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[ThinLTO] Simplify checking for single external copy (NFCI) #164861

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teresajohnson merged 2 commits into from
Oct 24, 2025
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[ThinLTO] Simplify checking for single external copy (NFCI) #164861

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[ThinLTO] Simplify checking for single external copy (NFCI)
teresajohnson Oct 23, 2025
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teresajohnson Oct 24, 2025
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14 changes: 7 additions & 7 deletions llvm/lib/LTO/LTO.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -471,16 +471,14 @@ static void thinLTOInternalizeAndPromoteGUID(
ValueInfo VI, function_ref<bool(StringRef, ValueInfo)> isExported,
function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
isPrevailing) {
auto ExternallyVisibleCopies =
llvm::count_if(VI.getSummaryList(),
[](const std::unique_ptr<GlobalValueSummary> &Summary) {
return !GlobalValue::isLocalLinkage(Summary->linkage());
});

// Before performing index-based internalization and promotion for this GUID,
// the local flag should be consistent with the summary list linkage types.
VI.verifyLocal();

bool SingleExternallyVisibleCopy =
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@mingmingl-llvm mingmingl-llvm Oct 23, 2025

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Optional suggestion: make this const bool so it's clearer it doesn't get modified later.

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@teresajohnson teresajohnson Oct 24, 2025

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done

VI.getSummaryList().size() == 1 &&
!GlobalValue::isLocalLinkage(VI.getSummaryList().front()->linkage());

for (auto &S : VI.getSummaryList()) {
// First see if we need to promote an internal value because it is not
// exported.
Expand Down Expand Up @@ -543,7 +541,9 @@ static void thinLTOInternalizeAndPromoteGUID(
GlobalValue::isExternalWeakLinkage(S->linkage()))
continue;

if (isPrevailing(VI.getGUID(), S.get()) && ExternallyVisibleCopies == 1)
// We may have a single summary copy that is externally visible but not
// prevailing if the prevailing copy is in a native object.
if (SingleExternallyVisibleCopy && isPrevailing(VI.getGUID(), S.get()))
S->setLinkage(GlobalValue::InternalLinkage);
}
}
Expand Down