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[Reflection] Reduce string copying in TypeRefBuilder (NFC) #40891

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Merged
merged 1 commit into from
Jan 18, 2022
+7 −7
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[Reflection] Reduce string copying in TypeRefBuilder (NFC) #40891

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14 changes: 7 additions & 7 deletions stdlib/public/Reflection/TypeRefBuilder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -107,7 +107,7 @@ TypeRefBuilder::normalizeReflectionName(RemoteRef<char> reflectionName) {
if (!mangling.isSuccess()) {
return {};
}
return mangling.result();
return std::move(mangling.result());
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Actually, I think this should be reverted, since it disables RVO

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My understanding is that RVO doesn't apply here, as this value is of type string, but the return type is Optional<string>. This change does not trigger the -Wpessimizing-move warning.

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I'll restate that, I think RVO does happen here – for the Optional. This move applies to the value going inside of the Optional, not the Optional itself.

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maybe this would be more clear if the code was explicit:

return Optional(std::move(…));

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I see, makes sense!

}
}

Expand Down Expand Up @@ -194,16 +194,16 @@ const TypeRef *TypeRefBuilder::lookupSuperclass(const TypeRef *TR) {

RemoteRef<FieldDescriptor>
TypeRefBuilder::getFieldTypeInfo(const TypeRef *TR) {
std::string MangledName;
const std::string *MangledName;
if (auto N = dyn_cast<NominalTypeRef>(TR))
MangledName = N->getMangledName();
MangledName = &N->getMangledName();
else if (auto BG = dyn_cast<BoundGenericTypeRef>(TR))
MangledName = BG->getMangledName();
MangledName = &BG->getMangledName();
else
return nullptr;

// Try the cache.
auto Found = FieldTypeInfoCache.find(MangledName);
auto Found = FieldTypeInfoCache.find(*MangledName);
if (Found != FieldTypeInfoCache.end())
return Found->second;

Expand All @@ -216,13 +216,13 @@ TypeRefBuilder::getFieldTypeInfo(const TypeRef *TR) {
continue;
auto CandidateMangledName = readTypeRef(FD, FD->MangledTypeName);
if (auto NormalizedName = normalizeReflectionName(CandidateMangledName))
FieldTypeInfoCache[*NormalizedName] = FD;
FieldTypeInfoCache[std::move(*NormalizedName)] = FD;
}

// Since we're done with the current ReflectionInfo, increment early in
// case we get a cache hit.
++FirstUnprocessedReflectionInfoIndex;
Found = FieldTypeInfoCache.find(MangledName);
Found = FieldTypeInfoCache.find(*MangledName);
if (Found != FieldTypeInfoCache.end())
return Found->second;
}
Expand Down