runtime/vm/globals.h

// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#ifndef RUNTIME_VM_GLOBALS_H_
#define RUNTIME_VM_GLOBALS_H_

// This file contains global definitions for the VM library only. Anything that
// is more globally useful should be added to 'vm/globals.h'.

#include "platform/globals.h"

#if defined(_WIN32)
// Undef conflicting defines.
#undef PARITY_EVEN
#undef PARITY_ODD
#undef near
#endif  // defined(_WIN32)

namespace dart {

#if defined(DART_COMPRESSED_POINTERS)
static constexpr intptr_t kCompressedWordSize = kInt32Size;
static constexpr intptr_t kCompressedWordSizeLog2 = kInt32SizeLog2;
typedef uint32_t compressed_uword;
typedef int32_t compressed_word;
#else
static constexpr intptr_t kCompressedWordSize = kWordSize;
static constexpr intptr_t kCompressedWordSizeLog2 = kWordSizeLog2;
typedef uintptr_t compressed_uword;
typedef intptr_t compressed_word;
#endif

// Smi should fit into the compressed word in the heap objects,
// with 1 bit dedicated to the heap pointer tag and 1 bit for sign.
// So its magnitude has N=30 bits (on 32-bit architectures or 64-bit
// architectures with compressed pointers) or N=62 bits (on 64-bit
// architectures without compressed pointers).
// Smi value range is from -(2^N) to (2^N)-1.
static constexpr intptr_t kSmiBits = kCompressedWordSize * kBitsPerByte - 2;
static constexpr intptr_t kSmiMax = (static_cast<intptr_t>(1) << kSmiBits) - 1;
static constexpr intptr_t kSmiMin = -(static_cast<intptr_t>(1) << kSmiBits);

// Hard coded from above but for 32-bit architectures.
static constexpr intptr_t kSmiBits32 = kBitsPerInt32 - 2;
static constexpr intptr_t kSmiMax32 =
    (static_cast<intptr_t>(1) << kSmiBits32) - 1;
static constexpr intptr_t kSmiMin32 = -(static_cast<intptr_t>(1) << kSmiBits32);

// Number of bytes per BigInt digit.
const intptr_t kBytesPerBigIntDigit = 4;

// 32-bit: 2^32 addresses => kMaxAddrSpaceMB = 2^(32 - MBLog2) = 2^12 MB
// 64-bit: 2^48 addresses => kMaxAddrSpaceMB = 2^(48 - MBLog2) = 2^28 MB
const intptr_t kMaxAddrSpaceMB = (kWordSize <= 4) ? 4096 : 268435456;
const intptr_t kMaxAddrSpaceInWords = kMaxAddrSpaceMB >> kWordSizeLog2
                                                             << MBLog2;
// The default old gen heap size in MB, where 0 -- unlimited.
// 32-bit: OS limit is 2 or 3 GB
// 64-bit: Linux's limit is
//   sysctl vm.max_map_count (default 2^16) * 512 KB Pages = 32 GB
// Set the VM limit below the OS limit to increase the likelihood of failing
// gracefully with a Dart OutOfMemory exception instead of SIGABORT.
const intptr_t kDefaultMaxOldGenHeapSize = (kWordSize <= 4) ? 1536 : 30720;
const intptr_t kDefaultNewGenSemiMaxSize = (kWordSize <= 4) ? 8 : 16;

#define kPosInfinity bit_cast<double>(0x7ff0000000000000)
#define kNegInfinity bit_cast<double>(0xfff0000000000000)

#if defined(PRODUCT) && defined(DEBUG)
#error Both PRODUCT and DEBUG defined.
#endif  // defined(PRODUCT) && defined(DEBUG)

#if defined(PRODUCT)
#define NOT_IN_PRODUCT(code)
#define ONLY_IN_PRODUCT(code) code
#else  // defined(PRODUCT)
#define NOT_IN_PRODUCT(code) code
#define ONLY_IN_PRODUCT(code)
#endif  // defined(PRODUCT)

#if defined(DART_PRECOMPILED_RUNTIME) && defined(DART_PRECOMPILER)
#error DART_PRECOMPILED_RUNTIME and DART_PRECOMPILER are mutually exclusive
#endif  // defined(DART_PRECOMPILED_RUNTIME) && defined(DART_PRECOMPILER)

#if defined(DART_PRECOMPILED_RUNTIME) && defined(DART_NOSNAPSHOT)
#error DART_PRECOMPILED_RUNTIME and DART_NOSNAPSHOT are mutually exclusive
#endif  // defined(DART_PRECOMPILED_RUNTIME) && defined(DART_NOSNAPSHOT)

#if defined(DART_PRECOMPILED_RUNTIME)
#define NOT_IN_PRECOMPILED(code)
#define ONLY_IN_PRECOMPILED(code) code
#else
#define NOT_IN_PRECOMPILED(code) code
#define ONLY_IN_PRECOMPILED(code)
#endif  // defined(DART_PRECOMPILED_RUNTIME)

#if defined(TARGET_ARCH_IA32)
#define NOT_IN_IA32(code)
#else
#define NOT_IN_IA32(code) code
#endif

#if defined(DART_PRECOMPILED_RUNTIME)
#define NOT_IN_PRECOMPILED_RUNTIME(code)
#else
#define NOT_IN_PRECOMPILED_RUNTIME(code) code
#endif  // defined(DART_PRECOMPILED_RUNTIME)

// Note: we include timeline support even in PRODUCT builds.
#if !defined(DART_DISABLE_TIMELINE)
#define SUPPORT_TIMELINE 1
#endif

