Source/JavaScriptCore/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     dataLog("Generated JIT code for ");
  49     va_list argList;
  50     va_start(argList, format);
  51     WTF::dataLogV(format, argList);
  52     va_end(argList);
  53     dataLog(":\n");
  54
  55     dataLog("    Code at [%p, %p):\n", result.code().executableAddress(), static_cast<char*>(result.code().executableAddress()) + result.size());
  56     if (!tryToDisassemble(result.code(), m_size, "    ", WTF::dataFile()))
  57         dataLog("        <no disassembly available>\n");
  58
  59     return result;
  60 }
  61
  62 void LinkBuffer::linkCode(void* ownerUID, JITCompilationEffort effort)
  63 {
  64     ASSERT(!m_code);
  65 #if !ENABLE(BRANCH_COMPACTION)
  66     m_executableMemory = m_assembler->m_assembler.executableCopy(*m_globalData, ownerUID, effort);
  67     if (!m_executableMemory)
  68         return;
  69     m_code = m_executableMemory->start();
  70     m_size = m_assembler->m_assembler.codeSize();
  71     ASSERT(m_code);
  72 #else
  73     m_initialSize = m_assembler->m_assembler.codeSize();
  74     m_executableMemory = m_globalData->executableAllocator.allocate(*m_globalData, m_initialSize, ownerUID, effort);
  75     if (!m_executableMemory)
  76         return;
  77     m_code = (uint8_t*)m_executableMemory->start();
  78     ASSERT(m_code);
  79     ExecutableAllocator::makeWritable(m_code, m_initialSize);
  80     uint8_t* inData = (uint8_t*)m_assembler->unlinkedCode();
  81     uint8_t* outData = reinterpret_cast<uint8_t*>(m_code);
  82     int readPtr = 0;
  83     int writePtr = 0;
  84     Vector<LinkRecord>& jumpsToLink = m_assembler->jumpsToLink();
  85     unsigned jumpCount = jumpsToLink.size();
  86     for (unsigned i = 0; i < jumpCount; ++i) {
  87         int offset = readPtr - writePtr;
  88         ASSERT(!(offset & 1));
  89
  90         // Copy the instructions from the last jump to the current one.
  91         size_t regionSize = jumpsToLink[i].from() - readPtr;
  92         uint16_t* copySource = reinterpret_cast_ptr<uint16_t*>(inData + readPtr);
  93         uint16_t* copyEnd = reinterpret_cast_ptr<uint16_t*>(inData + readPtr + regionSize);
  94         uint16_t* copyDst = reinterpret_cast_ptr<uint16_t*>(outData + writePtr);
  95         ASSERT(!(regionSize % 2));
  96         ASSERT(!(readPtr % 2));
  97         ASSERT(!(writePtr % 2));
  98         while (copySource != copyEnd)
  99             *copyDst++ = *copySource++;
 100         m_assembler->recordLinkOffsets(readPtr, jumpsToLink[i].from(), offset);
 101         readPtr += regionSize;
 102         writePtr += regionSize;
 103
 104         // Calculate absolute address of the jump target, in the case of backwards
 105         // branches we need to be precise, forward branches we are pessimistic
 106         const uint8_t* target;
 107         if (jumpsToLink[i].to() >= jumpsToLink[i].from())
 108             target = outData + jumpsToLink[i].to() - offset; // Compensate for what we have collapsed so far
 109         else
 110             target = outData + jumpsToLink[i].to() - m_assembler->executableOffsetFor(jumpsToLink[i].to());
 111
 112         JumpLinkType jumpLinkType = m_assembler->computeJumpType(jumpsToLink[i], outData + writePtr, target);
 113         // Compact branch if we can...
