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[SelectionDAG] Move SelectionDAG::getAllOnesConstant out of line. NFC #102995

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Aug 13, 2024
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[SelectionDAG] Move SelectionDAG::getAllOnesConstant out of line. NFC #102995

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c66a777
[SelectionDAG] Move SelectionDAG::getAllOnesConstant out of line.
topperc Aug 13, 2024
5a802e0
fixup! clang-format
topperc Aug 13, 2024
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5 changes: 1 addition & 4 deletions llvm/include/llvm/CodeGen/SelectionDAG.h
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Original file line number Diff line number Diff line change
Expand Up @@ -675,10 +675,7 @@ class SelectionDAG {
bool isTarget = false, bool isOpaque = false);

SDValue getAllOnesConstant(const SDLoc &DL, EVT VT, bool IsTarget = false,
bool IsOpaque = false) {
return getConstant(APInt::getAllOnes(VT.getScalarSizeInBits()), DL, VT,
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Can't this just use -1 and let the implementation extend to APInt if it's larger?

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Doing that is exactly how most i128 miscompiles get introduced ;) Note that getConstant() performs a zero extension, not a sign extension.

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But that sounds like a bug, generally constants are sign extended in other contexts in llvm (e.g. in MachineOperand)

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No, constants in LLVM are zero extended by default. They only get sign extended to 64 bit as a result of normal integer promotion rules. Some APIs have a flag to switch to sign extension instead, and everyone always forgets to set it when necessary, because things look like they work correctly for small integer types. (See also #80309.)

IsTarget, IsOpaque);
}
bool IsOpaque = false);

SDValue getConstant(const ConstantInt &Val, const SDLoc &DL, EVT VT,
bool isTarget = false, bool isOpaque = false);
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6 changes: 6 additions & 0 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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Expand Up @@ -1748,6 +1748,12 @@ SDValue SelectionDAG::getConstant(const ConstantInt &Val, const SDLoc &DL,
return Result;
}

SDValue SelectionDAG::getAllOnesConstant(const SDLoc &DL, EVT VT, bool IsTarget,
bool IsOpaque) {
return getConstant(APInt::getAllOnes(VT.getScalarSizeInBits()), DL, VT,
IsTarget, IsOpaque);
}

SDValue SelectionDAG::getIntPtrConstant(uint64_t Val, const SDLoc &DL,
bool isTarget) {
return getConstant(Val, DL, TLI->getPointerTy(getDataLayout()), isTarget);
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