assembler/LinkBuffer.cpp

   1 /*
   2  * Copyright (C) 2012-2015 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 (m_alreadyDisassembled)
  63         return result;
  64
  65     StringPrintStream out;
  66     out.printf("Generated JIT code for ");
  67     va_list argList;
  68     va_start(argList, format);
  69     out.vprintf(format, argList);
  70     va_end(argList);
  71     out.printf(":\n");
  72
  73     out.printf("    Code at [%p, %p):\n", result.code().executableAddress(), static_cast<char*>(result.code().executableAddress()) + result.size());
  74
  75     CString header = out.toCString();
  76
  77     if (Options::asyncDisassembly()) {
  78         disassembleAsynchronously(header, result, m_size, "    ");
  79         return result;
  80     }
  81
  82     dataLog(header);
  83     disassemble(result.code(), m_size, "    ", WTF::dataFile());
  84
  85     return result;
  86 }
  87
  88 #if ENABLE(BRANCH_COMPACTION)
  89 static ALWAYS_INLINE void recordLinkOffsets(AssemblerData& assemblerData, int32_t regionStart, int32_t regionEnd, int32_t offset)
  90 {
  91     int32_t ptr = regionStart / sizeof(int32_t);
  92     const int32_t end = regionEnd / sizeof(int32_t);
  93     int32_t* offsets = reinterpret_cast<int32_t*>(assemblerData.buffer());
  94     while (ptr < end)
  95         offsets[ptr++] = offset;
  96 }
  97
  98 template <typename InstructionType>
  99 void LinkBuffer::copyCompactAndLinkCode(MacroAssembler& macroAssembler, void* ownerUID, JITCompilationEffort effort)
 100 {
 101     m_initialSize = macroAssembler.m_assembler.codeSize();
 102     allocate(m_initialSize, ownerUID, effort);
 103     if (didFailToAllocate())
 104         return;
 105     Vector<LinkRecord, 0, UnsafeVectorOverflow>& jumpsToLink = macroAssembler.jumpsToLink();
 106     m_assemblerStorage = macroAssembler.m_assembler.buffer().releaseAssemblerData();
 107     uint8_t* inData = reinterpret_cast<uint8_t*>(m_assemblerStorage.buffer());
 108     uint8_t* outData = reinterpret_cast<uint8_t*>(m_code);
 109     int readPtr = 0;
 110     int writePtr = 0;
 111     unsigned jumpCount = jumpsToLink.size();
 112     for (unsigned i = 0; i < jumpCount; ++i) {
 113         int offset = readPtr - writePtr;
 114         ASSERT(!(offset & 1));
 115
 116         // Copy the instructions from the last jump to the current one.
 117         size_t regionSize = jumpsToLink[i].from() - readPtr;
 118         InstructionType* copySource = reinterpret_cast_ptr<InstructionType*>(inData + readPtr);
 119         InstructionType* copyEnd = reinterpret_cast_ptr<InstructionType*>(inData + readPtr + regionSize);
 120         InstructionType* copyDst = reinterpret_cast_ptr<InstructionType*>(outData + writePtr);
 121         ASSERT(!(regionSize % 2));
 122         ASSERT(!(readPtr % 2));
 123         ASSERT(!(writePtr % 2));
 124         while (copySource != copyEnd)
 125             *copyDst++ = *copySource++;
 126         recordLinkOffsets(m_assemblerStorage, readPtr, jumpsToLink[i].from(), offset);
 127         readPtr += regionSize;
 128         writePtr += regionSize;
 129
 130         // Calculate absolute address of the jump target, in the case of backwards
 131         // branches we need to be precise, forward branches we are pessimistic
 132         const uint8_t* target;
 133         if (jumpsToLink[i].to() >= jumpsToLink[i].from())
 134             target = outData + jumpsToLink[i].to() - offset; // Compensate for what we have collapsed so far
 135         else
 136             target = outData + jumpsToLink[i].to() - executableOffsetFor(jumpsToLink[i].to());
 137
 138         JumpLinkType jumpLinkType = MacroAssembler::computeJumpType(jumpsToLink[i], outData + writePtr, target);
 139         // Compact branch if we can...
