Bug Summary

File:var/lib/jenkins/workspace/firefox-scan-build/js/src/threading/LockGuard.h
Warning:line 31, column 19
Called C++ object pointer is uninitialized

Annotated Source Code

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clang -cc1 -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name Utility.cpp -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -ffp-contract=off -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/js/src/util -fcoverage-compilation-dir=/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/js/src/util -resource-dir /usr/lib/llvm-19/lib/clang/19 -include /var/lib/jenkins/workspace/firefox-scan-build/config/gcc_hidden.h -include /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/mozilla-config.h -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/stl_wrappers -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/system_wrappers -U _FORTIFY_SOURCE -D _FORTIFY_SOURCE=2 -D DEBUG=1 -D WASM_SUPPORTS_HUGE_MEMORY -D JS_CACHEIR_SPEW -D JS_STRUCTURED_SPEW -D JS_HAS_CTYPES -D FFI_BUILDING -D EXPORT_JS_API -D MOZ_HAS_MOZGLUE -D MOZ_SUPPORT_LEAKCHECKING -I /var/lib/jenkins/workspace/firefox-scan-build/js/src/util -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/js/src/util -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/js/src -I /var/lib/jenkins/workspace/firefox-scan-build/js/src -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/nspr -I /var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/nss -D MOZILLA_CLIENT -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/x86_64-linux-gnu/c++/14 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/backward -internal-isystem /usr/lib/llvm-19/lib/clang/19/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/14/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O3 -Wno-error=tautological-type-limit-compare -Wno-invalid-offsetof -Wno-range-loop-analysis -Wno-deprecated-anon-enum-enum-conversion -Wno-deprecated-enum-enum-conversion -Wno-deprecated-this-capture -Wno-inline-new-delete -Wno-error=deprecated-declarations -Wno-error=array-bounds -Wno-error=free-nonheap-object -Wno-error=atomic-alignment -Wno-error=deprecated-builtins -Wno-psabi -Wno-error=builtin-macro-redefined -Wno-vla-cxx-extension -Wno-unknown-warning-option -fdeprecated-macro -ferror-limit 19 -fstrict-flex-arrays=1 -stack-protector 2 -fstack-clash-protection -ftrivial-auto-var-init=pattern -fno-rtti -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fno-sized-deallocation -fno-aligned-allocation -vectorize-loops -vectorize-slp -analyzer-checker optin.performance.Padding -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/scan-build-2024-09-22-115206-3586786-1 -x c++ /var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp

/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp

→
1/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2 * vim: set ts=8 sts=2 et sw=2 tw=80:
3 * This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7/* Various JS utility functions. */
8
9#include "js/Utility.h"
10
11#include "mozilla/Assertions.h"
12#include "mozilla/Atomics.h"
13#include "mozilla/Maybe.h"
14#include "mozilla/ThreadLocal.h"
15
16#include <stdio.h>
17
18#include "jstypes.h"
19
20#include "util/Poison.h"
21#include "vm/HelperThreads.h"
22#include "vm/JSContext.h"
23
24using namespace js;
25
26using mozilla::Maybe;
27
28#if defined(DEBUG1) || defined(JS_OOM_BREAKPOINT)
29/* For OOM testing functionality in Utility.h. */
30namespace js {
31
32mozilla::Atomic<AutoEnterOOMUnsafeRegion*> AutoEnterOOMUnsafeRegion::owner_;
33
34namespace oom {
35
36JS_PUBLIC_DATA FailureSimulator simulator;
37static MOZ_THREAD_LOCAL(uint32_t)__thread ::mozilla::detail::ThreadLocal< uint32_t, ::mozilla
::detail::ThreadLocalNativeStorage> threadType;
38
39bool InitThreadType() { return threadType.init(); }
40
41void SetThreadType(ThreadType type) { threadType.set(type); }
42
43uint32_t GetThreadType(void) { return threadType.get(); }
44
45static inline bool IsHelperThreadType(uint32_t thread) {
46 return thread != THREAD_TYPE_NONE && thread != THREAD_TYPE_MAIN;
47}
48
49void FailureSimulator::simulateFailureAfter(Kind kind, uint64_t checks,
50 uint32_t thread, bool always) {
51 Maybe<AutoLockHelperThreadState> lock;
52 if (IsHelperThreadType(targetThread_) || IsHelperThreadType(thread)) {
53 lock.emplace();
54 WaitForAllHelperThreads(lock.ref());
55 }
56
57 MOZ_ASSERT(counter_ + checks > counter_)do { static_assert( mozilla::detail::AssertionConditionType<
decltype(counter_ + checks > counter_)>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(counter_ + checks > counter_
))), 0))) { do { } while (false); MOZ_ReportAssertionFailure(
"counter_ + checks > counter_", "/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp"
, 57); AnnotateMozCrashReason("MOZ_ASSERT" "(" "counter_ + checks > counter_"
")"); do { *((volatile int*)__null) = 57; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
58 MOZ_ASSERT(thread > js::THREAD_TYPE_NONE && thread < js::THREAD_TYPE_MAX)do { static_assert( mozilla::detail::AssertionConditionType<
decltype(thread > js::THREAD_TYPE_NONE && thread <
js::THREAD_TYPE_MAX)>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(thread > js::THREAD_TYPE_NONE
&& thread < js::THREAD_TYPE_MAX))), 0))) { do { }
while (false); MOZ_ReportAssertionFailure("thread > js::THREAD_TYPE_NONE && thread < js::THREAD_TYPE_MAX"
, "/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp"
, 58); AnnotateMozCrashReason("MOZ_ASSERT" "(" "thread > js::THREAD_TYPE_NONE && thread < js::THREAD_TYPE_MAX"
")"); do { *((volatile int*)__null) = 58; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
59 targetThread_ = thread;
60 maxChecks_ = counter_ + checks;
61 failAlways_ = always;
62 kind_ = kind;
63}
64
65void FailureSimulator::reset() {
66 Maybe<AutoLockHelperThreadState> lock;
67 if (IsHelperThreadType(targetThread_)) {
1
Taking false branch
→
68 lock.emplace();
69 WaitForAllHelperThreads(lock.ref());
70 }
71
72 targetThread_ = THREAD_TYPE_NONE;
73 maxChecks_ = UINT64_MAX(18446744073709551615UL);
74 failAlways_ = false;
75 kind_ = Kind::Nothing;
76}
2
←
Calling implicit destructor for 'Maybe<js::AutoLockHelperThreadState>'
→
3
←
Calling '~MaybeStorage'
→
77
78} // namespace oom
79} // namespace js
80#endif // defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
81
82#if defined(FUZZING)
83namespace js {
84namespace oom {
85JS_PUBLIC_DATA size_t largeAllocLimit = 0;
86void InitLargeAllocLimit() {
87 char* limitStr = getenv("MOZ_FUZZ_LARGE_ALLOC_LIMIT");
88 if (limitStr) {
89 largeAllocLimit = atoll(limitStr);
90 }
91}
92} // namespace oom
93} // namespace js
94#endif
95
96JS_PUBLIC_DATA arena_id_t js::MallocArena;
97JS_PUBLIC_DATA arena_id_t js::BackgroundMallocArena;
98JS_PUBLIC_DATA arena_id_t js::ArrayBufferContentsArena;
99JS_PUBLIC_DATA arena_id_t js::StringBufferArena;
100
101void js::InitMallocAllocator() {
102 arena_params_t mallocArenaParams;
103 mallocArenaParams.mMaxDirtyIncreaseOverride = 5;
104 MallocArena = moz_create_arena_with_params(&mallocArenaParams);
105 BackgroundMallocArena = moz_create_arena_with_params(&mallocArenaParams);
106
107 arena_params_t params;
108 params.mMaxDirtyIncreaseOverride = 5;
109 params.mFlags |= ARENA_FLAG_RANDOMIZE_SMALL_ENABLED1;
110 ArrayBufferContentsArena = moz_create_arena_with_params(&params);
111 StringBufferArena = moz_create_arena_with_params(&params);
112}
113
114void js::ShutDownMallocAllocator() {
115 // Until Bug 1364359 is fixed it is unsafe to call moz_dispose_arena.
116 // moz_dispose_arena(MallocArena);
117 // moz_dispose_arena(ArrayBufferContentsArena);
118}
119
120extern void js::AssertJSStringBufferInCorrectArena(const void* ptr) {
121// `jemalloc_ptr_info()` only exists if MOZ_MEMORY is defined, and it only
122// returns an arenaId if MOZ_DEBUG is defined. Otherwise, this function is
123// a no-op.
