Simplify em_js func types check. NFC (#24821)

As far as I can tell, the only reason we had to re-parse the module here
is because update_metadata didn't update em_js_func_types which might've
been changed by legalization.

I've consolidates imports reading into read_module_imports so it now
consistently reads any relevant info both during the initial module
parsing and in the update_metadata.

Author: RReverser

tools/emscripten.py

@@ -317,26 +317,15 @@ def emscript(in_wasm, out_wasm, outfile_js, js_syms, finalize=True, base_metadat
     update_settings_glue(out_wasm, metadata, base_metadata)
 
   if not settings.WASM_BIGINT and metadata.em_js_funcs:
-    import_map = {}
-
-    with webassembly.Module(in_wasm) as module:
-      types = module.get_types()
-      for imp in module.get_imports():
-        if imp.module not in ('GOT.mem', 'GOT.func'):
-          import_map[imp.field] = imp
-
     for em_js_func, raw in metadata.em_js_funcs.items():
       c_sig = raw.split('<::>')[0].strip('()')
       if not c_sig or c_sig == 'void':
         c_sig = []
       else:
         c_sig = c_sig.split(',')
-      if em_js_func in import_map:
-        imp = import_map[em_js_func]
-        assert imp.kind == webassembly.ExternType.FUNC
-        signature = types[imp.type]
-        if len(signature.params) != len(c_sig):
-          diagnostics.warning('em-js-i64', 'using 64-bit arguments in EM_JS function without WASM_BIGINT is not yet fully supported: `%s` (%s, %s)', em_js_func, c_sig, signature.params)
+      signature = metadata.em_js_func_types.get(em_js_func)
+      if signature and len(signature.params) != len(c_sig):
+        diagnostics.warning('em-js-i64', 'using 64-bit arguments in EM_JS function without WASM_BIGINT is not yet fully supported: `%s` (%s, %s)', em_js_func, c_sig, signature.params)
 
   asm_consts = create_asm_consts(metadata)
   em_js_funcs = create_em_js(metadata)

tools/extract_metadata.py

@@ -264,25 +264,32 @@ def get_tag_exports(module):
   return rtn
 
 
-def update_metadata(filename, metadata):
-  imports = []
-  invoke_funcs = []
-  with webassembly.Module(filename) as module:
-    for i in module.get_imports():
-      if i.kind == webassembly.ExternType.FUNC:
-        if i.field.startswith('invoke_'):
-          invoke_funcs.append(i.field)
-        else:
-          imports.append(i.field)
-      elif i.kind in (webassembly.ExternType.GLOBAL, webassembly.ExternType.TAG):
+def read_module_imports(module, metadata):
+  em_js_funcs = metadata.em_js_funcs
+  types = module.get_types()
+
+  imports = metadata.imports = []
+  invoke_funcs = metadata.invoke_funcs = []
+  em_js_func_types = metadata.em_js_func_types = {}
+
+  for i in module.get_imports():
+    if i.kind == webassembly.ExternType.FUNC:
+      if i.field.startswith('invoke_'):
+        invoke_funcs.append(i.field)
+      else:
+        if i.field in em_js_funcs:
+          em_js_func_types[i.field] = types[i.type]
         imports.append(i.field)
+    elif i.kind in (webassembly.ExternType.GLOBAL, webassembly.ExternType.TAG):
+      imports.append(i.field)
 
+
+def update_metadata(filename, metadata):
+  with webassembly.Module(filename) as module:
     metadata.function_exports = get_function_exports(module)
     metadata.tag_exports = get_tag_exports(module)
     metadata.all_exports = [utils.removeprefix(e.name, '__em_js__') for e in module.get_exports()]
-
-  metadata.imports = imports
-  metadata.invoke_funcs = invoke_funcs
+    read_module_imports(module, metadata)
 
 
 def get_string_at(module, address):
@@ -298,25 +305,24 @@ class Metadata:
   em_asm_consts: Dict[int, str]
   js_deps: List[str]
   em_js_funcs: Dict[str, str]
-  em_js_func_types: Dict[str, str]
+  em_js_func_types: Dict[str, webassembly.FuncType]
   features: List[str]
   invoke_funcs: List[str]
   main_reads_params: bool
-  global_exports: List[str]
+  global_exports: Dict[str, str]
+  function_exports: Dict[str, webassembly.FuncType]
+  tag_exports: List[str]
+  all_exports: List[str]
 
   def __init__(self):
     pass
 
 
 def extract_metadata(filename):
-  import_names = []
-  invoke_funcs = []
   em_js_funcs = {}
-  em_js_func_types = {}
 
   with webassembly.Module(filename) as module:
     exports = module.get_exports()
-    imports = module.get_imports()
 
     export_map = {e.name: e for e in exports}
     for e in exports:
@@ -326,18 +332,6 @@ def extract_metadata(filename):
         string_address = to_unsigned(get_global_value(globl))
         em_js_funcs[name] = get_string_at(module, string_address)
 
-    for i in imports:
-      if i.kind == webassembly.ExternType.FUNC:
-        if i.field.startswith('invoke_'):
-          invoke_funcs.append(i.field)
-        else:
-          if i.field in em_js_funcs:
-            types = module.get_types()
-            em_js_func_types[i.field] = types[i.type]
-          import_names.append(i.field)
-      elif i.kind in (webassembly.ExternType.GLOBAL, webassembly.ExternType.TAG):
-        import_names.append(i.field)
-
     features = module.parse_features_section()
     features = ['--enable-' + f[1] for f in features if f[0] == '+']
     features = [f.replace('--enable-atomics', '--enable-threads') for f in features]
@@ -347,18 +341,17 @@ def extract_metadata(filename):
     # If main does not read its parameters, it will just be a stub that
     # calls __original_main (which has no parameters).
     metadata = Metadata()
-    metadata.imports = import_names
     metadata.function_exports = get_function_exports(module)
     metadata.tag_exports = get_tag_exports(module)
     metadata.all_exports = [utils.removeprefix(e.name, '__em_js__') for e in exports]
     metadata.em_asm_consts = get_section_strings(module, export_map, 'em_asm')
     metadata.js_deps = [d for d in get_section_strings(module, export_map, 'em_lib_deps').values() if d]
     metadata.em_js_funcs = em_js_funcs
-    metadata.em_js_func_types = em_js_func_types
     metadata.features = features
-    metadata.invoke_funcs = invoke_funcs
     metadata.main_reads_params = get_main_reads_params(module, export_map)
     metadata.global_exports = get_global_exports(module, exports)
 
+    read_module_imports(module, metadata)
+
     # print("Metadata parsed: " + pprint.pformat(metadata))
     return metadata