assembler/LinkBuffer.cpp

   1 /*
   2  * Copyright (C) 2012 Apple Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1. Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2. Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
  17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #include "config.h"
  27 #include "LinkBuffer.h"
  28
  29 #if ENABLE(ASSEMBLER)
  30
  31 #include "Options.h"
  32
  33 namespace JSC {
  34
  35 LinkBuffer::CodeRef LinkBuffer::finalizeCodeWithoutDisassembly()
  36 {
  37     performFinalization();
  38
  39     return CodeRef(m_executableMemory);
  40 }
  41
  42 LinkBuffer::CodeRef LinkBuffer::finalizeCodeWithDisassembly(const char* format, ...)
  43 {
  44     ASSERT(Options::showDisassembly() || Options::showDFGDisassembly());
  45
  46     CodeRef result = finalizeCodeWithoutDisassembly();
  47
  48     dataLogF("Generated JIT code for ");
  49     va_list argList;
  50     va_start(argList, format);
  51     WTF::dataLogFV(format, argList);
  52     va_end(argList);
  53     dataLogF(":\n");
  54
  55     dataLogF("    Code at [%p, %p):\n", result.code().executableAddress(), static_cast<char*>(result.code().executableAddress()) + result.size());
  56     disassemble(result.code(), m_size, "    ", WTF::dataFile());
  57
  58     return result;
  59 }
  60
  61 #if ENABLE(BRANCH_COMPACTION)
  62 template <typename InstructionType>
  63 void LinkBuffer::copyCompactAndLinkCode(void* ownerUID, JITCompilationEffort effort)
  64 {
  65     m_initialSize = m_assembler->m_assembler.codeSize();
  66     m_executableMemory = m_vm->executableAllocator.allocate(*m_vm, m_initialSize, ownerUID, effort);
  67     if (!m_executableMemory)
  68         return;
  69     m_code = (uint8_t*)m_executableMemory->start();
  70     ASSERT(m_code);
  71     ExecutableAllocator::makeWritable(m_code, m_initialSize);
  72     uint8_t* inData = (uint8_t*)m_assembler->unlinkedCode();
  73     uint8_t* outData = reinterpret_cast<uint8_t*>(m_code);
  74     int readPtr = 0;
  75     int writePtr = 0;
  76     Vector<LinkRecord, 0, UnsafeVectorOverflow>& jumpsToLink = m_assembler->jumpsToLink();
  77     unsigned jumpCount = jumpsToLink.size();
  78     for (unsigned i = 0; i < jumpCount; ++i) {
  79         int offset = readPtr - writePtr;
  80         ASSERT(!(offset & 1));
  81
  82         // Copy the instructions from the last jump to the current one.
  83         size_t regionSize = jumpsToLink[i].from() - readPtr;
  84         InstructionType* copySource = reinterpret_cast_ptr<InstructionType*>(inData + readPtr);
  85         InstructionType* copyEnd = reinterpret_cast_ptr<InstructionType*>(inData + readPtr + regionSize);
  86         InstructionType* copyDst = reinterpret_cast_ptr<InstructionType*>(outData + writePtr);
  87         ASSERT(!(regionSize % 2));
  88         ASSERT(!(readPtr % 2));
  89         ASSERT(!(writePtr % 2));
  90         while (copySource != copyEnd)
  91             *copyDst++ = *copySource++;
  92         m_assembler->recordLinkOffsets(readPtr, jumpsToLink[i].from(), offset);
  93         readPtr += regionSize;
  94         writePtr += regionSize;
  95
  96         // Calculate absolute address of the jump target, in the case of backwards
  97         // branches we need to be precise, forward branches we are pessimistic
  98         const uint8_t* target;
  99         if (jumpsToLink[i].to() >= jumpsToLink[i].from())
 100             target = outData + jumpsToLink[i].to() - offset; // Compensate for what we have collapsed so far
 101         else
 102             target = outData + jumpsToLink[i].to() - m_assembler->executableOffsetFor(jumpsToLink[i].to());
 103
 104         JumpLinkType jumpLinkType = m_assembler->computeJumpType(jumpsToLink[i], outData + writePtr, target);
 105         // Compact branch if we can...
 106         if (m_assembler->canCompact(jumpsToLink[i].type())) {
 107             // Step back in the write stream
 108             int32_t delta = m_assembler->jumpSizeDelta(jumpsToLink[i].type(), jumpLinkType);
 109             if (delta) {
 110                 writePtr -= delta;
 111                 m_assembler->recordLinkOffsets(jumpsToLink[i].from() - delta, readPtr, readPtr - writePtr);
 112             }
 113         }
 114         jumpsToLink[i].setFrom(writePtr);
 115     }
 116     // Copy everything after the last jump
 117     memcpy(outData + writePtr, inData + readPtr, m_initialSize - readPtr);
 118     m_assembler->recordLinkOffsets(readPtr, m_initialSize, readPtr - writePtr);
 119
 120     for (unsigned i = 0; i < jumpCount; ++i) {
 121         uint8_t* location = outData + jumpsToLink[i].from();
 122         uint8_t* target = outData + jumpsToLink[i].to() - m_assembler->executableOffsetFor(jumpsToLink[i].to());
 123         m_assembler->link(jumpsToLink[i], location, target);
 124     }
 125
 126     jumpsToLink.clear();
 127     m_size = writePtr + m_initialSize - readPtr;
 128     m_executableMemory->shrink(m_size);
 129
 130 #if DUMP_LINK_STATISTICS
 131     dumpLinkStatistics(m_code, m_initialSize, m_size);
 132 #endif
 133 #if DUMP_CODE
 134     dumpCode(m_code, m_size);
 135 #endif
 136 }
 137 #endif
 138
 139
 140 void LinkBuffer::linkCode(void* ownerUID, JITCompilationEffort effort)
 141 {
 142     ASSERT(!m_code);
 143 #if !ENABLE(BRANCH_COMPACTION)
 144     m_executableMemory = m_assembler->m_assembler.executableCopy(*m_vm, ownerUID, effort);
 145     if (!m_executableMemory)
 146         return;
 147     m_code = m_executableMemory->start();
 148     m_size = m_assembler->m_assembler.codeSize();
 149     ASSERT(m_code);
 150 #elif CPU(ARM_THUMB2)
 151     copyCompactAndLinkCode<uint16_t>(ownerUID, effort);
 152 #elif CPU(ARM64)
 153     copyCompactAndLinkCode<uint32_t>(ownerUID, effort);
 154 #endif
 155 }
 156
 157 void LinkBuffer::performFinalization()
 158 {
 159 #ifndef NDEBUG
 160     ASSERT(!m_completed);
 161     ASSERT(isValid());
 162     m_completed = true;
 163 #endif
 164
 165 #if ENABLE(BRANCH_COMPACTION)
 166     ExecutableAllocator::makeExecutable(code(), m_initialSize);
 167 #else
 168     ExecutableAllocator::makeExecutable(code(), m_size);
 169 #endif
 170     MacroAssembler::cacheFlush(code(), m_size);
 171 }
 172
 173 #if DUMP_LINK_STATISTICS
 174 void LinkBuffer::dumpLinkStatistics(void* code, size_t initializeSize, size_t finalSize)
 175 {
 176     static unsigned linkCount = 0;
 177     static unsigned totalInitialSize = 0;
 178     static unsigned totalFinalSize = 0;
 179     linkCount++;
 180     totalInitialSize += initialSize;
 181     totalFinalSize += finalSize;
 182     dataLogF("link %p: orig %u, compact %u (delta %u, %.2f%%)\n",
 183             code, static_cast<unsigned>(initialSize), static_cast<unsigned>(finalSize),
 184             static_cast<unsigned>(initialSize - finalSize),
 185             100.0 * (initialSize - finalSize) / initialSize);
 186     dataLogF("\ttotal %u: orig %u, compact %u (delta %u, %.2f%%)\n",
 187             linkCount, totalInitialSize, totalFinalSize, totalInitialSize - totalFinalSize,
 188             100.0 * (totalInitialSize - totalFinalSize) / totalInitialSize);
 189 }
 190 #endif
 191
 192 #if DUMP_CODE
 193 void LinkBuffer::dumpCode(void* code, size_t size)
 194 {
 195 #if CPU(ARM_THUMB2)
 196     // Dump the generated code in an asm file format that can be assembled and then disassembled
 197     // for debugging purposes. For example, save this output as jit.s:
 198     //   gcc -arch armv7 -c jit.s
 199     //   otool -tv jit.o
 200     static unsigned codeCount = 0;
 201     unsigned short* tcode = static_cast<unsigned short*>(code);
 202     size_t tsize = size / sizeof(short);
 203     char nameBuf[128];
 204     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 205     dataLogF("\t.syntax unified\n"
 206             "\t.section\t__TEXT,__text,regular,pure_instructions\n"
 207             "\t.globl\t%s\n"
 208             "\t.align 2\n"
 209             "\t.code 16\n"
 210             "\t.thumb_func\t%s\n"
 211             "# %p\n"
 212             "%s:\n", nameBuf, nameBuf, code, nameBuf);
 213
 214     for (unsigned i = 0; i < tsize; i++)
 215         dataLogF("\t.short\t0x%x\n", tcode[i]);
 216 #elif CPU(ARM_TRADITIONAL)
 217     //   gcc -c jit.s
 218     //   objdump -D jit.o
 219     static unsigned codeCount = 0;
 220     unsigned int* tcode = static_cast<unsigned int*>(code);
 221     size_t tsize = size / sizeof(unsigned int);
 222     char nameBuf[128];
 223     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 224     dataLogF("\t.globl\t%s\n"
 225             "\t.align 4\n"
 226             "\t.code 32\n"
 227             "\t.text\n"
 228             "# %p\n"
 229             "%s:\n", nameBuf, code, nameBuf);
 230
 231     for (unsigned i = 0; i < tsize; i++)
 232         dataLogF("\t.long\t0x%x\n", tcode[i]);
 233 #endif
 234 }
 235 #endif
 236
 237 } // namespace JSC
 238
 239 #endif // ENABLE(ASSEMBLER)
 240
 241