--- old/src/java.base/share/classes/java/lang/invoke/MethodHandles.java 2016-04-20 15:11:42.000000000 +0200 +++ new/src/java.base/share/classes/java/lang/invoke/MethodHandles.java 2016-04-20 15:11:42.000000000 +0200 @@ -4476,12 +4476,16 @@ * @since 9 */ public static MethodHandle countedLoop(MethodHandle start, MethodHandle end, MethodHandle init, MethodHandle body) { - MethodHandle returnVar = dropArguments(init == null || init.type().returnType() == void.class ? - zero(void.class) : identity(init.type().returnType()), 0, int.class, int.class); + boolean voidReturn = init == null || init.type().returnType() == void.class; + MethodHandle adaptedBody = body == null ? + dropArguments(voidReturn ? zero(void.class) : identity(init.type().returnType()), 0, int.class) : + body; + MethodHandle returnVar = dropArguments(voidReturn ? zero(void.class) : identity(init.type().returnType()), + 0, int.class, int.class); MethodHandle[] indexVar = {start, MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_countedLoopStep)}; MethodHandle[] loopLimit = {end, null, MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_countedLoopPred), returnVar}; MethodHandle[] bodyClause = {init, - filterArgument(dropArguments(body, 1, int.class), 0, + filterArgument(dropArguments(adaptedBody, 1, int.class), 0, MethodHandleImpl.getConstantHandle(MethodHandleImpl.MH_decrementCounter))}; return loop(indexVar, loopLimit, bodyClause); } --- old/test/java/lang/invoke/LoopCombinatorTest.java 2016-04-20 15:11:43.000000000 +0200 +++ new/test/java/lang/invoke/LoopCombinatorTest.java 2016-04-20 15:11:43.000000000 +0200 @@ -29,6 +29,7 @@ * @bug 8150956 * @bug 8150957 * @bug 8153637 + * @bug 8154751 * @run testng/othervm -ea -esa test.java.lang.invoke.LoopCombinatorTest */ @@ -347,6 +348,23 @@ } @Test + public static void testCountedLoopEmpty() throws Throwable { + // for (int i = 0; i < 5; ++i) { /* empty */ } + MethodHandle loop = MethodHandles.countedLoop(MethodHandles.constant(int.class, 5), null, null); + assertEquals(methodType(void.class), loop.type()); + loop.invoke(); + } + + @Test + public static void testCountedRangeLoopEmpty() throws Throwable { + // for (int i = -5; i < 5; ++i) { /* empty */ } + MethodHandle loop = MethodHandles.countedLoop(MethodHandles.constant(int.class, -5), + MethodHandles.constant(int.class, 5), null, null); + assertEquals(methodType(void.class), loop.type()); + loop.invoke(); + } + + @Test public static void testIterateSum() throws Throwable { // Integer[] a = new Integer[]{1,2,3,4,5,6}; int sum = 0; for (int e : a) { sum += e; } return sum; => 21 MethodHandle loop = MethodHandles.iteratedLoop(Iterate.MH_sumIterator, Iterate.MH_sumInit, Iterate.MH_sumStep);