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[Reflection] Gracefully handle the absence of objc_debug_taggedpointer_ext_* variables. #22999

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Merged
merged 1 commit into from
Mar 1, 2019
Merged

[Reflection] Gracefully handle the absence of objc_debug_taggedpointer_ext_* variables. #22999

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46 changes: 28 additions & 18 deletions include/swift/Remote/MetadataReader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2451,6 +2451,12 @@ class MetadataReader {
tryFindSymbol(_address, symbolName); \
tryReadSymbol(_address, dest); \
} while (0)
# define tryFindAndReadSymbolWithDefault(dest, symbolName, default) do { \
dest = default; \
auto _address = Reader->getSymbolAddress(symbolName); \
if (_address) \
tryReadSymbol(_address, dest); \
} while (0)

tryFindAndReadSymbol(TaggedPointerMask,
"objc_debug_taggedpointer_mask");
Expand All @@ -2463,30 +2469,34 @@ class MetadataReader {
if (!TaggedPointerClassesAddr)
finish(TaggedPointerEncodingKind::Error);
TaggedPointerClasses = TaggedPointerClassesAddr.getAddressData();
tryFindAndReadSymbol(TaggedPointerExtendedMask,
"objc_debug_taggedpointer_ext_mask");
tryFindAndReadSymbol(TaggedPointerExtendedSlotShift,
"objc_debug_taggedpointer_ext_slot_shift");
tryFindAndReadSymbol(TaggedPointerExtendedSlotMask,
"objc_debug_taggedpointer_ext_slot_mask");
tryFindSymbol(TaggedPointerExtendedClassesAddr,
"objc_debug_taggedpointer_ext_classes");
if (!TaggedPointerExtendedClassesAddr)
finish(TaggedPointerEncodingKind::Error);
TaggedPointerExtendedClasses =
TaggedPointerExtendedClassesAddr.getAddressData();

// Extended tagged pointers don't exist on older OSes. Handle those
// by setting the variables to zero.
tryFindAndReadSymbolWithDefault(TaggedPointerExtendedMask,
"objc_debug_taggedpointer_ext_mask",
0);
tryFindAndReadSymbolWithDefault(TaggedPointerExtendedSlotShift,
"objc_debug_taggedpointer_ext_slot_shift",
0);
tryFindAndReadSymbolWithDefault(TaggedPointerExtendedSlotMask,
"objc_debug_taggedpointer_ext_slot_mask",
0);
auto TaggedPointerExtendedClassesAddr =
Reader->getSymbolAddress("objc_debug_taggedpointer_ext_classes");
if (TaggedPointerExtendedClassesAddr)
TaggedPointerExtendedClasses =
TaggedPointerExtendedClassesAddr.getAddressData();

// The tagged pointer obfuscator is not present on older OSes, in
// which case we can treat it as zero.
TaggedPointerObfuscator = 0;
auto TaggedPointerObfuscatorAddr = Reader->getSymbolAddress(
"objc_debug_taggedpointer_obfuscator");
if (TaggedPointerObfuscatorAddr)
tryReadSymbol(TaggedPointerObfuscatorAddr, TaggedPointerObfuscator);

tryFindAndReadSymbolWithDefault(TaggedPointerObfuscator,
"objc_debug_taggedpointer_obfuscator",
0);

# undef tryFindSymbol
# undef tryReadSymbol
# undef tryFindAndReadSymbol
# undef tryFindAndReadSymbolWithDefault

return finish(TaggedPointerEncodingKind::Extended);
}
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