Use direct table access over dynCall where possible

This change starts the transition away from dynCall and towards
direct use of the wasm table.

In particular this change replaces the use of dynCall in invoke_xx
functions where possible.  dynCall is still needed for functions with
i64 in thier signature when WASM_BIGINT is not enabled.  When
WASM_BIGING is enabled this change removes all use of dynCall by
invoke_xx functions.

Author: sbc100

src/library_browser.js

@@ -1181,15 +1181,9 @@ var LibraryBrowser = {
     Browser.mainLoop.arg = arg;
 
     var browserIterationFunc;
-    if (typeof arg !== 'undefined') {
-      browserIterationFunc = function() {
-        Module['dynCall_vi'](func, arg);
-      };
-    } else {
-      browserIterationFunc = function() {
-        Module['dynCall_v'](func);
-      };
-    }
+    browserIterationFunc = function() {
+      tableCall(func, arg);
+    };
 
 #if USE_CLOSURE_COMPILER
     // Closure compiler bug(?): Closure does not see that the assignment

src/library_exceptions.js

@@ -194,7 +194,7 @@ var LibraryExceptions = {
       var destructor = info.get_destructor();
       if (destructor) {
         // In Wasm, destructors return 'this' as in ARM
-        Module['dynCall_ii'](destructor, info.excPtr);
+        tableCall(destructor, info.excPtr);
       }
       ___cxa_free_exception(info.excPtr);
 #if EXCEPTION_DEBUG

src/library_sdl.js

@@ -873,7 +873,7 @@ var LibrarySDL = {
       if (!SDL.eventHandler) return;
 
       while (SDL.pollEvent(SDL.eventHandlerTemp)) {
-        Module['dynCall_iii'](SDL.eventHandler, SDL.eventHandlerContext, SDL.eventHandlerTemp);
+        tableCall(SDL.eventHandler, SDL.eventHandlerContext, SDL.eventHandlerTemp);
       }
     },
 

src/library_webgpu.js

@@ -1018,7 +1018,7 @@ var LibraryWebGPU = {
       if (ev.error instanceof GPUValidationError) type = Validation;
       else if (ev.error instanceof GPUOutOfMemoryError) type = OutOfMemory;
       var messagePtr = allocateUTF8(ev.error.message);
-      dynCall_viii(callback, type, messagePtr, userdata);
+      tableCall(callback, type, messagePtr, userdata);
       _free(messagePtr);
     };
   },
@@ -1031,9 +1031,9 @@ var LibraryWebGPU = {
     var completionValue = {{{ gpu.makeU64ToNumber('completionValue_low', 'completionValue_high') }}};
 
     fence.onCompletion(completionValue).then(function() {
-      dynCall_vii(callback, 0 /* WEBGPU_FENCE_COMPLETION_STATUS_SUCCESS */, userdata);
+      tableCall(callback, 0 /* WEBGPU_FENCE_COMPLETION_STATUS_SUCCESS */, userdata);
     }, function() {
-      dynCall_vii(callback, 1 /* WEBGPU_FENCE_COMPLETION_STATUS_ERROR */, userdata);
+      tableCall(callback, 1 /* WEBGPU_FENCE_COMPLETION_STATUS_ERROR */, userdata);
     });
   },
 
@@ -1374,10 +1374,10 @@ var LibraryWebGPU = {
     // `callback` takes (WGPUBufferMapAsyncStatus status, void * userdata)
 
     buffer["mapAsync"](mode, offset, size).then(function() {
-      dynCall_vii(callback, 0 /* WGPUBufferMapAsyncStatus_Success */, userdata);
+      tableCall(callback, 0 /* WGPUBufferMapAsyncStatus_Success */, userdata);
     }, function() {
       // TODO(kainino0x): Figure out how to pick other error status values.
-      dynCall_vii(callback, 1 /* WGPUBufferMapAsyncStatus_Error */, userdata);
+      tableCall(callback, 1 /* WGPUBufferMapAsyncStatus_Error */, userdata);
     });
   },
 

src/preamble.js

@@ -44,10 +44,7 @@ if (typeof WebAssembly !== 'object') {
 
 var wasmMemory;
 
-// In fastcomp asm.js, we don't need a wasm Table at all.
-// In the wasm backend, we polyfill the WebAssembly object,
-// so this creates a (non-native-wasm) table for us.
-#include "runtime_init_table.js"
+#include "runtime_table.js"
 
