Support 5 segment source mappings

src/parser/contexts.h

@@ -1792,7 +1792,7 @@ struct ParseDefsCtx : TypeParserCtx<ParseDefsCtx> {
       wasm.debugInfoFileNames.push_back(std::string(file));
     }
     irBuilder.setDebugLocation(
-      Function::DebugLocation({it->second, *line, *col}));
+      Function::DebugLocation({it->second, *line, *col, std::nullopt}));
   }
 
   Result<> makeBlock(Index pos,

src/wasm.h

@@ -2072,19 +2072,20 @@ class Function : public Importable {
   // Source maps debugging info: map expression nodes to their file, line, col.
   struct DebugLocation {
     BinaryLocation fileIndex, lineNumber, columnNumber;
+    std::optional<BinaryLocation> nameIndex;
     bool operator==(const DebugLocation& other) const {
       return fileIndex == other.fileIndex && lineNumber == other.lineNumber &&
-             columnNumber == other.columnNumber;
+             columnNumber == other.columnNumber && nameIndex == other.nameIndex;
     }
     bool operator!=(const DebugLocation& other) const {
       return !(*this == other);
     }
     bool operator<(const DebugLocation& other) const {
-      return fileIndex != other.fileIndex
-               ? fileIndex < other.fileIndex
-               : lineNumber != other.lineNumber
-                   ? lineNumber < other.lineNumber
-                   : columnNumber < other.columnNumber;
+      return fileIndex != other.fileIndex     ? fileIndex < other.fileIndex
+             : lineNumber != other.lineNumber ? lineNumber < other.lineNumber
+             : columnNumber != other.columnNumber
+               ? columnNumber < other.columnNumber
+               : nameIndex < other.nameIndex;
     }
   };
   // One can explicitly set the debug location of an expression to

src/wasm/wasm-binary.cpp

@@ -1185,7 +1185,7 @@ void WasmBinaryWriter::writeSymbolMap() {
 }
 
 void WasmBinaryWriter::initializeDebugInfo() {
-  lastDebugLocation = {0, /* lineNumber = */ 1, 0};
+  lastDebugLocation = {0, /* lineNumber = */ 1, 0, std::nullopt};
 }
 
 void WasmBinaryWriter::writeSourceMapProlog() {
@@ -1245,21 +1245,30 @@ static void writeBase64VLQ(std::ostream& out, int32_t n) {
 void WasmBinaryWriter::writeSourceMapEpilog() {
   // write source map entries
   size_t lastOffset = 0;
-  Function::DebugLocation lastLoc = {0, /* lineNumber = */ 1, 0};
+  BinaryLocation lastFileIndex = 0;
+  BinaryLocation lastLineNumber = 1;
+  BinaryLocation lastColumnNumber = 0;
+  BinaryLocation lastNameIndex = 0;
   for (const auto& [offset, loc] : sourceMapLocations) {
     if (lastOffset > 0) {
       *sourceMap << ",";
     }
     writeBase64VLQ(*sourceMap, int32_t(offset - lastOffset));
     lastOffset = offset;
     if (loc) {
-      // There is debug information for this location, so emit the next 3
-      // fields and update lastLoc.
-      writeBase64VLQ(*sourceMap, int32_t(loc->fileIndex - lastLoc.fileIndex));
-      writeBase64VLQ(*sourceMap, int32_t(loc->lineNumber - lastLoc.lineNumber));
-      writeBase64VLQ(*sourceMap,
-                     int32_t(loc->columnNumber - lastLoc.columnNumber));
-      lastLoc = *loc;
+      writeBase64VLQ(*sourceMap, int32_t(loc->fileIndex - lastFileIndex));
+      lastFileIndex = loc->fileIndex;
+
+      writeBase64VLQ(*sourceMap, int32_t(loc->lineNumber - lastLineNumber));
+      lastLineNumber = loc->lineNumber;
+
+      writeBase64VLQ(*sourceMap, int32_t(loc->columnNumber - lastColumnNumber));
+      lastColumnNumber = loc->columnNumber;
+
+      if (loc->nameIndex) {
+        writeBase64VLQ(*sourceMap, int32_t(*loc->nameIndex - lastNameIndex));
+        lastNameIndex = *loc->nameIndex;
+      }
     }
   }
   *sourceMap << "\"}";
@@ -1712,7 +1721,7 @@ WasmBinaryReader::WasmBinaryReader(Module& wasm,
                                    FeatureSet features,
                                    const std::vector<char>& input)
   : wasm(wasm), allocator(wasm.allocator), input(input), sourceMap(nullptr),
-    nextDebugPos(0), nextDebugLocation{0, 0, 0},
+    nextDebugPos(0), nextDebugLocation{0, 0, 0, std::nullopt},
     nextDebugLocationHasDebugInfo(false), debugLocation() {
   wasm.features = features;
 }
@@ -2903,7 +2912,12 @@ void WasmBinaryReader::readSourceMapHeader() {
     uint32_t lineNumber =
       readBase64VLQ(*sourceMap) + 1; // adjust zero-based line number
     uint32_t columnNumber = readBase64VLQ(*sourceMap);
-    nextDebugLocation = {fileIndex, lineNumber, columnNumber};
+    std::optional<BinaryLocation> nameIndex;
+    peek = sourceMap->peek();
+    if (!(peek == ',' || peek == '\"')) {
+      nameIndex = readBase64VLQ(*sourceMap);
+    }
+    nextDebugLocation = {fileIndex, lineNumber, columnNumber, nameIndex};
     nextDebugLocationHasDebugInfo = true;
   }
 }
@@ -2958,7 +2972,13 @@ void WasmBinaryReader::readNextDebugLocation() {
     int32_t columnNumberDelta = readBase64VLQ(*sourceMap);
     uint32_t columnNumber = nextDebugLocation.columnNumber + columnNumberDelta;
 
-    nextDebugLocation = {fileIndex, lineNumber, columnNumber};
+    std::optional<BinaryLocation> nameIndex;
+    peek = sourceMap->peek();
+    if (!(peek == ',' || peek == '\"')) {
+      nameIndex = readBase64VLQ(*sourceMap);
+    }
+
+    nextDebugLocation = {fileIndex, lineNumber, columnNumber, nameIndex};
     nextDebugLocationHasDebugInfo = true;
   }
 }