124#if defined(MOZ_MEMORY1) && defined(MOZ_DEBUG1)
125 if (ptr && !TlsContext.get()->nursery().isInside(ptr)) {
126 jemalloc_ptr_info_t ptrInfo{};
127 jemalloc_ptr_info(ptr, &ptrInfo);
128 MOZ_ASSERT(ptrInfo.tag != TagUnknown)do { static_assert( mozilla::detail::AssertionConditionType<
decltype(ptrInfo.tag != TagUnknown)>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(ptrInfo.tag != TagUnknown)))
, 0))) { do { } while (false); MOZ_ReportAssertionFailure("ptrInfo.tag != TagUnknown"
, "/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp"
, 128); AnnotateMozCrashReason("MOZ_ASSERT" "(" "ptrInfo.tag != TagUnknown"
")"); do { *((volatile int*)__null) = 128; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
129 MOZ_ASSERT(ptrInfo.arenaId == js::StringBufferArena)do { static_assert( mozilla::detail::AssertionConditionType<
decltype(ptrInfo.arenaId == js::StringBufferArena)>::isValid
, "invalid assertion condition"); if ((__builtin_expect(!!(!(
!!(ptrInfo.arenaId == js::StringBufferArena))), 0))) { do { }
while (false); MOZ_ReportAssertionFailure("ptrInfo.arenaId == js::StringBufferArena"
, "/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp"
, 129); AnnotateMozCrashReason("MOZ_ASSERT" "(" "ptrInfo.arenaId == js::StringBufferArena"
")"); do { *((volatile int*)__null) = 129; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
130 }
131#endif
132}
133
134JS_PUBLIC_API void JS_Assert(const char* s, const char* file, int ln) {
135 MOZ_ReportAssertionFailure(s, file, ln);
136 MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp"
, 136); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile
int*)__null) = 136; __attribute__((nomerge)) ::abort(); } while
(false); } while (false);
137}
138
139#ifdef __linux__1
140
141# include <malloc.h>
142# include <stdlib.h>
143
144namespace js {
145
146// This function calls all the vanilla heap allocation functions. It is never
147// called, and exists purely to help config/check_vanilla_allocations.py. See
148// that script for more details.
149extern MOZ_COLD__attribute__((cold)) void AllTheNonBasicVanillaNewAllocations() {
150 // posix_memalign and aligned_alloc aren't available on all Linux
151 // configurations.
152 // valloc was deprecated in Android 5.0
153 // char* q;
154 // posix_memalign((void**)&q, 16, 16);
155
156 intptr_t p = intptr_t(malloc(16)) + intptr_t(calloc(1, 16)) +
157 intptr_t(realloc(nullptr, 16)) + intptr_t(new char) +
158 intptr_t(new char) + intptr_t(new char) +
159 intptr_t(new char[16]) + intptr_t(memalign(16, 16)) +
160 // intptr_t(q) +
161 // intptr_t(aligned_alloc(16, 16)) +
162 // intptr_t(valloc(4096)) +
163 intptr_t(strdup("dummy"));
164
165 printf("%u\n", uint32_t(p)); // make sure |p| is not optimized away
166
167 free((int*)p); // this would crash if ever actually called
168
169 MOZ_CRASH()do { do { } while (false); MOZ_ReportCrash("" , "/var/lib/jenkins/workspace/firefox-scan-build/js/src/util/Utility.cpp"
, 169); AnnotateMozCrashReason("MOZ_CRASH(" ")"); do { *((volatile
int*)__null) = 169; __attribute__((nomerge)) ::abort(); } while
(false); } while (false);
170}
171
172} // namespace js
173
174#endif // __linux__
←

/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h

→
1/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/* vim: set ts=8 sts=2 et sw=2 tw=80: */
3/* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7/* A class for optional values and in-place lazy construction. */
8
9#ifndef mozilla_Maybe_h
10#define mozilla_Maybe_h
11
12#include <functional>
13#include <new> // for placement new
14#include <ostream>
15#include <type_traits>
16#include <utility>
17
18#include "mozilla/Alignment.h"
19#include "mozilla/Assertions.h"
20#include "mozilla/Attributes.h"
21#include "mozilla/MaybeStorageBase.h"
22#include "mozilla/MemoryChecking.h"
23#include "mozilla/OperatorNewExtensions.h"
24#include "mozilla/Poison.h"
25#include "mozilla/ThreadSafety.h"
26
27class nsCycleCollectionTraversalCallback;
28
29template <typename T>
30inline void CycleCollectionNoteChild(
31 nsCycleCollectionTraversalCallback& aCallback, T* aChild, const char* aName,
32 uint32_t aFlags);
33
34namespace mozilla {
35
36struct Nothing {};
37
38inline constexpr bool operator==(const Nothing&, const Nothing&) {
39 return true;
40}
41
42template <class T>
43class Maybe;
44
45namespace detail {
46
47// You would think that poisoning Maybe instances could just be a call
48// to mozWritePoison. Unfortunately, using a simple call to
49// mozWritePoison generates poor code on MSVC for small structures. The
50// generated code contains (always not-taken) branches and does a bunch
51// of setup for `rep stos{l,q}`, even though we know at compile time
52// exactly how many words we're poisoning. Instead, we're going to
53// force MSVC to generate the code we want via recursive templates.
54
55// Write the given poisonValue into p at offset*sizeof(uintptr_t).
56template <size_t offset>
57inline void WritePoisonAtOffset(void* p, const uintptr_t poisonValue) {
58 memcpy(static_cast<char*>(p) + offset * sizeof(poisonValue), &poisonValue,
59 sizeof(poisonValue));
60}
61
62template <size_t Offset, size_t NOffsets>
63struct InlinePoisoner {
64 static void poison(void* p, const uintptr_t poisonValue) {
65 WritePoisonAtOffset<Offset>(p, poisonValue);
66 InlinePoisoner<Offset + 1, NOffsets>::poison(p, poisonValue);
67 }
68};
69
70template <size_t N>
71struct InlinePoisoner<N, N> {
72 static void poison(void*, const uintptr_t) {
73 // All done!
74 }
75};
76
77// We can't generate inline code for large structures, though, because we'll
78// blow out recursive template instantiation limits, and the code would be
79// bloated to boot. So provide a fallback to the out-of-line poisoner.
80template <size_t ObjectSize>
81struct OutOfLinePoisoner {
82 static MOZ_NEVER_INLINE__attribute__((noinline)) void poison(void* p, const uintptr_t) {
83 mozWritePoison(p, ObjectSize);
84 }
85};
86
87template <typename T>
88inline void PoisonObject(T* p) {
89 const uintptr_t POISON = mozPoisonValue();
90 std::conditional_t<(sizeof(T) <= 8 * sizeof(POISON)),
91 InlinePoisoner<0, sizeof(T) / sizeof(POISON)>,
92 OutOfLinePoisoner<sizeof(T)>>::poison(p, POISON);
93}
94
95template <typename T>
96struct MaybePoisoner {
97 static const size_t N = sizeof(T);
98
99 static void poison(void* aPtr) {
100#ifdef MOZ_DIAGNOSTIC_ASSERT_ENABLED1
101 if (N >= sizeof(uintptr_t)) {
102 PoisonObject(static_cast<std::remove_cv_t<T>*>(aPtr));
103 }
104#endif
105 MOZ_MAKE_MEM_UNDEFINED(aPtr, N)do { } while (0);
106 }
107};
108
109template <typename T,
110 bool TriviallyDestructibleAndCopyable =
111 IsTriviallyDestructibleAndCopyable<T>,
112 bool Copyable = std::is_copy_constructible_v<T>,
113 bool Movable = std::is_move_constructible_v<T>>
114class Maybe_CopyMove_Enabler;
115
116#define MOZ_MAYBE_COPY_OPS() \
117 Maybe_CopyMove_Enabler(const Maybe_CopyMove_Enabler& aOther) { \
118 if (downcast(aOther).isSome()) { \
119 downcast(*this).emplace(*downcast(aOther)); \
120 } \
121 } \
122 \
123 Maybe_CopyMove_Enabler& operator=(const Maybe_CopyMove_Enabler& aOther) { \
124 return downcast(*this).template operator= <T>(downcast(aOther)); \
125 }
126
127#define MOZ_MAYBE_MOVE_OPS() \
128 constexpr Maybe_CopyMove_Enabler(Maybe_CopyMove_Enabler&& aOther) { \
129 if (downcast(aOther).isSome()) { \
