painless: fix disabled loop counter

modules/lang-painless/src/main/java/org/elasticsearch/painless/MethodWriter.java

@@ -118,17 +118,16 @@ public final class MethodWriter extends GeneratorAdapter {
     }
 
     public void writeLoopCounter(int slot, int count, Location location) {
-        if (slot > -1) {
+        assert slot != -1;
-            writeDebugInfo(location);
+        writeDebugInfo(location);
-            final Label end = new Label();
+        final Label end = new Label();
 
-            iinc(slot, -count);
+        iinc(slot, -count);
-            visitVarInsn(Opcodes.ILOAD, slot);
+        visitVarInsn(Opcodes.ILOAD, slot);
-            push(0);
+        push(0);
-            ifICmp(GeneratorAdapter.GT, end);
+        ifICmp(GeneratorAdapter.GT, end);
-            throwException(PAINLESS_ERROR_TYPE, "The maximum number of statements that can be executed in a loop has been reached.");
+        throwException(PAINLESS_ERROR_TYPE, "The maximum number of statements that can be executed in a loop has been reached.");
-            mark(end);
+        mark(end);
-        }
     }
 
     public void writeCast(final Cast cast) {

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SDo.java

@@ -113,7 +113,9 @@ public final class SDo extends AStatement {
         condition.fals = end;
         condition.write(writer, globals);
 
-        writer.writeLoopCounter(loopCounter.getSlot(), Math.max(1, block.statementCount), location);
+        if (loopCounter != null) {
+            writer.writeLoopCounter(loopCounter.getSlot(), Math.max(1, block.statementCount), location);
+        }
 
         writer.goTo(start);
         writer.mark(end);

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SFor.java

@@ -176,10 +176,14 @@ public final class SFor extends AStatement {
                 ++statementCount;
             }
 
-            writer.writeLoopCounter(loopCounter.getSlot(), statementCount, location);
+            if (loopCounter != null) {
+                writer.writeLoopCounter(loopCounter.getSlot(), statementCount, location);
+            }
             block.write(writer, globals);
         } else {
-            writer.writeLoopCounter(loopCounter.getSlot(), 1, location);
+            if (loopCounter != null) {
+                writer.writeLoopCounter(loopCounter.getSlot(), 1, location);
+            }
         }
 
         if (afterthought != null) {

modules/lang-painless/src/main/java/org/elasticsearch/painless/node/SWhile.java

@@ -113,13 +113,17 @@ public final class SWhile extends AStatement {
         condition.write(writer, globals);
 
         if (block != null) {
-            writer.writeLoopCounter(loopCounter.getSlot(), Math.max(1, block.statementCount), location);
+            if (loopCounter != null) {
+                writer.writeLoopCounter(loopCounter.getSlot(), Math.max(1, block.statementCount), location);
+            }
 
             block.continu = begin;
             block.brake = end;
             block.write(writer, globals);
         } else {
-            writer.writeLoopCounter(loopCounter.getSlot(), 1, location);
+            if (loopCounter != null) {
+                writer.writeLoopCounter(loopCounter.getSlot(), 1, location);
+            }
         }
 
         if (block == null || !block.allEscape) {

modules/lang-painless/src/test/java/org/elasticsearch/painless/BasicStatementTests.java

@@ -1,5 +1,7 @@
 package org.elasticsearch.painless;
 
+import java.util.Collections;
+
 /*
  * Licensed to Elasticsearch under one or more contributor
  * license agreements. See the NOTICE file distributed with
@@ -223,4 +225,25 @@ public class BasicStatementTests extends ScriptTestCase {
         assertEquals(10, exec("def i = 1; if (i == 1) {i = 2; return 10}"));
         assertEquals(10, exec("def i = 1; if (i == 1) {i = 2; return 10} else {return 12}"));
     }
+    
+    public void testArrayLoopWithoutCounter() {
+       assertEquals(6L, exec("long sum = 0; long[] array = new long[] { 1, 2, 3 };" + 
+                              "for (int i = 0; i < array.length; i++) { sum += array[i] } return sum", 
+                              Collections.emptyMap(),
+                              Collections.singletonMap(CompilerSettings.MAX_LOOP_COUNTER, "0"),
+                              null
+       ));
+       assertEquals(6L, exec("long sum = 0; long[] array = new long[] { 1, 2, 3 };" + 
+                             "int i = 0; while (i < array.length) { sum += array[i++] } return sum", 
+                             Collections.emptyMap(),
+                             Collections.singletonMap(CompilerSettings.MAX_LOOP_COUNTER, "0"),
+                             null
+       ));
+       assertEquals(6L, exec("long sum = 0; long[] array = new long[] { 1, 2, 3 };" + 
+                             "int i = 0; do { sum += array[i++] } while (i < array.length); return sum", 
+                             Collections.emptyMap(),
+                             Collections.singletonMap(CompilerSettings.MAX_LOOP_COUNTER, "0"),
+                             null
+       ));
+    }
 }