 140         if (MacroAssembler::canCompact(jumpsToLink[i].type())) {
 141             // Step back in the write stream
 142             int32_t delta = MacroAssembler::jumpSizeDelta(jumpsToLink[i].type(), jumpLinkType);
 143             if (delta) {
 144                 writePtr -= delta;
 145                 recordLinkOffsets(m_assemblerStorage, jumpsToLink[i].from() - delta, readPtr, readPtr - writePtr);
 146             }
 147         }
 148         jumpsToLink[i].setFrom(writePtr);
 149     }
 150     // Copy everything after the last jump
 151     memcpy(outData + writePtr, inData + readPtr, m_initialSize - readPtr);
 152     recordLinkOffsets(m_assemblerStorage, readPtr, m_initialSize, readPtr - writePtr);
 153
 154     for (unsigned i = 0; i < jumpCount; ++i) {
 155         uint8_t* location = outData + jumpsToLink[i].from();
 156         uint8_t* target = outData + jumpsToLink[i].to() - executableOffsetFor(jumpsToLink[i].to());
 157         MacroAssembler::link(jumpsToLink[i], location, target);
 158     }
 159
 160     jumpsToLink.clear();
 161     shrink(writePtr + m_initialSize - readPtr);
 162
 163 #if DUMP_LINK_STATISTICS
 164     dumpLinkStatistics(m_code, m_initialSize, m_size);
 165 #endif
 166 #if DUMP_CODE
 167     dumpCode(m_code, m_size);
 168 #endif
 169 }
 170 #endif
 171
 172
 173 void LinkBuffer::linkCode(MacroAssembler& macroAssembler, void* ownerUID, JITCompilationEffort effort)
 174 {
 175 #if !ENABLE(BRANCH_COMPACTION)
 176 #if defined(ASSEMBLER_HAS_CONSTANT_POOL) && ASSEMBLER_HAS_CONSTANT_POOL
 177     macroAssembler.m_assembler.buffer().flushConstantPool(false);
 178 #endif
 179     AssemblerBuffer& buffer = macroAssembler.m_assembler.buffer();
 180     allocate(buffer.codeSize(), ownerUID, effort);
 181     if (!m_didAllocate)
 182         return;
 183     ASSERT(m_code);
 184 #if CPU(ARM_TRADITIONAL)
 185     macroAssembler.m_assembler.prepareExecutableCopy(m_code);
 186 #endif
 187     memcpy(m_code, buffer.data(), buffer.codeSize());
 188 #if CPU(MIPS)
 189     macroAssembler.m_assembler.relocateJumps(buffer.data(), m_code);
 190 #endif
 191 #elif CPU(ARM_THUMB2)
 192     copyCompactAndLinkCode<uint16_t>(macroAssembler, ownerUID, effort);
 193 #elif CPU(ARM64)
 194     copyCompactAndLinkCode<uint32_t>(macroAssembler, ownerUID, effort);
 195 #endif
 196 }
 197
 198 void LinkBuffer::allocate(size_t initialSize, void* ownerUID, JITCompilationEffort effort)
 199 {
 200     if (m_code) {
 201         if (initialSize > m_size)
 202             return;
 203
 204         m_didAllocate = true;
 205         m_size = initialSize;
 206         return;
 207     }
 208
 209     m_executableMemory = m_vm->executableAllocator.allocate(*m_vm, initialSize, ownerUID, effort);
 210     if (!m_executableMemory)
 211         return;
 212     ExecutableAllocator::makeWritable(m_executableMemory->start(), m_executableMemory->sizeInBytes());
 213     m_code = m_executableMemory->start();
 214     m_size = initialSize;
 215     m_didAllocate = true;
 216 }
 217
 218 void LinkBuffer::shrink(size_t newSize)
 219 {
 220     if (!m_executableMemory)
 221         return;
 222     m_size = newSize;
 223     m_executableMemory->shrink(m_size);
 224 }
