js/src/jit/BytecodeAnalysis.h

   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
  54  public:
  55   explicit BytecodeAnalysis(TempAllocator& alloc, JSScript* script);
  56
  57   [[nodiscard]] bool init(TempAllocator& alloc);
  58
  59   BytecodeInfo& info(jsbytecode* pc) {
  60     uint32_t pcOffset = script_->pcToOffset(pc);
  61     MOZ_ASSERT(infos_[pcOffset].initialized);
  62     return infos_[pcOffset];
  63   }
  64
  65   BytecodeInfo* maybeInfo(jsbytecode* pc) {
  66     uint32_t pcOffset = script_->pcToOffset(pc);
  67     if (infos_[pcOffset].initialized) {
  68       return &infos_[pcOffset];
  69     }
  70     return nullptr;
  71   }
  72
  73   void checkWarpSupport(JSOp op);
  74 };
  75
  76 // Whether this script uses the frame's environment chain. The result is cached
  77 // in JitScript and used by WarpBuilder.
  78 bool ScriptUsesEnvironmentChain(JSScript* script);
  79
  80 }  // namespace jit
  81 }  // namespace js
  82
  83 #endif /* jit_BytecodeAnalysis_h */