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/*
* Copyright (C) 2014 Apple Inc. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 APPLE INC. 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.
*/
#include "config.h"
#include "UnlinkedInstructionStream.h"
namespace JSC {
// Unlinked instructions are packed in a simple stream format.
//
// The first byte is always the opcode.
// It's followed by an opcode-dependent number of argument values.
// The first 3 bits of each value determines the format:
//
// 5-bit positive integer (1 byte total)
// 5-bit negative integer (1 byte total)
// 13-bit positive integer (2 bytes total)
// 13-bit negative integer (2 bytes total)
// 5-bit constant register index, based at 0x40000000 (1 byte total)
// 13-bit constant register index, based at 0x40000000 (2 bytes total)
// 32-bit raw value (5 bytes total)
enum PackedValueType {
Positive5Bit = 0,
Negative5Bit,
Positive13Bit,
Negative13Bit,
ConstantRegister5Bit,
ConstantRegister13Bit,
Full32Bit
};
UnlinkedInstructionStream::Reader::Reader(const UnlinkedInstructionStream& stream)
: m_stream(stream)
, m_index(0)
{
}
inline unsigned char UnlinkedInstructionStream::Reader::read8()
{
return m_stream.m_data.data()[m_index++];
}
inline unsigned UnlinkedInstructionStream::Reader::read32()
{
const unsigned char* data = &m_stream.m_data.data()[m_index];
unsigned char type = data[0] >> 5;
switch (type) {
case Positive5Bit:
m_index++;
return data[0];
case Negative5Bit:
m_index++;
return 0xffffffe0 | data[0];
case Positive13Bit:
m_index += 2;
return ((data[0] & 0x1F) << 8) | data[1];
case Negative13Bit:
m_index += 2;
return 0xffffe000 | ((data[0] & 0x1F) << 8) | data[1];
case ConstantRegister5Bit:
m_index++;
return 0x40000000 | (data[0] & 0x1F);
case ConstantRegister13Bit:
m_index += 2;
return 0x40000000 | ((data[0] & 0x1F) << 8) | data[1];
default:
ASSERT(type == Full32Bit);
m_index += 5;
return data[1] | data[2] << 8 | data[3] << 16 | data[4] << 24;
}
}
const UnlinkedInstruction* UnlinkedInstructionStream::Reader::next()
{
m_unpackedBuffer[0].u.opcode = static_cast<OpcodeID>(read8());
unsigned opLength = opcodeLength(m_unpackedBuffer[0].u.opcode);
for (unsigned i = 1; i < opLength; ++i)
m_unpackedBuffer[i].u.index = read32();
return m_unpackedBuffer;
}
static void append8(unsigned char*& ptr, unsigned char value)
{
*(ptr++) = value;
}
static void append32(unsigned char*& ptr, unsigned value)
{
if (!(value & 0xffffffe0)) {
*(ptr++) = value;
return;
}
if ((value & 0xffffffe0) == 0xffffffe0) {
*(ptr++) = (Negative5Bit << 5) | (value & 0x1f);
return;
}
if ((value & 0xffffffe0) == 0x40000000) {
*(ptr++) = (ConstantRegister5Bit << 5) | (value & 0x1f);
return;
}
if (!(value & 0xffffe000)) {
*(ptr++) = (Positive13Bit << 5) | ((value >> 8) & 0x1f);
*(ptr++) = value & 0xff;
return;
}
if ((value & 0xffffe000) == 0xffffe000) {
*(ptr++) = (Negative13Bit << 5) | ((value >> 8) & 0x1f);
*(ptr++) = value & 0xff;
return;
}
if ((value & 0xffffe000) == 0x40000000) {
*(ptr++) = (ConstantRegister13Bit << 5) | ((value >> 8) & 0x1f);
*(ptr++) = value & 0xff;
return;
}
*(ptr++) = Full32Bit << 5;
*(ptr++) = value & 0xff;
*(ptr++) = (value >> 8) & 0xff;
*(ptr++) = (value >> 16) & 0xff;
*(ptr++) = (value >> 24) & 0xff;
}
UnlinkedInstructionStream::UnlinkedInstructionStream(const Vector<UnlinkedInstruction>& instructions)
: m_instructionCount(instructions.size())
{
Vector<unsigned char> buffer;
// Reserve enough space up front so we never have to reallocate when appending.
buffer.resizeToFit(m_instructionCount * 5);
unsigned char* ptr = buffer.data();
const UnlinkedInstruction* instructionsData = instructions.data();
for (unsigned i = 0; i < m_instructionCount;) {
const UnlinkedInstruction* pc = &instructionsData[i];
OpcodeID opcode = pc[0].u.opcode;
append8(ptr, opcode);
unsigned opLength = opcodeLength(opcode);
for (unsigned j = 1; j < opLength; ++j)
append32(ptr, pc[j].u.index);
i += opLength;
}
buffer.shrink(ptr - buffer.data());
m_data = RefCountedArray<unsigned char>(buffer);
}
#ifndef NDEBUG
const RefCountedArray<UnlinkedInstruction>& UnlinkedInstructionStream::unpackForDebugging() const
{
if (!m_unpackedInstructionsForDebugging.size()) {
m_unpackedInstructionsForDebugging = RefCountedArray<UnlinkedInstruction>(m_instructionCount);
Reader instructionReader(*this);
for (unsigned i = 0; !instructionReader.atEnd(); ) {
const UnlinkedInstruction* pc = instructionReader.next();
unsigned opLength = opcodeLength(pc[0].u.opcode);
for (unsigned j = 0; j < opLength; ++j)
m_unpackedInstructionsForDebugging[i++] = pc[j];
}
}
return m_unpackedInstructionsForDebugging;
}
#endif
}
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