always use Math.imul, with fast polyfill. will be useful for faster 64-bit math

4 files changed, 5 insertions, 9 deletions

diff --git a/emscripten.py b/emscripten.py
index af762a21..b3e153c1 100755
--- a/emscripten.py
+++ b/emscripten.py
@@ -322,10 +322,7 @@ def emscript(infile, settings, outfile, libraries=[]):
     function_tables_defs = '\n'.join([info[0] for info in infos] + [info[1] for info in infos])
 
     asm_setup = ''
-    maths = ['Math.' + func for func in ['floor', 'abs', 'sqrt', 'pow', 'cos', 'sin', 'tan', 'acos', 'asin', 'atan', 'atan2', 'exp', 'log', 'ceil']]
-    if settings['USE_MATH_IMUL']:
-      maths += ['Math.imul']
-      asm_setup += 'if (!Math.imul) Math.imul = function(x, y) { return (x*y)|0 }; // # not a real polyfill since semantics not identical, but close and fairly fast\n'
+    maths = ['Math.' + func for func in ['floor', 'abs', 'sqrt', 'pow', 'cos', 'sin', 'tan', 'acos', 'asin', 'atan', 'atan2', 'exp', 'log', 'ceil', 'imul']]
     fundamentals = ['Math', 'Int8Array', 'Int16Array', 'Int32Array', 'Uint8Array', 'Uint16Array', 'Uint32Array', 'Float32Array', 'Float64Array']
     math_envs = ['Runtime.bitshift64', 'Math.min'] # TODO: move min to maths
     asm_setup += '\n'.join(['var %s = %s;' % (f.replace('.', '_'), f) for f in math_envs])
diff --git a/src/parseTools.js b/src/parseTools.js
index 15c2169b..514d74d0 100644
--- a/src/parseTools.js
+++ b/src/parseTools.js
@@ -1046,10 +1046,8 @@ function asmMultiplyI32(a, b) {
   if ((isNumber(a) && Math.abs(a) < TWO_TWENTY) || (isNumber(b) && Math.abs(b) < TWO_TWENTY)) {
     return '(((' + a + ')*(' + b + '))&-1)'; // small enough to emit directly as a multiply
   }
-  if (USE_MATH_IMUL) {
-    return 'Math.imul(' + a + ',' + b + ')';
-  }
-  return '(~~(+((' + a + ')|0) * +((' + b + ')|0)))';
+  return 'Math.imul(' + a + ',' + b + ')';
+  // non-imul version: return '(~~(+((' + a + ')|0) * +((' + b + ')|0)))';
 }
 
 function asmFloatToInt(x) {
diff --git a/src/preamble.js b/src/preamble.js
index 503b09f1..b355f130 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -742,6 +742,8 @@ Module['writeArrayToMemory'] = writeArrayToMemory;
 {{{ unSign }}}
 {{{ reSign }}}
 
+if (!Math.imul) Math.imul = function(x, y) { return (x*y)|0 }; // # not a real polyfill since semantics not identical, but close and fast
+
 // 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
diff --git a/src/settings.js b/src/settings.js
index f4e23c5b..1023ee11 100644
--- a/src/settings.js
+++ b/src/settings.js
@@ -325,7 +325,6 @@ var BENCHMARK = 0; // If 1, will just time how long main() takes to execute, and
 var ASM_JS = 0; // If 1, generate code in asm.js format. XXX This is highly experimental,
                 // and will not work on most codebases yet. It is NOT recommended that you
                 // try this yet.
-var USE_MATH_IMUL = 1; // If 1, use Math.imul when normal int math can't be done in ASM_JS
 
 var EXPLICIT_ZEXT = 0; // If 1, generate an explicit conversion of zext i1 to i32, using ?: