v8/src/utils.h

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// Copyright 2012 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_UTILS_H_
#define V8_UTILS_H_
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <algorithm>
#include "allocation.h"
#include "checks.h"
#include "globals.h"
namespace v8 {
namespace internal {
// ----------------------------------------------------------------------------
// General helper functions
#define IS_POWER_OF_TWO(x) (((x) & ((x) - 1)) == 0)
// Returns true iff x is a power of 2 (or zero). Cannot be used with the
// maximally negative value of the type T (the -1 overflows).
template <typename T>
inline bool IsPowerOf2(T x) {
return IS_POWER_OF_TWO(x);
}
// X must be a power of 2. Returns the number of trailing zeros.
inline int WhichPowerOf2(uint32_t x) {
ASSERT(IsPowerOf2(x));
ASSERT(x != 0);
int bits = 0;
#ifdef DEBUG
int original_x = x;
#endif
if (x >= 0x10000) {
bits += 16;
x >>= 16;
}
if (x >= 0x100) {
bits += 8;
x >>= 8;
}
if (x >= 0x10) {
bits += 4;
x >>= 4;
}
switch (x) {
default: UNREACHABLE();
case 8: bits++; // Fall through.
case 4: bits++; // Fall through.
case 2: bits++; // Fall through.
case 1: break;
}
ASSERT_EQ(1 << bits, original_x);
return bits;
return 0;
}
inline int MostSignificantBit(uint32_t x) {
static const int msb4[] = {0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4};
int nibble = 0;
if (x & 0xffff0000) {
nibble += 16;
x >>= 16;
}
if (x & 0xff00) {
nibble += 8;
x >>= 8;
}
if (x & 0xf0) {
nibble += 4;
x >>= 4;
}
return nibble + msb4[x];
}
// The C++ standard leaves the semantics of '>>' undefined for
// negative signed operands. Most implementations do the right thing,
// though.
inline int ArithmeticShiftRight(int x, int s) {
return x >> s;
}
// Compute the 0-relative offset of some absolute value x of type T.
// This allows conversion of Addresses and integral types into
// 0-relative int offsets.
template <typename T>
inline intptr_t OffsetFrom(T x) {
return x - static_cast<T>(0);
}
// Compute the absolute value of type T for some 0-relative offset x.
// This allows conversion of 0-relative int offsets into Addresses and
// integral types.
template <typename T>
inline T AddressFrom(intptr_t x) {
return static_cast<T>(static_cast<T>(0) + x);
}
// Return the largest multiple of m which is <= x.
template <typename T>
inline T RoundDown(T x, intptr_t m) {
ASSERT(IsPowerOf2(m));
return AddressFrom<T>(OffsetFrom(x) & -m);
}
// Return the smallest multiple of m which is >= x.
template <typename T>
inline T RoundUp(T x, intptr_t m) {
return RoundDown<T>(static_cast<T>(x + m - 1), m);
}
// Increment a pointer until it has the specified alignment.
// This works like RoundUp, but it works correctly on pointer types where
// sizeof(*pointer) might not be 1.
template<class T>
T AlignUp(T pointer, size_t alignment) {
ASSERT(sizeof(pointer) == sizeof(uintptr_t));
uintptr_t pointer_raw = reinterpret_cast<uintptr_t>(pointer);
return reinterpret_cast<T>(RoundUp(pointer_raw, alignment));
}
template <typename T>
int Compare(const T& a, const T& b) {
if (a == b)
return 0;
else if (a < b)
return -1;
else
return 1;
}
template <typename T>
int PointerValueCompare(const T* a, const T* b) {
return Compare<T>(*a, *b);
}
// Compare function to compare the object pointer value of two
// handlified objects. The handles are passed as pointers to the
// handles.
template<typename T> class Handle; // Forward declaration.
template <typename T>
int HandleObjectPointerCompare(const Handle<T>* a, const Handle<T>* b) {
return Compare<T*>(*(*a), *(*b));
}
// Returns the smallest power of two which is >= x. If you pass in a
// number that is already a power of two, it is returned as is.