130 downcast(*this).emplace(std::move(*downcast(aOther))); \
131 downcast(aOther).reset(); \
132 } \
133 } \
134 \
135 constexpr Maybe_CopyMove_Enabler& operator=( \
136 Maybe_CopyMove_Enabler&& aOther) { \
137 downcast(*this).template operator= <T>(std::move(downcast(aOther))); \
138 \
139 return *this; \
140 }
141
142#define MOZ_MAYBE_DOWNCAST() \
143 static constexpr Maybe<T>& downcast(Maybe_CopyMove_Enabler& aObj) { \
144 return static_cast<Maybe<T>&>(aObj); \
145 } \
146 static constexpr const Maybe<T>& downcast( \
147 const Maybe_CopyMove_Enabler& aObj) { \
148 return static_cast<const Maybe<T>&>(aObj); \
149 }
150
151template <typename T>
152class Maybe_CopyMove_Enabler<T, true, true, true> {
153 public:
154 Maybe_CopyMove_Enabler() = default;
155
156 Maybe_CopyMove_Enabler(const Maybe_CopyMove_Enabler&) = default;
157 Maybe_CopyMove_Enabler& operator=(const Maybe_CopyMove_Enabler&) = default;
158 constexpr Maybe_CopyMove_Enabler(Maybe_CopyMove_Enabler&& aOther) {
159 downcast(aOther).reset();
160 }
161 constexpr Maybe_CopyMove_Enabler& operator=(Maybe_CopyMove_Enabler&& aOther) {
162 downcast(aOther).reset();
163 return *this;
164 }
165
166 private:
167 MOZ_MAYBE_DOWNCAST()
168};
169
170template <typename T>
171class Maybe_CopyMove_Enabler<T, true, false, true> {
172 public:
173 Maybe_CopyMove_Enabler() = default;
174
175 Maybe_CopyMove_Enabler(const Maybe_CopyMove_Enabler&) = delete;
176 Maybe_CopyMove_Enabler& operator=(const Maybe_CopyMove_Enabler&) = delete;
177 constexpr Maybe_CopyMove_Enabler(Maybe_CopyMove_Enabler&& aOther) {
178 downcast(aOther).reset();
179 }
180 constexpr Maybe_CopyMove_Enabler& operator=(Maybe_CopyMove_Enabler&& aOther) {
181 downcast(aOther).reset();
182 return *this;
183 }
184
185 private:
186 MOZ_MAYBE_DOWNCAST()
187};
188
189template <typename T>
190class Maybe_CopyMove_Enabler<T, false, true, true> {
191 public:
192 Maybe_CopyMove_Enabler() = default;
193
194 MOZ_MAYBE_COPY_OPS()
195 MOZ_MAYBE_MOVE_OPS()
196
197 private:
198 MOZ_MAYBE_DOWNCAST()
199};
200
201template <typename T>
202class Maybe_CopyMove_Enabler<T, false, false, true> {
203 public:
204 Maybe_CopyMove_Enabler() = default;
205
206 Maybe_CopyMove_Enabler(const Maybe_CopyMove_Enabler&) = delete;
207 Maybe_CopyMove_Enabler& operator=(const Maybe_CopyMove_Enabler&) = delete;
208 MOZ_MAYBE_MOVE_OPS()
209
210 private:
211 MOZ_MAYBE_DOWNCAST()
212};
213
214template <typename T>
215class Maybe_CopyMove_Enabler<T, false, true, false> {
216 public:
217 Maybe_CopyMove_Enabler() = default;
218
219 MOZ_MAYBE_COPY_OPS()
220 Maybe_CopyMove_Enabler(Maybe_CopyMove_Enabler&&) = delete;
221 Maybe_CopyMove_Enabler& operator=(Maybe_CopyMove_Enabler&&) = delete;
222
223 private:
224 MOZ_MAYBE_DOWNCAST()
225};
226
227template <typename T, bool TriviallyDestructibleAndCopyable>
228class Maybe_CopyMove_Enabler<T, TriviallyDestructibleAndCopyable, false,
229 false> {
230 public:
231 Maybe_CopyMove_Enabler() = default;
232
233 Maybe_CopyMove_Enabler(const Maybe_CopyMove_Enabler&) = delete;
234 Maybe_CopyMove_Enabler& operator=(const Maybe_CopyMove_Enabler&) = delete;
235 Maybe_CopyMove_Enabler(Maybe_CopyMove_Enabler&&) = delete;
236 Maybe_CopyMove_Enabler& operator=(Maybe_CopyMove_Enabler&&) = delete;
237};
238
239#undef MOZ_MAYBE_COPY_OPS
240#undef MOZ_MAYBE_MOVE_OPS
241#undef MOZ_MAYBE_DOWNCAST
242
243template <typename T, bool TriviallyDestructibleAndCopyable =
244 IsTriviallyDestructibleAndCopyable<T>>
245struct MaybeStorage;
246
247template <typename T>
248struct MaybeStorage<T, false> : MaybeStorageBase<T> {
249 protected:
250 char mIsSome = false; // not bool -- guarantees minimal space consumption
251
252 MaybeStorage() = default;
253 explicit MaybeStorage(const T& aVal)
254 : MaybeStorageBase<T>{aVal}, mIsSome{true} {}
255 explicit MaybeStorage(T&& aVal)
256 : MaybeStorageBase<T>{std::move(aVal)}, mIsSome{true} {}
257
258 template <typename... Args>
259 explicit MaybeStorage(std::in_place_t, Args&&... aArgs)
260 : MaybeStorageBase<T>{std::in_place, std::forward<Args>(aArgs)...},
261 mIsSome{true} {}
262
263 public:
264 // Copy and move operations are no-ops, since copying is moving is implemented
265 // by Maybe_CopyMove_Enabler.
266
267 MaybeStorage(const MaybeStorage&) : MaybeStorageBase<T>{} {}
268 MaybeStorage& operator=(const MaybeStorage&) { return *this; }
269 MaybeStorage(MaybeStorage&&) : MaybeStorageBase<T>{} {}
270 MaybeStorage& operator=(MaybeStorage&&) { return *this; }
271
272 ~MaybeStorage() {
273 if (mIsSome
3.1
Field 'mIsSome' is 0
3.1
Field 'mIsSome' is 0
3.1
Field 'mIsSome' is 0
3.1
Field 'mIsSome' is 0
3.1
Field 'mIsSome' is 0
) {
4
←
Taking false branch
→
274 this->addr()->T::~T();
275 }
276 }
5
←
Calling implicit destructor for 'MaybeStorageBase<js::AutoLockHelperThreadState, false>'
→
6
←
Calling '~Union'
→
277};
278
279template <typename T>
280struct MaybeStorage<T, true> : MaybeStorageBase<T> {
281 protected:
282 char mIsSome = false; // not bool -- guarantees minimal space consumption
283
284 constexpr MaybeStorage() = default;
285 constexpr explicit MaybeStorage(const T& aVal)
286 : MaybeStorageBase<T>{aVal}, mIsSome{true} {}
287 constexpr explicit MaybeStorage(T&& aVal)
288 : MaybeStorageBase<T>{std::move(aVal)}, mIsSome{true} {}
289
290 template <typename... Args>
291 constexpr explicit MaybeStorage(std::in_place_t, Args&&... aArgs)
292 : MaybeStorageBase<T>{std::in_place, std::forward<Args>(aArgs)...},
293 mIsSome{true} {}
294};
295
296template <typename T>
297struct IsMaybeImpl : std::false_type {};
298
299template <typename T>
300struct IsMaybeImpl<Maybe<T>> : std::true_type {};
301
302template <typename T>
303using IsMaybe = IsMaybeImpl<std::decay_t<T>>;
304
305} // namespace detail
306
307template <typename T, typename U = typename std::remove_cv<
308 typename std::remove_reference<T>::type>::type>
309constexpr Maybe<U> Some(T&& aValue);
310
311/*
312 * Maybe is a container class which contains either zero or one elements. It
313 * serves two roles. It can represent values which are *semantically* optional,
314 * augmenting a type with an explicit 'Nothing' value. In this role, it provides
315 * methods that make it easy to work with values that may be missing, along with
316 * equality and comparison operators so that Maybe values can be stored in
317 * containers. Maybe values can be constructed conveniently in expressions using
318 * type inference, as follows:
319 *
320 * void doSomething(Maybe<Foo> aFoo) {
321 * if (aFoo) // Make sure that aFoo contains a value...
322 * aFoo->takeAction(); // and then use |aFoo->| to access it.
323 * } // |*aFoo| also works!
324 *
325 * doSomething(Nothing()); // Passes a Maybe<Foo> containing no value.
326 * doSomething(Some(Foo(100))); // Passes a Maybe<Foo> containing |Foo(100)|.
327 *
328 * You'll note that it's important to check whether a Maybe contains a value
329 * before using it, using conversion to bool, |isSome()|, or |isNothing()|. You
330 * can avoid these checks, and sometimes write more readable code, using
331 * |valueOr()|, |ptrOr()|, and |refOr()|, which allow you to retrieve the value
332 * in the Maybe and provide a default for the 'Nothing' case. You can also use
333 * |apply()| to call a function only if the Maybe holds a value, and |map()| to
334 * transform the value in the Maybe, returning another Maybe with a possibly
335 * different type.
