Bug 1158632 - IonBuilder TableSwitch, fill-the-gap cases should encore the PC of the default block. r=h4writer

js/src/jit-test/tests/ion/bug1158632.js

@@ -0,0 +1,13 @@
+for (var j = 0; j < 1; ++j) {
+  function f(x) {
+    x = 4294967295 >>> 4294967295 % x
+    switch (-1) {
+      case 1:
+      // case 0:
+      case -1:
+        x = 0;
+      // default:
+    }
+  }
+  f();
+}

js/src/jit/IonBuilder.cpp

@@ -3406,34 +3406,34 @@ IonBuilder::tableSwitch(JSOp op, jssrcnote* sn)
         casepc = pc + GET_JUMP_OFFSET(pc2);
 
         MOZ_ASSERT(casepc >= pc && casepc <= exitpc);
+        MBasicBlock* caseblock;
 
-        MBasicBlock* caseblock = newBlock(current, casepc);
-        if (!caseblock)
-            return ControlStatus_Error;
-
-        // If the casepc equals the current pc, it is not a written case,
-        // but a filled gap. That way we can use a tableswitch instead of
-        // condswitch, even if not all numbers are consecutive.
-        // In that case this block goes to the default case
         if (casepc == pc) {
+            // If the casepc equals the current pc, it is not a written case,
+            // but a filled gap. That way we can use a tableswitch instead of
+            // condswitch, even if not all numbers are consecutive.
+            // In that case this block goes to the default case
+            caseblock = newBlock(current, defaultpc);
+            if (!caseblock)
+                return ControlStatus_Error;
             caseblock->end(MGoto::New(alloc(), defaultcase));
             if (!defaultcase->addPredecessor(alloc(), caseblock))
                 return ControlStatus_Error;
-        }
+        } else {
+            // If this is an actual case (not filled gap),
+            // add this block to the list that still needs to get processed.
+            caseblock = newBlock(current, casepc);
+            if (!caseblock)
+                return ControlStatus_Error;
 
-        tableswitch->addCase(tableswitch->addSuccessor(caseblock));
-
-        // If this is an actual case (not filled gap),
-        // add this block to the list that still needs to get processed.
-        if (casepc != pc) {
             tableswitch->addBlock(caseblock);
-
             // Add constant to indicate which case this is for use by
             // processNextTableSwitchCase.
             MConstant* constant = MConstant::New(alloc(), Int32Value(i + low));
             caseblock->add(constant);
         }
 
+        tableswitch->addCase(tableswitch->addSuccessor(caseblock));
         pc2 += JUMP_OFFSET_LEN;
     }