Remove source map 'names' field support

ChangeLog.md

@@ -20,6 +20,9 @@ See docs/process.md for more on how version tagging works.
 
 4.0.24 (in development)
 -----------------------
+- Source map's 'names' field support is removed, because the way we used it was
+  inconsistent with JS and was not supported in browser devtools. We plan to
+  provide this information using Scopes encoding later. (#26149)
 - compiler-rt, libcxx, libcxxabi, and libunwind were updated to LLVM 21.1.8.
 - (#26036, #26045, and #26058)
 - Calling pthread_create in a single-threaded build will now return ENOTSUP

test/test_other.py

@@ -9651,36 +9651,32 @@ def check_source_map_loc_info(address, func, loc):
       out = self.run_process(
           [emsymbolizer, '-s', 'sourcemap', 'test_dwarf.wasm', address],
           stdout=PIPE).stdout
-      self.assertIn(func, out)
+      if func:
+        self.assertIn(func, out)
       self.assertIn(loc, out)
 
     def do_tests(src):
       # 1. Test DWARF + source map together
-      # For DWARF, we check for the full inlined info for both function names and
-      # source locations. Source maps does not provide inlined info. So we only
-      # check for the info of the outermost function.
+      # For DWARF, we check for the full inlined info for both function names
+      # and source locations. Source maps does not provide inlining information
+      # and function name, so we only check for the info of the outermost
+      # location.
       self.run_process([EMCC, test_file(src), '-g', '-gsource-map', '-O1', '-o',
                         'test_dwarf.js'])
       check_dwarf_loc_info(out_to_js_call_addr, out_to_js_call_func,
                            out_to_js_call_loc)
-      check_source_map_loc_info(out_to_js_call_addr, out_to_js_call_func[0],
+      check_source_map_loc_info(out_to_js_call_addr, None,
                                 out_to_js_call_loc[0])
       check_dwarf_loc_info(unreachable_addr, unreachable_func, unreachable_loc)
-      # Source map shows the original (inlined) source location with the original
-      # function name
-      check_source_map_loc_info(unreachable_addr, unreachable_func[0],
-                                unreachable_loc[0])
+      # Source map shows the original (inlined) source location
+      check_source_map_loc_info(unreachable_addr, None, unreachable_loc[0])
 
       # 2. Test source map only
-      # The addresses, function names, and source locations are the same across
-      # the builds because they are relative offsets from the code section, so we
-      # don't need to recompute them
       self.run_process([EMCC, test_file(src), '-gsource-map', '-O1', '-o',
                         'test_dwarf.js'])
-      check_source_map_loc_info(out_to_js_call_addr, out_to_js_call_func[0],
+      check_source_map_loc_info(out_to_js_call_addr, None,
                                 out_to_js_call_loc[0])
-      check_source_map_loc_info(unreachable_addr, unreachable_func[0],
-                                unreachable_loc[0])
+      check_source_map_loc_info(unreachable_addr, None, unreachable_loc[0])
 
       # 3. Test DWARF only
       self.run_process([EMCC, test_file(src), '-g', '-O1', '-o',

tools/wasm-sourcemap.py

@@ -31,6 +31,9 @@
 
 logger = logging.getLogger('wasm-sourcemap')
 
+# FIXME: Generate Scopes info
+generate_scopes = False
+
 
 def parse_args(args):
   parser = argparse.ArgumentParser(prog='wasm-sourcemap.py', description=__doc__)
@@ -399,12 +402,17 @@ def read_dwarf_info(wasm, options):
     logger.debug('Reading DWARF information from %s' % wasm)
     if not os.path.exists(options.dwarfdump):
       utils.exit_with_error('llvm-dwarfdump not found: ' + options.dwarfdump)
-    # We need only three tags in the debug info: DW_TAG_compile_unit for
-    # source location, and DW_TAG_subprogram and DW_TAG_inlined_subroutine
-    # for the function ranges.
-    dwarfdump_cmd = [options.dwarfdump, '-debug-info', '-debug-line', wasm,
-                     '-t', 'DW_TAG_compile_unit', '-t', 'DW_TAG_subprogram',
-                     '-t', 'DW_TAG_inlined_subroutine']
+    dwarfdump_cmd = [options.dwarfdump, '-debug-info', '-debug-line', wasm]
+    if generate_scopes:
+      # We need only three tags in the debug info: DW_TAG_compile_unit for
+      # source location, and DW_TAG_subprogram and DW_TAG_inlined_subroutine
+      # for the function ranges.
+      dwarfdump_cmd += ['-t', 'DW_TAG_compile_unit', '-t', 'DW_TAG_subprogram',
+                        '-t', 'DW_TAG_inlined_subroutine']
+    else:
+      # We only need the top-level DW_TAG_compile_unit tags when not generating
+      # the names field
+      dwarfdump_cmd += ['--recurse-depth=0']
     proc = shared.check_call(dwarfdump_cmd, stdout=shared.PIPE)
     output = proc.stdout
   else:
@@ -481,7 +489,10 @@ def read_dwarf_info(wasm, options):
   # return entries sorted by the address field
   entries = sorted(entries, key=lambda entry: entry['address'])
 
-  func_ranges = extract_func_ranges(debug_info)
+  if generate_scopes:
+    func_ranges = extract_func_ranges(debug_info)
+  else:
+    func_ranges = []
   return entries, func_ranges