refactor a lookupImport method

4 files changed, 26 insertions, 20 deletions

diff --git a/README.md b/README.md
index 0c8284a35..ecfb42ae7 100644
--- a/README.md
+++ b/README.md
@@ -72,13 +72,10 @@ emcc src.cpp -o a.html --separate-asm
 
 That will emit `a.html`, `a.js`, and `a.asm.js`. That last file is the asm.js module, which you can pass into `asm2wasm`.
 
-If you want an optimized buid, use
+For basic tests, that command should work, but in general you need a few more arguments to emcc, see emcc's usage in `emcc_to_wasm.js.sh`, specifically
 
-```
-emcc src.cpp -o a.html --separate-asm -O[2,3,etc.] -s ALIASING_FUNCTION_POINTERS=0
-```
-
-You need `ALIASING_FUNCTION_POINTERS=0` because WebAssembly does not allow aliased function pointers (there is a single table).
+ * `ALIASING_FUNCTION_POINTERS=0` because WebAssembly does not allow aliased function pointers (there is a single table).
+ * `GLOBAL_BASE=1000` because WebAssembly lacks global variables, so `asm2wasm` maps them onto addresses in memory. This requires that you have some reserved space for those variables. With that argument, we reserve the area up to `1000`.
 
 ## Testing
 
@@ -113,6 +110,5 @@ Same as Emscripten: MIT license.
 
  * Waiting for switch to stablize on the spec repo; switches are Nop'ed.
  * Reference interpreter lacks module importing support; imports are Nop'ed in native builds, but enabled in emcc builds (so wasm.js works).
- * WebAssembly lacks global variables, so `asm2wasm` maps them onto addresses in memory. This requires that you have some reserved space for those variables. You can do that with `emcc -s GLOBAL_BASE=1000`. We still need to write the code to copy the globals there.
  * Memory section needs the right size.
 
diff --git a/emcc_to_wasm.js.sh b/emcc_to_wasm.js.sh
index 528871746..c4c3a4bf3 100755
--- a/emcc_to_wasm.js.sh
+++ b/emcc_to_wasm.js.sh
@@ -3,7 +3,7 @@
 set -e
 
 echo "calling emcc"
-emcc -o a.html --separate-asm -profiling -s TOTAL_MEMORY=67108864 -s GLOBAL_BASE=1024 $@
+emcc -o a.html --separate-asm -profiling -s TOTAL_MEMORY=67108864 -s GLOBAL_BASE=1024 -s ALIASING_FUNCTION_POINTERS=0 $@
 
 # we now have a.asm.js and a.js
 
diff --git a/src/js/post.js b/src/js/post.js
index fe9e1b516..c9e29f6e8 100644
--- a/src/js/post.js
+++ b/src/js/post.js
@@ -31,12 +31,29 @@
     parent: Module // Module inside wasm-js.cpp refers to wasm-js.cpp; this allows access to the outside program.
   };
 
+  wasmJS['lookupImport'] = function(mod, base) {
+    var lookup = info;
+    if (mod.indexOf('.') < 0) {
+      lookup = (lookup || {})[mod];
+    } else {
+      var parts = mod.split('.');
+      lookup = (lookup || {})[parts[0]];
+      lookup = (lookup || {})[parts[1]];
+    }
+    lookup = (lookup || {})[base];
+    if (!lookup) {
+      abort('bad CallImport to (' + mod + ').' + base);
+    }
+    return lookup;
+  }
+
   // The asm.js function, called to "link" the asm.js module.
   Module['asm'] = function(global, env, buffer) {
     assert(buffer === theBuffer); // we should not even need to pass it as a 3rd arg for wasm, but that's the asm.js way.
     // write the provided data to a location the wasm instance can get at it.
     info.global = global;
     info.env = env;
+    wasmJS['_load_mapped_globals'](); // now that we have global and env, we can ready the provided imported globals, copying them to their mapped locations.
     return wasmJS['asmExports'];
   };
 })();
diff --git a/src/wasm-js.cpp b/src/wasm-js.cpp
index 4c8e27423..bedc65d48 100644
--- a/src/wasm-js.cpp
+++ b/src/wasm-js.cpp
@@ -95,18 +95,7 @@ extern "C" void EMSCRIPTEN_KEEPALIVE load_asm(char *input) {
         var base = Pointer_stringify($1);
         var tempArguments = Module['tempArguments'];
         Module['tempArguments'] = null;
-        var lookup = Module['info'];
-        if (mod.indexOf('.') < 0) {
-          lookup = (lookup || {})[mod];
-        } else {
-          var parts = mod.split('.');
-          lookup = (lookup || {})[parts[0]];
-          lookup = (lookup || {})[parts[1]];
-        }
-        lookup = (lookup || {})[base];
-        if (!lookup) {
-          abort('bad CallImport to (' + mod + ').' + base);
-        }
+        var lookup = Module['lookupImport'](mod, base);
         return lookup.apply(null, tempArguments);
       }, import->module.str, import->base.str));
     }
@@ -173,6 +162,10 @@ extern "C" void EMSCRIPTEN_KEEPALIVE load_asm(char *input) {
   instance = new ModuleInstance(*wasm, new JSExternalInterface());
 }
 
+// Ready the provided imported globals, copying them to their mapped locations.
+extern "C" void EMSCRIPTEN_KEEPALIVE load_mapped_globals() {
+}
+
 // Does a call from js into an export of the module.
 extern "C" double EMSCRIPTEN_KEEPALIVE call_from_js(const char *target) {
   IString name(target);