1 files changed, 210 insertions, 0 deletions
diff --git a/js/src/jit/JitAllocPolicy.h b/js/src/jit/JitAllocPolicy.h
new file mode 100644
index 000000000..bf1629290
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+++ b/js/src/jit/JitAllocPolicy.h
@@ -0,0 +1,210 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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);
+    }
+
+    MOZ_MUST_USE void* allocate(size_t bytes)
+    {
+        LifoAlloc::AutoFallibleScope fallibleAllocator(lifoAlloc());
+        void* p = lifoScope_.alloc().alloc(bytes);
+        if (!ensureBallast())
+            return nullptr;
+        return p;
+    }
+
+    template <typename T>
+    MOZ_MUST_USE 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();
+    }
+
+    MOZ_MUST_USE 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 {
+    }
+    MOZ_MUST_USE 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 */