Fix some source map and name section behavior (#23182)

1) This causes -g0 to fullyl override -gsource-map (removing the name
section)
when it comes later on the command line

2) -gsplit-dwarf and -gsource-map work together resulting in dwarf,
source
maps and name section together.

Author: dschuff

emcc.py

@@ -1268,6 +1268,13 @@ def consume_arg_file():
       if is_int(requested_level):
         # the -gX value is the debug level (-g1, -g2, etc.)
         settings.DEBUG_LEVEL = validate_arg_level(requested_level, 4, 'invalid debug level: ' + arg)
+        if settings.DEBUG_LEVEL == 0:
+          # Set these explicitly so -g0 overrides previous -g on the cmdline
+          settings.GENERATE_DWARF = 0
+          settings.GENERATE_SOURCE_MAP = 0
+          settings.EMIT_NAME_SECTION = 0
+        elif settings.DEBUG_LEVEL > 1:
+          settings.EMIT_NAME_SECTION = 1
         # if we don't need to preserve LLVM debug info, do not keep this flag
         # for clang
         if settings.DEBUG_LEVEL < 3:
@@ -1298,17 +1305,20 @@ def consume_arg_file():
           settings.GENERATE_DWARF = 1
         elif requested_level == 'source-map':
           settings.GENERATE_SOURCE_MAP = 1
+          settings.EMIT_NAME_SECTION = 1
           newargs[i] = '-g'
         else:
           # Other non-integer levels (e.g. -gline-tables-only or -gdwarf-5) are
           # usually clang flags that emit DWARF. So we pass them through to
           # clang and make the emscripten code treat it like any other DWARF.
           settings.GENERATE_DWARF = 1
+          settings.EMIT_NAME_SECTION = 1
         # In all cases set the emscripten debug level to 3 so that we do not
         # strip during link (during compile, this does not make a difference).
         settings.DEBUG_LEVEL = 3
     elif check_flag('-profiling') or check_flag('--profiling'):
       settings.DEBUG_LEVEL = max(settings.DEBUG_LEVEL, 2)
+      settings.EMIT_NAME_SECTION = 1
     elif check_flag('-profiling-funcs') or check_flag('--profiling-funcs'):
       settings.EMIT_NAME_SECTION = 1
     elif newargs[i] == '--tracing' or newargs[i] == '--memoryprofiler':

test/test_other.py

@@ -3095,8 +3095,7 @@ def test_dwarf_sourcemap_names(self):
       # TODO: It seems odd that -gsource-map leaves behind a name section. Should it?
       (['-gsource-map'], False, True, True),
       (['-g1', '-Oz', '-gsource-map'], False, True, True),
-      # -g0 does not override -gsource-map but does remove name section. TODO: should it?
-      (['-gsource-map', '-g0'], False, True, False),
+      (['-gsource-map', '-g0'], False, False, False),
       # --emit-symbol-map should not affect the results
       (['--emit-symbol-map', '-gsource-map'], False, True, True),
       (['--emit-symbol-map'], False, False, False),
@@ -3105,7 +3104,7 @@ def test_dwarf_sourcemap_names(self):
       (['-sASYNCIFY=1', '-gsource-map'], False, True, True),
       (['-g', '-gsource-map'], True, True, True),
       (['-g2', '-gsource-map'], False, True, True),
-      # (['-gsplit-dwarf', '-gsource-map'], True, True, True), TODO this currently fails!
+      (['-gsplit-dwarf', '-gsource-map'], True, True, True),
       (['-gsource-map', '-sWASM_BIGINT', '-sERROR_ON_WASM_CHANGES_AFTER_LINK'], False, True, True),
     ]:
       print(flags, expect_dwarf, expect_sourcemap, expect_names)

tools/emscripten.py

@@ -501,12 +501,14 @@ def finalize_wasm(infile, outfile, js_syms):
 
   # if we don't need to modify the wasm, don't tell finalize to emit a wasm file
   modify_wasm = False
+  need_name_section = False
 
   if settings.WASM2JS:
     # wasm2js requires full legalization (and will do extra wasm binary
     # later processing later anyhow)
     modify_wasm = True
   if settings.DEBUG_LEVEL >= 2 or settings.ASYNCIFY_ADD or settings.ASYNCIFY_ADVISE or settings.ASYNCIFY_ONLY or settings.ASYNCIFY_REMOVE or settings.EMIT_SYMBOL_MAP or settings.EMIT_NAME_SECTION:
+    need_name_section = True
     args.append('-g')
   if settings.WASM_BIGINT:
     args.append('--bigint')
@@ -568,12 +570,18 @@ def finalize_wasm(infile, outfile, js_syms):
                infile]
         shared.check_call(cmd)
 
-  if not settings.GENERATE_DWARF or not settings.EMIT_PRODUCERS_SECTION:
-    # For sections we no longer need, strip now to speed subsequent passes
+  # For sections we no longer need, strip now to speed subsequent passes.
+  # If Binaryen is not needed, this is also our last chance to strip.
+  strip_sections = []
+  if not settings.EMIT_PRODUCERS_SECTION:
+    strip_sections += ['producers']
+  if not need_name_section:
+    strip_sections += ['name']
+
+  if strip_sections or not settings.GENERATE_DWARF:
     building.save_intermediate(outfile, 'strip.wasm')
-    sections = ['producers'] if not settings.EMIT_PRODUCERS_SECTION else []
     building.strip(infile, outfile, debug=not settings.GENERATE_DWARF,
-                   sections=sections)
+                   sections=strip_sections)
 
   metadata = get_metadata(outfile, outfile, modify_wasm, args)