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[TableGen] Ignore inaccessible memory when checking pattern flags #90061

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Merged
merged 1 commit into from
Apr 26, 2024
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[TableGen] Ignore inaccessible memory when checking pattern flags #90061

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10 changes: 9 additions & 1 deletion llvm/utils/TableGen/Common/CodeGenDAGPatterns.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3616,7 +3616,15 @@ class InstAnalyzer {
hasChain = true;

if (const CodeGenIntrinsic *IntInfo = N.getIntrinsicInfo(CDP)) {
ModRefInfo MR = IntInfo->ME.getModRef();
// Ignore reads/writes to inaccessible memory. These should not imply
// mayLoad/mayStore on the instruction because they are often used to
// model dependencies that Machine IR expresses as uses/defs of a
// special physical register.
ModRefInfo MR = ModRefInfo::NoModRef;
for (MemoryEffects::Location Loc : MemoryEffects::locations()) {
if (Loc != MemoryEffects::Location::InaccessibleMem)
MR |= IntInfo->ME.getModRef();
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Silly typo here. It should have been:

Suggested change
MR |= IntInfo->ME.getModRef();
MR |= IntInfo->ME.getModRef(Loc);

Because of this the patch had no effect, and if I fix the typo then it causes some build failures.

I will revert and rethink.

}
// If this is an intrinsic, analyze it.
if (isRefSet(MR))
mayLoad = true; // These may load memory.
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