336 *
337 * Maybe's other role is to support lazily constructing objects without using
338 * dynamic storage. A Maybe directly contains storage for a value, but it's
339 * empty by default. |emplace()|, as mentioned above, can be used to construct a
340 * value in Maybe's storage. The value a Maybe contains can be destroyed by
341 * calling |reset()|; this will happen automatically if a Maybe is destroyed
342 * while holding a value.
343 *
344 * It's a common idiom in C++ to use a pointer as a 'Maybe' type, with a null
345 * value meaning 'Nothing' and any other value meaning 'Some'. You can convert
346 * from such a pointer to a Maybe value using 'ToMaybe()'.
347 *
348 * Maybe is inspired by similar types in the standard library of many other
349 * languages (e.g. Haskell's Maybe and Rust's Option). In the C++ world it's
350 * very similar to std::optional, which was proposed for C++14 and originated in
351 * Boost. The most important differences between Maybe and std::optional are:
352 *
353 * - std::optional<T> may be compared with T. We deliberately forbid that.
354 * - std::optional has |valueOr()|, equivalent to Maybe's |valueOr()|, but
355 * lacks corresponding methods for |refOr()| and |ptrOr()|.
356 * - std::optional lacks |map()| and |apply()|, making it less suitable for
357 * functional-style code.
358 * - std::optional lacks many convenience functions that Maybe has. Most
359 * unfortunately, it lacks equivalents of the type-inferred constructor
360 * functions |Some()| and |Nothing()|.
361 */
362template <class T>
363class MOZ_INHERIT_TYPE_ANNOTATIONS_FROM_TEMPLATE_ARGS Maybe
364 : private detail::MaybeStorage<T>,
365 public detail::Maybe_CopyMove_Enabler<T> {
366 template <typename, bool, bool, bool>
367 friend class detail::Maybe_CopyMove_Enabler;
368
369 template <typename U, typename V>
370 friend constexpr Maybe<V> Some(U&& aValue);
371
372 struct SomeGuard {};
373
374 template <typename U>
375 constexpr Maybe(U&& aValue, SomeGuard)
376 : detail::MaybeStorage<T>{std::forward<U>(aValue)} {}
377
378 using detail::MaybeStorage<T>::mIsSome;
379 using detail::MaybeStorage<T>::mStorage;
380
381 void poisonData() { detail::MaybePoisoner<T>::poison(&mStorage.val); }
382
383 public:
384 using ValueType = T;
385
386 MOZ_ALLOW_TEMPORARY constexpr Maybe() = default;
387
388 MOZ_ALLOW_TEMPORARY MOZ_IMPLICIT constexpr Maybe(Nothing) : Maybe{} {}
389
390 template <typename... Args>
391 constexpr explicit Maybe(std::in_place_t, Args&&... aArgs)
392 : detail::MaybeStorage<T>{std::in_place, std::forward<Args>(aArgs)...} {}
393
394 /**
395 * Maybe<T> can be copy-constructed from a Maybe<U> if T is constructible from
396 * a const U&.
397 */
398 template <typename U,
399 std::enable_if_t<std::is_constructible_v<T, const U&>, bool> = true>
400 MOZ_IMPLICIT Maybe(const Maybe<U>& aOther) {
401 if (aOther.isSome()) {
402 emplace(*aOther);
403 }
404 }
405
406 template <typename U, std::enable_if_t<!std::is_constructible_v<T, const U&>,
407 bool> = true>
408 explicit Maybe(const Maybe<U>& aOther) = delete;
409
410 /**
411 * Maybe<T> can be move-constructed from a Maybe<U> if T is constructible from
412 * a U&&.
413 */
414 template <typename U,
415 std::enable_if_t<std::is_constructible_v<T, U&&>, bool> = true>
416 MOZ_IMPLICIT Maybe(Maybe<U>&& aOther) {
417 if (aOther.isSome()) {
418 emplace(std::move(*aOther));
419 aOther.reset();
420 }
421 }
422 template <typename U,
423 std::enable_if_t<!std::is_constructible_v<T, U&&>, bool> = true>
424 explicit Maybe(Maybe<U>&& aOther) = delete;
425
426 template <typename U,
427 std::enable_if_t<std::is_constructible_v<T, const U&>, bool> = true>
428 Maybe& operator=(const Maybe<U>& aOther) {
429 if (aOther.isSome()) {
430 if (mIsSome) {
431 ref() = aOther.ref();
432 } else {
433 emplace(*aOther);
434 }
435 } else {
436 reset();
437 }
438 return *this;
439 }
440
441 template <typename U, std::enable_if_t<!std::is_constructible_v<T, const U&>,
442 bool> = true>
443 Maybe& operator=(const Maybe<U>& aOther) = delete;
444
445 template <typename U,
446 std::enable_if_t<std::is_constructible_v<T, U&&>, bool> = true>
447 Maybe& operator=(Maybe<U>&& aOther) {
448 if (aOther.isSome()) {
449 if (mIsSome) {
450 ref() = std::move(aOther.ref());
451 } else {
452 emplace(std::move(*aOther));
453 }
454 aOther.reset();
455 } else {
456 reset();
457 }
458
459 return *this;
460 }
461
462 template <typename U,
463 std::enable_if_t<!std::is_constructible_v<T, U&&>, bool> = true>
464 Maybe& operator=(Maybe<U>&& aOther) = delete;
465
466 constexpr Maybe& operator=(Nothing) {
467 reset();
468 return *this;
469 }
470
471 /* Methods that check whether this Maybe contains a value */
472 constexpr explicit operator bool() const { return isSome(); }
473 constexpr bool isSome() const { return mIsSome; }
474 constexpr bool isNothing() const { return !mIsSome; }
475
476 /* Returns the contents of this Maybe<T> by value. Unsafe unless |isSome()|.
477 */
478 constexpr T value() const&;
479 constexpr T value() &&;
480 constexpr T value() const&&;
481
482 /**
483 * Move the contents of this Maybe<T> out of internal storage and return it
484 * without calling the destructor. The internal storage is also reset to
485 * avoid multiple calls. Unsafe unless |isSome()|.
486 */
487 constexpr T extract() {
488 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 488); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 488; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
489 T v = std::move(mStorage.val);
490 reset();
491 return v;
492 }
493
494 /**
495 * Returns the value (possibly |Nothing()|) by moving it out of this Maybe<T>
496 * and leaving |Nothing()| in its place.
497 */
498 Maybe<T> take() { return std::exchange(*this, Nothing()); }
499
500 /*
501 * Returns the contents of this Maybe<T> by value. If |isNothing()|, returns
502 * the default value provided.
503 *
504 * Note: If the value passed to aDefault is not the result of a trivial
505 * expression, but expensive to evaluate, e.g. |valueOr(ExpensiveFunction())|,
506 * use |valueOrFrom| instead, e.g.
507 * |valueOrFrom([arg] { return ExpensiveFunction(arg); })|. This ensures
508 * that the expensive expression is only evaluated when its result will
509 * actually be used.
510 */
511 template <typename V>
512 constexpr T valueOr(V&& aDefault) const {
513 if (isSome()) {
514 return ref();
515 }
516 return std::forward<V>(aDefault);
517 }
518
519 /*
520 * Returns the contents of this Maybe<T> by value. If |isNothing()|, returns
521 * the value returned from the function or functor provided.
522 */
523 template <typename F>
524 constexpr T valueOrFrom(F&& aFunc) const {
525 if (isSome()) {
526 return ref();
527 }
528 return aFunc();
529 }
530
531 /* Returns the contents of this Maybe<T> by pointer. Unsafe unless |isSome()|.
532 */
533 T* ptr();
534 constexpr const T* ptr() const;
535
536 /*
537 * Returns the contents of this Maybe<T> by pointer. If |isNothing()|,
538 * returns the default value provided.
539 */
540 T* ptrOr(T* aDefault) {
541 if (isSome()) {
542 return ptr();
543 }
544 return aDefault;
545 }
546
547 constexpr const T* ptrOr(const T* aDefault) const {
548 if (isSome()) {
549 return ptr();
550 }
551 return aDefault;
552 }
553
554 /*
555 * Returns the contents of this Maybe<T> by pointer. If |isNothing()|,
556 * returns the value returned from the function or functor provided.
557 */
558 template <typename F>
559 T* ptrOrFrom(F&& aFunc) {
560 if (isSome()) {
561 return ptr();
562 }
563 return aFunc();
564 }
565
566 template <typename F>
567 const T* ptrOrFrom(F&& aFunc) const {
568 if (isSome()) {
569 return ptr();
570 }
571 return aFunc();
572 }
573
574 constexpr T* operator->();
575 constexpr const T* operator->() const;
576
577 /* Returns the contents of this Maybe<T> by ref. Unsafe unless |isSome()|. */
578 constexpr T& ref() &;
579 constexpr const T& ref() const&;
580 constexpr T&& ref() &&;
581 constexpr const T&& ref() const&&;
582
583 /*
584 * Returns the contents of this Maybe<T> by ref. If |isNothing()|, returns
585 * the default value provided.
