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Speed up class_getImageName #37913

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Merged
merged 1 commit into from
Jun 15, 2021
Merged

Speed up class_getImageName #37913

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15 changes: 14 additions & 1 deletion stdlib/public/runtime/ObjCRuntimeGetImageNameFromClass.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,13 @@
#include <objc/message.h>
#include <TargetConditionals.h>

#if __has_include(<mach-o/dyld_priv.h>)
#include <mach-o/dyld_priv.h>
#define APPLE_OS_SYSTEM 1
#else
#define APPLE_OS_SYSTEM 0
#endif

// Note: There are more #includes below under "Function patching machinery".
// Those are only relevant to the function patching machinery.

Expand Down Expand Up @@ -69,11 +76,17 @@ typedef BOOL (*objc_hook_getImageName)(
const void *descriptor = classAsMetadata->getDescription();
assert(descriptor &&
"all non-artificial Swift classes should have a descriptor");
#if APPLE_OS_SYSTEM
// Use a more efficient internal API when building the system libraries
// for Apple OSes.
*outImageName = dyld_image_path_containing_address(descriptor);
#else
Dl_info imageInfo = {};
if (!dladdr(descriptor, &imageInfo))
return NO;
*outImageName = imageInfo.dli_fname;
return imageInfo.dli_fname != nullptr;
#endif
return *outImageName != nullptr;
}

return NO;
Expand Down