// Implementation is from "Hacker's Delight" by Henry S. Warren, Jr.,
// figure 3-3, page 48, where the function is called clp2.
inline uint32_t RoundUpToPowerOf2(uint32_t x) {
ASSERT(x <= 0x80000000u);
x = x - 1;
x = x | (x >> 1);
x = x | (x >> 2);
x = x | (x >> 4);
x = x | (x >> 8);
x = x | (x >> 16);
return x + 1;
}
inline uint32_t RoundDownToPowerOf2(uint32_t x) {
uint32_t rounded_up = RoundUpToPowerOf2(x);
if (rounded_up > x) return rounded_up >> 1;
return rounded_up;
}
template <typename T, typename U>
inline bool IsAligned(T value, U alignment) {
return (value & (alignment - 1)) == 0;
}
// Returns true if (addr + offset) is aligned.
inline bool IsAddressAligned(Address addr,
intptr_t alignment,
int offset = 0) {
intptr_t offs = OffsetFrom(addr + offset);
return IsAligned(offs, alignment);
}
// Returns the maximum of the two parameters.
template <typename T>
T Max(T a, T b) {
return a < b ? b : a;
}
// Returns the minimum of the two parameters.
template <typename T>
T Min(T a, T b) {
return a < b ? a : b;
}
Improve code for integral modulus calculation. Depending on what we know about the right operand, we basically do 3 different things (and the code is actually structured this way): * If we statically know that the right operand is a power of 2, we do some bit fiddling instead of doing a "real" modulus calculation. This should actually be done on the Hydrogen level, not on the Lithium level, but this will be a separate CL. * If type feedback tells us that the right operand is a power of 2, we do the same as above, but guarded by conditional deoptimization to make sure that the assumption is still valid. In the long run, we should make this guard visible on the Hydrogen level to make it visible for GVN and other optimizations. * In the general case we only do the minimum steps necessary and don't try to be too clever, because cleverness actually slows us down on real-world code. If we look at the code gerators for LModI, we actually see that we basically have 3 (4 on ARM) fundamentally different translations. I don't really like lumping them together, they should probably be different Lithium instructions. For the time being, I restructured the generators to make this crystal-clear, at the cost of some duplication regarding the power-of-2 cases. This will go away when we do the strength reduction on the Hydrogen level, so I'd like to keep it as it is for now. Note that the MIPS part was only slightly restructured, there is still some work to do there. R=jkummerow@chromium.org Review URL: https://codereview.chromium.org/15769010 git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15034 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
2013-06-10 12:05:54 +00:00
// Returns the absolute value of its argument.
template <typename T>
T Abs(T a) {
return a < 0 ? -a : a;
}
// Returns the negative absolute value of its argument.
template <typename T>
T NegAbs(T a) {
return a < 0 ? a : -a;
}
inline int StrLength(const char* string) {
size_t length = strlen(string);
ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
return static_cast<int>(length);
}
// TODO(svenpanne) Clean up the whole power-of-2 mess.
inline int32_t WhichPowerOf2Abs(int32_t x) {
return (x == kMinInt) ? 31 : WhichPowerOf2(Abs(x));
}
// ----------------------------------------------------------------------------
// BitField is a help template for encoding and decode bitfield with
// unsigned content.
template<class T, int shift, int size, class U>
class BitFieldBase {
public:
// A type U mask of bit field. To use all bits of a type U of x bits
// in a bitfield without compiler warnings we have to compute 2^x
// without using a shift count of x in the computation.
static const U kOne = static_cast<U>(1U);
static const U kMask = ((kOne << shift) << size) - (kOne << shift);
static const U kShift = shift;
static const U kSize = size;
// Value for the field with all bits set.
static const T kMax = static_cast<T>((1U << size) - 1);
// Tells whether the provided value fits into the bit field.
static bool is_valid(T value) {
return (static_cast<U>(value) & ~static_cast<U>(kMax)) == 0;
}
// Returns a type U with the bit field value encoded.
static U encode(T value) {
ASSERT(is_valid(value));
return static_cast<U>(value) << shift;
}
// Returns a type U with the bit field value updated.
static U update(U previous, T value) {
return (previous & ~kMask) | encode(value);
}
// Extracts the bit field from the value.
static T decode(U value) {
return static_cast<T>((value & kMask) >> shift);
}
};
template<class T, int shift, int size>
class BitField : public BitFieldBase<T, shift, size, uint32_t> { };
template<class T, int shift, int size>
class BitField64 : public BitFieldBase<T, shift, size, uint64_t> { };
// ----------------------------------------------------------------------------
// Hash function.
static const uint32_t kZeroHashSeed = 0;
// Thomas Wang, Integer Hash Functions.
