collapse elses after the if block breaks or continues, other minor js optimizer fixes

3 files changed, 160 insertions, 36 deletions

diff --git a/tools/js-optimizer.js b/tools/js-optimizer.js
index d84c664a..a0595b88 100644
--- a/tools/js-optimizer.js
+++ b/tools/js-optimizer.js
@@ -239,7 +239,7 @@ function emptyNode() {
 // Dump the AST. Useful for debugging. For example,
 //  node tools/js-optimizer.js ABSOLUTE_PATH_TO_FILE dumpAst
 function dumpAst(ast) {
-  printErr(JSON.stringify(ast));
+  printErr(JSON.stringify(ast, null, '  '));
 }
 
 function dumpSrc(ast) {
@@ -801,18 +801,24 @@ function vacuum(ast) {
     if (node[0] == 'block' && (!node[1] || (typeof node[1] != 'object') || node[1].length == 0 || (node[1].length == 1 && isEmpty(node[1])))) return true;
     return false;
   }
-  function simplifyList(node, i) {
+  function simplifyList(node, si) {
     var changed = false;
-    var pre = node[i].length;
-    node[i] = node[i].filter(function(node) { return !isEmpty(node) });
-    if (node[i].length < pre) changed = true;
-    // Also, seek blocks with single items we can simplify
-    node[i] = node[i].map(function(subNode) {
-      if (subNode[0] == 'block' && typeof subNode[1] == 'object' && subNode[1].length == 1 && subNode[1][0][0] == 'if') {
-        return subNode[1][0];
+    // Merge block items into this list, thus removing unneeded |{ .. }|'s
+    var statements = node[si];
+    var i = 0;
+    while (i < statements.length) {
+      var subNode = statements[i];
+      if (subNode[0] == 'block') {
+        statements.splice.apply(statements, [i, 1].concat(subNode[1] || []));
+        changed = true;
+      } else {
+        i++;
       }
-      return subNode;
-    });
+    }
+    // Remove empty items
+    var pre = node[si].length;
+    node[si] = node[si].filter(function(node) { return !isEmpty(node) });
+    if (node[si].length < pre) changed = true;
     if (changed) {
       return node;
     }
@@ -1002,6 +1008,35 @@ function hoistMultiples(ast) {
   });
 
   vacuum(ast);
+
+  // Afterpass: Reduce
+  //    if (..) { .. break|continue } else { .. }
+  // to
+  //    if (..) { .. break|continue } ..
+  traverseGenerated(ast, function(container, type) {
+    var statements = getStatements(container);
+    if (!statements) return;
+    for (var i = 0; i < statements.length; i++) {
+      var node = statements[i];
+      if (node[0] == 'if' && node[2][0] == 'block' && node[3] && node[3][0] == 'block') {
+        var stat1 = node[2][1], stat2 = node[3][1];
+        // If break|continue in the latter and not the former, reverse them
+        if (!(stat1[stat1.length-1][0] in LOOP_FLOW) && (stat2[stat2.length-1][0] in LOOP_FLOW)) {
+          var temp = node[3];
+          node[3] = node[2];
+          node[2] = temp;
+          node[1] = ['unary-prefix', '!', node[1]];
+          simplifyNotComps(node[1]); // bake the ! into the expression
+          stat1 = node[2][1];
+          stat2 = node[3][1];
+        }
+        if (stat1[stat1.length-1][0] in LOOP_FLOW) {
+          statements.splice.apply(statements, [i+1, 0].concat(stat2));
+          node[3] = null;
+        }
+      }
+    }
+  });
 }
 
