stdlib/public/SwiftShims/System.h - third_party/swift - Git at Google

 //===--- System.h - Swift ABI system-specific constants ---------*- C++ -*-===//
 //
 // This source file is part of the Swift.org open source project
 //
 // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//
 //
 // Here are some fun facts about the target platforms we support!
 //
 //===----------------------------------------------------------------------===//

 #ifndef SWIFT_ABI_SYSTEM_H
 #define SWIFT_ABI_SYSTEM_H

 // In general, these macros are expected to expand to host-independent
 // integer constant expressions.  This allows the same data to feed
 // both the compiler and runtime implementation.

 /******************************* Default Rules ********************************/

 /// The least valid pointer value for an actual pointer (as opposed to
 /// Objective-C pointers, which may be tagged pointers and are covered
 /// separately).  Values up to this are "extra inhabitants" of the
 /// pointer representation, and payloaded enum types can take
 /// advantage of that as they see fit.
 ///
 /// By default, we assume that there's at least an unmapped page at
 /// the bottom of the address space.  4K is a reasonably likely page
 /// size.
 ///
 /// The minimum possible value for this macro is 1; we always assume
 /// that the null representation is available.
 #define SWIFT_ABI_DEFAULT_LEAST_VALID_POINTER 4096

 /// The bitmask of spare bits in a function pointer.
 #define SWIFT_ABI_DEFAULT_FUNCTION_SPARE_BITS_MASK 0

 /// The bitmask of spare bits in a Swift heap object pointer.  A Swift
 /// heap object allocation will never set any of these bits.
 #define SWIFT_ABI_DEFAULT_SWIFT_SPARE_BITS_MASK 0

 /// The bitmask of reserved bits in an Objective-C object pointer.
 /// By default we assume the ObjC runtime doesn't use tagged pointers.
 #define SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK 0

 /// The number of low bits in an Objective-C object pointer that
 /// are reserved by the Objective-C runtime.
 #define SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS 0

 /// The ObjC runtime will not use pointer values for which
 /// ``pointer & SWIFT_ABI_XXX_OBJC_RESERVED_BITS_MASK == 0 &&
 /// pointer & SWIFT_ABI_XXX_SWIFT_SPARE_BITS_MASK != 0``.

 // Weak references use a marker to tell when they are controlled by
 // the ObjC runtime and when they are controlled by the Swift runtime.
 // Non-ObjC platforms don't use this marker.
 #define SWIFT_ABI_DEFAULT_OBJC_WEAK_REFERENCE_MARKER_MASK 0
 #define SWIFT_ABI_DEFAULT_OBJC_WEAK_REFERENCE_MARKER_VALUE 0

 // BridgeObject uses this bit to indicate a tagged value.
 #define SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_32 0U
 #define SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64 0x8000000000000000ULL

 // Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
 #define SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK 0xFF00000000000007ULL

 /*********************************** i386 *************************************/

 // Heap objects are pointer-aligned, so the low two bits are unused.
 #define SWIFT_ABI_I386_SWIFT_SPARE_BITS_MASK 0x00000003U

 // ObjC weak reference discriminator is the LSB.
 #define SWIFT_ABI_I386_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_I386_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)

 // BridgeObject uses this bit to indicate whether it holds an ObjC object or
 // not.
 #define SWIFT_ABI_I386_IS_OBJC_BIT 0x00000002U

 /*********************************** arm **************************************/

 // Heap objects are pointer-aligned, so the low two bits are unused.
 #define SWIFT_ABI_ARM_SWIFT_SPARE_BITS_MASK 0x00000003U

 // ObjC weak reference discriminator is the LSB.
 #define SWIFT_ABI_ARM_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_ARM_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)

 // BridgeObject uses this bit to indicate whether it holds an ObjC object or
 // not.
 #define SWIFT_ABI_ARM_IS_OBJC_BIT 0x00000002U

 /*********************************** x86-64 ***********************************/

 /// Darwin reserves the low 4GB of address space.
 #define SWIFT_ABI_DARWIN_X86_64_LEAST_VALID_POINTER 0x100000000ULL

 // Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
 // This is conservative: in practice architectual limitations and other
 // compatiblity concerns likely constrain the address space to 52 bits.
 #define SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK                                 \
   SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

 // Objective-C reserves the low bit for tagged pointers on macOS, but
 // reserves the high bit on simulators.
 #define SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK 0x0000000000000001ULL
 #define SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS 1
 #define SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
 #define SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS 0


 // BridgeObject uses this bit to indicate whether it holds an ObjC object or
 // not.
 #define SWIFT_ABI_X86_64_IS_OBJC_BIT 0x4000000000000000ULL

 // ObjC weak reference discriminator is the bit reserved for ObjC tagged
 // pointers plus one more low bit.
 #define SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS)

 /*********************************** arm64 ************************************/

 /// Darwin reserves the low 4GB of address space.
 #define SWIFT_ABI_DARWIN_ARM64_LEAST_VALID_POINTER 0x100000000ULL

 // TBI guarantees the top byte of pointers is unused, but ARMv8.5-A
 // claims the bottom four bits of that for memory tagging.
 // Heap objects are eight-byte aligned.
 #define SWIFT_ABI_ARM64_SWIFT_SPARE_BITS_MASK 0xF000000000000007ULL

 // Objective-C reserves just the high bit for tagged pointers.
 #define SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
 #define SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS 0

 // BridgeObject uses this bit to indicate whether it holds an ObjC object or
 // not.
 #define SWIFT_ABI_ARM64_IS_OBJC_BIT 0x4000000000000000ULL

 // ObjC weak reference discriminator is the high bit
 // reserved for ObjC tagged pointers plus the LSB.
 #define SWIFT_ABI_ARM64_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_ARM64_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS)

 /*********************************** powerpc64 ********************************/

 // Heap objects are pointer-aligned, so the low three bits are unused.
 #define SWIFT_ABI_POWERPC64_SWIFT_SPARE_BITS_MASK                              \
   SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

 /*********************************** s390x ************************************/

 // Top byte of pointers is unused, and heap objects are eight-byte aligned.
 // On s390x it is theoretically possible to have high bit set but in practice
 // it is unlikely.
 #define SWIFT_ABI_S390X_SWIFT_SPARE_BITS_MASK SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

 // Objective-C reserves just the high bit for tagged pointers.
 #define SWIFT_ABI_S390X_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
 #define SWIFT_ABI_S390X_OBJC_NUM_RESERVED_LOW_BITS 0

 // BridgeObject uses this bit to indicate whether it holds an ObjC object or
 // not.
 #define SWIFT_ABI_S390X_IS_OBJC_BIT 0x4000000000000000ULL

 // ObjC weak reference discriminator is the high bit
 // reserved for ObjC tagged pointers plus the LSB.
 #define SWIFT_ABI_S390X_OBJC_WEAK_REFERENCE_MARKER_MASK  \
   (SWIFT_ABI_S390X_OBJC_RESERVED_BITS_MASK |          \
    1<<SWIFT_ABI_S390X_OBJC_NUM_RESERVED_LOW_BITS)
 #define SWIFT_ABI_S390X_OBJC_WEAK_REFERENCE_MARKER_VALUE \
   (1<<SWIFT_ABI_S390X_OBJC_NUM_RESERVED_LOW_BITS)

 #endif /* SWIFT_ABI_SYSTEM_H */
	//===--- System.h - Swift ABI system-specific constants ---------- C++ --===//
	//
	// This source file is part of the Swift.org open source project
	//
	// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
	// Licensed under Apache License v2.0 with Runtime Library Exception
	//
	// See https://swift.org/LICENSE.txt for license information
	// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
	//
	//===----------------------------------------------------------------------===//
	//
	// Here are some fun facts about the target platforms we support!
	//
	//===----------------------------------------------------------------------===//

	#ifndef SWIFT_ABI_SYSTEM_H
	#define SWIFT_ABI_SYSTEM_H

	// In general, these macros are expected to expand to host-independent
	// integer constant expressions. This allows the same data to feed
	// both the compiler and runtime implementation.