586 */
587 constexpr T& refOr(T& aDefault) {
588 if (isSome()) {
589 return ref();
590 }
591 return aDefault;
592 }
593
594 constexpr const T& refOr(const T& aDefault) const {
595 if (isSome()) {
596 return ref();
597 }
598 return aDefault;
599 }
600
601 /*
602 * Returns the contents of this Maybe<T> by ref. If |isNothing()|, returns the
603 * value returned from the function or functor provided.
604 */
605 template <typename F>
606 constexpr T& refOrFrom(F&& aFunc) {
607 if (isSome()) {
608 return ref();
609 }
610 return aFunc();
611 }
612
613 template <typename F>
614 constexpr const T& refOrFrom(F&& aFunc) const {
615 if (isSome()) {
616 return ref();
617 }
618 return aFunc();
619 }
620
621 constexpr T& operator*() &;
622 constexpr const T& operator*() const&;
623 constexpr T&& operator*() &&;
624 constexpr const T&& operator*() const&&;
625
626 /* If |isSome()|, runs the provided function or functor on the contents of
627 * this Maybe. */
628 template <typename Func>
629 constexpr Maybe& apply(Func&& aFunc) & {
630 if (isSome()) {
631 std::forward<Func>(aFunc)(ref());
632 }
633 return *this;
634 }
635
636 template <typename Func>
637 constexpr const Maybe& apply(Func&& aFunc) const& {
638 if (isSome()) {
639 std::forward<Func>(aFunc)(ref());
640 }
641 return *this;
642 }
643
644 template <typename Func>
645 constexpr Maybe& apply(Func&& aFunc) && {
646 if (isSome()) {
647 std::forward<Func>(aFunc)(extract());
648 }
649 return *this;
650 }
651
652 template <typename Func>
653 constexpr Maybe& apply(Func&& aFunc) const&& {
654 if (isSome()) {
655 std::forward<Func>(aFunc)(extract());
656 }
657 return *this;
658 }
659
660 /*
661 * If |isSome()|, runs the provided function and returns the result wrapped
662 * in a Maybe. If |isNothing()|, returns an empty Maybe value with the same
663 * value type as what the provided function would have returned.
664 */
665 template <typename Func>
666 constexpr auto map(Func&& aFunc) & {
667 if (isSome()) {
668 return Some(std::forward<Func>(aFunc)(ref()));
669 }
670 return Maybe<decltype(std::forward<Func>(aFunc)(ref()))>{};
671 }
672
673 template <typename Func>
674 constexpr auto map(Func&& aFunc) const& {
675 if (isSome()) {
676 return Some(std::forward<Func>(aFunc)(ref()));
677 }
678 return Maybe<decltype(std::forward<Func>(aFunc)(ref()))>{};
679 }
680
681 template <typename Func>
682 constexpr auto map(Func&& aFunc) && {
683 if (isSome()) {
684 return Some(std::forward<Func>(aFunc)(extract()));
685 }
686 return Maybe<decltype(std::forward<Func>(aFunc)(extract()))>{};
687 }
688
689 template <typename Func>
690 constexpr auto map(Func&& aFunc) const&& {
691 if (isSome()) {
692 return Some(std::forward<Func>(aFunc)(extract()));
693 }
694 return Maybe<decltype(std::forward<Func>(aFunc)(extract()))>{};
695 }
696
697 /*
698 * If |isSome()|, runs the provided function or functor on the contents of
699 * this Maybe and returns the result. Note that the provided function or
700 * functor must return a Maybe<U> of any type U.
701 * If |isNothing()|, returns an empty Maybe value with the same type as what
702 * the provided function would have returned.
703 */
704 template <typename Func>
705 constexpr auto andThen(Func&& aFunc) & {
706 static_assert(std::is_invocable_v<Func, T&>);
707 using U = std::invoke_result_t<Func, T&>;
708 static_assert(detail::IsMaybe<U>::value);
709 if (isSome()) {
710 return std::invoke(std::forward<Func>(aFunc), ref());
711 }
712 return std::remove_cv_t<std::remove_reference_t<U>>{};
713 }
714
715 template <typename Func>
716 constexpr auto andThen(Func&& aFunc) const& {
717 static_assert(std::is_invocable_v<Func, const T&>);
718 using U = std::invoke_result_t<Func, const T&>;
719 static_assert(detail::IsMaybe<U>::value);
720 if (isSome()) {
721 return std::invoke(std::forward<Func>(aFunc), ref());
722 }
723 return std::remove_cv_t<std::remove_reference_t<U>>{};
724 }
725
726 template <typename Func>
727 constexpr auto andThen(Func&& aFunc) && {
728 static_assert(std::is_invocable_v<Func, T&&>);
729 using U = std::invoke_result_t<Func, T&&>;
730 static_assert(detail::IsMaybe<U>::value);
731 if (isSome()) {
732 return std::invoke(std::forward<Func>(aFunc), extract());
733 }
734 return std::remove_cv_t<std::remove_reference_t<U>>{};
735 }
736
737 template <typename Func>
738 constexpr auto andThen(Func&& aFunc) const&& {
739 static_assert(std::is_invocable_v<Func, const T&&>);
740 using U = std::invoke_result_t<Func, const T&&>;
741 static_assert(detail::IsMaybe<U>::value);
742 if (isSome()) {
743 return std::invoke(std::forward<Func>(aFunc), extract());
744 }
745 return std::remove_cv_t<std::remove_reference_t<U>>{};
746 }
747
748 /*
749 * If |isNothing()|, runs the provided function or functor and returns its
750 * result. If |isSome()|, returns the contained value wrapped in a Maybe.
751 */
752 template <typename Func>
753 constexpr Maybe orElse(Func&& aFunc) & {
754 static_assert(std::is_invocable_v<Func>);
755 using U = std::invoke_result_t<Func>;
756 static_assert(
757 std::is_same_v<Maybe, std::remove_cv_t<std::remove_reference_t<U>>>);
758 if (isSome()) {
759 return *this;
760 }
761 return std::invoke(std::forward<Func>(aFunc));
762 }
763
764 template <typename Func>
765 constexpr Maybe orElse(Func&& aFunc) const& {
766 static_assert(std::is_invocable_v<Func>);
767 using U = std::invoke_result_t<Func>;
768 static_assert(
769 std::is_same_v<Maybe, std::remove_cv_t<std::remove_reference_t<U>>>);
770 if (isSome()) {
771 return *this;
772 }
773 return std::invoke(std::forward<Func>(aFunc));
774 }
775
776 template <typename Func>
777 constexpr Maybe orElse(Func&& aFunc) && {
778 static_assert(std::is_invocable_v<Func>);
779 using U = std::invoke_result_t<Func>;
780 static_assert(
781 std::is_same_v<Maybe, std::remove_cv_t<std::remove_reference_t<U>>>);
782 if (isSome()) {
783 return std::move(*this);
784 }
785 return std::invoke(std::forward<Func>(aFunc));
786 }
787
788 template <typename Func>
789 constexpr Maybe orElse(Func&& aFunc) const&& {
790 static_assert(std::is_invocable_v<Func>);
791 using U = std::invoke_result_t<Func>;
792 static_assert(
793 std::is_same_v<Maybe, std::remove_cv_t<std::remove_reference_t<U>>>);
794 if (isSome()) {
795 return std::move(*this);
796 }
797 return std::invoke(std::forward<Func>(aFunc));
798 }
799
800 /* If |isSome()|, empties this Maybe and destroys its contents. */
801 constexpr void reset() {
802 if (isSome()) {
803 if constexpr (!std::is_trivially_destructible_v<T>) {
804 /*
805 * Static analyzer gets confused if we have Maybe<MutexAutoLock>,
806 * so we suppress thread-safety warnings here
807 */
808 MOZ_PUSH_IGNORE_THREAD_SAFETYGCC diagnostic push GCC diagnostic ignored "-Wthread-safety"
809 ref().T::~T();
810 MOZ_POP_THREAD_SAFETYGCC diagnostic pop
811 poisonData();
812 }
813 mIsSome = false;
814 }
815 }
816
817 /*
818 * Constructs a T value in-place in this empty Maybe<T>'s storage. The
819 * arguments to |emplace()| are the parameters to T's constructor.
