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diff --git a/deps/v8/src/wasm/wasm-module-sourcemap.h b/deps/v8/src/wasm/wasm-module-sourcemap.h
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+++ b/deps/v8/src/wasm/wasm-module-sourcemap.h
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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_