1 files changed, 61 insertions, 13 deletions

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 466771803..920baf944 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -1189,7 +1189,7 @@ void WasmBinaryWriter::writeSymbolMap() {
 }
 
 void WasmBinaryWriter::initializeDebugInfo() {
-  lastDebugLocation = {0, /* lineNumber = */ 1, 0};
+  lastDebugLocation = {0, /* lineNumber = */ 1, 0, std::nullopt};
 }
 
 void WasmBinaryWriter::writeSourceMapProlog() {
@@ -1225,7 +1225,17 @@ void WasmBinaryWriter::writeSourceMapProlog() {
     // TODO respect JSON string encoding, e.g. quotes and control chars.
     *sourceMap << "\"" << wasm->debugInfoFileNames[i] << "\"";
   }
-  *sourceMap << "],\"names\":[],\"mappings\":\"";
+  *sourceMap << "],\"names\":[";
+
+  for (size_t i = 0; i < wasm->debugInfoSymbolNames.size(); i++) {
+    if (i > 0) {
+      *sourceMap << ",";
+    }
+    // TODO respect JSON string encoding, e.g. quotes and control chars.
+    *sourceMap << "\"" << wasm->debugInfoSymbolNames[i] << "\"";
+  }
+
+  *sourceMap << "],\"mappings\":\"";
 }
 
 static void writeBase64VLQ(std::ostream& out, int32_t n) {
@@ -1249,7 +1259,10 @@ 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 lastSymbolNameIndex = 0;
   for (const auto& [offset, loc] : sourceMapLocations) {
     if (lastOffset > 0) {
       *sourceMap << ",";
@@ -1257,13 +1270,20 @@ void WasmBinaryWriter::writeSourceMapEpilog() {
     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->symbolNameIndex) {
+        writeBase64VLQ(*sourceMap,
+                       int32_t(*loc->symbolNameIndex - lastSymbolNameIndex));
+        lastSymbolNameIndex = *loc->symbolNameIndex;
+      }
     }
   }
   *sourceMap << "\"}";
@@ -1716,7 +1736,7 @@ 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;
 }
@@ -2885,6 +2905,21 @@ void WasmBinaryReader::readSourceMapHeader() {
     mustReadChar(']');
   }
 
+  if (findField("names")) {
+    skipWhitespace();
+    mustReadChar('[');
+    if (!maybeReadChar(']')) {
+      do {
+        std::string symbol;
+        readString(symbol);
+        Index index = wasm.debugInfoSymbolNames.size();
+        wasm.debugInfoSymbolNames.push_back(symbol);
+        debugInfoSymbolNameIndices[symbol] = index;
+      } while (maybeReadChar(','));
+      mustReadChar(']');
+    }
+  }
+
   if (!findField("mappings")) {
     throw MapParseException("cannot find the 'mappings' field in map");
   }
@@ -2911,7 +2946,12 @@ 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> symbolNameIndex;
+    peek = sourceMap->peek();
+    if (!(peek == ',' || peek == '\"')) {
+      symbolNameIndex = readBase64VLQ(*sourceMap);
+    }
+    nextDebugLocation = {fileIndex, lineNumber, columnNumber, symbolNameIndex};
     nextDebugLocationHasDebugInfo = true;
   }
 }
@@ -2966,7 +3006,15 @@ void WasmBinaryReader::readNextDebugLocation() {
     int32_t columnNumberDelta = readBase64VLQ(*sourceMap);
     uint32_t columnNumber = nextDebugLocation.columnNumber + columnNumberDelta;
 
-    nextDebugLocation = {fileIndex, lineNumber, columnNumber};
+    std::optional<BinaryLocation> symbolNameIndex;
+    peek = sourceMap->peek();
+    if (!(peek == ',' || peek == '\"')) {
+      int32_t symbolNameIndexDelta = readBase64VLQ(*sourceMap);
+      symbolNameIndex =
+        nextDebugLocation.symbolNameIndex.value_or(0) + symbolNameIndexDelta;
+    }
+
+    nextDebugLocation = {fileIndex, lineNumber, columnNumber, symbolNameIndex};
     nextDebugLocationHasDebugInfo = true;
   }
 }