assembler/LinkBuffer.cpp

   1 /*
   2  * Copyright (C) 2012, 2013, 2014 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 "CodeBlock.h"
  32 #include "JITCode.h"
  33 #include "JSCInlines.h"
  34 #include "Options.h"
  35 #include "VM.h"
  36 #include <wtf/CompilationThread.h>
  37
  38 namespace JSC {
  39
  40 bool shouldShowDisassemblyFor(CodeBlock* codeBlock)
  41 {
  42     if (JITCode::isOptimizingJIT(codeBlock->jitType()) && Options::showDFGDisassembly())
  43         return true;
  44     return Options::showDisassembly();
  45 }
  46
  47 LinkBuffer::CodeRef LinkBuffer::finalizeCodeWithoutDisassembly()
  48 {
  49     performFinalization();
  50
  51     ASSERT(m_didAllocate);
  52     if (m_executableMemory)
  53         return CodeRef(m_executableMemory);
  54
  55     return CodeRef::createSelfManagedCodeRef(MacroAssemblerCodePtr(m_code));
  56 }
  57
  58 LinkBuffer::CodeRef LinkBuffer::finalizeCodeWithDisassembly(const char* format, ...)
  59 {
  60     CodeRef result = finalizeCodeWithoutDisassembly();
  61
  62 #if ENABLE(DISASSEMBLER)
  63     dataLogF("Generated JIT code for ");
  64     va_list argList;
  65     va_start(argList, format);
  66     WTF::dataLogFV(format, argList);
  67     va_end(argList);
  68     dataLogF(":\n");
  69
  70     dataLogF("    Code at [%p, %p):\n", result.code().executableAddress(), static_cast<char*>(result.code().executableAddress()) + result.size());
  71     disassemble(result.code(), m_size, "    ", WTF::dataFile());
  72 #else
  73     UNUSED_PARAM(format);
  74 #endif // ENABLE(DISASSEMBLER)
  75
  76     return result;
  77 }
  78
  79 #if ENABLE(BRANCH_COMPACTION)
  80 static ALWAYS_INLINE void recordLinkOffsets(AssemblerData& assemblerData, int32_t regionStart, int32_t regionEnd, int32_t offset)
  81 {
  82     int32_t ptr = regionStart / sizeof(int32_t);
  83     const int32_t end = regionEnd / sizeof(int32_t);
  84     int32_t* offsets = reinterpret_cast<int32_t*>(assemblerData.buffer());
  85     while (ptr < end)
  86         offsets[ptr++] = offset;
  87 }
  88
  89 template <typename InstructionType>
  90 void LinkBuffer::copyCompactAndLinkCode(MacroAssembler& macroAssembler, void* ownerUID, JITCompilationEffort effort)
  91 {
  92     m_initialSize = macroAssembler.m_assembler.codeSize();
  93     allocate(m_initialSize, ownerUID, effort);
  94     if (didFailToAllocate())
  95         return;
  96     Vector<LinkRecord, 0, UnsafeVectorOverflow>& jumpsToLink = macroAssembler.jumpsToLink();
  97     m_assemblerStorage = macroAssembler.m_assembler.buffer().releaseAssemblerData();
  98     uint8_t* inData = reinterpret_cast<uint8_t*>(m_assemblerStorage.buffer());
  99     uint8_t* outData = reinterpret_cast<uint8_t*>(m_code);
 100     int readPtr = 0;
 101     int writePtr = 0;
 102     unsigned jumpCount = jumpsToLink.size();
 103     for (unsigned i = 0; i < jumpCount; ++i) {
 104         int offset = readPtr - writePtr;
 105         ASSERT(!(offset & 1));
 106
 107         // Copy the instructions from the last jump to the current one.
