js/public/Utility.h
author Masayuki Nakano <masayuki@d-toybox.com>
Fri, 19 May 2017 17:49:41 +0900
changeset 359318 b75c111837a802ceb953dba50a3c5a193d53ca22
parent 347661 16f71512d5874b5aa6200b02484925d434d5eb07
child 366754 b9422e6c4ec52b37be51d923639cd877e86c01c7
permissions -rw-r--r--
Bug 1339543 part 4 Change nsIWidget::ExecuteNativeKeyBinding() to nsIWidget::GetEditCommands() which just retrieves edit commands for the type r=smaug Now, nsIWidget::ExecuteNativeKeyBinding() isn't used by anybody for executing edit commands. Instead, they need array of edit commands for the key combination. So, the method should be renamed to GetEditCommands() and just return edit commands as an array. MozReview-Commit-ID: 4G0B1lJ8Lbe

/* -*- 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 js_Utility_h
#define js_Utility_h

#include "mozilla/Assertions.h"
#include "mozilla/Atomics.h"
#include "mozilla/Attributes.h"
#include "mozilla/Compiler.h"
#include "mozilla/Move.h"
#include "mozilla/Scoped.h"
#include "mozilla/TemplateLib.h"
#include "mozilla/UniquePtr.h"

#include <stdlib.h>
#include <string.h>

#ifdef JS_OOM_DO_BACKTRACES
#include <execinfo.h>
#include <stdio.h>
#endif

#include "jstypes.h"

/* The public JS engine namespace. */
namespace JS {}

/* The mozilla-shared reusable template/utility namespace. */
namespace mozilla {}

/* The private JS engine namespace. */
namespace js {}

#define JS_STATIC_ASSERT(cond)           static_assert(cond, "JS_STATIC_ASSERT")
#define JS_STATIC_ASSERT_IF(cond, expr)  MOZ_STATIC_ASSERT_IF(cond, expr, "JS_STATIC_ASSERT_IF")

extern MOZ_NORETURN MOZ_COLD JS_PUBLIC_API(void)
JS_Assert(const char* s, const char* file, int ln);

/*
 * Custom allocator support for SpiderMonkey
 */
#if defined JS_USE_CUSTOM_ALLOCATOR
# include "jscustomallocator.h"
#else

namespace js {
namespace oom {

/*
 * To make testing OOM in certain helper threads more effective,
 * allow restricting the OOM testing to a certain helper thread
 * type. This allows us to fail e.g. in off-thread script parsing
 * without causing an OOM in the active thread first.
 */
enum ThreadType {
    THREAD_TYPE_NONE = 0,       // 0
    THREAD_TYPE_COOPERATING,    // 1
    THREAD_TYPE_WASM,           // 2
    THREAD_TYPE_ION,            // 3
    THREAD_TYPE_PARSE,          // 4
    THREAD_TYPE_COMPRESS,       // 5
    THREAD_TYPE_GCHELPER,       // 6
    THREAD_TYPE_GCPARALLEL,     // 7
    THREAD_TYPE_PROMISE_TASK,   // 8
    THREAD_TYPE_MAX             // Used to check shell function arguments
};

/*
 * Getter/Setter functions to encapsulate mozilla::ThreadLocal,
 * implementation is in jsutil.cpp.
 */
# if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
extern bool InitThreadType(void);
extern void SetThreadType(ThreadType);
extern uint32_t GetThreadType(void);
# else
inline bool InitThreadType(void) { return true; }
inline void SetThreadType(ThreadType t) {};
inline uint32_t GetThreadType(void) { return 0; }
# endif

