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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef jit_JitAllocPolicy_h
#define jit_JitAllocPolicy_h
#include "mozilla/Attributes.h"
#include "mozilla/GuardObjects.h"
#include "mozilla/OperatorNewExtensions.h"
#include "mozilla/TypeTraits.h"
#include "jscntxt.h"
#include "ds/LifoAlloc.h"
#include "jit/InlineList.h"
#include "jit/Ion.h"
namespace js {
namespace jit {
class TempAllocator
{
LifoAllocScope lifoScope_;
public:
// Most infallible JIT allocations are small, so we use a ballast of 16
// KiB. And with a ballast of 16 KiB, a chunk size of 32 KiB works well,
// because TempAllocators with a peak allocation size of less than 16 KiB
// (which is most of them) only have to allocate a single chunk.
static const size_t BallastSize; // 16 KiB
static const size_t PreferredLifoChunkSize; // 32 KiB
explicit TempAllocator(LifoAlloc* lifoAlloc)
: lifoScope_(lifoAlloc)
{
lifoAlloc->setAsInfallibleByDefault();
}
void* allocateInfallible(size_t bytes)
{
return lifoScope_.alloc().allocInfallible(bytes);
}
[[nodiscard]] void* allocate(size_t bytes)
{
LifoAlloc::AutoFallibleScope fallibleAllocator(lifoAlloc());
void* p = lifoScope_.alloc().alloc(bytes);
if (!ensureBallast())
return nullptr;
return p;
}
template <typename T>
[[nodiscard]] T* allocateArray(size_t n)
{
LifoAlloc::AutoFallibleScope fallibleAllocator(lifoAlloc());
size_t bytes;
if (MOZ_UNLIKELY(!CalculateAllocSize<T>(n, &bytes)))
return nullptr;
T* p = static_cast<T*>(lifoScope_.alloc().alloc(bytes));
if (MOZ_UNLIKELY(!ensureBallast()))
return nullptr;
return p;
}
// View this allocator as a fallible allocator.
struct Fallible { TempAllocator& alloc; };
Fallible fallible() { return { *this }; }
LifoAlloc* lifoAlloc() {
return &lifoScope_.alloc();
}
[[nodiscard]] bool ensureBallast() {
JS_OOM_POSSIBLY_FAIL_BOOL();
return lifoScope_.alloc().ensureUnusedApproximate(BallastSize);
}
};
class JitAllocPolicy
{
TempAllocator& alloc_;
public:
MOZ_IMPLICIT JitAllocPolicy(TempAllocator& alloc)
: alloc_(alloc)
{}
template <typename T>
T* maybe_pod_malloc(size_t numElems) {
size_t bytes;
if (MOZ_UNLIKELY(!CalculateAllocSize<T>(numElems, &bytes)))
return nullptr;
return static_cast<T*>(alloc_.allocate(bytes));
}
template <typename T>
T* maybe_pod_calloc(size_t numElems) {
T* p = maybe_pod_malloc<T>(numElems);
if (MOZ_LIKELY(p))
memset(p, 0, numElems * sizeof(T));
return p;
}
template <typename T>
T* maybe_pod_realloc(T* p, size_t oldSize, size_t newSize) {
T* n = pod_malloc<T>(newSize);
if (MOZ_UNLIKELY(!n))
return n;
MOZ_ASSERT(!(oldSize & mozilla::tl::MulOverflowMask<sizeof(T)>::value));
memcpy(n, p, Min(oldSize * sizeof(T), newSize * sizeof(T)));
return n;
}
template <typename T>
T* pod_malloc(size_t numElems) {
return maybe_pod_malloc<T>(numElems);
}
template <typename T>
T* pod_calloc(size_t numElems) {
return maybe_pod_calloc<T>(numElems);
}
template <typename T>
T* pod_realloc(T* ptr, size_t oldSize, size_t newSize) {
return maybe_pod_realloc<T>(ptr, oldSize, newSize);
}
void free_(void* p) {
}
void reportAllocOverflow() const {
}
[[nodiscard]] bool checkSimulatedOOM() const {
return !js::oom::ShouldFailWithOOM();
}
};
class AutoJitContextAlloc
{
TempAllocator tempAlloc_;
JitContext* jcx_;
TempAllocator* prevAlloc_;
public:
explicit AutoJitContextAlloc(JSContext* cx)
: tempAlloc_(&cx->tempLifoAlloc()),
jcx_(GetJitContext()),
prevAlloc_(jcx_->temp)
{
jcx_->temp = &tempAlloc_;
}
~AutoJitContextAlloc() {
MOZ_ASSERT(jcx_->temp == &tempAlloc_);
jcx_->temp = prevAlloc_;
}
};
struct TempObject
{
inline void* operator new(size_t nbytes, TempAllocator::Fallible view) throw() {
return view.alloc.allocate(nbytes);
}
inline void* operator new(size_t nbytes, TempAllocator& alloc) {
return alloc.allocateInfallible(nbytes);
}
template <class T>
inline void* operator new(size_t nbytes, T* pos) {
static_assert(mozilla::IsConvertible<T*, TempObject*>::value,
"Placement new argument type must inherit from TempObject");
return pos;
}
template <class T>
inline void* operator new(size_t nbytes, mozilla::NotNullTag, T* pos) {
static_assert(mozilla::IsConvertible<T*, TempObject*>::value,
"Placement new argument type must inherit from TempObject");
MOZ_ASSERT(pos);
return pos;
}
};
template <typename T>
class TempObjectPool
{
TempAllocator* alloc_;
InlineForwardList<T> freed_;
public:
TempObjectPool()
: alloc_(nullptr)
{}
void setAllocator(TempAllocator& alloc) {
MOZ_ASSERT(freed_.empty());
alloc_ = &alloc;
}
T* allocate() {
MOZ_ASSERT(alloc_);
if (freed_.empty())
return new(alloc_->fallible()) T();
return freed_.popFront();
}
void free(T* obj) {
freed_.pushFront(obj);
}
void clear() {
freed_.clear();
}
};
} // namespace jit
} // namespace js
#endif /* jit_JitAllocPolicy_h */
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