do not emit direct multiplies of <32 bit in asm, asm only has 32-bit multiply

1 files changed, 2 insertions, 1 deletions

diff --git a/src/parseTools.js b/src/parseTools.js
index 7d1a7cd9..ae5831ae 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -1393,7 +1393,8 @@ function getFastValue(a, op, b, type) {
       if (!(type in Runtime.FLOAT_TYPES)) {
         // if guaranteed small enough to not overflow into a double, do a normal multiply
         var bits = getBits(type) || 32; // default is 32-bit multiply for things like getelementptr indexes
-        if ((isNumber(a) && Math.abs(a) < TWO_TWENTY) || (isNumber(b) && Math.abs(b) < TWO_TWENTY) || bits < 32) {
+        // Note that we can emit simple multiple in non-asm.js mode, but asm.js will not parse "16-bit" multiple, so must do imul there
+        if ((isNumber(a) && Math.abs(a) < TWO_TWENTY) || (isNumber(b) && Math.abs(b) < TWO_TWENTY) || (bits < 32 && !ASM_JS)) {
           return '(((' + a + ')*(' + b + '))&' + ((Math.pow(2, bits)-1)|0) + ')'; // keep a non-eliminatable coercion directly on this
         }
         return 'Math.imul(' + a + ',' + b + ')';