1 files changed, 23 insertions, 9 deletions

diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index d04807a7..1de06e4c 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -405,13 +405,16 @@ function removeUnneededLabelSettings(ast) {
 // Various expression simplifications. Pre run before closure (where we still have metadata), Post run after.
 
 var USEFUL_BINARY_OPS = set('<<', '>>', '|', '&', '^');
+var COMPARE_OPS = set('<', '<=', '>', '>=', '==', '===', '!=');
 
 function simplifyExpressionsPre(ast) {
-  // Look for (x&A)<<B>>B and replace it with X&A if possible.
-  function simplifySignExtends(ast) {
+  // Simplify common expressions used to perform integer conversion operations
+  // in cases where no conversion is needed.
+  function simplifyIntegerConversions(ast) {
     traverse(ast, function(node, type) {
       if (type === 'binary'       && node[1]    === '>>' && node[3][0] === 'num' &&
           node[2][0] === 'binary' && node[2][1] === '<<' && node[2][3][0] === 'num' && node[3][1] === node[2][3][1]) {
+        // Transform (x&A)<<B>>B to X&A.
         var innerNode = node[2][2];
         var shifts = node[3][1];
         if (innerNode[0] === 'binary' && innerNode[1] === '&' && innerNode[3][0] === 'num') {
@@ -420,6 +423,15 @@ function simplifyExpressionsPre(ast) {
             return innerNode;
           }
         }
+      } else if (type === 'binary' && node[1] === '&' && node[3][0] === 'num') {
+        // Rewrite (X < Y) & 1 to (X < Y)|0. (Subsequent passes will eliminate
+        // the |0 if possible.)
+        var input = node[2];
+        var amount = node[3][1];
+        if (input[0] === 'binary' && (input[1] in COMPARE_OPS) && amount == 1) {
+          node[1] = '|';
+          node[3][1] = 0;
+        }
       }
     });
   }
@@ -763,7 +775,7 @@ function simplifyExpressionsPre(ast) {
   }
 
   traverseGeneratedFunctions(ast, function(func) {
-    simplifySignExtends(func);
+    simplifyIntegerConversions(func);
     simplifyBitops(func);
     joinAdditions(func);
     // simplifyZeroComp(func); TODO: investigate performance
@@ -2730,8 +2742,9 @@ function relocate(ast) {
   assert(asm); // we also assume we are normalized
 
   var replacements = extraInfo.replacements;
-  var fBase = extraInfo.fBase;
+  var fBases = extraInfo.fBases;
   var hBase = extraInfo.hBase;
+  var m;
 
   traverse(ast, function(node, type) {
     switch(type) {
@@ -2743,13 +2756,14 @@ function relocate(ast) {
       case 'binary': {
         if (node[1] == '+' && node[2][0] == 'name') {
           var base = null;
-          if (node[2][1] == 'F_BASE') {
-            base = fBase;
-          } else if (node[2][1] == 'H_BASE') {
+          if (node[2][1] == 'H_BASE') {
             base = hBase;
+          } else if (m = /^F_BASE_(\w+)$/.exec(node[2][1])) {
+            base = fBases[m[1]] || 0; // 0 if the parent has no function table for this, but the child does. so no relocation needed
           }
-          if (base) {
+          if (base !== null) {
             var other = node[3];
+            if (base === 0) return other;
             if (other[0] == 'num') {
               other[1] += base;
               return other;
@@ -2887,7 +2901,7 @@ arguments_.slice(1).forEach(function(arg) {
   passes[arg](ast);
 });
 if (asm && last) {
-  asmLoopOptimizer(ast);
+  asmLoopOptimizer(ast); // TODO: move out of last, to make last faster when done later (as in side modules)
   prepDotZero(ast);
 }
 var js = astToSrc(ast, minifyWhitespace), old;