 #if USE_PTHREADS
 // For sending to workers.
@@ -428,11 +425,7 @@ function callRuntimeCallbacks(callbacks) {
     }
     var func = callback.func;
     if (typeof func === 'number') {
-      if (callback.arg === undefined) {
-        Module['dynCall_v'](func);
-      } else {
-        Module['dynCall_vi'](func, callback.arg);
-      }
+      tableCall(func, callback.arg);
     } else {
       func(callback.arg === undefined ? null : callback.arg);
     }
@@ -902,6 +895,7 @@ function createWasm() {
     // then exported.
     // TODO: do not create a Memory earlier in JS
     wasmMemory = exports['memory'];
+    wasmTable = exports['__indirect_function_table'];
     updateGlobalBufferAndViews(wasmMemory.buffer);
 #if ASSERTIONS
     writeStackCookie();

src/preamble_minimal.js

@@ -102,7 +102,7 @@ assert(buffer instanceof SharedArrayBuffer, 'requested a shared WebAssembly.Memo
 #endif
 #endif
 
-#include "runtime_init_table.js"
+#include "runtime_table.js"
 
 #else
 
@@ -211,11 +211,7 @@ function callRuntimeCallbacks(callbacks) {
     }
     var func = callback.func;
     if (typeof func === 'number') {
-      if (callback.arg === undefined) {
-        dynCall_v(func);
-      } else {
-        dynCall_vi(func, callback.arg);
-      }
+      tableCall(func, callback.arg);
     } else {
       func(callback.arg === undefined ? null : callback.arg);
     }

src/runtime_init_table.js

@@ -0,0 +1,31 @@
+/**
+ * @license
+ * Copyright 2017 The Emscripten Authors
+ * SPDX-License-Identifier: MIT
+ */
+
+#if STANDALONE_WASM // standalone wasm creates the table in the wasm
+var wasmTable;
+#else
+var wasmTable = new WebAssembly.Table({
+  'initial': {{{ getQuoted('WASM_TABLE_SIZE') }}},
+#if !ALLOW_TABLE_GROWTH
+  'maximum': {{{ getQuoted('WASM_TABLE_SIZE') }}},
+#endif
+  'element': 'anyfunc'
+});
+#endif
+
+// TODO(sbc): Avoid this gross hack using `rest` ES6 operator once we
+// enable ES6: https://github.com/emscripten-core/emscripten/issues/11984
+// function tableCall(ptr, ...args) {
+//  return wasmTable.get(ptr).apply(null, args);
+// }
+var tableCallArgs = [];
+function tableCall(ptr) {
+  tableCallArgs.length = arguments.length - 1;
+  for (var i = 1; i < arguments.length; i++) {
+    tableCallArgs[i - 1] = arguments[i];
+  }
+  return wasmTable.get(ptr).apply(null, tableCallArgs);
+}

src/runtime_table.js

@@ -301,7 +301,7 @@ function createInvokeFunction(sig) {
   return function() {
     var sp = stackSave();
     try {
-      return Module['dynCall_' + sig].apply(null, arguments);
+      return dynCall(sig, arguments[0], Array.prototype.slice.call(arguments, 1));
     } catch(e) {
       stackRestore(sp);
       if (e !== e+0 && e !== 'longjmp') throw e;
@@ -602,24 +602,32 @@ function makeBigInt(low, high, unsigned) {
 
 /** @param {Array=} args */
 function dynCall(sig, ptr, args) {
-  if (args && args.length) {
 #if ASSERTIONS
+  if (args && args.length) {
     // j (64-bit integer) must be passed in as two numbers [low 32, high 32].
     assert(args.length === sig.substring(1).replace(/j/g, '--').length);
-#endif
-#if ASSERTIONS
-    assert(('dynCall_' + sig) in Module, 'bad function pointer type - no table for sig \'' + sig + '\'');
-#endif
-    return Module['dynCall_' + sig].apply(null, [ptr].concat(args));
   } else {
-#if ASSERTIONS
     assert(sig.length == 1);
+  }
 #endif
+
+#if !WASM_BIGINT
+  if (sig.indexOf('j') != -1) {
 #if ASSERTIONS
-    assert(('dynCall_' + sig) in Module, 'bad function pointer type - no table for sig \'' + sig + '\'');
+      assert(('dynCall_' + sig) in Module, 'bad function pointer type - no table for sig \'' + sig + '\'');
 #endif
-    return Module['dynCall_' + sig].call(null, ptr);
+    if (args && args.length) {
+      return Module['dynCall_' + sig].apply(null, [ptr].concat(args));
+    } else {
+      return Module['dynCall_' + sig].call(null, ptr);
+    }
   }
+#endif
+
+  // TODO(sbc): Use ...args once ES6 is allowed:
+  // tableCall(ptr, ...args);
+  // https://github.com/emscripten-core/emscripten/issues/11984
+  return tableCall.apply(null, [ptr].concat(args));
 }
 
 var tempRet0 = 0;

