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[5.1][Runtime] Use a #define for the value of swift_isaMask. #24676

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Merged
merged 1 commit into from
May 10, 2019
Merged

[5.1][Runtime] Use a #define for the value of swift_isaMask. #24676

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24 changes: 23 additions & 1 deletion stdlib/public/runtime/Private.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,10 @@
#include "swift/Runtime/Metadata.h"
#include "llvm/Support/Compiler.h"

#if defined(__APPLE__) && defined(__MACH__)
#include <TargetConditionals.h>
#endif

// Opaque ISAs need to use object_getClass which is in runtime.h
#if SWIFT_HAS_OPAQUE_ISAS
#include <objc/runtime.h>
Expand Down Expand Up @@ -84,6 +88,24 @@ class TypeInfo {
#if SWIFT_HAS_ISA_MASKING
SWIFT_RUNTIME_EXPORT
uintptr_t swift_isaMask;

// Hardcode the mask. We have our own copy of the value, as it's hard to work
// out the proper includes from libobjc. The values MUST match the ones from
// libobjc. Debug builds check these values against objc_debug_isa_class_mask
// from libobjc.
# if TARGET_OS_SIMULATOR
// Simulators don't currently use isa masking, but we still want to emit
// swift_isaMask and the corresponding code in case that changes. libobjc's
// mask has the bottom bits clear to include pointer alignment, match that
// value here.
# define SWIFT_ISA_MASK 0xfffffffffffffff8ULL
# elif __arm64__
# define SWIFT_ISA_MASK 0x0000000ffffffff8ULL
# elif __x86_64__
# define SWIFT_ISA_MASK 0x00007ffffffffff8ULL
# else
# error Unknown architecture for masked isa.
# endif
#endif

#if SWIFT_OBJC_INTEROP
Expand Down Expand Up @@ -134,7 +156,7 @@ class TypeInfo {

#if SWIFT_HAS_ISA_MASKING
// Apply the mask.
bits &= swift_isaMask;
bits &= SWIFT_ISA_MASK;
#endif

// The result is a class pointer.
Expand Down
19 changes: 7 additions & 12 deletions stdlib/public/runtime/SwiftObject.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -58,17 +58,7 @@
OBJC_EXPORT __attribute__((__weak_import__))
const uintptr_t objc_debug_isa_class_mask;

static uintptr_t computeISAMask() {
// The versions of the Objective-C runtime which use non-pointer
// ISAs also export this symbol.
if (auto runtimeSymbol = &objc_debug_isa_class_mask)
return *runtimeSymbol;
return ~uintptr_t(0);
}

SWIFT_ALLOWED_RUNTIME_GLOBAL_CTOR_BEGIN
uintptr_t swift::swift_isaMask = computeISAMask();
SWIFT_ALLOWED_RUNTIME_GLOBAL_CTOR_END
uintptr_t swift::swift_isaMask = SWIFT_ISA_MASK;
#endif

const ClassMetadata *swift::_swift_getClass(const void *object) {
Expand Down Expand Up @@ -204,7 +194,12 @@ Class _swift_classOfObjCHeapObject(OpaqueValue *value) {


@implementation SwiftObject
+ (void)initialize {}
+ (void)initialize {
#if SWIFT_HAS_ISA_MASKING
assert(&objc_debug_isa_class_mask);
assert(objc_debug_isa_class_mask == SWIFT_ISA_MASK);
#endif
}

+ (instancetype)allocWithZone:(struct _NSZone *)zone {
assert(zone == nullptr);
Expand Down