} /* namespace oom */
} /* namespace js */

# if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)

#ifdef JS_OOM_BREAKPOINT
static MOZ_NEVER_INLINE void js_failedAllocBreakpoint() { asm(""); }
#define JS_OOM_CALL_BP_FUNC() js_failedAllocBreakpoint()
#else
#define JS_OOM_CALL_BP_FUNC() do {} while(0)
#endif

namespace js {
namespace oom {

/*
 * Out of memory testing support.  We provide various testing functions to
 * simulate OOM conditions and so we can test that they are handled correctly.
 */

extern JS_PUBLIC_DATA(uint32_t) targetThread;
extern JS_PUBLIC_DATA(uint64_t) maxAllocations;
extern JS_PUBLIC_DATA(uint64_t) counter;
extern JS_PUBLIC_DATA(bool) failAlways;

extern void
SimulateOOMAfter(uint64_t allocations, uint32_t thread, bool always);

extern void
ResetSimulatedOOM();

inline bool
IsThreadSimulatingOOM()
{
    return js::oom::targetThread && js::oom::targetThread == js::oom::GetThreadType();
}

inline bool
IsSimulatedOOMAllocation()
{
    return IsThreadSimulatingOOM() &&
           (counter == maxAllocations || (counter > maxAllocations && failAlways));
}

inline bool
ShouldFailWithOOM()
{
    if (!IsThreadSimulatingOOM())
        return false;

    counter++;
    if (IsSimulatedOOMAllocation()) {
        JS_OOM_CALL_BP_FUNC();
        return true;
    }
    return false;
}

inline bool
HadSimulatedOOM() {
    return counter >= maxAllocations;
}

} /* namespace oom */
} /* namespace js */

#  define JS_OOM_POSSIBLY_FAIL()                                              \
    do {                                                                      \
        if (js::oom::ShouldFailWithOOM())                                     \
            return nullptr;                                                   \
    } while (0)

#  define JS_OOM_POSSIBLY_FAIL_BOOL()                                         \
    do {                                                                      \
        if (js::oom::ShouldFailWithOOM())                                     \
            return false;                                                     \
    } while (0)

# else

#  define JS_OOM_POSSIBLY_FAIL() do {} while(0)
#  define JS_OOM_POSSIBLY_FAIL_BOOL() do {} while(0)
namespace js {
namespace oom {
static inline bool IsSimulatedOOMAllocation() { return false; }
static inline bool ShouldFailWithOOM() { return false; }
} /* namespace oom */
} /* namespace js */

# endif /* DEBUG || JS_OOM_BREAKPOINT */

namespace js {

/* Disable OOM testing in sections which are not OOM safe. */
struct MOZ_RAII JS_PUBLIC_DATA(AutoEnterOOMUnsafeRegion)
{
    MOZ_NORETURN MOZ_COLD void crash(const char* reason);
    MOZ_NORETURN MOZ_COLD void crash(size_t size, const char* reason);

    using AnnotateOOMAllocationSizeCallback = void(*)(size_t);
    static AnnotateOOMAllocationSizeCallback annotateOOMSizeCallback;
    static void setAnnotateOOMAllocationSizeCallback(AnnotateOOMAllocationSizeCallback callback) {
        annotateOOMSizeCallback = callback;
    }

#if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
    AutoEnterOOMUnsafeRegion()
      : oomEnabled_(oom::IsThreadSimulatingOOM() && oom::maxAllocations != UINT64_MAX),
        oomAfter_(0)
    {
        if (oomEnabled_) {
            MOZ_ALWAYS_TRUE(owner_.compareExchange(nullptr, this));
            oomAfter_ = int64_t(oom::maxAllocations) - int64_t(oom::counter);
            oom::maxAllocations = UINT64_MAX;
        }
    }

    ~AutoEnterOOMUnsafeRegion() {
        if (oomEnabled_) {
            MOZ_ASSERT(oom::maxAllocations == UINT64_MAX);
            int64_t maxAllocations = int64_t(oom::counter) + oomAfter_;
            MOZ_ASSERT(maxAllocations >= 0,
                       "alloc count + oom limit exceeds range, your oom limit is probably too large");
            oom::maxAllocations = uint64_t(maxAllocations);
            MOZ_ALWAYS_TRUE(owner_.compareExchange(this, nullptr));
        }
    }

  private:
    // Used to catch concurrent use from other threads.
    static mozilla::Atomic<AutoEnterOOMUnsafeRegion*> owner_;

    bool oomEnabled_;
    int64_t oomAfter_;
#endif
};

