tor-browser

The Tor Browser
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BytecodeAnalysis.h (2604B)

      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 #ifndef jit_BytecodeAnalysis_h
      8 #define jit_BytecodeAnalysis_h
      9 
     10 #include "jit/JitAllocPolicy.h"
     11 #include "js/Vector.h"
     12 #include "vm/JSScript.h"
     13 
     14 namespace js {
     15 namespace jit {
     16 
     17 // Basic information about bytecodes in the script.  Used to help baseline
     18 // compilation.
     19 struct BytecodeInfo {
     20  static const uint16_t MAX_STACK_DEPTH = 0xffffU;
     21  uint16_t stackDepth;
     22  bool initialized : 1;
     23  bool jumpTarget : 1;
     24 
     25  // If true, this is a JSOp::LoopHead where we can OSR into Ion/Warp code.
     26  bool loopHeadCanOsr : 1;
     27 
     28  // See the comment above normallyReachable in BytecodeAnalysis.cpp for how
     29  // this works.
     30  bool jumpTargetNormallyReachable : 1;
     31 
     32  // True if the script has a resume offset for this bytecode op.
     33  bool hasResumeOffset : 1;
     34 
     35  void init(unsigned depth) {
     36    MOZ_ASSERT(depth <= MAX_STACK_DEPTH);
     37    MOZ_ASSERT_IF(initialized, stackDepth == depth);
     38    initialized = true;
     39    stackDepth = depth;
     40  }
     41 
     42  void setJumpTarget(bool normallyReachable) {
     43    jumpTarget = true;
     44    if (normallyReachable) {
     45      jumpTargetNormallyReachable = true;
     46    }
     47  }
     48 };
     49 
     50 class BytecodeAnalysis {
     51  JSScript* script_;
     52  Vector<BytecodeInfo, 0, JitAllocPolicy> infos_;
     53  bool disableIon_ = false;
     54  bool disableInlining_ = false;
     55 
     56  void disableIon() { disableIon_ = true; }
     57  bool ionDisabled() const { return disableIon_; }
     58  void disableInlining() { disableInlining_ = true; }
     59 
     60 public:
     61  explicit BytecodeAnalysis(TempAllocator& alloc, JSScript* script);
     62 
     63  [[nodiscard]] bool init(TempAllocator& alloc);
     64 
     65  BytecodeInfo& info(jsbytecode* pc) {
     66    uint32_t pcOffset = script_->pcToOffset(pc);
     67    MOZ_ASSERT(infos_[pcOffset].initialized);
     68    return infos_[pcOffset];
     69  }
     70 
     71  BytecodeInfo* maybeInfo(jsbytecode* pc) {
     72    uint32_t pcOffset = script_->pcToOffset(pc);
     73    if (infos_[pcOffset].initialized) {
     74      return &infos_[pcOffset];
     75    }
     76    return nullptr;
     77  }
     78 
     79  void checkWarpSupport(JSOp op);
     80 
     81  bool isIonDisabled() const { return disableIon_; }
     82  bool isInliningDisabled() const { return disableInlining_; }
     83 };
     84 
     85 // Whether this script uses the frame's environment chain. The result is cached
     86 // in JitScript and used by WarpBuilder.
     87 bool ScriptUsesEnvironmentChain(JSScript* script);
     88 
     89 }  // namespace jit
     90 }  // namespace js
     91 
     92 #endif /* jit_BytecodeAnalysis_h */