[WebAssembly] Use hardcoded list expected undefined symbols (#21)

Rather than generate wasm.syms from wasm.js (which includes
a huge superset of the number of symbols actaully expected
to be undefined at link time) simply hardcode that list as
a test file, which lld can read.

arch/wasm32/wasm.js

@@ -951,11 +951,7 @@ var ffi = (function() {
 if (arguments.length < 1)
   throw new Error('Expected at least one wasm module to load.');
 
-if (arguments[0] == '--dump-ffi-symbols') {
+function load_wasm(file_path) {
-  for (var name in ffi["env"])
-    print(name)
-} else {
-  function load_wasm(file_path) {
   // TODO this should be split up in load, check dependencies, and then resolve
   // dependencies. That would make it easier to do lazy loading. We could do
   // this by catching load exceptions + adding to ffi and trying again, but
@@ -973,14 +969,14 @@ if (arguments[0] == '--dump-ffi-symbols') {
     heap_size_bytes = heap.byteLength;
   }
   return instance;
-  }
+}
 
-  // Load modules in reverse, adding their exports to the ffi object.
+// Load modules in reverse, adding their exports to the ffi object.
-  // This is analogous to how the linker resolves symbols: the later modules
+// This is analogous to how the linker resolves symbols: the later modules
-  // export symbols used by the earlier modules, and allow shadowing.
+// export symbols used by the earlier modules, and allow shadowing.
-  // Note that all modules, as well as the main module, share a heap.
+// Note that all modules, as well as the main module, share a heap.
-  var modules = {};
+var modules = {};
-  for (var i = arguments.length - 1; i > 0; --i) {
+for (var i = arguments.length - 1; i > 0; --i) {
   var path = arguments[i];
   modules[i] = load_wasm(path);
   for (var f in modules[i].exports) {
@@ -991,21 +987,21 @@ if (arguments[0] == '--dump-ffi-symbols') {
     if (modules[i].exports[f] instanceof Function)
       ffi['env'][f] = modules[i].exports[f];
   }
-  }
+}
 
-  // Load the main module once the ffi object has been fully populated.
+// Load the main module once the ffi object has been fully populated.
-  var main_module = arguments[0];
+var main_module = arguments[0];
-  modules[0] = load_wasm(main_module);
+modules[0] = load_wasm(main_module);
 
-  // TODO check that `main` exists in modules[0].exports and error out if not.
+// TODO check that `main` exists in modules[0].exports and error out if not.
 
-  try {
+try {
   var ret = modules[0].exports.main();
   stdio.__flush_stdout();
   print(main_module + '::main() returned ' + ret);
   if (ret != stdlib.EXIT_SUCCESS)
     throw new Error('main reported failure');
-  } catch (e) {
+} catch (e) {
   stdio.__flush_stdout();
   if (e instanceof TerminateWasmException) {
     print('Program terminated with: ' + e);
@@ -1034,5 +1030,4 @@ if (arguments[0] == '--dump-ffi-symbols') {
         ('Unknown exception of type `' + typeof(e) + '`: ' + e));
     throw e;
   }
-  }
 }

arch/wasm32/wasm.syms

@@ -0,0 +1,34 @@
+# Symbols we want wasm.js to define at runtime
+_Exit
+abort
+puts
+
+# Musl syscall interface, provided by wasm.js
+__syscall
+__syscall0
+__syscall1
+__syscall2
+__syscall3
+__syscall4
+__syscall5
+__syscall6
+__syscall_cp
+
+# Symbols not supported by clang but currently expected to work on the
+# wasm waterfall
+# TODO(sbc): remove these
+__builtin_isinff
+__builtin_isinfl
+__builtin_clrsb
+__builtin_clrsbl
+__builtin_clrsbll
+__builtin_apply
+__builtin_apply_args
+__builtin_malloc
+
+# Part of musl we still don't compile for wasm
+__lock
+__unlock
+__set_thread_area
+setjmp
+longjmp