// http://www.concentric.net/~Ttwang/tech/inthash.htm
inline uint32_t ComputeIntegerHash(uint32_t key, uint32_t seed) {
uint32_t hash = key;
hash = hash ^ seed;
hash = ~hash + (hash << 15); // hash = (hash << 15) - hash - 1;
hash = hash ^ (hash >> 12);
hash = hash + (hash << 2);
hash = hash ^ (hash >> 4);
hash = hash * 2057; // hash = (hash + (hash << 3)) + (hash << 11);
hash = hash ^ (hash >> 16);
return hash;
}
inline uint32_t ComputeLongHash(uint64_t key) {
uint64_t hash = key;
hash = ~hash + (hash << 18); // hash = (hash << 18) - hash - 1;
hash = hash ^ (hash >> 31);
hash = hash * 21; // hash = (hash + (hash << 2)) + (hash << 4);
hash = hash ^ (hash >> 11);
hash = hash + (hash << 6);
hash = hash ^ (hash >> 22);
return static_cast<uint32_t>(hash);
}
inline uint32_t ComputePointerHash(void* ptr) {
return ComputeIntegerHash(
static_cast<uint32_t>(reinterpret_cast<intptr_t>(ptr)),
v8::internal::kZeroHashSeed);
}
// ----------------------------------------------------------------------------
// Miscellaneous
// A static resource holds a static instance that can be reserved in
// a local scope using an instance of Access. Attempts to re-reserve
// the instance will cause an error.
template <typename T>
class StaticResource {
public:
StaticResource() : is_reserved_(false) {}
private:
template <typename S> friend class Access;
T instance_;
bool is_reserved_;
};
// Locally scoped access to a static resource.
template <typename T>
class Access {
public:
explicit Access(StaticResource<T>* resource)
: resource_(resource)
, instance_(&resource->instance_) {
ASSERT(!resource->is_reserved_);
resource->is_reserved_ = true;
}
~Access() {
resource_->is_reserved_ = false;
resource_ = NULL;
instance_ = NULL;
}
T* value() { return instance_; }
T* operator -> () { return instance_; }
private:
StaticResource<T>* resource_;
T* instance_;
};
template <typename T>
class Vector {
public:
Vector() : start_(NULL), length_(0) {}
Vector(T* data, int length) : start_(data), length_(length) {
ASSERT(length == 0 || (length > 0 && data != NULL));
}
static Vector<T> New(int length) {
return Vector<T>(NewArray<T>(length), length);
}
// Returns a vector using the same backing storage as this one,
// spanning from and including 'from', to but not including 'to'.
Vector<T> SubVector(int from, int to) {
SLOW_ASSERT(to <= length_);
SLOW_ASSERT(from < to);
ASSERT(0 <= from);
return Vector<T>(start() + from, to - from);
}
// Returns the length of the vector.
int length() const { return length_; }
// Returns whether or not the vector is empty.
bool is_empty() const { return length_ == 0; }
// Returns the pointer to the start of the data in the vector.
T* start() const { return start_; }
// Access individual vector elements - checks bounds in debug mode.
T& operator[](int index) const {
ASSERT(0 <= index && index < length_);
return start_[index];
}
const T& at(int index) const { return operator[](index); }
T& first() { return start_[0]; }
T& last() { return start_[length_ - 1]; }
// Returns a clone of this vector with a new backing store.
Vector<T> Clone() const {
T* result = NewArray<T>(length_);
for (int i = 0; i < length_; i++) result[i] = start_[i];
return Vector<T>(result, length_);
}
void Sort(int (*cmp)(const T*, const T*)) {
std::sort(start(), start() + length(), RawComparer(cmp));
}
void Sort() {
std::sort(start(), start() + length());
}
void Truncate(int length) {
ASSERT(length <= length_);
length_ = length;
}
// Releases the array underlying this vector. Once disposed the
// vector is empty.
void Dispose() {
DeleteArray(start_);
start_ = NULL;
length_ = 0;
}
inline Vector<T> operator+(int offset) {
ASSERT(offset < length_);
return Vector<T>(start_ + offset, length_ - offset);
}
// Factory method for creating empty vectors.
static Vector<T> empty() { return Vector<T>(NULL, 0); }
template<typename S>
static Vector<T> cast(Vector<S> input) {
return Vector<T>(reinterpret_cast<T*>(input.start()),
input.length() * sizeof(S) / sizeof(T));
}
protected:
void set_start(T* start) { start_ = start; }
private:
T* start_;
int length_;
class RawComparer {
public:
explicit RawComparer(int (*cmp)(const T*, const T*)) : cmp_(cmp) {}
bool operator()(const T& a, const T& b) {
return cmp_(&a, &b) < 0;
}
private:
int (*cmp_)(const T*, const T*);
};
};
// A pointer that can only be set once and doesn't allow NULL values.