 108         size_t regionSize = jumpsToLink[i].from() - readPtr;
 109         InstructionType* copySource = reinterpret_cast_ptr<InstructionType*>(inData + readPtr);
 110         InstructionType* copyEnd = reinterpret_cast_ptr<InstructionType*>(inData + readPtr + regionSize);
 111         InstructionType* copyDst = reinterpret_cast_ptr<InstructionType*>(outData + writePtr);
 112         ASSERT(!(regionSize % 2));
 113         ASSERT(!(readPtr % 2));
 114         ASSERT(!(writePtr % 2));
 115         while (copySource != copyEnd)
 116             *copyDst++ = *copySource++;
 117         recordLinkOffsets(m_assemblerStorage, readPtr, jumpsToLink[i].from(), offset);
 118         readPtr += regionSize;
 119         writePtr += regionSize;
 120
 121         // Calculate absolute address of the jump target, in the case of backwards
 122         // branches we need to be precise, forward branches we are pessimistic
 123         const uint8_t* target;
 124         if (jumpsToLink[i].to() >= jumpsToLink[i].from())
 125             target = outData + jumpsToLink[i].to() - offset; // Compensate for what we have collapsed so far
 126         else
 127             target = outData + jumpsToLink[i].to() - executableOffsetFor(jumpsToLink[i].to());
 128
 129         JumpLinkType jumpLinkType = MacroAssembler::computeJumpType(jumpsToLink[i], outData + writePtr, target);
 130         // Compact branch if we can...
 131         if (MacroAssembler::canCompact(jumpsToLink[i].type())) {
 132             // Step back in the write stream
 133             int32_t delta = MacroAssembler::jumpSizeDelta(jumpsToLink[i].type(), jumpLinkType);
 134             if (delta) {
 135                 writePtr -= delta;
 136                 recordLinkOffsets(m_assemblerStorage, jumpsToLink[i].from() - delta, readPtr, readPtr - writePtr);
 137             }
 138         }
 139         jumpsToLink[i].setFrom(writePtr);
 140     }
 141     // Copy everything after the last jump
 142     memcpy(outData + writePtr, inData + readPtr, m_initialSize - readPtr);
 143     recordLinkOffsets(m_assemblerStorage, readPtr, m_initialSize, readPtr - writePtr);
 144
 145     for (unsigned i = 0; i < jumpCount; ++i) {
 146         uint8_t* location = outData + jumpsToLink[i].from();
 147         uint8_t* target = outData + jumpsToLink[i].to() - executableOffsetFor(jumpsToLink[i].to());
 148         MacroAssembler::link(jumpsToLink[i], location, target);
 149     }
 150
 151     jumpsToLink.clear();
 152     shrink(writePtr + m_initialSize - readPtr);
 153
 154 #if DUMP_LINK_STATISTICS
 155     dumpLinkStatistics(m_code, m_initialSize, m_size);
 156 #endif
 157 #if DUMP_CODE
 158     dumpCode(m_code, m_size);
 159 #endif
 160 }
 161 #endif
 162
 163
 164 void LinkBuffer::linkCode(MacroAssembler& macroAssembler, void* ownerUID, JITCompilationEffort effort)
 165 {
 166 #if !ENABLE(BRANCH_COMPACTION)
 167 #if defined(ASSEMBLER_HAS_CONSTANT_POOL) && ASSEMBLER_HAS_CONSTANT_POOL
 168     macroAssembler.m_assembler.buffer().flushConstantPool(false);
 169 #endif
 170     AssemblerBuffer& buffer = macroAssembler.m_assembler.buffer();
 171     allocate(buffer.codeSize(), ownerUID, effort);
 172     if (!m_didAllocate)
 173         return;
 174     ASSERT(m_code);
 175 #if CPU(ARM_TRADITIONAL)
 176     macroAssembler.m_assembler.prepareExecutableCopy(m_code);
 177 #endif
 178     memcpy(m_code, buffer.data(), buffer.codeSize());
 179 #if CPU(MIPS)
 180     macroAssembler.m_assembler.relocateJumps(buffer.data(), m_code);
 181 #endif
 182 #elif CPU(ARM_THUMB2)
 183     copyCompactAndLinkCode<uint16_t>(macroAssembler, ownerUID, effort);
 184 #elif CPU(ARM64)
 185     copyCompactAndLinkCode<uint32_t>(macroAssembler, ownerUID, effort);
 186 #endif
 187 }
 188
 189 void LinkBuffer::allocate(size_t initialSize, void* ownerUID, JITCompilationEffort effort)
 190 {
 191     if (m_code) {
 192         if (initialSize > m_size)