820 */
821 template <typename... Args>
822 constexpr void emplace(Args&&... aArgs);
823
824 template <typename U>
825 constexpr std::enable_if_t<std::is_same_v<T, U> &&
826 std::is_copy_constructible_v<U> &&
827 !std::is_move_constructible_v<U>>
828 emplace(U&& aArgs) {
829 emplace(aArgs);
830 }
831
832 friend std::ostream& operator<<(std::ostream& aStream,
833 const Maybe<T>& aMaybe) {
834 if (aMaybe) {
835 aStream << aMaybe.ref();
836 } else {
837 aStream << "<Nothing>";
838 }
839 return aStream;
840 }
841};
842
843template <typename T>
844class Maybe<T&> {
845 public:
846 constexpr Maybe() = default;
847 constexpr MOZ_IMPLICIT Maybe(Nothing) {}
848
849 void emplace(T& aRef) { mValue = &aRef; }
850
851 /* Methods that check whether this Maybe contains a value */
852 constexpr explicit operator bool() const { return isSome(); }
853 constexpr bool isSome() const { return mValue; }
854 constexpr bool isNothing() const { return !mValue; }
855
856 T& ref() const {
857 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 857); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 857; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
858 return *mValue;
859 }
860
861 T* operator->() const { return &ref(); }
862 T& operator*() const { return ref(); }
863
864 // Deliberately not defining value and ptr accessors, as these may be
865 // confusing on a reference-typed Maybe.
866
867 // XXX Should we define refOr?
868
869 void reset() { mValue = nullptr; }
870
871 template <typename Func>
872 const Maybe& apply(Func&& aFunc) const {
873 if (isSome()) {
874 std::forward<Func>(aFunc)(ref());
875 }
876 return *this;
877 }
878
879 template <typename Func>
880 auto map(Func&& aFunc) const {
881 Maybe<decltype(std::forward<Func>(aFunc)(ref()))> val;
882 if (isSome()) {
883 val.emplace(std::forward<Func>(aFunc)(ref()));
884 }
885 return val;
886 }
887
888 template <typename Func>
889 constexpr auto andThen(Func&& aFunc) const {
890 static_assert(std::is_invocable_v<Func, T&>);
891 using U = std::invoke_result_t<Func, T&>;
892 static_assert(detail::IsMaybe<U>::value);
893 if (isSome()) {
894 return std::invoke(std::forward<Func>(aFunc), ref());
895 }
896 return std::remove_cv_t<std::remove_reference_t<U>>{};
897 }
898
899 template <typename Func>
900 constexpr Maybe orElse(Func&& aFunc) const {
901 static_assert(std::is_invocable_v<Func>);
902 using U = std::invoke_result_t<Func>;
903 static_assert(
904 std::is_same_v<Maybe, std::remove_cv_t<std::remove_reference_t<U>>>);
905 if (isSome()) {
906 return *this;
907 }
908 return std::invoke(std::forward<Func>(aFunc));
909 }
910
911 bool refEquals(const Maybe<T&>& aOther) const {
912 return mValue == aOther.mValue;
913 }
914
915 bool refEquals(const T& aOther) const { return mValue == &aOther; }
916
917 private:
918 T* mValue = nullptr;
919};
920
921template <typename T>
922constexpr T Maybe<T>::value() const& {
923 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 923); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 923; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
924 return ref();
925}
926
927template <typename T>
928constexpr T Maybe<T>::value() && {
929 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 929); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 929; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
930 return std::move(ref());
931}
932
933template <typename T>
934constexpr T Maybe<T>::value() const&& {
935 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 935); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 935; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
936 return std::move(ref());
937}
938
939template <typename T>
940T* Maybe<T>::ptr() {
941 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 941); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 941; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
942 return &ref();
943}
944
945template <typename T>
946constexpr const T* Maybe<T>::ptr() const {
947 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 947); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 947; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
948 return &ref();
949}
950
951template <typename T>
952constexpr T* Maybe<T>::operator->() {
953 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 953); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 953; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
954 return ptr();
955}
956
957template <typename T>
958constexpr const T* Maybe<T>::operator->() const {
959 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 959); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 959; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
960 return ptr();
961}
962
963template <typename T>
964constexpr T& Maybe<T>::ref() & {
965 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 965); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 965; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
966 return mStorage.val;
967}
968
969template <typename T>
970constexpr const T& Maybe<T>::ref() const& {
971 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 971); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 971; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
972 return mStorage.val;
973}
974
975template <typename T>
976constexpr T&& Maybe<T>::ref() && {
977 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 977); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 977; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
978 return std::move(mStorage.val);
979}
980
981template <typename T>
982constexpr const T&& Maybe<T>::ref() const&& {
983 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 983); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 983; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
984 return std::move(mStorage.val);
985}
986
987template <typename T>
988constexpr T& Maybe<T>::operator*() & {
989 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 989); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 989; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
990 return ref();
991}
992
993template <typename T>
994constexpr const T& Maybe<T>::operator*() const& {
995 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 995); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 995; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
996 return ref();
997}
998
999template <typename T>
1000constexpr T&& Maybe<T>::operator*() && {
1001 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 1001); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 1001; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
1002 return std::move(ref());
1003}
1004
1005template <typename T>
1006constexpr const T&& Maybe<T>::operator*() const&& {
1007 MOZ_RELEASE_ASSERT(isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 1007); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "isSome()"
")"); do { *((volatile int*)__null) = 1007; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
1008 return std::move(ref());
1009}
1010
1011template <typename T>
1012template <typename... Args>
1013constexpr void Maybe<T>::emplace(Args&&... aArgs) {
1014 MOZ_RELEASE_ASSERT(!isSome())do { static_assert( mozilla::detail::AssertionConditionType<
decltype(!isSome())>::isValid, "invalid assertion condition"
); if ((__builtin_expect(!!(!(!!(!isSome()))), 0))) { do { } while
(false); MOZ_ReportAssertionFailure("!isSome()", "/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/Maybe.h"
, 1014); AnnotateMozCrashReason("MOZ_RELEASE_ASSERT" "(" "!isSome()"
")"); do { *((volatile int*)__null) = 1014; __attribute__((nomerge
)) ::abort(); } while (false); } } while (false);
1015 ::new (KnownNotNull, &mStorage.val) T(std::forward<Args>(aArgs)...);
1016 mIsSome = true;
1017}
1018
1019/*
1020 * Some() creates a Maybe<T> value containing the provided T value. If T has a
1021 * move constructor, it's used to make this as efficient as possible.
1022 *
1023 * Some() selects the type of Maybe it returns by removing any const, volatile,
1024 * or reference qualifiers from the type of the value you pass to it. This gives
1025 * it more intuitive behavior when used in expressions, but it also means that
1026 * if you need to construct a Maybe value that holds a const, volatile, or
1027 * reference value, you need to use emplace() instead.
1028 */
1029template <typename T, typename U>
1030constexpr Maybe<U> Some(T&& aValue) {
1031 return {std::forward<T>(aValue), typename Maybe<U>::SomeGuard{}};
1032}
1033
1034template <typename T>
1035constexpr Maybe<T&> SomeRef(T& aValue) {
1036 Maybe<T&> value;
1037 value.emplace(aValue);
1038 return value;
1039}
1040
1041template <typename T>
1042constexpr Maybe<T&> ToMaybeRef(T* const aPtr) {
1043 return aPtr ? SomeRef(*aPtr) : Nothing{};
1044}
1045
1046template <typename T>
1047Maybe<std::remove_cv_t<std::remove_reference_t<T>>> ToMaybe(T* aPtr) {
1048 if (aPtr) {
1049 return Some(*aPtr);
1050 }
1051 return Nothing();
1052}
1053
1054/*
1055 * Two Maybe<T> values are equal if
1056 * - both are Nothing, or
1057 * - both are Some, and the values they contain are equal.
1058 */
1059template <typename T>
1060constexpr bool operator==(const Maybe<T>& aLHS, const Maybe<T>& aRHS) {
1061 static_assert(!std::is_reference_v<T>,
1062 "operator== is not defined for Maybe<T&>, compare values or "
1063 "addresses explicitly instead");
1064 if (aLHS.isNothing() != aRHS.isNothing()) {
1065 return false;
1066 }
1067 return aLHS.isNothing() || *aLHS == *aRHS;
1068}
1069
1070template <typename T>
1071constexpr bool operator!=(const Maybe<T>& aLHS, const Maybe<T>& aRHS) {
1072 return !(aLHS == aRHS);
1073}
1074
1075/*
1076 * We support comparison to Nothing to allow reasonable expressions like:
1077 * if (maybeValue == Nothing()) { ... }
1078 */
1079template <typename T>
1080constexpr bool operator==(const Maybe<T>& aLHS, const Nothing& aRHS) {
1081 return aLHS.isNothing();
1082}
1083
1084template <typename T>
1085constexpr bool operator!=(const Maybe<T>& aLHS, const Nothing& aRHS) {
1086 return !(aLHS == aRHS);
1087}
1088
1089template <typename T>
1090constexpr bool operator==(const Nothing& aLHS, const Maybe<T>& aRHS) {
1091 return aRHS.isNothing();
1092}
1093
1094template <typename T>
1095constexpr bool operator!=(const Nothing& aLHS, const Maybe<T>& aRHS) {
1096 return !(aLHS == aRHS);
1097}
1098
1099/*
1100 * Maybe<T> values are ordered in the same way T values are ordered, except that
1101 * Nothing comes before anything else.
