8316679: C2 SuperWord: wrong result, load should not be moved before store if not comparable

Reviewed-by: kvn, thartmann
This commit is contained in:
Emanuel Peter 2023-10-04 07:54:30 +00:00
parent 0b0f8b55a6
commit 48f1a925e5
2 changed files with 106 additions and 7 deletions
src/hotspot/share/opto
test/hotspot/jtreg/compiler/loopopts/superword

@ -2565,18 +2565,18 @@ bool SuperWord::output() {
if (n->is_Load()) {
Node* ctl = n->in(MemNode::Control);
Node* mem = first->in(MemNode::Memory);
// Set the memory dependency of the LoadVector as early as possible.
// Walk up the memory chain, and ignore any StoreVector that provably
// does not have any memory dependency.
VPointer p1(n->as_Mem(), phase(), lpt(), nullptr, false);
// Identify the memory dependency for the new loadVector node by
// walking up through memory chain.
// This is done to give flexibility to the new loadVector node so that
// it can move above independent storeVector nodes.
while (mem->is_StoreVector()) {
VPointer p2(mem->as_Mem(), phase(), lpt(), nullptr, false);
int cmp = p1.cmp(p2);
if (VPointer::not_equal(cmp) || !VPointer::comparable(cmp)) {
if (p1.not_equal(p2)) {
// Either Less or Greater -> provably no overlap between the two memory regions.
mem = mem->in(MemNode::Memory);
} else {
break; // dependent memory
// No proof that there is no overlap. Stop here.
break;
}
}
Node* adr = first->in(MemNode::Address);

@ -0,0 +1,99 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
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*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
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*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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*/
/**
* @test
* @requires vm.compiler2.enabled
* @bug 8316679
* @summary In SuperWord::output, LoadVector can be moved before StoreVector, but only if it is proven to be safe.
* @key randomness
* @library /test/lib
* @run main/othervm -XX:CompileCommand=compileonly,compiler.loopopts.superword.TestMovingLoadBeforeStore::test*
* -Xbatch -XX:LoopUnrollLimit=100
* -XX:+UnlockDiagnosticVMOptions -XX:+StressLCM
* compiler.loopopts.superword.TestMovingLoadBeforeStore
*/
package compiler.loopopts.superword;
import java.util.Random;
import jdk.test.lib.Utils;
public class TestMovingLoadBeforeStore {
static int RANGE = 1024*64;
private static final Random random = Utils.getRandomInstance();
public static void main(String[] strArr) {
byte a[] = new byte[RANGE];
for (int i = 0; i < 100; i++) {
for (int j = 0; j < a.length; j++) {
a[j] = (byte)random.nextInt();
}
byte[] a_ref = a.clone();
byte[] a_res = a.clone();
ref1(a_ref, a_ref, i % 2);
test1(a_res, a_res, i % 2);
verify("a in test1", a_ref, a_res, a);
}
}
static void verify(String name, byte[] ref, byte[] res, byte[] orig) {
boolean fail = false;
for (int j = 0; j < ref.length; j++) {
if (ref[j] != res[j]) {
System.out.println("Wrong: " + j + ":" + ref[j] + " vs " + res[j] + " from " + orig[j]);
fail = true;
}
}
if (fail) {
throw new RuntimeException("wrong result for array " + name);
}
}
static void test1(byte[] a, byte[] b, int inv) {
for (int i = 0; i < RANGE-4; i+=4) {
a[i + 0]++;
a[i + 1]++;
a[i + 2]++;
a[i + 3]++;
b[inv + i + 0]++;
b[inv + i + 1]++;
b[inv + i + 2]++;
b[inv + i + 3]++;
}
}
static void ref1(byte[] a, byte[] b, int inv) {
for (int i = 0; i < RANGE-4; i+=4) {
a[i + 0]++;
a[i + 1]++;
a[i + 2]++;
a[i + 3]++;
b[inv + i + 0]++;
b[inv + i + 1]++;
b[inv + i + 2]++;
b[inv + i + 3]++;
}
}
}