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[TableGen] Report a better error when an InstAlias does not use a RegClass #168444

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[TableGen] Report a better error when an InstAlias does not use a RegClass #168444

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5 changes: 3 additions & 2 deletions llvm/utils/TableGen/Common/CodeGenInstAlias.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -55,9 +55,10 @@ static Expected<ResultOperand> matchSimpleOperand(const Init *Arg,
// Match 'RegClass:$name' or 'RegOp:$name'.
if (const Record *ArgRC = T.getInitValueAsRegClassLike(Arg)) {
if (ArgRC->isSubClassOf("RegisterClass")) {
if (!T.getRegisterClass(OpRC).hasSubClass(&T.getRegisterClass(ArgRC)))
if (!OpRC->isSubClassOf("RegisterClass") ||
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@s-barannikov s-barannikov Nov 17, 2025

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Maybe instead if (OpRC->isSubclassOf("RegClassByHwMode")) then report "HwMode support is not implemented"?

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@arichardson arichardson Nov 17, 2025

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Yeah that would give slightly better results but may be too restrictive. It does seem to work with HWModes as long as the RegClassByHwMode argument is the same, but it doesn't handle the subset case.

!T.getRegisterClass(OpRC).hasSubClass(&T.getRegisterClass(ArgRC)))
return createStringError(
"argument register class" + ArgRC->getName() +
"argument register class " + ArgRC->getName() +
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@arichardson arichardson Nov 17, 2025

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Considering the typo wasn't noticed there does not seem to be a test for this error case. If there's an existing test I can add this to easily I can do so, otherwise I'll have to try create a minimal testcase from scratch.

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@s-barannikov s-barannikov Nov 17, 2025

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There are no tests for this, as far as I remember.

" is not a subclass of operand register class " +
OpRC->getName());
if (!ArgName)
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