	/***************************** Default Rules ******************************/

	/// The least valid pointer value for an actual pointer (as opposed to
	/// Objective-C pointers, which may be tagged pointers and are covered
	/// separately). Values up to this are "extra inhabitants" of the
	/// pointer representation, and payloaded enum types can take
	/// advantage of that as they see fit.
	///
	/// By default, we assume that there's at least an unmapped page at
	/// the bottom of the address space. 4K is a reasonably likely page
	/// size.
	///
	/// The minimum possible value for this macro is 1; we always assume
	/// that the null representation is available.
	#define SWIFT_ABI_DEFAULT_LEAST_VALID_POINTER 4096

	/// The bitmask of spare bits in a function pointer.
	#define SWIFT_ABI_DEFAULT_FUNCTION_SPARE_BITS_MASK 0

	/// The bitmask of spare bits in a Swift heap object pointer. A Swift
	/// heap object allocation will never set any of these bits.
	#define SWIFT_ABI_DEFAULT_SWIFT_SPARE_BITS_MASK 0

	/// The bitmask of reserved bits in an Objective-C object pointer.
	/// By default we assume the ObjC runtime doesn't use tagged pointers.
	#define SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK 0

	/// The number of low bits in an Objective-C object pointer that
	/// are reserved by the Objective-C runtime.
	#define SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS 0

	/// The ObjC runtime will not use pointer values for which
	/// ``pointer & SWIFT_ABI_XXX_OBJC_RESERVED_BITS_MASK == 0 &&
	/// pointer & SWIFT_ABI_XXX_SWIFT_SPARE_BITS_MASK != 0``.

	// Weak references use a marker to tell when they are controlled by
	// the ObjC runtime and when they are controlled by the Swift runtime.
	// Non-ObjC platforms don't use this marker.
	#define SWIFT_ABI_DEFAULT_OBJC_WEAK_REFERENCE_MARKER_MASK 0
	#define SWIFT_ABI_DEFAULT_OBJC_WEAK_REFERENCE_MARKER_VALUE 0

	// BridgeObject uses this bit to indicate a tagged value.
	#define SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_32 0U
	#define SWIFT_ABI_DEFAULT_BRIDGEOBJECT_TAG_64 0x8000000000000000ULL

	// Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
	#define SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK 0xFF00000000000007ULL

	/********************************* i386 ***********************************/

	// Heap objects are pointer-aligned, so the low two bits are unused.
	#define SWIFT_ABI_I386_SWIFT_SPARE_BITS_MASK 0x00000003U

	// ObjC weak reference discriminator is the LSB.
	#define SWIFT_ABI_I386_OBJC_WEAK_REFERENCE_MARKER_MASK \
	(SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK \| \
	1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_I386_OBJC_WEAK_REFERENCE_MARKER_VALUE \
	(1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)

	// BridgeObject uses this bit to indicate whether it holds an ObjC object or
	// not.
	#define SWIFT_ABI_I386_IS_OBJC_BIT 0x00000002U

	/********************************* arm ************************************/

	// Heap objects are pointer-aligned, so the low two bits are unused.
	#define SWIFT_ABI_ARM_SWIFT_SPARE_BITS_MASK 0x00000003U

	// ObjC weak reference discriminator is the LSB.
	#define SWIFT_ABI_ARM_OBJC_WEAK_REFERENCE_MARKER_MASK \
	(SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK \| \
	1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_ARM_OBJC_WEAK_REFERENCE_MARKER_VALUE \
	(1<<SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS)

	// BridgeObject uses this bit to indicate whether it holds an ObjC object or
	// not.
	#define SWIFT_ABI_ARM_IS_OBJC_BIT 0x00000002U

	/********************************* x86-64 *********************************/

	/// Darwin reserves the low 4GB of address space.
	#define SWIFT_ABI_DARWIN_X86_64_LEAST_VALID_POINTER 0x100000000ULL

	// Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
	// This is conservative: in practice architectual limitations and other
	// compatiblity concerns likely constrain the address space to 52 bits.
	#define SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK \
	SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

	// Objective-C reserves the low bit for tagged pointers on macOS, but
	// reserves the high bit on simulators.
	#define SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK 0x0000000000000001ULL
	#define SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS 1
	#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
	#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS 0


	// BridgeObject uses this bit to indicate whether it holds an ObjC object or
	// not.
	#define SWIFT_ABI_X86_64_IS_OBJC_BIT 0x4000000000000000ULL

	// ObjC weak reference discriminator is the bit reserved for ObjC tagged
	// pointers plus one more low bit.
	#define SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_MASK \
	(SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK \| \
	1<<SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_X86_64_OBJC_WEAK_REFERENCE_MARKER_VALUE \
	(1<<SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_MASK \
	(SWIFT_ABI_X86_64_SIMULATOR_OBJC_RESERVED_BITS_MASK \| \
	1<<SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_X86_64_SIMULATOR_OBJC_WEAK_REFERENCE_MARKER_VALUE \
	(1<<SWIFT_ABI_X86_64_SIMULATOR_OBJC_NUM_RESERVED_LOW_BITS)

	/********************************* arm64 **********************************/

	/// Darwin reserves the low 4GB of address space.
	#define SWIFT_ABI_DARWIN_ARM64_LEAST_VALID_POINTER 0x100000000ULL

	// TBI guarantees the top byte of pointers is unused, but ARMv8.5-A
	// claims the bottom four bits of that for memory tagging.
	// Heap objects are eight-byte aligned.
	#define SWIFT_ABI_ARM64_SWIFT_SPARE_BITS_MASK 0xF000000000000007ULL

	// Objective-C reserves just the high bit for tagged pointers.
	#define SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
	#define SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS 0

	// BridgeObject uses this bit to indicate whether it holds an ObjC object or
	// not.
	#define SWIFT_ABI_ARM64_IS_OBJC_BIT 0x4000000000000000ULL

	// ObjC weak reference discriminator is the high bit
	// reserved for ObjC tagged pointers plus the LSB.
	#define SWIFT_ABI_ARM64_OBJC_WEAK_REFERENCE_MARKER_MASK \
	(SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK \| \
	1<<SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_ARM64_OBJC_WEAK_REFERENCE_MARKER_VALUE \
	(1<<SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS)

	/********************************* powerpc64 ******************************/

	// Heap objects are pointer-aligned, so the low three bits are unused.
	#define SWIFT_ABI_POWERPC64_SWIFT_SPARE_BITS_MASK \
	SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

	/********************************* s390x **********************************/

	// Top byte of pointers is unused, and heap objects are eight-byte aligned.
	// On s390x it is theoretically possible to have high bit set but in practice
	// it is unlikely.
	#define SWIFT_ABI_S390X_SWIFT_SPARE_BITS_MASK SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

	// Objective-C reserves just the high bit for tagged pointers.
	#define SWIFT_ABI_S390X_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
	#define SWIFT_ABI_S390X_OBJC_NUM_RESERVED_LOW_BITS 0

	// BridgeObject uses this bit to indicate whether it holds an ObjC object or
	// not.
	#define SWIFT_ABI_S390X_IS_OBJC_BIT 0x4000000000000000ULL

	// ObjC weak reference discriminator is the high bit
	// reserved for ObjC tagged pointers plus the LSB.
	#define SWIFT_ABI_S390X_OBJC_WEAK_REFERENCE_MARKER_MASK \
	(SWIFT_ABI_S390X_OBJC_RESERVED_BITS_MASK \| \
	1<<SWIFT_ABI_S390X_OBJC_NUM_RESERVED_LOW_BITS)
	#define SWIFT_ABI_S390X_OBJC_WEAK_REFERENCE_MARKER_VALUE \
	(1<<SWIFT_ABI_S390X_OBJC_NUM_RESERVED_LOW_BITS)

	#endif /* SWIFT_ABI_SYSTEM_H */