tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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Assembler-x86.cpp (2629B)

      1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
      2 * vim: set ts=8 sts=2 et sw=2 tw=80:
      3 * This Source Code Form is subject to the terms of the Mozilla Public
      4 * License, v. 2.0. If a copy of the MPL was not distributed with this
      5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      6 
      7 #include "jit/x86/Assembler-x86.h"
      8 
      9 #include "gc/Marking.h"
     10 #include "util/Memory.h"
     11 #include "wasm/WasmFrame.h"
     12 
     13 using namespace js;
     14 using namespace js::jit;
     15 
     16 ABIArg ABIArgGenerator::next(MIRType type) {
     17  switch (type) {
     18    case MIRType::Int32:
     19    case MIRType::Float32:
     20    case MIRType::Pointer:
     21    case MIRType::WasmAnyRef:
     22    case MIRType::WasmArrayData:
     23    case MIRType::StackResults:
     24      current_ = ABIArg(stackOffset_);
     25      stackOffset_ += sizeof(uint32_t);
     26      break;
     27    case MIRType::Double:
     28    case MIRType::Int64:
     29      current_ = ABIArg(stackOffset_);
     30      stackOffset_ += sizeof(uint64_t);
     31      break;
     32    case MIRType::Simd128:
     33      MOZ_ASSERT(kind_ == ABIKind::Wasm);
     34      // On Win64, >64 bit args need to be passed by reference.  However, wasm
     35      // doesn't allow passing SIMD values to JS, so the only way to reach this
     36      // is wasm to wasm calls.  Ergo we can break the native ABI here and use
     37      // the Wasm ABI instead.
     38      stackOffset_ = AlignBytes(stackOffset_, SimdMemoryAlignment);
     39      current_ = ABIArg(stackOffset_);
     40      stackOffset_ += Simd128DataSize;
     41      break;
     42    default:
     43      MOZ_CRASH("Unexpected argument type");
     44  }
     45  return current_;
     46 }
     47 
     48 void Assembler::executableCopy(uint8_t* buffer) {
     49  AssemblerX86Shared::executableCopy(buffer);
     50  for (RelativePatch& rp : jumps_) {
     51    X86Encoding::SetRel32(buffer + rp.offset, rp.target);
     52  }
     53 }
     54 
     55 class RelocationIterator {
     56  CompactBufferReader reader_;
     57  uint32_t offset_;
     58 
     59 public:
     60  explicit RelocationIterator(CompactBufferReader& reader) : reader_(reader) {}
     61 
     62  bool read() {
     63    if (!reader_.more()) {
     64      return false;
     65    }
     66    offset_ = reader_.readUnsigned();
     67    return true;
     68  }
     69 
     70  uint32_t offset() const { return offset_; }
     71 };
     72 
     73 static inline JitCode* CodeFromJump(uint8_t* jump) {
     74  uint8_t* target = (uint8_t*)X86Encoding::GetRel32Target(jump);
     75  return JitCode::FromExecutable(target);
     76 }
     77 
     78 void Assembler::TraceJumpRelocations(JSTracer* trc, JitCode* code,
     79                                     CompactBufferReader& reader) {
     80  RelocationIterator iter(reader);
     81  while (iter.read()) {
     82    JitCode* child = CodeFromJump(code->raw() + iter.offset());
     83    TraceManuallyBarrieredEdge(trc, &child, "rel32");
     84    MOZ_ASSERT(child == CodeFromJump(code->raw() + iter.offset()));
     85  }
     86 }