template<typename T>
class SetOncePointer {
public:
SetOncePointer() : pointer_(NULL) { }
bool is_set() const { return pointer_ != NULL; }
T* get() const {
ASSERT(pointer_ != NULL);
return pointer_;
}
void set(T* value) {
ASSERT(pointer_ == NULL && value != NULL);
pointer_ = value;
}
private:
T* pointer_;
};
template <typename T, int kSize>
class EmbeddedVector : public Vector<T> {
public:
EmbeddedVector() : Vector<T>(buffer_, kSize) { }
explicit EmbeddedVector(T initial_value) : Vector<T>(buffer_, kSize) {
for (int i = 0; i < kSize; ++i) {
buffer_[i] = initial_value;
}
}
// When copying, make underlying Vector to reference our buffer.
EmbeddedVector(const EmbeddedVector& rhs)
: Vector<T>(rhs) {
// TODO(jkummerow): Refactor #includes and use OS::MemCopy() instead.
memcpy(buffer_, rhs.buffer_, sizeof(T) * kSize);
set_start(buffer_);
}
EmbeddedVector& operator=(const EmbeddedVector& rhs) {
if (this == &rhs) return *this;
Vector<T>::operator=(rhs);
// TODO(jkummerow): Refactor #includes and use OS::MemCopy() instead.
memcpy(buffer_, rhs.buffer_, sizeof(T) * kSize);
this->set_start(buffer_);
return *this;
}
private:
T buffer_[kSize];
};
template <typename T>
class ScopedVector : public Vector<T> {
public:
explicit ScopedVector(int length) : Vector<T>(NewArray<T>(length), length) { }
~ScopedVector() {
DeleteArray(this->start());
}
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(ScopedVector);
};
#define STATIC_ASCII_VECTOR(x) \
v8::internal::Vector<const uint8_t>(reinterpret_cast<const uint8_t*>(x), \
ARRAY_SIZE(x)-1)
inline Vector<const char> CStrVector(const char* data) {
return Vector<const char>(data, StrLength(data));
}
inline Vector<const uint8_t> OneByteVector(const char* data, int length) {
return Vector<const uint8_t>(reinterpret_cast<const uint8_t*>(data), length);
}
inline Vector<const uint8_t> OneByteVector(const char* data) {
return OneByteVector(data, StrLength(data));
}
inline Vector<char> MutableCStrVector(char* data) {
return Vector<char>(data, StrLength(data));
}
inline Vector<char> MutableCStrVector(char* data, int max) {
int length = StrLength(data);
return Vector<char>(data, (length < max) ? length : max);
}
/*
* A class that collects values into a backing store.
* Specialized versions of the class can allow access to the backing store
* in different ways.
* There is no guarantee that the backing store is contiguous (and, as a
* consequence, no guarantees that consecutively added elements are adjacent
* in memory). The collector may move elements unless it has guaranteed not
* to.
*/
template <typename T, int growth_factor = 2, int max_growth = 1 * MB>
class Collector {
public:
explicit Collector(int initial_capacity = kMinCapacity)
: index_(0), size_(0) {
current_chunk_ = Vector<T>::New(initial_capacity);
}
virtual ~Collector() {
// Free backing store (in reverse allocation order).
current_chunk_.Dispose();
for (int i = chunks_.length() - 1; i >= 0; i--) {
chunks_.at(i).Dispose();
}
}
// Add a single element.
inline void Add(T value) {
if (index_ >= current_chunk_.length()) {
Grow(1);
}
current_chunk_[index_] = value;
index_++;
size_++;
}
// Add a block of contiguous elements and return a Vector backed by the
// memory area.
// A basic Collector will keep this vector valid as long as the Collector
// is alive.
inline Vector<T> AddBlock(int size, T initial_value) {
ASSERT(size > 0);
if (size > current_chunk_.length() - index_) {
Grow(size);
}
T* position = current_chunk_.start() + index_;
index_ += size;
size_ += size;
for (int i = 0; i < size; i++) {
position[i] = initial_value;
}
return Vector<T>(position, size);
}
// Add a contiguous block of elements and return a vector backed
// by the added block.
