set asm function table sizes to power of two, and add proper masking

3 files changed, 10 insertions, 1 deletions

diff --git a/src/jsifier.js b/src/jsifier.js
index a83b2d3d..50824562 100644
--- a/src/jsifier.js
+++ b/src/jsifier.js
@@ -1278,10 +1278,12 @@ function JSify(data, functionsOnly, givenFunctions) {
 
     if (byPointer) {
       var returnType = type.split(' ')[0];
+      var sig = Functions.getSignature(returnType, argsTypes);
       if (ASM_JS) {
         assert(returnType.search(/\("'\[,/) == -1); // XXX need isFunctionType(type, out)
+        ident = '(' + ident + ')&{{{ FTM_' + sig + ' }}}'; // the function table mask is set in emscripten.py
       }
-      ident = Functions.getTable(Functions.getSignature(returnType, argsTypes)) + '[' + ident + ']';
+      ident = Functions.getTable(sig) + '[' + ident + ']';
     }
 
     return ident + '(' + args.join(', ') + ')';
diff --git a/src/modules.js b/src/modules.js
index 71fec0cd..5c1d6a1d 100644
--- a/src/modules.js
+++ b/src/modules.js
@@ -259,6 +259,7 @@ var Functions = {
   // Generate code for function indexing
   generateIndexing: function() {
     var total = this.nextIndex;
+    if (ASM_JS) total = ceilPowerOfTwo(total); // must be power of 2 for mask
     function emptyTable(sig) {
       return zeros(total);
     }
diff --git a/src/utility.js b/src/utility.js
index 84b50ce9..63582ae8 100644
--- a/src/utility.js
+++ b/src/utility.js
@@ -321,6 +321,12 @@ function isPowerOfTwo(x) {
   return x > 0 && ((x & (x-1)) == 0);
 }
 
+function ceilPowerOfTwo(x) {
+  var ret = 1;
+  while (ret < x) ret <<= 1;
+  return ret;
+}
+
 function Benchmarker() {
   var starts = {}, times = {}, counts = {};
   this.start = function(id) {