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Linker: Avoid unnecessary work when moving named metadata 

IRLinker::mapUnneededSubprograms has to be sure that any "needed"
subprograms get linked in.  Rather than traversing through imported
entities using llvm::getSubprogram, call MapMetadata.  The latter
memoizes the result in the ValueMap (sharing work with
IRLinker::linkNamedMDNodes proper), and makes the local SmallPtrSet
redundant.

llvm-svn: 265231
This commit is contained in:
Duncan P. N. Exon Smith 2016-04-02 17:39:31 +00:00
parent 8958c40430
commit 0d60a9887f
1 changed files with 11 additions and 17 deletions
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28
llvm/lib/Linker/IRMover.cpp
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@ -1043,28 +1043,22 @@ void IRLinker::mapUnneededSubprograms() {
for (unsigned I = 0, E = CompileUnits->getNumOperands(); I != E; ++I) {
auto *CU = cast<DICompileUnit>(CompileUnits->getOperand(I));
assert(CU && "Expected valid compile unit");
// Ensure that we don't remove subprograms referenced by DIImportedEntity.
// It is not legal to have a DIImportedEntity with a null entity or scope.
// Using getDISubprogram handles the case where the subprogram is reached
// via an intervening DILexicalBlock.
// Seed the ValueMap with the imported entities, in case they reference new
// subprograms.
// FIXME: The DISubprogram for functions not linked in but kept due to
// being referenced by a DIImportedEntity should also get their
// IsDefinition flag is unset.
SmallPtrSet<DISubprogram *, 8> ImportedEntitySPs;
for (auto *IE : CU->getImportedEntities()) {
if (auto *SP = getDISubprogram(dyn_cast<MDNode>(IE->getEntity())))
ImportedEntitySPs.insert(SP);
if (auto *SP = getDISubprogram(dyn_cast<MDNode>(IE->getScope())))
ImportedEntitySPs.insert(SP);
}
if (MDTuple *IEs = CU->getImportedEntities().get())
(void)MapMetadata(IEs, ValueMap,
ValueMapperFlags | RF_NullMapMissingGlobalValues,
&TypeMap, &GValMaterializer);
// Try to insert nullptr into the map for any SP not referenced from
// functions and not in the imported entities. If the insertino succeeded,
// set HasUnneededSPs.
// Try to insert nullptr into the map for any SP not already mapped. If
// the insertion succeeds, we don't need this subprogram.
for (auto *Op : CU->getSubprograms())
if (!ImportedEntitySPs.count(Op))
if (ValueMap.MD().insert(std::make_pair(Op, TrackingMDRef())).second)
HasUnneededSPs = true;
if (ValueMap.MD().insert(std::make_pair(Op, TrackingMDRef())).second)
HasUnneededSPs = true;
}
}