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275ef489d4
IRGen uses a typedef, SpareBitVector, for its principal
purpose of tracking spare bits. Other uses should not
use this typedef, and I've tried to follow that, but I
did this rewrite mostly with sed and may have missed
some fixups.
This should be almost completely NFC. There may be
some subtle changes in spare bits for witness tables
and other off-beat pointer types. I also fixed a bug
where IRGen thought that thin functions were two
pointers wide, but this wouldn't have affected anything
because we never store thin functions anyway, since
they're not a valid AST type.
This commit repplies r24305 with two fixes:
- It fixes the computation of spare bits for unusual
integer types to use the already-agreed-upon type
size instead of recomputing it. This fixes the
i386 stdlib build. Joe and I agreed that we should
also change the size to use the LLVM alloc size
instead of the next power of 2, but this patch
does not do that yet.
- It changes the spare bits in function types back
to the empty set. I'll be changing this in a
follow-up, but it needs to be tied to runtime
changes. This fixes the regression test failures.
Swift SVN r24324
97 lines
4.0 KiB
C++
97 lines
4.0 KiB
C++
//===--- System.h - Swift ABI system-specific constants ---------*- C++ -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2015 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Here's some fun facts about the target platforms we support!
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//
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//===----------------------------------------------------------------------===//
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#ifndef SWIFT_ABI_SYSTEM_H
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#define SWIFT_ABI_SYSTEM_H
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// In general, these macros are expected to expand to host-independent
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// integer constant expressions. This allows the same data to feed
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// both the compiler and runtime implementation.
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/******************************* Default Rules ********************************/
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/// The least valid pointer value for an actual pointer (as opposed to
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/// Objective-C pointers, which may be tagged pointers and are covered
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/// separately). Values up to this are "extra inhabitants" of the
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/// pointer representation, and payloaded enum types can take
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/// advantage of that as they see fit.
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///
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/// By default, we assume that there's at least an unmapped page at
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/// the bottom of the address space. 4K is a reasonably likely page
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/// size.
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///
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/// The minimum possible value for this macro is 1; we always assume
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/// that the null representation is available.
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#define SWIFT_ABI_DEFAULT_LEAST_VALID_POINTER 4096
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/// The bitmask of spare bits in a function pointer.
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#define SWIFT_ABI_DEFAULT_FUNCTION_SPARE_BITS_MASK 0
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/// The bitmask of spare bits in a Swift heap object pointer. A Swift
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/// heap object allocation will never set any of these bits.
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#define SWIFT_ABI_DEFAULT_SWIFT_SPARE_BITS_MASK 0
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/// The bitmask of reserved bits in an Objective-C object pointer.
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/// By default we assume the ObjC runtime doesn't use tagged pointers.
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#define SWIFT_ABI_DEFAULT_OBJC_RESERVED_BITS_MASK 0
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/// The number of low bits in an Objective-C object pointer that
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/// are reserved by the Objective-C runtime.
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#define SWIFT_ABI_DEFAULT_OBJC_NUM_RESERVED_LOW_BITS 0
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/// The ObjC runtime will not use pointer values for which
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/// ``pointer & SWIFT_ABI_XXX_OBJC_RESERVED_BITS_MASK == 0 &&
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/// pointer & SWIFT_ABI_XXX_SWIFT_SPARE_BITS_MASK != 0``.
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/*********************************** i386 *************************************/
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// Heap objects are pointer-aligned, so the low two bits are unused.
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#define SWIFT_ABI_I386_SWIFT_SPARE_BITS_MASK 0x00000003U
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/*********************************** arm **************************************/
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// Heap objects are pointer-aligned, so the low two bits are unused.
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#define SWIFT_ABI_ARM_SWIFT_SPARE_BITS_MASK 0x00000003U
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/*********************************** x86-64 ***********************************/
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/// Darwin reserves the low 4GB of address space.
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#define SWIFT_ABI_DARWIN_X86_64_LEAST_VALID_POINTER (4ULL*1024*1024*1024)
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// Only the bottom 56 bits are used, and heap objects are eight-byte-aligned.
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//
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#define SWIFT_ABI_X86_64_SWIFT_SPARE_BITS_MASK 0xFF00000000000007ULL
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// Objective-C reserves the high and low bits for tagged pointers.
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// Systems exist which use either bit.
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#define SWIFT_ABI_X86_64_OBJC_RESERVED_BITS_MASK 0x8000000000000001ULL
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#define SWIFT_ABI_X86_64_OBJC_NUM_RESERVED_LOW_BITS 1
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/*********************************** arm64 ************************************/
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/// Darwin reserves the low 4GB of address space.
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#define SWIFT_ABI_DARWIN_ARM64_LEAST_VALID_POINTER (4ULL*1024*1024*1024)
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// TBI guarantees the top byte of pointers is unused.
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// Heap objects are eight-byte aligned.
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#define SWIFT_ABI_ARM64_SWIFT_SPARE_BITS_MASK 0xFF00000000000007ULL
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// Objective-C reserves just the high bit for tagged pointers.
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#define SWIFT_ABI_ARM64_OBJC_RESERVED_BITS_MASK 0x8000000000000000ULL
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#define SWIFT_ABI_ARM64_OBJC_NUM_RESERVED_LOW_BITS 0
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#endif /* SWIFT_ABI_SYSTEM_H */
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