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Runtime: Optional-like enums with single-refcounted payloads can share the refcounted value witnesses.

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swift_retain and objc_retain both handle nil already, so we can bypass the generic Optional value witnesses when instantiating Optional on a class type, which happens kind of a lot.

Swift SVN r23613
This commit is contained in:
Joe Groff
2014-12-02 17:34:36 +00:00
parent b44f7a5d3a
commit 27f49cd19d
4 changed files with 40 additions and 13 deletions
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16
stdlib/runtime/Metadata.cpp
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@@ -1217,7 +1217,7 @@ static OpaqueValue *pod_direct_initializeArrayWithTakeFrontToBack(
#define pod_indirect_initializeArrayWithTakeBackToFront \
pod_direct_initializeArrayWithTakeFrontToBack
void swift::swift_installCommonValueWitnesses(ValueWitnessTable *vwtable) {
void swift::installCommonValueWitnesses(ValueWitnessTable *vwtable) {
auto flags = vwtable->flags;
if (flags.isPOD()) {
// Use POD value witnesses.
@@ -1230,6 +1230,7 @@ void swift::swift_installCommonValueWitnesses(ValueWitnessTable *vwtable) {
FOR_ALL_FUNCTION_VALUE_WITNESSES(INSTALL_POD_INDIRECT_WITNESS)
#undef INSTALL_POD_INDIRECT_WITNESS
}
return;
}
if (vwtable->flags.isBitwiseTakable()) {
@@ -1251,9 +1252,16 @@ void swift::swift_installCommonValueWitnesses(ValueWitnessTable *vwtable) {
vwtable->initializeArrayWithTakeBackToFront
= pod_indirect_initializeArrayWithTakeBackToFront;
}
return;
}
if (!vwtable->flags.isInlineStorage()) {
// For values stored out-of-line, initializeBufferWithTakeOfBuffer is
// always a memcpy.
vwtable->initializeBufferWithTakeOfBuffer
= pod_indirect_initializeBufferWithTakeOfBuffer;
return;
}
return;
}
/*** Structs ***************************************************************/
@@ -1275,7 +1283,7 @@ void swift::swift_initStructMetadata_UniversalStrategy(size_t numFields,
vwtable->stride = layout.stride;
// Substitute in better value witnesses if we have them.
swift_installCommonValueWitnesses(vwtable);
installCommonValueWitnesses(vwtable);
// We have extra inhabitants if the first element does.
// FIXME: generalize this.