src/support.js

@@ -1,2 +1,3 @@
+__indirect_function_table
 _start
 memory

tests/other/metadce/libcxxabi_message_O3_STANDALONE_WASM.exports

@@ -1,2 +1,3 @@
+__indirect_function_table
 _start
 memory

tests/other/metadce/mem_O3_ALLOW_MEMORY_GROWTH_STANDALONE_WASM.exports

@@ -1,2 +1,3 @@
+__indirect_function_table
 _start
 memory

tests/other/metadce/mem_O3_STANDALONE_WASM.exports

@@ -1,2 +1,3 @@
+__indirect_function_table
 _start
 memory

tests/other/metadce/mem_no_argv_O3_STANDALONE_WASM.exports

@@ -1,2 +1,3 @@
+__indirect_function_table
 _start
 memory

tests/other/metadce/mem_no_argv_O3_STANDALONE_WASM_flto.exports

@@ -1,3 +1,4 @@
+__indirect_function_table
 _initialize
 foo
 memory

tests/other/metadce/mem_no_main_O3_STANDALONE_WASM_noentry.exports

@@ -7168,7 +7168,7 @@ def test_metadce_mem(self, filename, *args):
                            [], [], 128), # noqa
     # argc/argv support code etc. is in the wasm
     'O3_standalone':      ('libcxxabi_message.cpp', ['-O3', '-s', 'STANDALONE_WASM'],
-                           [], [], 198), # noqa
+                           [], [], 242), # noqa
   })
   def test_metadce_libcxxabi_message(self, filename, *args):
     self.run_metadce_test(filename, *args)

tests/test_other.py

@@ -484,6 +484,8 @@ def lld_flags_for_executable(external_symbol_list):
   if not Settings.STANDALONE_WASM:
     cmd.append('--import-memory')
     cmd.append('--import-table')
+  else:
+    cmd.append('--export-table')
 
   if Settings.USE_PTHREADS:
     cmd.append('--shared-memory')
@@ -1136,7 +1138,10 @@ def add_to_path(dirname):
       logger.error(proc.stderr) # print list of errors (possibly long wall of text if input was minified)
 
       # Exit and print final hint to get clearer output
-      exit_with_error('closure compiler failed (rc: %d.%s)', proc.returncode, '' if pretty else ' the error message may be clearer with -g1 and EMCC_DEBUG=2 set')
+      msg = 'closure compiler failed (rc: %d): %s' % (proc.returncode, shared.shlex_join(cmd))
+      if not pretty:
+        msg += ' the error message may be clearer with -g1 and EMCC_DEBUG=2 set'
+      exit_with_error(msg)
 
     if len(proc.stderr.strip()) > 0 and Settings.CLOSURE_WARNINGS != 'quiet':
       # print list of warnings (possibly long wall of text if input was minified)
@@ -1227,6 +1232,12 @@ def metadce(js_file, wasm_file, minify_whitespace, debug_info):
       'reaches': [],
       'root': True
     })
+    graph.append({
+      'export': '__indirect_function_table',
+      'name': 'emcc$export$__indirect_function_table',
+      'reaches': [],
+      'root': True
+    })
   # fix wasi imports TODO: support wasm stable with an option?
   WASI_IMPORTS = set([
     'environ_get',

tools/building.py

@@ -1221,16 +1221,22 @@ def make_dynCall(sig):
   def make_invoke(sig, named=True):
     legal_sig = JS.legalize_sig(sig) # TODO: do this in extcall, jscall?
     args = ','.join(['a' + str(i) for i in range(1, len(legal_sig))])
-    args = 'index' + (',' if args else '') + args
     ret = 'return ' if sig[0] != 'v' else ''
-    body = '%s%s(%s);' % (ret, JS.make_dynCall(sig), args)
+    args = 'index' + (',' if args else '') + args
+    # wasm2c doesn't yet support for the new `tableCall`
+    if Settings.WASM2C or not JS.is_legal_sig(sig):
+      body = '%s%s(%s);' % (ret, JS.make_dynCall(sig), args)
+    else:
+      body = '%stableCall(%s);' % (ret, args)
     # C++ exceptions are numbers, and longjmp is a string 'longjmp'
     if Settings.SUPPORT_LONGJMP:
       rethrow = "if (e !== e+0 && e !== 'longjmp') throw e;"
     else:
       rethrow = "if (e !== e+0) throw e;"
 
-    ret = '''function%s(%s) {
+    name = (' invoke_' + sig) if named else ''
+    ret = '''\
+function%s(%s) {
   var sp = stackSave();
   try {
     %s
@@ -1239,7 +1245,8 @@ def make_invoke(sig, named=True):
     %s
     _setThrew(1, 0);
   }
-}''' % ((' invoke_' + sig) if named else '', args, body, rethrow)
+}''' % (name, args, body, rethrow)
+
     return ret
 
   @staticmethod