// A basic Collector will keep this vector valid as long as the Collector
// is alive.
inline Vector<T> AddBlock(Vector<const T> source) {
if (source.length() > current_chunk_.length() - index_) {
Grow(source.length());
}
T* position = current_chunk_.start() + index_;
index_ += source.length();
size_ += source.length();
for (int i = 0; i < source.length(); i++) {
position[i] = source[i];
}
return Vector<T>(position, source.length());
}
// Write the contents of the collector into the provided vector.
void WriteTo(Vector<T> destination) {
ASSERT(size_ <= destination.length());
int position = 0;
for (int i = 0; i < chunks_.length(); i++) {
Vector<T> chunk = chunks_.at(i);
for (int j = 0; j < chunk.length(); j++) {
destination[position] = chunk[j];
position++;
}
}
for (int i = 0; i < index_; i++) {
destination[position] = current_chunk_[i];
position++;
}
}
// Allocate a single contiguous vector, copy all the collected
// elements to the vector, and return it.
// The caller is responsible for freeing the memory of the returned
// vector (e.g., using Vector::Dispose).
Vector<T> ToVector() {
Vector<T> new_store = Vector<T>::New(size_);
WriteTo(new_store);
return new_store;
}
// Resets the collector to be empty.
virtual void Reset();
// Total number of elements added to collector so far.
inline int size() { return size_; }
protected:
static const int kMinCapacity = 16;
List<Vector<T> > chunks_;
Vector<T> current_chunk_; // Block of memory currently being written into.
int index_; // Current index in current chunk.
int size_; // Total number of elements in collector.
// Creates a new current chunk, and stores the old chunk in the chunks_ list.
void Grow(int min_capacity) {
ASSERT(growth_factor > 1);
int new_capacity;
int current_length = current_chunk_.length();
if (current_length < kMinCapacity) {
// The collector started out as empty.
new_capacity = min_capacity * growth_factor;
if (new_capacity < kMinCapacity) new_capacity = kMinCapacity;
} else {
int growth = current_length * (growth_factor - 1);
if (growth > max_growth) {
growth = max_growth;
}
new_capacity = current_length + growth;
if (new_capacity < min_capacity) {
new_capacity = min_capacity + growth;
}
}
NewChunk(new_capacity);
ASSERT(index_ + min_capacity <= current_chunk_.length());
}
// Before replacing the current chunk, give a subclass the option to move
// some of the current data into the new chunk. The function may update
// the current index_ value to represent data no longer in the current chunk.
// Returns the initial index of the new chunk (after copied data).
virtual void NewChunk(int new_capacity) {
Vector<T> new_chunk = Vector<T>::New(new_capacity);
if (index_ > 0) {
chunks_.Add(current_chunk_.SubVector(0, index_));
} else {
current_chunk_.Dispose();
}
current_chunk_ = new_chunk;
index_ = 0;
}
};
/*
* A collector that allows sequences of values to be guaranteed to
* stay consecutive.
* If the backing store grows while a sequence is active, the current
* sequence might be moved, but after the sequence is ended, it will
* not move again.
* NOTICE: Blocks allocated using Collector::AddBlock(int) can move
* as well, if inside an active sequence where another element is added.
*/
template <typename T, int growth_factor = 2, int max_growth = 1 * MB>
class SequenceCollector : public Collector<T, growth_factor, max_growth> {
public:
explicit SequenceCollector(int initial_capacity)
: Collector<T, growth_factor, max_growth>(initial_capacity),
sequence_start_(kNoSequence) { }
virtual ~SequenceCollector() {}
void StartSequence() {
ASSERT(sequence_start_ == kNoSequence);
sequence_start_ = this->index_;
}
Vector<T> EndSequence() {
ASSERT(sequence_start_ != kNoSequence);
int sequence_start = sequence_start_;
sequence_start_ = kNoSequence;
if (sequence_start == this->index_) return Vector<T>();
return this->current_chunk_.SubVector(sequence_start, this->index_);
}
// Drops the currently added sequence, and all collected elements in it.
void DropSequence() {
ASSERT(sequence_start_ != kNoSequence);
int sequence_length = this->index_ - sequence_start_;
this->index_ = sequence_start_;
this->size_ -= sequence_length;
sequence_start_ = kNoSequence;
}
virtual void Reset() {
sequence_start_ = kNoSequence;
this->Collector<T, growth_factor, max_growth>::Reset();
}
private:
static const int kNoSequence = -1;
int sequence_start_;
// Move the currently active sequence to the new chunk.
virtual void NewChunk(int new_capacity) {
if (sequence_start_ == kNoSequence) {
// Fall back on default behavior if no sequence has been started.
