The Tor Browser: js/src/jit/x64/Assembler-x64.cpp@6474c204b198 (annotated)

js/src/jit/x64/Assembler-x64.cpp@6474c204b198 (annotated)

js/src/jit/x64/Assembler-x64.cpp

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
  * vim: set ts=8 sts=4 et sw=4 tw=99:
  * This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 #include "jit/x64/Assembler-x64.h"
 #include "gc/Marking.h"
 using namespace js;
 using namespace js::jit;
 ABIArgGenerator::ABIArgGenerator()
   :
 #if defined(XP_WIN)
     regIndex_(0),
     stackOffset_(ShadowStackSpace),
 #else
     intRegIndex_(0),
     floatRegIndex_(0),
     stackOffset_(0),
 #endif
     current_()
 {}
 ABIArg
 ABIArgGenerator::next(MIRType type)
 {
 #if defined(XP_WIN)
     JS_STATIC_ASSERT(NumIntArgRegs == NumFloatArgRegs);
     if (regIndex_ == NumIntArgRegs) {
         current_ = ABIArg(stackOffset_);
         stackOffset_ += sizeof(uint64_t);
         return current_;
     }
     switch (type) {
       case MIRType_Int32:
       case MIRType_Pointer:
         current_ = ABIArg(IntArgRegs[regIndex_++]);
         break;
       case MIRType_Float32:
       case MIRType_Double:
         current_ = ABIArg(FloatArgRegs[regIndex_++]);
         break;
       default:
         MOZ_ASSUME_UNREACHABLE("Unexpected argument type");
     }
     return current_;
 #else
     switch (type) {
       case MIRType_Int32:
       case MIRType_Pointer:
         if (intRegIndex_ == NumIntArgRegs) {
             current_ = ABIArg(stackOffset_);
             stackOffset_ += sizeof(uint64_t);
             break;
         }
         current_ = ABIArg(IntArgRegs[intRegIndex_++]);
         break;
       case MIRType_Double:
       case MIRType_Float32:
         if (floatRegIndex_ == NumFloatArgRegs) {
             current_ = ABIArg(stackOffset_);
             stackOffset_ += sizeof(uint64_t);
             break;
         }
         current_ = ABIArg(FloatArgRegs[floatRegIndex_++]);
         break;
       default:
         MOZ_ASSUME_UNREACHABLE("Unexpected argument type");
     }
     return current_;
 #endif
 }
 // Avoid r11, which is the MacroAssembler's ScratchReg.
 const Register ABIArgGenerator::NonArgReturnVolatileReg0 = r10;
 const Register ABIArgGenerator::NonArgReturnVolatileReg1 = r12;
 const Register ABIArgGenerator::NonVolatileReg = r13;
 void
 Assembler::writeRelocation(JmpSrc src, Relocation::Kind reloc)
 {
     if (!jumpRelocations_.length()) {
         // The jump relocation table starts with a fixed-width integer pointing
         // to the start of the extended jump table. But, we don't know the
         // actual extended jump table offset yet, so write a 0 which we'll
         // patch later.
         jumpRelocations_.writeFixedUint32_t(0);
     }
     if (reloc == Relocation::JITCODE) {
         jumpRelocations_.writeUnsigned(src.offset());
         jumpRelocations_.writeUnsigned(jumps_.length());
     }
 }
 void
 Assembler::addPendingJump(JmpSrc src, ImmPtr target, Relocation::Kind reloc)
 {
     JS_ASSERT(target.value != nullptr);
     // Emit reloc before modifying the jump table, since it computes a 0-based
     // index. This jump is not patchable at runtime.
     if (reloc == Relocation::JITCODE)
         writeRelocation(src, reloc);
     enoughMemory_ &= jumps_.append(RelativePatch(src.offset(), target.value, reloc));
 }
 size_t
 Assembler::addPatchableJump(JmpSrc src, Relocation::Kind reloc)
 {
     // This jump is patchable at runtime so we always need to make sure the
     // jump table is emitted.
     writeRelocation(src, reloc);
     size_t index = jumps_.length();
     enoughMemory_ &= jumps_.append(RelativePatch(src.offset(), nullptr, reloc));
     return index;
 }
 /* static */
 uint8_t *
 Assembler::PatchableJumpAddress(JitCode *code, size_t index)
 {
     // The assembler stashed the offset into the code of the fragments used
     // for far jumps at the start of the relocation table.
     uint32_t jumpOffset = * (uint32_t *) code->jumpRelocTable();
     jumpOffset += index * SizeOfJumpTableEntry;
     JS_ASSERT(jumpOffset + SizeOfExtendedJump <= code->instructionsSize());
     return code->raw() + jumpOffset;
 }
 /* static */
 void
 Assembler::PatchJumpEntry(uint8_t *entry, uint8_t *target)
 {
     uint8_t **index = (uint8_t **) (entry + SizeOfExtendedJump - sizeof(void*));
