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

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arichardson merged 1 commit into from
Dec 5, 2025
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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.

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@arichardson arichardson Dec 4, 2025

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I have some follow-up changes to improve this (printing essentially what you suggested) including a test.

!T.getRegisterClass(OpRC).hasSubClass(&T.getRegisterClass(ArgRC)))
return createStringError(
"argument register class" + ArgRC->getName() +
"argument register class " + ArgRC->getName() +
" is not a subclass of operand register class " +
OpRC->getName());
if (!ArgName)
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