 114         if (m_assembler->canCompact(jumpsToLink[i].type())) {
 115             // Step back in the write stream
 116             int32_t delta = m_assembler->jumpSizeDelta(jumpsToLink[i].type(), jumpLinkType);
 117             if (delta) {
 118                 writePtr -= delta;
 119                 m_assembler->recordLinkOffsets(jumpsToLink[i].from() - delta, readPtr, readPtr - writePtr);
 120             }
 121         }
 122         jumpsToLink[i].setFrom(writePtr);
 123     }
 124     // Copy everything after the last jump
 125     memcpy(outData + writePtr, inData + readPtr, m_initialSize - readPtr);
 126     m_assembler->recordLinkOffsets(readPtr, m_initialSize, readPtr - writePtr);
 127
 128     for (unsigned i = 0; i < jumpCount; ++i) {
 129         uint8_t* location = outData + jumpsToLink[i].from();
 130         uint8_t* target = outData + jumpsToLink[i].to() - m_assembler->executableOffsetFor(jumpsToLink[i].to());
 131         m_assembler->link(jumpsToLink[i], location, target);
 132     }
 133
 134     jumpsToLink.clear();
 135     m_size = writePtr + m_initialSize - readPtr;
 136     m_executableMemory->shrink(m_size);
 137
 138 #if DUMP_LINK_STATISTICS
 139     dumpLinkStatistics(m_code, m_initialSize, m_size);
 140 #endif
 141 #if DUMP_CODE
 142     dumpCode(m_code, m_size);
 143 #endif
 144 #endif
 145 }
 146
 147 void LinkBuffer::performFinalization()
 148 {
 149 #ifndef NDEBUG
 150     ASSERT(!m_completed);
 151     ASSERT(isValid());
 152     m_completed = true;
 153 #endif
 154
 155 #if ENABLE(BRANCH_COMPACTION)
 156     ExecutableAllocator::makeExecutable(code(), m_initialSize);
 157 #else
 158     ExecutableAllocator::makeExecutable(code(), m_size);
 159 #endif
 160     MacroAssembler::cacheFlush(code(), m_size);
 161 }
 162
 163 #if DUMP_LINK_STATISTICS
 164 void LinkBuffer::dumpLinkStatistics(void* code, size_t initializeSize, size_t finalSize)
 165 {
 166     static unsigned linkCount = 0;
 167     static unsigned totalInitialSize = 0;
 168     static unsigned totalFinalSize = 0;
 169     linkCount++;
 170     totalInitialSize += initialSize;
 171     totalFinalSize += finalSize;
 172     dataLog("link %p: orig %u, compact %u (delta %u, %.2f%%)\n",
 173             code, static_cast<unsigned>(initialSize), static_cast<unsigned>(finalSize),
 174             static_cast<unsigned>(initialSize - finalSize),
 175             100.0 * (initialSize - finalSize) / initialSize);
 176     dataLog("\ttotal %u: orig %u, compact %u (delta %u, %.2f%%)\n",
 177             linkCount, totalInitialSize, totalFinalSize, totalInitialSize - totalFinalSize,
 178             100.0 * (totalInitialSize - totalFinalSize) / totalInitialSize);
 179 }
 180 #endif
 181
 182 #if DUMP_CODE
 183 void LinkBuffer::dumpCode(void* code, size_t size)
 184 {
 185 #if CPU(ARM_THUMB2)
 186     // Dump the generated code in an asm file format that can be assembled and then disassembled
 187     // for debugging purposes. For example, save this output as jit.s:
 188     //   gcc -arch armv7 -c jit.s
 189     //   otool -tv jit.o
 190     static unsigned codeCount = 0;
 191     unsigned short* tcode = static_cast<unsigned short*>(code);
 192     size_t tsize = size / sizeof(short);
 193     char nameBuf[128];
 194     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 195     dataLog("\t.syntax unified\n"
 196             "\t.section\t__TEXT,__text,regular,pure_instructions\n"
 197             "\t.globl\t%s\n"
 198             "\t.align 2\n"
 199             "\t.code 16\n"
 200             "\t.thumb_func\t%s\n"
 201             "# %p\n"
 202             "%s:\n", nameBuf, nameBuf, code, nameBuf);
 203
 204     for (unsigned i = 0; i < tsize; i++)
 205         dataLog("\t.short\t0x%x\n", tcode[i]);
 206 #elif CPU(ARM_TRADITIONAL)
 207     //   gcc -c jit.s
 208     //   objdump -D jit.o
 209     static unsigned codeCount = 0;
 210     unsigned int* tcode = static_cast<unsigned int*>(code);
 211     size_t tsize = size / sizeof(unsigned int);
 212     char nameBuf[128];
 213     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 214     dataLog("\t.globl\t%s\n"
 215             "\t.align 4\n"
 216             "\t.code 32\n"
 217             "\t.text\n"
 218             "# %p\n"
 219             "%s:\n", nameBuf, code, nameBuf);
 220
 221     for (unsigned i = 0; i < tsize; i++)
 222         dataLog("\t.long\t0x%x\n", tcode[i]);
 223 #endif
 224 }
 225 #endif
 226
 227 } // namespace JSC
 228
 229 #endif // ENABLE(ASSEMBLER)
 230
 231