1102 */
1103template <typename T>
1104constexpr bool operator<(const Maybe<T>& aLHS, const Maybe<T>& aRHS) {
1105 if (aLHS.isNothing()) {
1106 return aRHS.isSome();
1107 }
1108 if (aRHS.isNothing()) {
1109 return false;
1110 }
1111 return *aLHS < *aRHS;
1112}
1113
1114template <typename T>
1115constexpr bool operator>(const Maybe<T>& aLHS, const Maybe<T>& aRHS) {
1116 return !(aLHS < aRHS || aLHS == aRHS);
1117}
1118
1119template <typename T>
1120constexpr bool operator<=(const Maybe<T>& aLHS, const Maybe<T>& aRHS) {
1121 return aLHS < aRHS || aLHS == aRHS;
1122}
1123
1124template <typename T>
1125constexpr bool operator>=(const Maybe<T>& aLHS, const Maybe<T>& aRHS) {
1126 return !(aLHS < aRHS);
1127}
1128
1129template <typename T>
1130inline void ImplCycleCollectionTraverse(
1131 nsCycleCollectionTraversalCallback& aCallback, mozilla::Maybe<T>& aField,
1132 const char* aName, uint32_t aFlags = 0) {
1133 if (aField) {
1134 ImplCycleCollectionTraverse(aCallback, aField.ref(), aName, aFlags);
1135 }
1136}
1137
1138template <typename T>
1139inline void ImplCycleCollectionUnlink(mozilla::Maybe<T>& aField) {
1140 if (aField) {
1141 ImplCycleCollectionUnlink(aField.ref());
1142 }
1143}
1144
1145} // namespace mozilla
1146
1147#endif /* mozilla_Maybe_h */
←

/var/lib/jenkins/workspace/firefox-scan-build/obj-x86_64-pc-linux-gnu/dist/include/mozilla/MaybeStorageBase.h

→
1/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/* vim: set ts=8 sts=2 et sw=2 tw=80: */
3/* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7/* Internal storage class used e.g. by Maybe and Result. This file doesn't
8 * contain any public declarations. */
9
10#ifndef mfbt_MaybeStorageBase_h
11#define mfbt_MaybeStorageBase_h
12
13#include <type_traits>
14#include <utility>
15
16namespace mozilla::detail {
17
18template <typename T>
19constexpr bool IsTriviallyDestructibleAndCopyable =
20 std::is_trivially_destructible_v<T> &&
21 (std::is_trivially_copy_constructible_v<T> ||
22 !std::is_copy_constructible_v<T>);
23
24template <typename T, bool TriviallyDestructibleAndCopyable =
25 IsTriviallyDestructibleAndCopyable<T>>
26struct MaybeStorageBase;
27
28template <typename T>
29struct MaybeStorageBase<T, false> {
30 protected:
31 using NonConstT = std::remove_const_t<T>;
32
33 union Union {
34 Union() {}
35 explicit Union(const T& aVal) : val{aVal} {}
36 template <typename U,
37 typename = std::enable_if_t<std::is_move_constructible_v<U>>>
38 explicit Union(U&& aVal) : val{std::forward<U>(aVal)} {}
39 template <typename... Args>
40 explicit Union(std::in_place_t, Args&&... aArgs)
41 : val{std::forward<Args>(aArgs)...} {}
42
43 ~Union() {}
7
←
Calling implicit destructor for 'AutoLockHelperThreadState'
→
8
←
Calling '~LockGuard'
→
44
45 NonConstT val;
46 } mStorage;
47
48 public:
49 MaybeStorageBase() = default;
50 explicit MaybeStorageBase(const T& aVal) : mStorage{aVal} {}
51 explicit MaybeStorageBase(T&& aVal) : mStorage{std::move(aVal)} {}
52 template <typename... Args>
53 explicit MaybeStorageBase(std::in_place_t, Args&&... aArgs)
54 : mStorage{std::in_place, std::forward<Args>(aArgs)...} {}
55
56 const T* addr() const { return &mStorage.val; }
57 T* addr() { return &mStorage.val; }
58};
59
60template <typename T>
61struct MaybeStorageBase<T, true> {
62 protected:
63 using NonConstT = std::remove_const_t<T>;
64
65 union Union {
66 constexpr Union() : dummy() {}
67 constexpr explicit Union(const T& aVal) : val{aVal} {}
68 constexpr explicit Union(T&& aVal) : val{std::move(aVal)} {}
69 template <typename... Args>
70 constexpr explicit Union(std::in_place_t, Args&&... aArgs)
71 : val{std::forward<Args>(aArgs)...} {}
72
73 NonConstT val;
74 char dummy;
75 } mStorage;
76
77 public:
78 constexpr MaybeStorageBase() = default;
79 constexpr explicit MaybeStorageBase(const T& aVal) : mStorage{aVal} {}
80 constexpr explicit MaybeStorageBase(T&& aVal) : mStorage{std::move(aVal)} {}
81
82 template <typename... Args>
83 constexpr explicit MaybeStorageBase(std::in_place_t, Args&&... aArgs)
84 : mStorage{std::in_place, std::forward<Args>(aArgs)...} {}
85
86 constexpr const T* addr() const { return &mStorage.val; }
87 constexpr T* addr() { return &mStorage.val; }
88};
89
90} // namespace mozilla::detail
91
92#endif
←

/var/lib/jenkins/workspace/firefox-scan-build/js/src/vm/HelperThreads.h

→
1/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
2 * vim: set ts=8 sts=2 et sw=2 tw=80:
3 * This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7/*
8 * API for managing off-thread work.
9 */
10
11#ifndef vm_HelperThreads_h
12#define vm_HelperThreads_h
13
14#include "mozilla/Variant.h"
15
16#include "js/AllocPolicy.h"
17#include "js/HelperThreadAPI.h"
18#include "js/shadow/Zone.h"
19#include "js/UniquePtr.h"
20#include "js/Vector.h"
21#include "threading/LockGuard.h"
22#include "threading/Mutex.h"
23#include "wasm/WasmConstants.h"
24
25namespace mozilla {
26union Utf8Unit;
27}
28
29namespace JS {
30class JS_PUBLIC_API ReadOnlyCompileOptions;
31class JS_PUBLIC_API ReadOnlyDecodeOptions;
32class Zone;
33
34template <typename UnitT>
35class SourceText;
36} // namespace JS
37
38namespace js {
39
40class AutoLockHelperThreadState;
41struct PromiseHelperTask;
42class SourceCompressionTask;
43
44namespace frontend {
45struct CompilationStencil;
46}
47
48namespace gc {
49class GCRuntime;
50}
51
52namespace jit {
53class IonCompileTask;
54class IonFreeTask;
55class JitRuntime;
56using IonFreeCompileTasks = Vector<IonCompileTask*, 8, SystemAllocPolicy>;
57} // namespace jit
58
59namespace wasm {
60struct CompileTask;
61struct CompileTaskState;
62struct CompleteTier2GeneratorTask;
63using UniqueCompleteTier2GeneratorTask = UniquePtr<CompleteTier2GeneratorTask>;
64struct PartialTier2CompileTask;
65using UniquePartialTier2CompileTask = UniquePtr<PartialTier2CompileTask>;
66} // namespace wasm
67
68/*
69 * Lock protecting all mutable shared state accessed by helper threads, and used
70 * by all condition variables.
71 */
72extern Mutex gHelperThreadLock MOZ_UNANNOTATED;
73
74// Set of tasks to dispatch when the helper thread state lock is released.
75class AutoHelperTaskQueue {
76 public:
77 ~AutoHelperTaskQueue() { dispatchQueuedTasks(); }
78 bool hasQueuedTasks() const { return !tasksToDispatch.empty(); }
79 void queueTaskToDispatch(JS::HelperThreadTask* task) const;
80 void dispatchQueuedTasks();
81
82 private:
83 // TODO: Convert this to use a linked list.
84 mutable Vector<JS::HelperThreadTask*, 1, SystemAllocPolicy> tasksToDispatch;
85};
86
87// A lock guard for data protected by the helper thread lock.
88//
89// This can also queue helper thread tasks to be triggered when the lock is
90// released.
91class MOZ_RAII AutoLockHelperThreadState
92 : public AutoHelperTaskQueue, // Must come before LockGuard.
93 public LockGuard<Mutex> {
94 public:
95 AutoLockHelperThreadState() : LockGuard<Mutex>(gHelperThreadLock) {}
96 AutoLockHelperThreadState(const AutoLockHelperThreadState&) = delete;
97
98 private:
99 friend class UnlockGuard<AutoLockHelperThreadState>;
100 void unlock() {
101 LockGuard<Mutex>::unlock();
102 dispatchQueuedTasks();
103 }
104
105 friend class GlobalHelperThreadState;
106};
107
108using AutoUnlockHelperThreadState = UnlockGuard<AutoLockHelperThreadState>;
109
110// Create data structures used by helper threads.