 // Simplifies loops
diff --git a/tools/test-js-optimizer-output.js b/tools/test-js-optimizer-output.js
index 17c06a95..ca76cae1 100644
--- a/tools/test-js-optimizer-output.js
+++ b/tools/test-js-optimizer-output.js
@@ -68,9 +68,7 @@ function loopy() {
     something();
   } while (0);
   next();
-  {
-    something();
-  }
+  something();
 }
 function ignoreLoopy() {
   b$for_cond$4 : while (1) {
@@ -141,12 +139,11 @@ function hoisting() {
   }
   pause(7);
   while (1) {
-    if ($i < $N) {
-      somethingElse();
-    } else {
+    if ($i >= $N) {
       __label__ = 3;
       break;
     }
+    somethingElse();
     if ($i < $N) {
       somethingElse();
     }
@@ -166,15 +163,43 @@ function hoisting() {
       }
       __label__ = 39;
       break;
-    } else {
-      __label__ = 38;
     }
+    __label__ = 38;
   } while (0);
   if (__label__ == 38) {
     var $79 = $_pr6;
   }
   pause(9);
   var $cmp70 = ($call69 | 0) != 0;
+  pause(10);
+  while (check()) {
+    if ($i < $N) {
+      callOther();
+      break;
+    }
+    somethingElse();
+    if ($i1 < $N) {
+      callOther();
+      continue;
+    }
+    somethingElse();
+    if ($i2 >= $N) {
+      somethingElse();
+      break;
+    }
+    callOther();
+    if ($i3 >= $N) {
+      somethingElse();
+      continue;
+    }
+    callOther();
+    if ($i4 < $N) {
+      callOther();
+      break;
+    }
+    somethingElse();
+    continue;
+  }
 }
 function innerShouldAlsoBeHoisted() {
   function hoisting() {
@@ -208,9 +233,7 @@ function sleep() {
 }
 function demangle($cmp) {
   do {
-    if ($cmp) {
-      __label__ = 3;
-    } else {
+    if (!$cmp) {
       if (something()) {
         __label__ = 3;
         break;
@@ -218,6 +241,7 @@ function demangle($cmp) {
       more();
       break;
     }
+    __label__ = 3;
   } while (0);
   if (__label__ == 3) {
     final();
@@ -259,25 +283,21 @@ function moreLabels() {
     }
     if ($cmp1) {
       break;
-    } else {
-      inc();
     }
+    inc();
   }
   pause(999);
   $while_body$$while_end$31 : do {
     if ($cmp3) {
       var $6 = $5;
-      {
-        while (1) {
-          var $6;
-          $iter = $6 + 3;
-          if (FHEAP[$iter + 1] < $pct_addr) {
-            var $6 = $iter;
-          } else {
-            var $_lcssa = $iter;
-            break $while_body$$while_end$31;
-          }
+      while (1) {
+        var $6;
+        $iter = $6 + 3;
+        if (FHEAP[$iter + 1] >= $pct_addr) {
+          var $_lcssa = $iter;
+          break $while_body$$while_end$31;
         }
+        var $6 = $iter;
       }
     } else {
       var $_lcssa = $5;
@@ -286,4 +306,9 @@ function moreLabels() {
   var $_lcssa;
   cheez();
 }
-// EMSCRIPTEN_GENERATED_FUNCTIONS: ["abc", "xyz", "xyz2", "expr", "loopy", "bits", "maths", "hoisting", "demangle", "lua", "moreLabels"]
+function notComps() {
+  if (HEAP32[$incdec_ptr71_i + 8 >> 2] != 0) {
+    shoo();
+  }
+}
+// EMSCRIPTEN_GENERATED_FUNCTIONS: ["abc", "xyz", "xyz2", "expr", "loopy", "bits", "maths", "hoisting", "demangle", "lua", "moreLabels", "notComps"]
diff --git a/tools/test-js-optimizer.js b/tools/test-js-optimizer.js
index 95985bc8..18c9ac75 100644
--- a/tools/test-js-optimizer.js
+++ b/tools/test-js-optimizer.js
@@ -226,6 +226,65 @@ function hoisting() {
   $if_then72$$if_end73$126 : do {
     if (__label__ == 40) {} else if (__label__ == 41) {}
   } while (0);
+  pause(10);
+  while(check()) {
+    if ($i < $N) {
+      __label__ = 2;
+    } else {
+      __label__ = 3;
+    }
+    if (__label__ == 2) {
+      callOther();
+      break;
+    } else if (__label__ == 3) {
+      somethingElse();
+    }
+    if ($i1 < $N) {
+      __label__ = 2;
+    } else {
+      __label__ = 3;
+    }
+    if (__label__ == 2) {
+      callOther();
+      continue;
+    } else if (__label__ == 3) {
+      somethingElse();
+    }
+    if ($i2 < $N) {
+      __label__ = 2;
+    } else {
+      __label__ = 3;
+    }
+    if (__label__ == 2) {
+      callOther();
+    } else if (__label__ == 3) {
+      somethingElse();
+      break;
+    }
+    if ($i3 < $N) {
+      __label__ = 2;
+    } else {
+      __label__ = 3;
+    }
+    if (__label__ == 2) {
+      callOther();
+    } else if (__label__ == 3) {
+      somethingElse();
+      continue;
+    }
+    if ($i4 < $N) {
+      __label__ = 2;
+    } else {
+      __label__ = 3;
+    }
+    if (__label__ == 2) {
+      callOther();
+      break;
+    } else if (__label__ == 3) {
+      somethingElse();
+      continue;
+    }
+  }
 }
 function innerShouldAlsoBeHoisted() {
   function hoisting() {
@@ -358,4 +417,9 @@ function moreLabels() {
   var $_lcssa;
   cheez();
 }
-// EMSCRIPTEN_GENERATED_FUNCTIONS: ["abc", "xyz", "xyz2", "expr", "loopy", "bits", "maths", "hoisting", "demangle", "lua", "moreLabels"]
+function notComps() {
+  if (!(HEAP32[$incdec_ptr71_i + 8 >> 2] == 0)) {
+    shoo();
+  }
+}
+// EMSCRIPTEN_GENERATED_FUNCTIONS: ["abc", "xyz", "xyz2", "expr", "loopy", "bits", "maths", "hoisting", "demangle", "lua", "moreLabels", "notComps"]