} /* namespace js */

static inline void* js_malloc(size_t bytes)
{
    JS_OOM_POSSIBLY_FAIL();
    return malloc(bytes);
}

static inline void* js_calloc(size_t bytes)
{
    JS_OOM_POSSIBLY_FAIL();
    return calloc(bytes, 1);
}

static inline void* js_calloc(size_t nmemb, size_t size)
{
    JS_OOM_POSSIBLY_FAIL();
    return calloc(nmemb, size);
}

static inline void* js_realloc(void* p, size_t bytes)
{
    // realloc() with zero size is not portable, as some implementations may
    // return nullptr on success and free |p| for this.  We assume nullptr
    // indicates failure and that |p| is still valid.
    MOZ_ASSERT(bytes != 0);

    JS_OOM_POSSIBLY_FAIL();
    return realloc(p, bytes);
}

static inline void js_free(void* p)
{
    free(p);
}

static inline char* js_strdup(const char* s)
{
    JS_OOM_POSSIBLY_FAIL();
    return strdup(s);
}
#endif/* JS_USE_CUSTOM_ALLOCATOR */

#include <new>

/*
 * Low-level memory management in SpiderMonkey:
 *
 *  ** Do not use the standard malloc/free/realloc: SpiderMonkey allows these
 *     to be redefined (via JS_USE_CUSTOM_ALLOCATOR) and Gecko even #define's
 *     these symbols.
 *
 *  ** Do not use the builtin C++ operator new and delete: these throw on
 *     error and we cannot override them not to.
 *
 * Allocation:
 *
 * - If the lifetime of the allocation is tied to the lifetime of a GC-thing
 *   (that is, finalizing the GC-thing will free the allocation), call one of
 *   the following functions:
 *
 *     JSContext::{malloc_,realloc_,calloc_,new_}
 *     JSRuntime::{malloc_,realloc_,calloc_,new_}
 *
 *   These functions accumulate the number of bytes allocated which is used as
 *   part of the GC-triggering heuristic.
 *
 *   The difference between the JSContext and JSRuntime versions is that the
 *   cx version reports an out-of-memory error on OOM. (This follows from the
 *   general SpiderMonkey idiom that a JSContext-taking function reports its
 *   own errors.)
 *
 * - Otherwise, use js_malloc/js_realloc/js_calloc/js_new
 *
 * Deallocation:
 *
 * - Ordinarily, use js_free/js_delete.
 *
 * - For deallocations during GC finalization, use one of the following
 *   operations on the FreeOp provided to the finalizer:
 *
 *     FreeOp::{free_,delete_}
 *
 *   The advantage of these operations is that the memory is batched and freed
 *   on another thread.
 */

/*
 * Given a class which should provide a 'new' method, add
 * JS_DECLARE_NEW_METHODS (see js::MallocProvider for an example).
 *
 * Note: Do not add a ; at the end of a use of JS_DECLARE_NEW_METHODS,
 * or the build will break.
 */
#define JS_DECLARE_NEW_METHODS(NEWNAME, ALLOCATOR, QUALIFIERS) \
    template <class T, typename... Args> \
    QUALIFIERS T * \
    NEWNAME(Args&&... args) MOZ_HEAP_ALLOCATOR { \
        void* memory = ALLOCATOR(sizeof(T)); \
        return MOZ_LIKELY(memory) \
            ? new(memory) T(mozilla::Forward<Args>(args)...) \
            : nullptr; \
    }

/*
 * Given a class which should provide 'make' methods, add
 * JS_DECLARE_MAKE_METHODS (see js::MallocProvider for an example).  This
 * method is functionally the same as JS_DECLARE_NEW_METHODS: it just declares
 * methods that return mozilla::UniquePtr instances that will singly-manage
 * ownership of the created object.
 *
 * Note: Do not add a ; at the end of a use of JS_DECLARE_MAKE_METHODS,
 * or the build will break.
 */
#define JS_DECLARE_MAKE_METHODS(MAKENAME, NEWNAME, QUALIFIERS)\
    template <class T, typename... Args> \
    QUALIFIERS mozilla::UniquePtr<T, JS::DeletePolicy<T>> \
    MAKENAME(Args&&... args) MOZ_HEAP_ALLOCATOR { \
        T* ptr = NEWNAME<T>(mozilla::Forward<Args>(args)...); \
        return mozilla::UniquePtr<T, JS::DeletePolicy<T>>(ptr); \
    }

