallPositionWrapper(CI, this, /*AllowReturnsFirstArg*/ true);

CLI.setDebugLoc(dl)
.setChain(Chain)
Expand Down Expand Up @@ -9117,10 +9127,7 @@ SDValue SelectionDAG::getMemcpy(
IsTailCall = *OverrideTailCall;
} else {
bool LowersToMemcpy = StringRef(MemCpyName) == StringRef("memcpy");
bool ReturnsFirstArg = CI && funcReturnsFirstArgOfCall(*CI);
IsTailCall = CI && CI->isTailCall() &&
isInTailCallPosition(*CI, getTarget(),
ReturnsFirstArg && LowersToMemcpy);
IsTailCall = isInTailCallPositionWrapper(CI, this, LowersToMemcpy);
}

CLI.setDebugLoc(dl)
Expand Down Expand Up @@ -9234,10 +9241,7 @@ SDValue SelectionDAG::getMemmove(SDValue Chain, const SDLoc &dl, SDValue Dst,
} else {
bool LowersToMemmove =
TLI->getLibcallName(RTLIB::MEMMOVE) == StringRef("memmove");
bool ReturnsFirstArg = CI && funcReturnsFirstArgOfCall(*CI);
IsTailCall = CI && CI->isTailCall() &&
isInTailCallPosition(*CI, getTarget(),
ReturnsFirstArg && LowersToMemmove);
IsTailCall = isInTailCallPositionWrapper(CI, this, LowersToMemmove);
}

CLI.setDebugLoc(dl)
Expand Down
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