this->Collector<T, growth_factor, max_growth>::NewChunk(new_capacity);
return;
}
int sequence_length = this->index_ - sequence_start_;
Vector<T> new_chunk = Vector<T>::New(sequence_length + new_capacity);
ASSERT(sequence_length < new_chunk.length());
for (int i = 0; i < sequence_length; i++) {
new_chunk[i] = this->current_chunk_[sequence_start_ + i];
}
if (sequence_start_ > 0) {
this->chunks_.Add(this->current_chunk_.SubVector(0, sequence_start_));
} else {
this->current_chunk_.Dispose();
}
this->current_chunk_ = new_chunk;
this->index_ = sequence_length;
sequence_start_ = 0;
}
};
// Compare ASCII/16bit chars to ASCII/16bit chars.
template <typename lchar, typename rchar>
inline int CompareCharsUnsigned(const lchar* lhs,
const rchar* rhs,
int chars) {
const lchar* limit = lhs + chars;
#ifdef V8_HOST_CAN_READ_UNALIGNED
if (sizeof(*lhs) == sizeof(*rhs)) {
// Number of characters in a uintptr_t.
static const int kStepSize = sizeof(uintptr_t) / sizeof(*lhs); // NOLINT
while (lhs <= limit - kStepSize) {
if (*reinterpret_cast<const uintptr_t*>(lhs) !=
*reinterpret_cast<const uintptr_t*>(rhs)) {
break;
}
lhs += kStepSize;
rhs += kStepSize;
}
}
#endif
while (lhs < limit) {
int r = static_cast<int>(*lhs) - static_cast<int>(*rhs);
if (r != 0) return r;
++lhs;
++rhs;
}
return 0;
}
template<typename lchar, typename rchar>
inline int CompareChars(const lchar* lhs, const rchar* rhs, int chars) {
ASSERT(sizeof(lchar) <= 2);
ASSERT(sizeof(rchar) <= 2);
if (sizeof(lchar) == 1) {
if (sizeof(rchar) == 1) {
return CompareCharsUnsigned(reinterpret_cast<const uint8_t*>(lhs),
reinterpret_cast<const uint8_t*>(rhs),
chars);
} else {
return CompareCharsUnsigned(reinterpret_cast<const uint8_t*>(lhs),
reinterpret_cast<const uint16_t*>(rhs),
chars);
}
} else {
if (sizeof(rchar) == 1) {
return CompareCharsUnsigned(reinterpret_cast<const uint16_t*>(lhs),
reinterpret_cast<const uint8_t*>(rhs),
chars);
} else {
return CompareCharsUnsigned(reinterpret_cast<const uint16_t*>(lhs),
reinterpret_cast<const uint16_t*>(rhs),
chars);
}
}
}
// Calculate 10^exponent.
inline int TenToThe(int exponent) {
ASSERT(exponent <= 9);
ASSERT(exponent >= 1);
int answer = 10;
for (int i = 1; i < exponent; i++) answer *= 10;
return answer;
}
// The type-based aliasing rule allows the compiler to assume that pointers of
// different types (for some definition of different) never alias each other.
// Thus the following code does not work:
//
// float f = foo();
// int fbits = *(int*)(&f);
//
// The compiler 'knows' that the int pointer can't refer to f since the types
// don't match, so the compiler may cache f in a register, leaving random data
// in fbits. Using C++ style casts makes no difference, however a pointer to
// char data is assumed to alias any other pointer. This is the 'memcpy
// exception'.
//
// Bit_cast uses the memcpy exception to move the bits from a variable of one
// type of a variable of another type. Of course the end result is likely to
// be implementation dependent. Most compilers (gcc-4.2 and MSVC 2005)
// will completely optimize BitCast away.
//
// There is an additional use for BitCast.
// Recent gccs will warn when they see casts that may result in breakage due to
// the type-based aliasing rule. If you have checked that there is no breakage
// you can use BitCast to cast one pointer type to another. This confuses gcc
// enough that it can no longer see that you have cast one pointer type to
// another thus avoiding the warning.
// We need different implementations of BitCast for pointer and non-pointer
// values. We use partial specialization of auxiliary struct to work around
// issues with template functions overloading.
template <class Dest, class Source>
struct BitCastHelper {
STATIC_ASSERT(sizeof(Dest) == sizeof(Source));
INLINE(static Dest cast(const Source& source)) {
Dest dest;
// TODO(jkummerow): Refactor #includes and use OS::MemCopy() instead.
