leave bool&1 as is if not going straight into a bitwise operator, to work around v8 issue 2513

3 files changed, 22 insertions, 26 deletions

diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index 2004efda..5b01dae0 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -136,6 +136,7 @@ var CONTROL_FLOW = set('do', 'while', 'for', 'if', 'switch');
 var NAME_OR_NUM = set('name', 'num');
 var ASSOCIATIVE_BINARIES = set('+', '*', '|', '&', '^');
 var ALTER_FLOW = set('break', 'continue', 'return');
+var BITWISE = set('|', '&', '^');
 
 var BREAK_CAPTURERS = set('do', 'while', 'for', 'switch');
 var CONTINUE_CAPTURERS = LOOP;
@@ -387,14 +388,18 @@ function simplifyExpressions(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;
+      } else if (type === 'binary' && (node[1] in BITWISE)) {
+        for (var i = 2; i <= 3; i++) {
+          var subNode = node[i];
+          if (subNode[0] === 'binary' && subNode[1] === '&' && subNode[3][0] === 'num' && subNode[3][1] == 1) {
+            // Rewrite (X < Y) & 1 to X < Y , when it is going into a bitwise operator. We could
+            // remove even more (just replace &1 with |0, then subsequent passes could remove the |0)
+            // but v8 issue #2513 means the code would then run very slowly in chrome.
+            var input = subNode[2];
+            if (input[0] === 'binary' && (input[1] in COMPARE_OPS)) {
+              node[i] = input;
+            }
+          }
         }
       }
     });
diff --git a/tools/test-js-optimizer-asm-pre-output.js b/tools/test-js-optimizer-asm-pre-output.js
index 5281b87c..da3ebb4f 100644
--- a/tools/test-js-optimizer-asm-pre-output.js
+++ b/tools/test-js-optimizer-asm-pre-output.js
@@ -106,15 +106,11 @@ function sign_extension_simplification() {
  }
 }
 function compare_result_simplification() {
- HEAP32[$4] = HEAP32[$5] < HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] > HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] <= HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] <= HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] == HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] === HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] != HEAP32[$6];
- HEAP32[$4] = HEAP32[$5] !== HEAP32[$6];
- var x = HEAP32[$5] != HEAP32[$6] | 0;
+ f((a > b & 1) + 1 | 0);
+ f(a > b | z);
+ f(a > b | c > d);
+ HEAP32[$4] = HEAP32[$5] < HEAP32[$6] & 1;
+ var x = HEAP32[$5] != HEAP32[$6] & 1;
 }
 function tempDoublePtr($45, $14, $28, $42) {
  $45 = $45 | 0;
diff --git a/tools/test-js-optimizer-asm-pre.js b/tools/test-js-optimizer-asm-pre.js
index d48d736e..08d8c2d4 100644
--- a/tools/test-js-optimizer-asm-pre.js
+++ b/tools/test-js-optimizer-asm-pre.js
@@ -113,16 +113,11 @@ function sign_extension_simplification() {
  }
 }
 function compare_result_simplification() {
- // Eliminate these '&1's.
+ f(((a > b)&1) + 1 | 0);
+ f(((a > b)&1) | z);
+ f(((a > b)&1) | (c > d & 1));
+ // Don't eliminate these '&1's.
  HEAP32[$4] = (HEAP32[$5] < HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] > HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] <= HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] <= HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] == HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] === HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] != HEAP32[$6]) & 1;
- HEAP32[$4] = (HEAP32[$5] !== HEAP32[$6]) & 1;
- // Convert the &1 to |0 here, since we don't get an implicit coersion.
  var x = (HEAP32[$5] != HEAP32[$6]) & 1;
 }
 function tempDoublePtr($45, $14, $28, $42) {