     *index = target;
 }
 void
 Assembler::finish()
 {
     if (!jumps_.length() || oom())
         return;
     // Emit the jump table.
     masm.align(SizeOfJumpTableEntry);
     extendedJumpTable_ = masm.size();
     // Now that we know the offset to the jump table, squirrel it into the
     // jump relocation buffer if any JitCode references exist and must be
     // tracked for GC.
     JS_ASSERT_IF(jumpRelocations_.length(), jumpRelocations_.length() >= sizeof(uint32_t));
     if (jumpRelocations_.length())
         *(uint32_t *)jumpRelocations_.buffer() = extendedJumpTable_;
     // Zero the extended jumps table.
     for (size_t i = 0; i < jumps_.length(); i++) {
 #ifdef DEBUG
         size_t oldSize = masm.size();
 #endif
         masm.jmp_rip(2);
         JS_ASSERT(masm.size() - oldSize == 6);
         // Following an indirect branch with ud2 hints to the hardware that
         // there's no fall-through. This also aligns the 64-bit immediate.
         masm.ud2();
         JS_ASSERT(masm.size() - oldSize == 8);
         masm.immediate64(0);
         JS_ASSERT(masm.size() - oldSize == SizeOfExtendedJump);
         JS_ASSERT(masm.size() - oldSize == SizeOfJumpTableEntry);
     }
 }
 void
 Assembler::executableCopy(uint8_t *buffer)
 {
     AssemblerX86Shared::executableCopy(buffer);
     for (size_t i = 0; i < jumps_.length(); i++) {
         RelativePatch &rp = jumps_[i];
         uint8_t *src = buffer + rp.offset;
         if (!rp.target) {
             // The patch target is nullptr for jumps that have been linked to
             // a label within the same code block, but may be repatched later
             // to jump to a different code block.
             continue;
         }
         if (JSC::X86Assembler::canRelinkJump(src, rp.target)) {
             JSC::X86Assembler::setRel32(src, rp.target);
         } else {
             // An extended jump table must exist, and its offset must be in
             // range.
             JS_ASSERT(extendedJumpTable_);
             JS_ASSERT((extendedJumpTable_ + i * SizeOfJumpTableEntry) <= size() - SizeOfJumpTableEntry);
             // Patch the jump to go to the extended jump entry.
             uint8_t *entry = buffer + extendedJumpTable_ + i * SizeOfJumpTableEntry;
             JSC::X86Assembler::setRel32(src, entry);
             // Now patch the pointer, note that we need to align it to
             // *after* the extended jump, i.e. after the 64-bit immedate.
             JSC::X86Assembler::repatchPointer(entry + SizeOfExtendedJump, rp.target);
         }
     }
 }
 class RelocationIterator
 {
     CompactBufferReader reader_;
     uint32_t tableStart_;
     uint32_t offset_;
     uint32_t extOffset_;
   public:
     RelocationIterator(CompactBufferReader &reader)
       : reader_(reader)
     {
         tableStart_ = reader_.readFixedUint32_t();
     }
     bool read() {
         if (!reader_.more())
             return false;
         offset_ = reader_.readUnsigned();
         extOffset_ = reader_.readUnsigned();
         return true;
     }
     uint32_t offset() const {
         return offset_;
     }
     uint32_t extendedOffset() const {
         return extOffset_;
     }
 };
 JitCode *
 Assembler::CodeFromJump(JitCode *code, uint8_t *jump)
 {
     uint8_t *target = (uint8_t *)JSC::X86Assembler::getRel32Target(jump);
     if (target >= code->raw() && target < code->raw() + code->instructionsSize()) {
         // This jump is within the code buffer, so it has been redirected to
         // the extended jump table.
         JS_ASSERT(target + SizeOfJumpTableEntry <= code->raw() + code->instructionsSize());
         target = (uint8_t *)JSC::X86Assembler::getPointer(target + SizeOfExtendedJump);
     }
     return JitCode::FromExecutable(target);
 }
 void
 Assembler::TraceJumpRelocations(JSTracer *trc, JitCode *code, CompactBufferReader &reader)
 {
     RelocationIterator iter(reader);
     while (iter.read()) {
         JitCode *child = CodeFromJump(code, code->raw() + iter.offset());
         MarkJitCodeUnbarriered(trc, &child, "rel32");
         JS_ASSERT(child == CodeFromJump(code, code->raw() + iter.offset()));
     }
 }

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js/src/jit/x64/Assembler-x64.cpp@6474c204b198 (annotated)

js/src/jit/x64/Assembler-x64.cpp