1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ART_LIBARTBASE_BASE_GLOBALS_H_
18#define ART_LIBARTBASE_BASE_GLOBALS_H_
19
20#include <stddef.h>
21#include <stdint.h>
22
23namespace art {
24
25static constexpr size_t KB = 1024;
26static constexpr size_t MB = KB * KB;
27static constexpr size_t GB = KB * KB * KB;
28
29// Runtime sizes.
30static constexpr size_t kBitsPerByte = 8;
31static constexpr size_t kBitsPerByteLog2 = 3;
32static constexpr int kBitsPerIntPtrT = sizeof(intptr_t) * kBitsPerByte;
33
34// Required stack alignment
35static constexpr size_t kStackAlignment = 16;
36
37// System page size. We check this against sysconf(_SC_PAGE_SIZE) at runtime, but use a simple
38// compile-time constant so the compiler can generate better code.
39static constexpr int kPageSize = 4096;
40
41// Returns whether the given memory offset can be used for generating
42// an implicit null check.
43static inline bool CanDoImplicitNullCheckOn(uintptr_t offset) {
44  return offset < kPageSize;
45}
46
47// Required object alignment
48static constexpr size_t kObjectAlignmentShift = 3;
49static constexpr size_t kObjectAlignment = 1u << kObjectAlignmentShift;
50static constexpr size_t kLargeObjectAlignment = kPageSize;
51
52// Clion, clang analyzer, etc can falsely believe that "if (kIsDebugBuild)" always
53// returns the same value. By wrapping into a call to another constexpr function, we force it
54// to realize that is not actually always evaluating to the same value.
55static constexpr bool GlobalsReturnSelf(bool self) { return self; }
56
57// Whether or not this is a debug build. Useful in conditionals where NDEBUG isn't.
58// TODO: Use only __clang_analyzer__ here. b/64455231
59#if defined(NDEBUG) && !defined(__CLION_IDE__)
60static constexpr bool kIsDebugBuild = GlobalsReturnSelf(false);
61#else
62static constexpr bool kIsDebugBuild = GlobalsReturnSelf(true);
63#endif
64
65#if defined(ART_PGO_INSTRUMENTATION)
66static constexpr bool kIsPGOInstrumentation = true;
67#else
68static constexpr bool kIsPGOInstrumentation = false;
69#endif
70
71// ART_TARGET - Defined for target builds of ART.
72// ART_TARGET_LINUX - Defined for target Linux builds of ART.
73// ART_TARGET_ANDROID - Defined for target Android builds of ART.
74// Note: Either ART_TARGET_LINUX or ART_TARGET_ANDROID need to be set when ART_TARGET is set.
75// Note: When ART_TARGET_LINUX is defined mem_map.h will not be using Ashmem for memory mappings
76// (usually only available on Android kernels).
77#if defined(ART_TARGET)
78// Useful in conditionals where ART_TARGET isn't.
79static constexpr bool kIsTargetBuild = true;
80# if defined(ART_TARGET_LINUX)
81static constexpr bool kIsTargetLinux = true;
82# elif defined(ART_TARGET_ANDROID)
83static constexpr bool kIsTargetLinux = false;
84# else
85# error "Either ART_TARGET_LINUX or ART_TARGET_ANDROID needs to be defined for target builds."
86# endif
87#else
88static constexpr bool kIsTargetBuild = false;
89# if defined(ART_TARGET_LINUX)
90# error "ART_TARGET_LINUX defined for host build."
91# elif defined(ART_TARGET_ANDROID)
92# error "ART_TARGET_ANDROID defined for host build."
93# else
94static constexpr bool kIsTargetLinux = false;
95# endif
96#endif
97
98// Additional statically-linked ART binaries (dex2oats, oatdumps, etc.) are
99// always available on the host
100#if !defined(ART_TARGET)
101static constexpr bool kHostStaticBuildEnabled = true;
102#else
103static constexpr bool kHostStaticBuildEnabled = false;
104#endif
105
106// Garbage collector constants.
107static constexpr bool kMovingCollector = true;
108static constexpr bool kMarkCompactSupport = false && kMovingCollector;
109// True if we allow moving classes.
110static constexpr bool kMovingClasses = !kMarkCompactSupport;
111
112// If true, enable the tlab allocator by default.
113#ifdef ART_USE_TLAB
114static constexpr bool kUseTlab = true;
115#else
116static constexpr bool kUseTlab = false;
117#endif
118
119// Kinds of tracing clocks.
120enum class TraceClockSource {
121  kThreadCpu,
122  kWall,
123  kDual,  // Both wall and thread CPU clocks.
124};
125
126#if defined(__linux__)
127static constexpr TraceClockSource kDefaultTraceClockSource = TraceClockSource::kDual;
128#else
129static constexpr TraceClockSource kDefaultTraceClockSource = TraceClockSource::kWall;
130#endif
131
132static constexpr bool kDefaultMustRelocate = true;
133
134// Size of a heap reference.
135static constexpr size_t kHeapReferenceSize = sizeof(uint32_t);
136
137}  // namespace art
138
139#endif  // ART_LIBARTBASE_BASE_GLOBALS_H_
140