source-position.h

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// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#ifndef V8_CODEGEN_SOURCE_POSITION_H_
#define V8_CODEGEN_SOURCE_POSITION_H_
 
#include <iosfwd>
 
#include "src/base/bit-field.h"
#include "src/common/globals.h"
#include "src/flags/flags.h"
#include "src/handles/handles.h"
 
namespace v8 {
namespace internal {
 
class InstructionStream;
class OptimizedCompilationInfo;
class Script;
class SharedFunctionInfo;
struct SourcePositionInfo;
 
// SourcePosition stores
// - is_external (1 bit true/false)
//
// - if is_external is true:
// - external_line (20 bits, non-negative int)
// - external_file_id (10 bits, non-negative int)
//
// - if is_external is false:
// - script_offset (30 bit non-negative int or kNoSourcePosition)
//
// - In both cases, there is an inlining_id.
// - inlining_id (16 bit non-negative int or kNotInlined).
//
// An "external" SourcePosition is one given by a file_id and a line,
// suitable for embedding references to .cc or .tq files.
// Otherwise, a SourcePosition contains an offset into a JavaScript
// file.
//
// A defined inlining_id refers to positions in
// OptimizedCompilationInfo::inlined_functions or
// DeoptimizationData::InliningPositions, depending on the compilation stage.
class SourcePosition final {
 public:
  explicit SourcePosition(int script_offset = kNoSourcePosition,
                          int inlining_id = kNotInlined)
      : value_(0) {
    SetIsExternal(false);
    SetScriptOffset(script_offset);
    SetInliningId(inlining_id);
  }
 
  // External SourcePositions should use the following method to construct
  // SourcePositions to avoid confusion.
  static SourcePosition External(int line, int file_id) {
    return SourcePosition(line, file_id, kNotInlined);
  }
 
  static SourcePosition Unknown() { return SourcePosition(); }
  bool IsKnown() const { return raw() != SourcePosition::Unknown().raw(); }
  bool isInlined() const {
    if (IsExternal()) return false;
    return InliningId() != kNotInlined;
  }
 
  bool IsExternal() const { return IsExternalField::decode(value_); }
  bool IsJavaScript() const { return !IsExternal(); }
 
  int ExternalLine() const {
    DCHECK(IsExternal());
    return ExternalLineField::decode(value_);
  }
 
  int ExternalFileId() const {
    DCHECK(IsExternal());
    return ExternalFileIdField::decode(value_);
  }
 
  // Assumes that the code object is optimized.
  std::vector<SourcePositionInfo> InliningStack(Isolate* isolate,
                                                Tagged<Code> code) const;
  std::vector<SourcePositionInfo> InliningStack(
      Isolate* isolate, OptimizedCompilationInfo* cinfo) const;
  SourcePositionInfo FirstInfo(Isolate* isolate, Tagged<Code> code) const;
 
  void Print(std::ostream& out, Tagged<Code> code) const;
  void PrintJson(std::ostream& out) const;
 
  int ScriptOffset() const {
    DCHECK(IsJavaScript());
    return ScriptOffsetField::decode(value_) - 1;
  }
  int InliningId() const { return InliningIdField::decode(value_) - 1; }
 
  void SetIsExternal(bool external) {
    value_ = IsExternalField::update(value_, external);
  }
  void SetExternalLine(int line) {
    DCHECK(IsExternal());
    value_ = ExternalLineField::update(value_, line);
  }
  void SetExternalFileId(int file_id) {
    DCHECK(IsExternal());
    value_ = ExternalFileIdField::update(value_, file_id);
  }
 
  void SetScriptOffset(int script_offset) {
    DCHECK(IsJavaScript());
    DCHECK_GE(script_offset, kNoSourcePosition);
    value_ = ScriptOffsetField::update(value_, script_offset + 1);
  }
  void SetInliningId(int inlining_id) {
    DCHECK_GE(inlining_id, kNotInlined);
    value_ = InliningIdField::update(value_, inlining_id + 1);
  }
 
  static const int kNotInlined = -1;
  static_assert(kNoSourcePosition == -1);
 
  int64_t raw() const { return static_cast<int64_t>(value_); }
  static SourcePosition FromRaw(int64_t raw) {
    SourcePosition position = Unknown();
    DCHECK_GE(raw, 0);
    position.value_ = static_cast<uint64_t>(raw);
    return position;
  }
 
 private:
  // Used by SourcePosition::External(line, file_id).
  SourcePosition(int line, int file_id, int inlining_id) : value_(0) {
    SetIsExternal(true);
    SetExternalLine(line);
    SetExternalFileId(file_id);
    SetInliningId(inlining_id);
  }
 
  void Print(std::ostream& out, Tagged<SharedFunctionInfo> function) const;
 
  using IsExternalField = base::BitField64<bool, 0, 1>;
 
  // The two below are only used if IsExternal() is true.
  using ExternalLineField = base::BitField64<int, 1, 20>;
  using ExternalFileIdField = base::BitField64<int, 21, 10>;
 
  // ScriptOffsetField is only used if IsExternal() is false.
  using ScriptOffsetField = base::BitField64<int, 1, 30>;
 
  // InliningId is in the high bits for better compression in
  // SourcePositionTable.
  using InliningIdField = base::BitField64<int, 31, 16>;
 
  // Leaving the highest bit untouched to allow for signed conversion.
  uint64_t value_;
};
 
inline bool operator==(const SourcePosition& lhs, const SourcePosition& rhs) {
  return lhs.raw() == rhs.raw();
}
 
inline bool operator!=(const SourcePosition& lhs, const SourcePosition& rhs) {
  return !(lhs == rhs);
}
 
struct InliningPosition {
  // position of the inlined call
  SourcePosition position = SourcePosition::Unknown();
 
  // references position in DeoptimizationData::literals()
  int inlined_function_id;
};
 
struct WasmInliningPosition {
  // Non-canonicalized (module-specific) index of the inlined function.
  int inlinee_func_index;
  // Whether the call was a tail call.
  bool was_tail_call;
  // Source location of the caller.
  SourcePosition caller_pos;
};
 
struct SourcePositionInfo {
  SourcePositionInfo(Isolate* isolate, SourcePosition pos,
                     DirectHandle<SharedFunctionInfo> f);
 
  SourcePosition position;
  IndirectHandle<SharedFunctionInfo> shared;
  IndirectHandle<Script> script;
  int line = -1;
  int column = -1;
};
 
std::ostream& operator<<(std::ostream& out, const SourcePosition& pos);
 
std::ostream& operator<<(std::ostream& out, const SourcePositionInfo& pos);
std::ostream& operator<<(std::ostream& out,
                         const std::vector<SourcePositionInfo>& stack);
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_CODEGEN_SOURCE_POSITION_H_