// All non-PRODUCT builds include profiler. We also include profiler
// whenever timeline with perfetto support is included as well as in
// precompiler builds (to enable stack dumping when precompiler crashes).
#if !defined(PRODUCT) ||                                                       \
    (defined(SUPPORT_TIMELINE) && defined(SUPPORT_PERFETTO))
#define DART_INCLUDE_PROFILER 1
#endif

#if defined(DART_INCLUDE_PROFILER) || defined(DART_PRECOMPILER)
#define DART_INCLUDE_STACK_DUMPER 1
#endif

// Include IL printer and disassembler functionality into non-PRODUCT builds,
// in all AOT compiler builds or when forced.
#if !defined(PRODUCT) || defined(DART_PRECOMPILER) ||                          \
    defined(FORCE_INCLUDE_DISASSEMBLER)
#if defined(DART_PRECOMPILED_RUNTIME) && defined(PRODUCT)
#error Requested to include IL printer into PRODUCT AOT runtime
#endif
#define INCLUDE_IL_PRINTER 1
#if !defined(FORCE_INCLUDE_DISASSEMBLER)
#define FORCE_INCLUDE_DISASSEMBLER 1
#endif
#endif

// Include HeapSnapshotWriter functionality if not in PRODUCT.
#if !defined(DART_ENABLE_HEAP_SNAPSHOT_WRITER) && !defined(PRODUCT)
#define DART_ENABLE_HEAP_SNAPSHOT_WRITER 1
#endif

#if defined(ARCH_IS_64_BIT) && !defined(IS_SIMARM_HOST64)
#define HASH_IN_OBJECT_HEADER 1
#endif

#define TARGET_HAS_FAST_WRITE_WRITE_FENCE 1
#define HOST_HAS_FAST_WRITE_WRITE_FENCE 1

#if defined(DEBUG)
#define SNAPSHOT_BACKTRACE
#endif

// The expression OFFSET_OF(type, field) computes the byte-offset of
// the specified field relative to the containing type.
//
// The expression OFFSET_OF_RETURNED_VALUE(type, accessor) computes the
// byte-offset of the return value of the accessor to the containing type.
//
// None of these use 0 or nullptr, which causes a problem with the compiler
// warnings we have enabled (which is also why 'offsetof' doesn't seem to work).
// The workaround is to use the non-zero value kOffsetOfPtr.
const intptr_t kOffsetOfPtr = 32;

#define OFFSET_OF(type, field)                                                 \
  (reinterpret_cast<intptr_t>(                                                 \
       &(reinterpret_cast<type*>(kOffsetOfPtr)->field)) -                      \
   kOffsetOfPtr)  // NOLINT

#define OFFSET_OF_RETURNED_VALUE(type, accessor)                               \
  (reinterpret_cast<intptr_t>(                                                 \
       (reinterpret_cast<type*>(kOffsetOfPtr)->accessor())) -                  \
   kOffsetOfPtr)  // NOLINT

#define SIZE_OF_RETURNED_VALUE(type, method)                                   \
  sizeof(reinterpret_cast<type*>(kOffsetOfPtr)->method())

#define SIZE_OF_DEREFERENCED_RETURNED_VALUE(type, method)                      \
  sizeof(*(reinterpret_cast<type*>(kOffsetOfPtr))->method())

#define OPEN_ARRAY_START(type, align)                                          \
  do {                                                                         \
    const uword result = reinterpret_cast<uword>(this) + sizeof(*this);        \
    ASSERT(Utils::IsAligned(result, alignof(align)));                          \
    return reinterpret_cast<type*>(result);                                    \
  } while (0)

// A type large enough to contain the value of the C++ vtable. This is needed
// to support the handle operations.
typedef uword cpp_vtable;

// When using GCC we can use GCC attributes to ensure that certain
// constants are 8 or 16 byte aligned.
#if defined(DART_HOST_OS_WINDOWS)
#define ALIGN8 __declspec(align(8))
#define ALIGN16 __declspec(align(16))
#else
#define ALIGN8 __attribute__((aligned(8)))
#define ALIGN16 __attribute__((aligned(16)))
#endif

// Zap value used to indicate uninitialized handle area (debug purposes).
#if defined(ARCH_IS_32_BIT)
static constexpr uword kZapUninitializedWord = 0xabababab;
#else
static constexpr uword kZapUninitializedWord = 0xabababababababab;
#endif

// Macros to get the contents of the fp register.
#if __GNUC__
#define GET_FP_REGISTER()                                                      \
  reinterpret_cast<uintptr_t>(__builtin_frame_address(0))
#elif _MSC_VER
#define GET_FP_REGISTER()                                                      \
  reinterpret_cast<uintptr_t>(_AddressOfReturnAddress()) - kWordSize
#else
#define GET_FP_REGISTER() 0
#endif

#if defined(TARGET_ARCH_ARM) || defined(TARGET_ARCH_ARM64) ||                  \
    defined(TARGET_ARCH_X64) || defined(TARGET_ARCH_RISCV32) ||                \
    defined(TARGET_ARCH_RISCV64)
#define TARGET_USES_OBJECT_POOL 1
#endif

#if defined(DART_PRECOMPILER) &&                                               \
    (defined(TARGET_ARCH_X64) || defined(TARGET_ARCH_ARM) ||                   \
     defined(TARGET_ARCH_ARM64) || defined(TARGET_ARCH_RISCV32) ||             \
     defined(TARGET_ARCH_RISCV64))
#define DART_SUPPORT_PRECOMPILATION 1
#endif

}  // namespace dart

#endif  // RUNTIME_VM_GLOBALS_H_