JS_DECLARE_NEW_METHODS(js_new, js_malloc, static MOZ_ALWAYS_INLINE)

namespace js {

/*
 * Calculate the number of bytes needed to allocate |numElems| contiguous
 * instances of type |T|.  Return false if the calculation overflowed.
 */
template <typename T>
MOZ_MUST_USE inline bool
CalculateAllocSize(size_t numElems, size_t* bytesOut)
{
    *bytesOut = numElems * sizeof(T);
    return (numElems & mozilla::tl::MulOverflowMask<sizeof(T)>::value) == 0;
}

/*
 * Calculate the number of bytes needed to allocate a single instance of type
 * |T| followed by |numExtra| contiguous instances of type |Extra|.  Return
 * false if the calculation overflowed.
 */
template <typename T, typename Extra>
MOZ_MUST_USE inline bool
CalculateAllocSizeWithExtra(size_t numExtra, size_t* bytesOut)
{
    *bytesOut = sizeof(T) + numExtra * sizeof(Extra);
    return (numExtra & mozilla::tl::MulOverflowMask<sizeof(Extra)>::value) == 0 &&
           *bytesOut >= sizeof(T);
}

} /* namespace js */

template <class T>
static MOZ_ALWAYS_INLINE void
js_delete(const T* p)
{
    if (p) {
        p->~T();
        js_free(const_cast<T*>(p));
    }
}

template<class T>
static MOZ_ALWAYS_INLINE void
js_delete_poison(const T* p)
{
    if (p) {
        p->~T();
        memset(const_cast<T*>(p), 0x3B, sizeof(T));
        js_free(const_cast<T*>(p));
    }
}

template <class T>
static MOZ_ALWAYS_INLINE T*
js_pod_malloc()
{
    return static_cast<T*>(js_malloc(sizeof(T)));
}

template <class T>
static MOZ_ALWAYS_INLINE T*
js_pod_calloc()
{
    return static_cast<T*>(js_calloc(sizeof(T)));
}

template <class T>
static MOZ_ALWAYS_INLINE T*
js_pod_malloc(size_t numElems)
{
    size_t bytes;
    if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(numElems, &bytes)))
        return nullptr;
    return static_cast<T*>(js_malloc(bytes));
}

template <class T>
static MOZ_ALWAYS_INLINE T*
js_pod_calloc(size_t numElems)
{
    size_t bytes;
    if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(numElems, &bytes)))
        return nullptr;
    return static_cast<T*>(js_calloc(bytes));
}

template <class T>
static MOZ_ALWAYS_INLINE T*
js_pod_realloc(T* prior, size_t oldSize, size_t newSize)
{
    MOZ_ASSERT(!(oldSize & mozilla::tl::MulOverflowMask<sizeof(T)>::value));
    size_t bytes;
    if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(newSize, &bytes)))
        return nullptr;
    return static_cast<T*>(js_realloc(prior, bytes));
}

namespace js {

template<typename T>
struct ScopedFreePtrTraits
{
    typedef T* type;
    static T* empty() { return nullptr; }
    static void release(T* ptr) { js_free(ptr); }
};
SCOPED_TEMPLATE(ScopedJSFreePtr, ScopedFreePtrTraits)

template <typename T>
struct ScopedDeletePtrTraits : public ScopedFreePtrTraits<T>
{
    static void release(T* ptr) { js_delete(ptr); }
};
SCOPED_TEMPLATE(ScopedJSDeletePtr, ScopedDeletePtrTraits)

template <typename T>
struct ScopedReleasePtrTraits : public ScopedFreePtrTraits<T>
{
    static void release(T* ptr) { if (ptr) ptr->release(); }
};
SCOPED_TEMPLATE(ScopedReleasePtr, ScopedReleasePtrTraits)