111bool CreateHelperThreadsState();
112
113// Destroy data structures used by helper threads.
114void DestroyHelperThreadsState();
115
116// Initialize helper threads unless already initialized.
117bool EnsureHelperThreadsInitialized();
118
119size_t GetHelperThreadCount();
120size_t GetHelperThreadCPUCount();
121size_t GetMaxWasmCompilationThreads();
122
123// This allows the JS shell to override GetCPUCount() when passed the
124// --thread-count=N option.
125bool SetFakeCPUCount(size_t count);
126
127// Enqueues a wasm compilation task.
128bool StartOffThreadWasmCompile(wasm::CompileTask* task,
129 wasm::CompileState state);
130
131// Remove any pending wasm compilation tasks queued with
132// StartOffThreadWasmCompile that match the arguments. Return the number
133// removed.
134size_t RemovePendingWasmCompileTasks(const wasm::CompileTaskState& taskState,
135 wasm::CompileState state,
136 const AutoLockHelperThreadState& lock);
137
138// Enqueues a wasm Complete Tier-2 compilation task. This (logically, at
139// least) manages a set of sub-tasks that perform compilation of groups of
140// functions.
141void StartOffThreadWasmCompleteTier2Generator(
142 wasm::UniqueCompleteTier2GeneratorTask task);
143
144// Enqueues a wasm Partial Tier-2 compilation task. This compiles one
145// function, doing so itself, without any sub-tasks.
146void StartOffThreadWasmPartialTier2Compile(
147 wasm::UniquePartialTier2CompileTask task);
148
149// Cancel all background Wasm Complete Tier-2 compilations, both the generator
150// task and the individual compilation tasks.
151void CancelOffThreadWasmCompleteTier2Generator();
152
153// Cancel a single background Wasm Partial Tier-2 compilation.
154void CancelOffThreadWasmPartialTier2Compile();
155
156/*
157 * If helper threads are available, call execute() then dispatchResolve() on the
158 * given task in a helper thread. If no helper threads are available, the given
159 * task is executed and resolved synchronously.
160 *
161 * This function takes ownership of task unconditionally; if it fails, task is
162 * deleted.
163 */
164bool StartOffThreadPromiseHelperTask(JSContext* cx,
165 UniquePtr<PromiseHelperTask> task);
166
167/*
168 * Like the JSContext-accepting version, but only safe to use when helper
169 * threads are available, so we can be sure we'll never need to fall back on
170 * synchronous execution.
171 *
172 * This function can be called from any thread, but takes ownership of the task
173 * only on success. On OOM, it is the caller's responsibility to arrange for the
174 * task to be cleaned up properly.
175 */
176bool StartOffThreadPromiseHelperTask(PromiseHelperTask* task);
177
178/*
179 * Schedule an off-thread Ion compilation for a script, given a task.
180 */
181bool StartOffThreadIonCompile(jit::IonCompileTask* task,
182 const AutoLockHelperThreadState& lock);
183
184void FinishOffThreadIonCompile(jit::IonCompileTask* task,
185 const AutoLockHelperThreadState& lock);
186
187// RAII class to handle batching compile tasks and starting an IonFreeTask.
188class MOZ_RAII AutoStartIonFreeTask {
189 jit::JitRuntime* jitRuntime_;
190
191 // If true, start an IonFreeTask even if the batch is small.
192 bool force_;
193
194 public:
195 explicit AutoStartIonFreeTask(jit::JitRuntime* jitRuntime, bool force = false)
196 : jitRuntime_(jitRuntime), force_(force) {}
197 ~AutoStartIonFreeTask();
198
199 [[nodiscard]] bool addIonCompileToFreeTaskBatch(jit::IonCompileTask* task);
200};
201
202struct ZonesInState {
203 JSRuntime* runtime;
204 JS::shadow::Zone::GCState state;
205};
206
207using CompilationSelector =
208 mozilla::Variant<JSScript*, JS::Zone*, ZonesInState, JSRuntime*>;
209
210/*
211 * Cancel scheduled or in progress Ion compilations.
212 */
213void CancelOffThreadIonCompile(const CompilationSelector& selector);
214
215inline void CancelOffThreadIonCompile(JSScript* script) {
216 CancelOffThreadIonCompile(CompilationSelector(script));
217}
218
219inline void CancelOffThreadIonCompile(JS::Zone* zone) {
220 CancelOffThreadIonCompile(CompilationSelector(zone));
221}
222
223inline void CancelOffThreadIonCompile(JSRuntime* runtime,
224 JS::shadow::Zone::GCState state) {
225 CancelOffThreadIonCompile(CompilationSelector(ZonesInState{runtime, state}));
226}
227
228inline void CancelOffThreadIonCompile(JSRuntime* runtime) {
229 CancelOffThreadIonCompile(CompilationSelector(runtime));
230}
231
232#ifdef DEBUG1
233bool HasOffThreadIonCompile(JS::Zone* zone);
234#endif
235
236/*
237 * Cancel all scheduled or in progress eager delazification phases for a
238 * runtime.
239 */
240void CancelOffThreadDelazify(JSRuntime* runtime);
241
242/*
243 * Wait for all delazification to complete.
244 */
245void WaitForAllDelazifyTasks(JSRuntime* rt);
246
247// Start off-thread delazification task, to race the delazification of inner
248// functions.
249void StartOffThreadDelazification(JSContext* maybeCx,
250 const JS::ReadOnlyCompileOptions& options,
251 const frontend::CompilationStencil& stencil);
252
253// Drain the task queues and wait for all helper threads to finish running.
254//
255// Note that helper threads are shared between runtimes and it's possible that
256// another runtime could saturate the helper thread system and cause this to
257// never return.
258void WaitForAllHelperThreads();
259void WaitForAllHelperThreads(AutoLockHelperThreadState& lock);
260
261// Enqueue a compression job to be processed later. These are started at the
262// start of the major GC after the next one.
263bool EnqueueOffThreadCompression(JSContext* cx,
264 UniquePtr<SourceCompressionTask> task);
265
266// Start handling any compression tasks for this runtime. Called at the start of
267// major GC.
268void StartHandlingCompressionsOnGC(JSRuntime* rt);
269
270// Cancel all scheduled, in progress, or finished compression tasks for
271// runtime.
272void CancelOffThreadCompressions(JSRuntime* runtime);
273
274void AttachFinishedCompressions(JSRuntime* runtime,
275 AutoLockHelperThreadState& lock);
276
277// Sweep pending tasks that are holding onto should-be-dead ScriptSources.
278void SweepPendingCompressions(AutoLockHelperThreadState& lock);
279
280// Run all pending source compression tasks synchronously, for testing purposes
281void RunPendingSourceCompressions(JSRuntime* runtime);
282
283// False if the off-thread source compression mechanism isn't being used. This
284// happens on low core count machines where we are concerned about blocking
285// main-thread execution.
286bool IsOffThreadSourceCompressionEnabled();
287
288} // namespace js
289
290#endif /* vm_HelperThreads_h */
←

/var/lib/jenkins/workspace/firefox-scan-build/js/src/threading/LockGuard.h

1/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2/* vim: set ts=8 sts=2 et sw=2 tw=80: */
3/* This Source Code Form is subject to the terms of the Mozilla Public
4 * License, v. 2.0. If a copy of the MPL was not distributed with this
5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
6
7#ifndef threading_LockGuard_h
8#define threading_LockGuard_h
9
10#include "mozilla/Attributes.h"
11
12namespace js {
13
14template <typename GuardT>
15class MOZ_RAII UnlockGuard;
16
17template <typename Mutex>
18class MOZ_RAII LockGuard {
19 friend class UnlockGuard<LockGuard<Mutex>>;
20 friend class ConditionVariable;
21 Mutex& mutex;
22
23 public:
24 explicit LockGuard(Mutex& mutex) : mutex(mutex) { lock(); }
25 ~LockGuard() { unlock(); }
9
←
Calling 'LockGuard::unlock'
→
26
27 LockGuard(const LockGuard& other) = delete;
28
29 protected:
30 void lock() { mutex.lock(); }
31 void unlock() { mutex.unlock(); }
10
←
Called C++ object pointer is uninitialized
32};
33
34// RAII class to temporarily unlock a LockGuard.
35template <typename GuardT>
36class MOZ_RAII UnlockGuard {
37 GuardT& guard;
38
39 public:
40 explicit UnlockGuard(GuardT& guard) : guard(guard) { guard.unlock(); }
41 ~UnlockGuard() { guard.lock(); }
42
43 UnlockGuard(const UnlockGuard& other) = delete;
44};
45
46} // namespace js
47
48#endif // threading_LockGuard_h