 225
 226 void LinkBuffer::performFinalization()
 227 {
 228 #ifndef NDEBUG
 229     ASSERT(!isCompilationThread());
 230     ASSERT(!m_completed);
 231     ASSERT(isValid());
 232     m_completed = true;
 233 #endif
 234
 235 #if ENABLE(BRANCH_COMPACTION)
 236     ExecutableAllocator::makeExecutable(code(), m_initialSize);
 237 #else
 238     ExecutableAllocator::makeExecutable(code(), m_size);
 239 #endif
 240     MacroAssembler::cacheFlush(code(), m_size);
 241 }
 242
 243 #if DUMP_LINK_STATISTICS
 244 void LinkBuffer::dumpLinkStatistics(void* code, size_t initializeSize, size_t finalSize)
 245 {
 246     static unsigned linkCount = 0;
 247     static unsigned totalInitialSize = 0;
 248     static unsigned totalFinalSize = 0;
 249     linkCount++;
 250     totalInitialSize += initialSize;
 251     totalFinalSize += finalSize;
 252     dataLogF("link %p: orig %u, compact %u (delta %u, %.2f%%)\n",
 253             code, static_cast<unsigned>(initialSize), static_cast<unsigned>(finalSize),
 254             static_cast<unsigned>(initialSize - finalSize),
 255             100.0 * (initialSize - finalSize) / initialSize);
 256     dataLogF("\ttotal %u: orig %u, compact %u (delta %u, %.2f%%)\n",
 257             linkCount, totalInitialSize, totalFinalSize, totalInitialSize - totalFinalSize,
 258             100.0 * (totalInitialSize - totalFinalSize) / totalInitialSize);
 259 }
 260 #endif
 261
 262 #if DUMP_CODE
 263 void LinkBuffer::dumpCode(void* code, size_t size)
 264 {
 265 #if CPU(ARM_THUMB2)
 266     // Dump the generated code in an asm file format that can be assembled and then disassembled
 267     // for debugging purposes. For example, save this output as jit.s:
 268     //   gcc -arch armv7 -c jit.s
 269     //   otool -tv jit.o
 270     static unsigned codeCount = 0;
 271     unsigned short* tcode = static_cast<unsigned short*>(code);
 272     size_t tsize = size / sizeof(short);
 273     char nameBuf[128];
 274     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 275     dataLogF("\t.syntax unified\n"
 276             "\t.section\t__TEXT,__text,regular,pure_instructions\n"
 277             "\t.globl\t%s\n"
 278             "\t.align 2\n"
 279             "\t.code 16\n"
 280             "\t.thumb_func\t%s\n"
 281             "# %p\n"
 282             "%s:\n", nameBuf, nameBuf, code, nameBuf);
 283
 284     for (unsigned i = 0; i < tsize; i++)
 285         dataLogF("\t.short\t0x%x\n", tcode[i]);
 286 #elif CPU(ARM_TRADITIONAL)
 287     //   gcc -c jit.s
 288     //   objdump -D jit.o
 289     static unsigned codeCount = 0;
 290     unsigned int* tcode = static_cast<unsigned int*>(code);
 291     size_t tsize = size / sizeof(unsigned int);
 292     char nameBuf[128];
 293     snprintf(nameBuf, sizeof(nameBuf), "_jsc_jit%u", codeCount++);
 294     dataLogF("\t.globl\t%s\n"
 295             "\t.align 4\n"
 296             "\t.code 32\n"
 297             "\t.text\n"
 298             "# %p\n"
 299             "%s:\n", nameBuf, code, nameBuf);
 300
 301     for (unsigned i = 0; i < tsize; i++)
 302         dataLogF("\t.long\t0x%x\n", tcode[i]);
 303 #endif
 304 }
 305 #endif
 306
 307 } // namespace JSC
 308
 309 #endif // ENABLE(ASSEMBLER)
 310
 311