} /* namespace js */

namespace JS {

template<typename T>
struct DeletePolicy
{
    constexpr DeletePolicy() {}

    template<typename U>
    MOZ_IMPLICIT DeletePolicy(DeletePolicy<U> other,
                              typename mozilla::EnableIf<mozilla::IsConvertible<U*, T*>::value,
                                                         int>::Type dummy = 0)
    {}

    void operator()(const T* ptr) {
        js_delete(const_cast<T*>(ptr));
    }
};

struct FreePolicy
{
    void operator()(const void* ptr) {
        js_free(const_cast<void*>(ptr));
    }
};

typedef mozilla::UniquePtr<char[], JS::FreePolicy> UniqueChars;
typedef mozilla::UniquePtr<char16_t[], JS::FreePolicy> UniqueTwoByteChars;

} // namespace JS

namespace js {

/* Integral types for all hash functions. */
typedef uint32_t HashNumber;
const unsigned HashNumberSizeBits = 32;

namespace detail {

/*
 * Given a raw hash code, h, return a number that can be used to select a hash
 * bucket.
 *
 * This function aims to produce as uniform an output distribution as possible,
 * especially in the most significant (leftmost) bits, even though the input
 * distribution may be highly nonrandom, given the constraints that this must
 * be deterministic and quick to compute.
 *
 * Since the leftmost bits of the result are best, the hash bucket index is
 * computed by doing ScrambleHashCode(h) / (2^32/N) or the equivalent
 * right-shift, not ScrambleHashCode(h) % N or the equivalent bit-mask.
 *
 * FIXME: OrderedHashTable uses a bit-mask; see bug 775896.
 */
inline HashNumber
ScrambleHashCode(HashNumber h)
{
    /*
     * Simply returning h would not cause any hash tables to produce wrong
     * answers. But it can produce pathologically bad performance: The caller
     * right-shifts the result, keeping only the highest bits. The high bits of
     * hash codes are very often completely entropy-free. (So are the lowest
     * bits.)
     *
     * So we use Fibonacci hashing, as described in Knuth, The Art of Computer
     * Programming, 6.4. This mixes all the bits of the input hash code h.
     *
     * The value of goldenRatio is taken from the hex
     * expansion of the golden ratio, which starts 1.9E3779B9....
     * This value is especially good if values with consecutive hash codes
     * are stored in a hash table; see Knuth for details.
     */
    static const HashNumber goldenRatio = 0x9E3779B9U;
    return h * goldenRatio;
}

} /* namespace detail */

} /* namespace js */

/* sixgill annotation defines */
#ifndef HAVE_STATIC_ANNOTATIONS
# define HAVE_STATIC_ANNOTATIONS
# ifdef XGILL_PLUGIN
#  define STATIC_PRECONDITION(COND)         __attribute__((precondition(#COND)))
#  define STATIC_PRECONDITION_ASSUME(COND)  __attribute__((precondition_assume(#COND)))
#  define STATIC_POSTCONDITION(COND)        __attribute__((postcondition(#COND)))
#  define STATIC_POSTCONDITION_ASSUME(COND) __attribute__((postcondition_assume(#COND)))
#  define STATIC_INVARIANT(COND)            __attribute__((invariant(#COND)))
#  define STATIC_INVARIANT_ASSUME(COND)     __attribute__((invariant_assume(#COND)))
#  define STATIC_ASSUME(COND)                        \
  JS_BEGIN_MACRO                                     \
    __attribute__((assume_static(#COND), unused))    \
    int STATIC_PASTE1(assume_static_, __COUNTER__);  \
  JS_END_MACRO
# else /* XGILL_PLUGIN */
#  define STATIC_PRECONDITION(COND)          /* nothing */
#  define STATIC_PRECONDITION_ASSUME(COND)   /* nothing */
#  define STATIC_POSTCONDITION(COND)         /* nothing */
#  define STATIC_POSTCONDITION_ASSUME(COND)  /* nothing */
#  define STATIC_INVARIANT(COND)             /* nothing */
#  define STATIC_INVARIANT_ASSUME(COND)      /* nothing */
#  define STATIC_ASSUME(COND)          JS_BEGIN_MACRO /* nothing */ JS_END_MACRO
# endif /* XGILL_PLUGIN */
# define STATIC_SKIP_INFERENCE STATIC_INVARIANT(skip_inference())
#endif /* HAVE_STATIC_ANNOTATIONS */

#endif /* js_Utility_h */