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// Copyright 2019 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_WASM_WASM_MODULE_SOURCEMAP_H_
#define V8_WASM_WASM_MODULE_SOURCEMAP_H_
#include <string>
#include <vector>
#include "include/v8.h"
#include "src/base/macros.h"
namespace v8 {
namespace internal {
namespace wasm {
// The class is for decoding and managing source map generated by a WebAssembly
// toolchain (e.g. Emscripten). This implementation mostly complies with the
// specification (https://sourcemaps.info/spec.html), with the following
// accommodations:
// 1. "names" field is an empty array in current source maps of WASM, hence it
// is not handled;
// 2. The semicolons divides "mappings" field into groups, each of which
// represents a line in the generated code. As *.wasm is in binary format, there
// is one "line" of generated code, and ";" is treated as illegal symbol in
// "mappings".
// 3. Though each comma-separated section may contains 1, 4 or 5 fields, we only
// consider "mappings" with 4 fields, i.e. start line of generated code, index
// into "sources" fields, start line of source code and start column of source
// code.
class V8_EXPORT_PRIVATE WasmModuleSourceMap {
public:
WasmModuleSourceMap(v8::Isolate* v8_isolate,
v8::Local<v8::String> src_map_str);
// Member valid_ is true only if the source map complies with specification
// and can be correctly decoded.
bool IsValid() const { return valid_; }
// Given a function located at [start, end) in WASM Module, this function
// checks if this function has its corresponding source code.
bool HasSource(size_t start, size_t end) const;
// Given a function's base address start and an address addr within, this
// function checks if the address can be mapped to an offset in this function.
// For example, we have the following memory layout for WASM functions, foo
// and bar, and O1, O2, O3 and O4 are the decoded offsets of source map:
//
// O1 --- O2 ----- O3 ----- O4
// --->|<-foo->|<--bar->|<-----
// --------------A-------------
//
// Address A of function bar should be mapped to its nearest lower offset, O2.
// However, O2 is an address of function foo, thus, this mapping is treated as
// invalid.
bool HasValidEntry(size_t start, size_t addr) const;
// This function is responsible for looking up an offset's corresponding line
// number in source file. It should only be called when current function is
// checked with IsValid, HasSource and HasValidEntry.
size_t GetSourceLine(size_t wasm_offset) const;
// This function is responsible for looking up an offset's corresponding
// source file name. It should only be called when current function is checked
// with IsValid, HasSource and HasValidEntry.
std::string GetFilename(size_t wasm_offset) const;
private:
std::vector<size_t> offsets;
std::vector<std::string> filenames;
std::vector<size_t> file_idxs;
std::vector<size_t> source_row;
// As column number in source file is always 0 in source map generated by
// WebAssembly toolchain, we will not store this value.
bool valid_ = false;
bool DecodeMapping(const std::string& s);
};
} // namespace wasm
} // namespace internal
} // namespace v8
#endif // V8_WASM_WASM_MODULE_SOURCEMAP_H_
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