1 files changed, 22 insertions, 2 deletions
diff --git a/src/preamble.js b/src/preamble.js
index 503b09f1..6f4b49de 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -447,7 +447,7 @@ function allocate(slab, types, allocator, ptr) {
   }
 #endif
 
-  var i = 0, type;
+  var i = 0, type, typeSize, previousType;
   while (i < size) {
     var curr = slab[i];
 
@@ -469,7 +469,13 @@ function allocate(slab, types, allocator, ptr) {
 #endif
 
     setValue(ret+i, curr, type);
-    i += Runtime.getNativeTypeSize(type);
+
+    // no need to look up size unless type changes, so cache it
+    if (previousType !== type) {
+      typeSize = Runtime.getNativeTypeSize(type);
+      previousType = type;
+    }
+    i += typeSize;
   }
 
   return ret;
@@ -742,6 +748,20 @@ Module['writeArrayToMemory'] = writeArrayToMemory;
 {{{ unSign }}}
 {{{ reSign }}}
 
+#if PRECISE_I32_MUL
+if (!Math.imul) Math.imul = function(a, b) {
+  var ah  = a >>> 16;
+  var al = a & 0xffff;
+  var bh  = b >>> 16;
+  var bl = b & 0xffff;
+  return (al*bl + ((ah*bl + al*bh) << 16))|0;
+};
+#else
+Math.imul = function(a, b) {
+  return (a*b)|0; // fast but imprecise
+};
+#endif
+
 // A counter of dependencies for calling run(). If we need to
 // do asynchronous work before running, increment this and
 // decrement it. Incrementing must happen in a place like