8080289: Intermediate writes in a loop not eliminated by optimizer
Summary: Move Stores out of loop (after or before) when possible
Reviewed-by: kvn, vlivanov
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/**
* @test
* @bug 8080289
* @summary Sink stores out of loops if possible
* @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:+PrintCompilation -XX:CompileCommand=dontinline,TestMoveStoresOutOfLoops::test* TestMoveStoresOutOfLoops
*
*/
import java.lang.reflect.*;
import java.util.*;
import java.util.function.*;
public class TestMoveStoresOutOfLoops {
private static long[] array = new long[10];
private static long[] array2 = new long[10];
private static boolean[] array3 = new boolean[1000];
private static byte[] byte_array = new byte[10];
// Array store should be moved out of the loop, value stored
// should be 999, the loop should be eliminated
static void test_after_1(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = i;
}
}
// Array store can't be moved out of loop because of following
// non loop invariant array access
static void test_after_2(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = i;
array2[i%10] = i;
}
}
// Array store can't be moved out of loop because of following
// use
static void test_after_3(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = i;
if (array[0] == -1) {
break;
}
}
}
// Array store can't be moved out of loop because of preceding
// use
static void test_after_4(int idx) {
for (int i = 0; i < 1000; i++) {
if (array[0] == -2) {
break;
}
array[idx] = i;
}
}
// All array stores should be moved out of the loop, one after
// the other
static void test_after_5(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = i;
array[idx+1] = i;
array[idx+2] = i;
array[idx+3] = i;
array[idx+4] = i;
array[idx+5] = i;
}
}
// Array store can be moved after the loop but needs to be
// cloned on both exit paths
static void test_after_6(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = i;
if (array3[i]) {
return;
}
}
}
// Optimize out redundant stores
static void test_stores_1(int ignored) {
array[0] = 0;
array[1] = 1;
array[2] = 2;
array[0] = 0;
array[1] = 1;
array[2] = 2;
}
static void test_stores_2(int idx) {
array[idx+0] = 0;
array[idx+1] = 1;
array[idx+2] = 2;
array[idx+0] = 0;
array[idx+1] = 1;
array[idx+2] = 2;
}
static void test_stores_3(int idx) {
byte_array[idx+0] = 0;
byte_array[idx+1] = 1;
byte_array[idx+2] = 2;
byte_array[idx+0] = 0;
byte_array[idx+1] = 1;
byte_array[idx+2] = 2;
}
// Array store can be moved out of the loop before the loop header
static void test_before_1(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = 999;
}
}
// Array store can't be moved out of the loop before the loop
// header because there's more than one store on this slice
static void test_before_2(int idx) {
for (int i = 0; i < 1000; i++) {
array[idx] = 999;
array[i%2] = 0;
}
}
// Array store can't be moved out of the loop before the loop
// header because of use before store
static int test_before_3(int idx) {
int res = 0;
for (int i = 0; i < 1000; i++) {
res += array[i%10];
array[idx] = 999;
}
return res;
}
// Array store can't be moved out of the loop before the loop
// header because of possible early exit
static void test_before_4(int idx) {
for (int i = 0; i < 1000; i++) {
if (idx / (i+1) > 0) {
return;
}
array[idx] = 999;
}
}
// Array store can't be moved out of the loop before the loop
// header because it doesn't postdominate the loop head
static void test_before_5(int idx) {
for (int i = 0; i < 1000; i++) {
if (i % 2 == 0) {
array[idx] = 999;
}
}
}
// Array store can be moved out of the loop before the loop header
static int test_before_6(int idx) {
int res = 0;
for (int i = 0; i < 1000; i++) {
if (i%2 == 1) {
res *= 2;
} else {
res++;
}
array[idx] = 999;
}
return res;
}
final HashMap<String,Method> tests = new HashMap<>();
{
for (Method m : this.getClass().getDeclaredMethods()) {
if (m.getName().matches("test_(before|after|stores)_[0-9]+")) {
assert(Modifier.isStatic(m.getModifiers())) : m;
tests.put(m.getName(), m);
}
}
}
boolean success = true;
void doTest(String name, Runnable init, Function<String, Boolean> check) throws Exception {
Method m = tests.get(name);
for (int i = 0; i < 20000; i++) {
init.run();
m.invoke(null, 0);
success = success && check.apply(name);
if (!success) {
break;
}
}
}
static void array_init() {
array[0] = -1;
}
static boolean array_check(String name) {
boolean success = true;
if (array[0] != 999) {
success = false;
System.out.println(name + " failed: array[0] = " + array[0]);
}
return success;
}
static void array_init2() {
for (int i = 0; i < 6; i++) {
array[i] = -1;
}
}
static boolean array_check2(String name) {
boolean success = true;
for (int i = 0; i < 6; i++) {
if (array[i] != 999) {
success = false;
System.out.println(name + " failed: array[" + i + "] = " + array[i]);
}
}
return success;
}
static void array_init3() {
for (int i = 0; i < 3; i++) {
array[i] = -1;
}
}
static boolean array_check3(String name) {
boolean success = true;
for (int i = 0; i < 3; i++) {
if (array[i] != i) {
success = false;
System.out.println(name + " failed: array[" + i + "] = " + array[i]);
}
}
return success;
}
static void array_init4() {
for (int i = 0; i < 3; i++) {
byte_array[i] = -1;
}
}
static boolean array_check4(String name) {
boolean success = true;
for (int i = 0; i < 3; i++) {
if (byte_array[i] != i) {
success = false;
System.out.println(name + " failed: byte_array[" + i + "] = " + byte_array[i]);
}
}
return success;
}
static public void main(String[] args) throws Exception {
TestMoveStoresOutOfLoops test = new TestMoveStoresOutOfLoops();
test.doTest("test_after_1", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_after_2", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_after_3", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_after_4", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_after_5", TestMoveStoresOutOfLoops::array_init2, TestMoveStoresOutOfLoops::array_check2);
test.doTest("test_after_6", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
array3[999] = true;
test.doTest("test_after_6", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_stores_1", TestMoveStoresOutOfLoops::array_init3, TestMoveStoresOutOfLoops::array_check3);
test.doTest("test_stores_2", TestMoveStoresOutOfLoops::array_init3, TestMoveStoresOutOfLoops::array_check3);
test.doTest("test_stores_3", TestMoveStoresOutOfLoops::array_init4, TestMoveStoresOutOfLoops::array_check4);
test.doTest("test_before_1", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_before_2", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_before_3", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_before_4", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_before_5", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
test.doTest("test_before_6", TestMoveStoresOutOfLoops::array_init, TestMoveStoresOutOfLoops::array_check);
if (!test.success) {
throw new RuntimeException("Some tests failed");
}
}
}