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[SelectionDAGBuilder] Use address width when lowering ptrtoaddr #139423

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Merged
merged 9 commits into from
Oct 15, 2025
Merged

[SelectionDAGBuilder] Use address width when lowering ptrtoaddr #139423

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3c8c76e
[𝘀𝗽𝗿] initial version
arichardson May 11, 2025
bb2e394
[𝘀𝗽𝗿] changes to main this commit is based on
arichardson May 11, 2025
d4520dc
remove unused variable
arichardson May 11, 2025
5015f04
[𝘀𝗽𝗿] changes introduced through rebase
arichardson Jun 11, 2025
1222b60
rebase
arichardson Jun 11, 2025
386da10
[𝘀𝗽𝗿] changes introduced through rebase
arichardson Aug 11, 2025
8afae27
rebase, no more test diff due to semantics change
arichardson Aug 11, 2025
ece738c
[𝘀𝗽𝗿] changes introduced through rebase
arichardson Oct 14, 2025
1c63da9
simplify, address comments
arichardson Oct 14, 2025
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10 changes: 8 additions & 2 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3971,8 +3971,14 @@ void SelectionDAGBuilder::visitSIToFP(const User &I) {
}

void SelectionDAGBuilder::visitPtrToAddr(const User &I) {
// FIXME: this is not correct for pointers with addr width != pointer width
visitPtrToInt(I);
SDValue N = getValue(I.getOperand(0));
// By definition the type of the ptrtoaddr must be equal to the address type.
const auto &TLI = DAG.getTargetLoweringInfo();
EVT AddrVT = TLI.getValueType(DAG.getDataLayout(), I.getType());
// The address width must be smaller or equal to the pointer representation
// width, so we lower ptrtoaddr as a truncate (possibly folded to a no-op).
N = DAG.getNode(ISD::TRUNCATE, getCurSDLoc(), AddrVT, N);
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@arsenm arsenm Aug 12, 2025

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If these are the same type, why do you need the truncate?

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@arichardson arichardson Aug 12, 2025

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While most targets will have them be the same, the Op0 type can be wider. This is the case e.g. for the AMD GPU buffer pointers.

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@arichardson arichardson Oct 14, 2025

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added a comment, hopefully makes sense now.

setValue(&I, N);
}

void SelectionDAGBuilder::visitPtrToInt(const User &I) {
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