 193             return;
 194
 195         m_didAllocate = true;
 196         m_size = initialSize;
 197         return;
 198     }
 199
 200     m_executableMemory = m_vm->executableAllocator.allocate(*m_vm, initialSize, ownerUID, effort);
 201     if (!m_executableMemory)
 202         return;
 203     ExecutableAllocator::makeWritable(m_executableMemory->start(), m_executableMemory->sizeInBytes());
 204     m_code = m_executableMemory->start();
 205     m_size = initialSize;
 206     m_didAllocate = true;
 207 }
 208
 209 void LinkBuffer::shrink(size_t newSize)
 210 {
 211     if (!m_executableMemory)
 212         return;
 213     m_size = newSize;
 214     m_executableMemory->shrink(m_size);
 215 }
 216
 217 void LinkBuffer::performFinalization()
 218 {
 219 #ifndef NDEBUG
 220     ASSERT(!isCompilationThread());
 221     ASSERT(!m_completed);
 222     ASSERT(isValid());
 223     m_completed = true;
 224 #endif
 225
 226 #if ENABLE(BRANCH_COMPACTION)
 227     ExecutableAllocator::makeExecutable(code(), m_initialSize);
 228 #else
 229     ExecutableAllocator::makeExecutable(code(), m_size);
 230 #endif
 231     MacroAssembler::cacheFlush(code(), m_size);
 232 }
 233
 234 #if DUMP_LINK_STATISTICS
 235 void LinkBuffer::dumpLinkStatistics(void* code, size_t initializeSize, size_t finalSize)
 236 {
 237     static unsigned linkCount = 0;
 238     static unsigned totalInitialSize = 0;
 239     static unsigned totalFinalSize = 0;
 240     linkCount++;
 241     totalInitialSize += initialSize;
 242     totalFinalSize += finalSize;
 243     dataLogF("link %p: orig %u, compact %u (delta %u, %.2f%%)\n",
 244             code, static_cast<unsigned>(initialSize), static_cast<unsigned>(finalSize),
 245             static_cast<unsigned>(initialSize - finalSize),
 246             100.0 * (initialSize - finalSize) / initialSize);
 247     dataLogF("\ttotal %u: orig %u, compact %u (delta %u, %.2f%%)\n",
 248             linkCount, totalInitialSize, totalFinalSize, totalInitialSize - totalFinalSize,
 249             100.0 * (totalInitialSize - totalFinalSize) / totalInitialSize);
 250 }
 251 #endif
 252
 253 #if DUMP_CODE
 254 void LinkBuffer::dumpCode(void* code, size_t size)
 255 {
 256 #if CPU(ARM_THUMB2)
 257     // Dump the generated code in an asm file format that can be assembled and then disassembled
 258     // for debugging purposes. For example, save this output as jit.s:
 259     //   gcc -arch armv7 -c jit.s
 260     //   otool -tv jit.o
 261     static unsigned codeCount = 0;
 262     unsigned short* tcode = static_cast<unsigned short*>(code);
 263     size_t tsize = size / sizeof(short);
 264     char nameBuf[128];
 265     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 266     dataLogF("\t.syntax unified\n"
 267             "\t.section\t__TEXT,__text,regular,pure_instructions\n"
 268             "\t.globl\t%s\n"
 269             "\t.align 2\n"
 270             "\t.code 16\n"
 271             "\t.thumb_func\t%s\n"
 272             "# %p\n"
 273             "%s:\n", nameBuf, nameBuf, code, nameBuf);
 274
 275     for (unsigned i = 0; i < tsize; i++)
 276         dataLogF("\t.short\t0x%x\n", tcode[i]);
 277 #elif CPU(ARM_TRADITIONAL)
 278     //   gcc -c jit.s
 279     //   objdump -D jit.o
 280     static unsigned codeCount = 0;
 281     unsigned int* tcode = static_cast<unsigned int*>(code);
 282     size_t tsize = size / sizeof(unsigned int);
 283     char nameBuf[128];
 284     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 285     dataLogF("\t.globl\t%s\n"
 286             "\t.align 4\n"
 287             "\t.code 32\n"
 288             "\t.text\n"
 289             "# %p\n"
 290             "%s:\n", nameBuf, code, nameBuf);
 291
 292     for (unsigned i = 0; i < tsize; i++)
 293         dataLogF("\t.long\t0x%x\n", tcode[i]);
 294 #endif
 295 }
 296 #endif
 297
 298 } // namespace JSC
 299
 300 #endif // ENABLE(ASSEMBLER)
 301
 302