do not optimize while into do-while if there are continues; fixes #1337

tools/js-optimizer.js

@@ -2807,6 +2807,23 @@ function asmLoopOptimizer(ast) {
         var stats = node[2][1];
         var last = stats[stats.length-1];
         if (last && last[0] === 'if' && !last[3] && last[2][0] === 'block' && last[2][1][0] && last[2][1][0][0] === 'break' && !last[2][1][0][1]) {
+          var abort = false;
+          var stack = 0;
+          traverse(stats, function(node, type) {
+            if (type == 'continue') {
+              if (stack == 0 || node[1]) { // abort if labeled (we do not analyze labels here yet), or a continue directly on us
+                abort = true;
+                return true;
+              }
+            } else if (type in LOOP) {
+              stack++;
+            }
+          }, function(node, type) {
+            if (type in LOOP) {
+              stack--;
+            }
+          });
+          if (abort) return;
           var conditionToBreak = last[1];
           stats.pop();
           node[0] = 'do';

tools/test-js-optimizer-asm-last-output.js

@@ -42,5 +42,33 @@ function looop() {
  do {
   do_it();
  } while (x());
+ while (1) {
+  do_it();
+  if (a()) continue;
+  if (!x()) {
+   break;
+  }
+ }
+ do {
+  do_it();
+  do {
+   if (a()) continue;
+  } while (b());
+ } while (x());
+ do {
+  do_it();
+  while (b()) {
+   if (a()) continue;
+  }
+ } while (x());
+ X : while (1) {
+  do_it();
+  while (b()) {
+   if (a()) continue X;
+  }
+  if (!x()) {
+   break;
+  }
+ }
 }
 

tools/test-js-optimizer-asm-last.js

@@ -51,6 +51,40 @@ function looop() {
    break;
   }
  }
+ while (1) {
+  do_it();
+  if (a()) continue; // we cannot move to do-while, continue will hit the while check
+  if (!x()) {
+   break;
+  }
+ }
+ while (1) {
+  do_it();
+  do {
+    if (a()) continue; // ok to optimize, continue is not for us
+  } while (b());
+  if (!x()) {
+   break;
+  }
+ }
+ while (1) {
+  do_it();
+  while (b()) {
+    if (a()) continue; // also ok to optimize, continue is not for us
+  }
+  if (!x()) {
+   break;
+  }
+ }
+ X: while (1) {
+  do_it();
+  while (b()) {
+    if (a()) continue X; // not ok to optimize
+  }
+  if (!x()) {
+   break;
+  }
+ }
 }
 // EMSCRIPTEN_GENERATED_FUNCTIONS: ["finall", "looop"]