memcpy(&dest, &source, sizeof(dest));
return dest;
}
};
template <class Dest, class Source>
struct BitCastHelper<Dest, Source*> {
INLINE(static Dest cast(Source* source)) {
return BitCastHelper<Dest, uintptr_t>::
cast(reinterpret_cast<uintptr_t>(source));
}
};
template <class Dest, class Source>
INLINE(Dest BitCast(const Source& source));
template <class Dest, class Source>
inline Dest BitCast(const Source& source) {
return BitCastHelper<Dest, Source>::cast(source);
}
template<typename ElementType, int NumElements>
class EmbeddedContainer {
public:
EmbeddedContainer() : elems_() { }
int length() const { return NumElements; }
const ElementType& operator[](int i) const {
ASSERT(i < length());
return elems_[i];
}
ElementType& operator[](int i) {
ASSERT(i < length());
return elems_[i];
}
private:
ElementType elems_[NumElements];
};
template<typename ElementType>
class EmbeddedContainer<ElementType, 0> {
public:
int length() const { return 0; }
const ElementType& operator[](int i) const {
UNREACHABLE();
static ElementType t = 0;
return t;
}
ElementType& operator[](int i) {
UNREACHABLE();
static ElementType t = 0;
return t;
}
};
// Helper class for building result strings in a character buffer. The
// purpose of the class is to use safe operations that checks the
// buffer bounds on all operations in debug mode.
// This simple base class does not allow formatted output.
class SimpleStringBuilder {
public:
// Create a string builder with a buffer of the given size. The
// buffer is allocated through NewArray<char> and must be
// deallocated by the caller of Finalize().
explicit SimpleStringBuilder(int size);
SimpleStringBuilder(char* buffer, int size)
: buffer_(buffer, size), position_(0) { }
~SimpleStringBuilder() { if (!is_finalized()) Finalize(); }
int size() const { return buffer_.length(); }
// Get the current position in the builder.
int position() const {
ASSERT(!is_finalized());
return position_;
}
// Reset the position.
void Reset() { position_ = 0; }
// Add a single character to the builder. It is not allowed to add
// 0-characters; use the Finalize() method to terminate the string
// instead.
void AddCharacter(char c) {
ASSERT(c != '\0');
ASSERT(!is_finalized() && position_ < buffer_.length());
buffer_[position_++] = c;
}
// Add an entire string to the builder. Uses strlen() internally to
// compute the length of the input string.
void AddString(const char* s);
// Add the first 'n' characters of the given string 's' to the
// builder. The input string must have enough characters.
void AddSubstring(const char* s, int n);
// Add character padding to the builder. If count is non-positive,
// nothing is added to the builder.
void AddPadding(char c, int count);
// Add the decimal representation of the value.
void AddDecimalInteger(int value);
// Finalize the string by 0-terminating it and returning the buffer.
char* Finalize();
protected:
Vector<char> buffer_;
int position_;
bool is_finalized() const { return position_ < 0; }
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(SimpleStringBuilder);
};
// A poor man's version of STL's bitset: A bit set of enums E (without explicit
// values), fitting into an integral type T.
template <class E, class T = int>
class EnumSet {
public:
explicit EnumSet(T bits = 0) : bits_(bits) {}
bool IsEmpty() const { return bits_ == 0; }
bool Contains(E element) const { return (bits_ & Mask(element)) != 0; }
bool ContainsAnyOf(const EnumSet& set) const {
return (bits_ & set.bits_) != 0;
}
void Add(E element) { bits_ |= Mask(element); }
void Add(const EnumSet& set) { bits_ |= set.bits_; }
void Remove(E element) { bits_ &= ~Mask(element); }
void Remove(const EnumSet& set) { bits_ &= ~set.bits_; }
void RemoveAll() { bits_ = 0; }
void Intersect(const EnumSet& set) { bits_ &= set.bits_; }
T ToIntegral() const { return bits_; }
bool operator==(const EnumSet& set) { return bits_ == set.bits_; }
bool operator!=(const EnumSet& set) { return bits_ != set.bits_; }
EnumSet<E, T> operator|(const EnumSet& set) const {
return EnumSet<E, T>(bits_ | set.bits_);
}
private:
T Mask(E element) const {
// The strange typing in ASSERT is necessary to avoid stupid warnings, see:
// http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43680
ASSERT(static_cast<int>(element) < static_cast<int>(sizeof(T) * CHAR_BIT));
return static_cast<T>(1) << element;
}
T bits_;
};
// Bit field extraction.
inline uint32_t unsigned_bitextract_32(int msb, int lsb, uint32_t x) {
return (x >> lsb) & ((1 << (1 + msb - lsb)) - 1);
}
inline uint64_t unsigned_bitextract_64(int msb, int lsb, uint64_t x) {
return (x >> lsb) & ((static_cast<uint64_t>(1) << (1 + msb - lsb)) - 1);
}
inline int32_t signed_bitextract_32(int msb, int lsb, int32_t x) {
return (x << (31 - msb)) >> (lsb + 31 - msb);
}
inline int signed_bitextract_64(int msb, int lsb, int x) {
// TODO(jbramley): This is broken for big bitfields.
