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[ABI] Define generic 64-bit address space and spare bits. #16425

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Merged
merged 1 commit into from
Nov 28, 2018
Merged

[ABI] Define generic 64-bit address space and spare bits. #16425

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16 changes: 12 additions & 4 deletions stdlib/public/SwiftShims/System.h
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,9 @@
#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.
Expand Down Expand Up @@ -104,7 +107,10 @@
#define SWIFT_ABI_DARWIN_X86_64_LEAST_VALID_POINTER 0x100000000ULL

// Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
#define SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK 0xFF00000000000007ULL
// 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.
Expand Down Expand Up @@ -138,7 +144,8 @@

// TBI guarantees the top byte of pointers is unused.
// Heap objects are eight-byte aligned.
#define SWIFT_ABI_ARM64_SWIFT_SPARE_BITS_MASK 0xFF00000000000007ULL
#define SWIFT_ABI_ARM64_SWIFT_SPARE_BITS_MASK \
SWIFT_ABI_DEFAULT_64BIT_SPARE_BITS_MASK

// Objective-C reserves just the high bit for tagged pointers.
#define SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
Expand All @@ -159,14 +166,15 @@
/*********************************** powerpc64 ********************************/

// Heap objects are pointer-aligned, so the low three bits are unused.
#define SWIFT_ABI_POWERPC64_SWIFT_SPARE_BITS_MASK 0x0000000000000007ULL
#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 0xFF00000000000007ULL
#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
Expand Down