add support for "wasm-function" symbol maps

application.tsx

@@ -16,7 +16,7 @@ import {SortMethod, SortField, SortDirection} from './profile-table-view'
 import {triangle} from './utils'
 import {Color} from './color'
 import {RowAtlas} from './row-atlas'
-import {importAsmJsSymbolMap} from './asm-js'
+import {importEmscriptenSymbolMap} from './emscripten'
 import {SandwichView} from './sandwich-view'
 import {saveToFile} from './file-format'
 
@@ -384,9 +384,9 @@ export class Application extends ReloadableComponent<{}, ApplicationState> {
         // a symbol map. If that's the case, we want to parse it, and apply the symbol
         // mapping to the already loaded profile. This can be use to take an opaque
         // profile and make it readable.
-        const map = importAsmJsSymbolMap(reader.result)
+        const map = importEmscriptenSymbolMap(reader.result)
         if (map) {
-          console.log('Importing as asm.js symbol map')
+          console.log('Importing as emscripten symbol map')
           let profile = this.state.profile
           profile.remapNames(name => map.get(name) || name)
           return profile

asm-js.test.ts → emscripten.test.ts

@@ -1,9 +1,9 @@
-import {importAsmJsSymbolMap} from './asm-js'
+import {importEmscriptenSymbolMap} from './emscripten'
 
-test('importAsmJSSymbolMap', () => {
+test('importEmscriptenSymbolMap', () => {
   // Valid symbol map
   expect(
-    importAsmJsSymbolMap(
+    importEmscriptenSymbolMap(
       [
         /* prettier: ignore */
         'a:A',
@@ -15,7 +15,7 @@ test('importAsmJSSymbolMap', () => {
 
   // Valid symbol map with trailing newline
   expect(
-    importAsmJsSymbolMap(
+    importEmscriptenSymbolMap(
       [
         /* prettier: ignore */
         'a:A',
@@ -27,14 +27,27 @@ test('importAsmJSSymbolMap', () => {
   ).toEqual(new Map([['a', 'A'], ['b', 'B'], ['c', 'C']]))
 
   // Valid symbol map with non-alpha characters
-
-  expect(importAsmJsSymbolMap('u6:__ZN8tinyxml210XMLCommentD0Ev\n')).toEqual(
+  expect(importEmscriptenSymbolMap('u6:__ZN8tinyxml210XMLCommentD0Ev\n')).toEqual(
     new Map([['u6', '__ZN8tinyxml210XMLCommentD0Ev']]),
   )
 
+  // WebAssembly symbol map
+  expect(
+    importEmscriptenSymbolMap(
+      [
+        /* prettier: ignore */
+        '0:A',
+        '1:B',
+        '2:C',
+      ].join('\n'),
+    ),
+  ).toEqual(
+    new Map([['wasm-function[0]', 'A'], ['wasm-function[1]', 'B'], ['wasm-function[2]', 'C']]),
+  )
+
   // Invalid symbol map
   expect(
-    importAsmJsSymbolMap(
+    importEmscriptenSymbolMap(
       [
         /* prettier: ignore */
         'a:A',
@@ -47,7 +60,7 @@ test('importAsmJSSymbolMap', () => {
 
   // Collapsed stack format should not be imported as an asm.js symbol map
   expect(
-    importAsmJsSymbolMap(
+    importEmscriptenSymbolMap(
       [
         /* prettier: ignore */
         'a;b 1',
@@ -58,6 +71,6 @@ test('importAsmJSSymbolMap', () => {
   ).toEqual(null)
 
   // Unrelated files
-  expect(importAsmJsSymbolMap('')).toEqual(null)
-  expect(importAsmJsSymbolMap('\n')).toEqual(null)
+  expect(importEmscriptenSymbolMap('')).toEqual(null)
+  expect(importEmscriptenSymbolMap('\n')).toEqual(null)
 })

emscripten.ts

@@ -0,0 +1,39 @@
+type EmscriptenSymbolMap = Map<string, string>
+
+// This imports symbol maps generated by emscripten using the "--emit-symbol-map" flag.
+// It allows you to visualize a profile captured in a release build as long as you also
+// have the associated symbol map. To do this, first drop the profile into speedscope
+// and then drop the symbol map. After the second drop, the symbols will be remapped to
+// their original names.
+export function importEmscriptenSymbolMap(contents: string): EmscriptenSymbolMap | null {
+  const lines = contents.split('\n')
+  if (!lines.length) return null
+
+  // Remove a trailing blank line if there is one
+  if (lines[lines.length - 1] === '') lines.pop()
+  if (!lines.length) return null
+
+  const map: EmscriptenSymbolMap = new Map()
+  const intRegex = /^(\d+):([\$\w]+)$/
+  const idRegex = /^([\$\w]+):([\$\w]+)$/
+
+  for (const line of lines) {
+    // Match lines like "103:__ZN8tinyxml210XMLCommentD0Ev"
+    const intMatch = intRegex.exec(line)
+    if (intMatch) {
+      map.set(`wasm-function[${intMatch[1]}]`, intMatch[2])
+      continue
+    }
+
+    // Match lines like "u6:__ZN8tinyxml210XMLCommentD0Ev"
+    const idMatch = idRegex.exec(line)
+    if (idMatch) {
+      map.set(idMatch[1], idMatch[2])
+      continue
+    }
+
+    return null
+  }
+
+  return map
+}