return (x << (63 - msb)) >> (lsb + 63 - msb);
}
// Check number width.
inline bool is_intn(int64_t x, unsigned n) {
ASSERT((0 < n) && (n < 64));
int64_t limit = static_cast<int64_t>(1) << (n - 1);
return (-limit <= x) && (x < limit);
}
inline bool is_uintn(int64_t x, unsigned n) {
ASSERT((0 < n) && (n < (sizeof(x) * kBitsPerByte)));
return !(x >> n);
}
template <class T>
inline T truncate_to_intn(T x, unsigned n) {
ASSERT((0 < n) && (n < (sizeof(x) * kBitsPerByte)));
return (x & ((static_cast<T>(1) << n) - 1));
}
#define INT_1_TO_63_LIST(V) \
V(1) V(2) V(3) V(4) V(5) V(6) V(7) V(8) \
V(9) V(10) V(11) V(12) V(13) V(14) V(15) V(16) \
V(17) V(18) V(19) V(20) V(21) V(22) V(23) V(24) \
V(25) V(26) V(27) V(28) V(29) V(30) V(31) V(32) \
V(33) V(34) V(35) V(36) V(37) V(38) V(39) V(40) \
V(41) V(42) V(43) V(44) V(45) V(46) V(47) V(48) \
V(49) V(50) V(51) V(52) V(53) V(54) V(55) V(56) \
V(57) V(58) V(59) V(60) V(61) V(62) V(63)
#define DECLARE_IS_INT_N(N) \
inline bool is_int##N(int64_t x) { return is_intn(x, N); }
#define DECLARE_IS_UINT_N(N) \
template <class T> \
inline bool is_uint##N(T x) { return is_uintn(x, N); }
#define DECLARE_TRUNCATE_TO_INT_N(N) \
template <class T> \
inline T truncate_to_int##N(T x) { return truncate_to_intn(x, N); }
INT_1_TO_63_LIST(DECLARE_IS_INT_N)
INT_1_TO_63_LIST(DECLARE_IS_UINT_N)
INT_1_TO_63_LIST(DECLARE_TRUNCATE_TO_INT_N)
#undef DECLARE_IS_INT_N
#undef DECLARE_IS_UINT_N
#undef DECLARE_TRUNCATE_TO_INT_N
class TypeFeedbackId {
public:
explicit TypeFeedbackId(int id) : id_(id) { }
int ToInt() const { return id_; }
static TypeFeedbackId None() { return TypeFeedbackId(kNoneId); }
bool IsNone() const { return id_ == kNoneId; }
private:
static const int kNoneId = -1;
int id_;
};
class BailoutId {
public:
explicit BailoutId(int id) : id_(id) { }
int ToInt() const { return id_; }
static BailoutId None() { return BailoutId(kNoneId); }
static BailoutId FunctionEntry() { return BailoutId(kFunctionEntryId); }
static BailoutId Declarations() { return BailoutId(kDeclarationsId); }
static BailoutId FirstUsable() { return BailoutId(kFirstUsableId); }
static BailoutId StubEntry() { return BailoutId(kStubEntryId); }
bool IsNone() const { return id_ == kNoneId; }
bool operator==(const BailoutId& other) const { return id_ == other.id_; }
bool operator!=(const BailoutId& other) const { return id_ != other.id_; }
private:
static const int kNoneId = -1;
// Using 0 could disguise errors.
static const int kFunctionEntryId = 2;
// This AST id identifies the point after the declarations have been visited.
// We need it to capture the environment effects of declarations that emit
// code (function declarations).
static const int kDeclarationsId = 3;
// Every FunctionState starts with this id.
static const int kFirstUsableId = 4;
// Every compiled stub starts with this id.
static const int kStubEntryId = 5;
int id_;
};
template <class C>
class ContainerPointerWrapper {
public:
typedef typename C::iterator iterator;
typedef typename C::reverse_iterator reverse_iterator;
explicit ContainerPointerWrapper(C* container) : container_(container) {}
iterator begin() { return container_->begin(); }
iterator end() { return container_->end(); }
reverse_iterator rbegin() { return container_->rbegin(); }
reverse_iterator rend() { return container_->rend(); }
private:
C* container_;
};
} } // namespace v8::internal
#endif // V8_UTILS_H_