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openjdk-1.8.0/8243670.patch

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From 00a03e7acf5509396c8a1ac90d3d661250750d9c Mon Sep 17 00:00:00 2001
Date: Fri, 22 Jan 2021 16:29:29 +0800
Subject: 8243670:Unexpected test result caused by C2
MergeMemNode::Ideal
Summary: <c2>: <Unexpected test result caused by C2 MergeMemNode>
LLT: hotspot/test/compiler/c2/TestReplaceEquivPhis.java
Bug url: https://bugs.openjdk.java.net/browse/JDK-8243670
---
hotspot/src/share/vm/opto/cfgnode.cpp | 24 ++++++
hotspot/src/share/vm/opto/memnode.cpp | 20 +----
hotspot/src/share/vm/opto/type.hpp | 7 ++
.../compiler/c2/TestReplaceEquivPhis.java | 77 +++++++++++++++++++
4 files changed, 109 insertions(+), 19 deletions(-)
create mode 100644 hotspot/test/compiler/c2/TestReplaceEquivPhis.java
diff --git a/hotspot/src/share/vm/opto/cfgnode.cpp b/hotspot/src/share/vm/opto/cfgnode.cpp
index dd5a5ec41..f3d223fbd 100644
--- a/hotspot/src/share/vm/opto/cfgnode.cpp
+++ b/hotspot/src/share/vm/opto/cfgnode.cpp
@@ -1156,6 +1156,30 @@ Node *PhiNode::Identity( PhaseTransform *phase ) {
if (id != NULL) return id;
}
+ // Looking for phis with identical inputs. If we find one that has
+ // type TypePtr::BOTTOM, replace the current phi with the bottom phi.
+ if (phase->is_IterGVN() && type() == Type::MEMORY && adr_type() !=
+ TypePtr::BOTTOM && !adr_type()->is_known_instance()) {
+ uint phi_len = req();
+ Node* phi_reg = region();
+ for (DUIterator_Fast imax, i = phi_reg->fast_outs(imax); i < imax; i++) {
+ Node* u = phi_reg->fast_out(i);
+ if (u->is_Phi() && u->as_Phi()->type() == Type::MEMORY &&
+ u->adr_type() == TypePtr::BOTTOM && u->in(0) == phi_reg &&
+ u->req() == phi_len) {
+ for (uint j = 1; j < phi_len; j++) {
+ if (in(j) != u->in(j)) {
+ u = NULL;
+ break;
+ }
+ }
+ if (u != NULL) {
+ return u;
+ }
+ }
+ }
+ }
+
return this; // No identity
}
diff --git a/hotspot/src/share/vm/opto/memnode.cpp b/hotspot/src/share/vm/opto/memnode.cpp
index 68a13dbd8..f2a2ee6a2 100644
--- a/hotspot/src/share/vm/opto/memnode.cpp
+++ b/hotspot/src/share/vm/opto/memnode.cpp
@@ -4418,25 +4418,7 @@ Node *MergeMemNode::Ideal(PhaseGVN *phase, bool can_reshape) {
new_mem = old_mmem->memory_at(i);
}
// else preceding memory was not a MergeMem
-
- // replace equivalent phis (unfortunately, they do not GVN together)
- if (new_mem != NULL && new_mem != new_base &&
- new_mem->req() == phi_len && new_mem->in(0) == phi_reg) {
- if (new_mem->is_Phi()) {
- PhiNode* phi_mem = new_mem->as_Phi();
- for (uint i = 1; i < phi_len; i++) {
- if (phi_base->in(i) != phi_mem->in(i)) {
- phi_mem = NULL;
- break;
- }
- }
- if (phi_mem != NULL) {
- // equivalent phi nodes; revert to the def
- new_mem = new_base;
- }
- }
- }
-
+
// maybe store down a new value
Node* new_in = new_mem;
if (new_in == new_base) new_in = empty_mem;
diff --git a/hotspot/src/share/vm/opto/type.hpp b/hotspot/src/share/vm/opto/type.hpp
index ec06f8d69..8da4a766d 100644
--- a/hotspot/src/share/vm/opto/type.hpp
+++ b/hotspot/src/share/vm/opto/type.hpp
@@ -432,6 +432,8 @@ public:
return exact_kls != NULL;
}
+ virtual bool is_known_instance() const { return false; }
+
private:
// support arrays
static const Type* _zero_type[T_CONFLICT+1];
@@ -1333,6 +1335,11 @@ public:
return _ptrtype;
}
+ bool is_known_instance() const {
+ return _ptrtype->is_known_instance();
+ }
+
+
#ifndef PRODUCT
virtual void dump2( Dict &d, uint depth, outputStream *st ) const;
#endif
diff --git a/hotspot/test/compiler/c2/TestReplaceEquivPhis.java b/hotspot/test/compiler/c2/TestReplaceEquivPhis.java
new file mode 100644
index 000000000..d4c93b390
--- /dev/null
+++ b/hotspot/test/compiler/c2/TestReplaceEquivPhis.java
@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) 2020, Huawei Technologies Co. Ltd. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * 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
+ * accompanied this code).
+ *
+ * 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.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/**
+ * @test
+ * @bug 8243670
+ * @summary Unexpected test result caused by C2 MergeMemNode::Ideal
+ *
+ * @run main/othervm -Xcomp -XX:-SplitIfBlocks
+ * -XX:CompileOnly=compiler.c2.TestReplaceEquivPhis::test
+ * -XX:-BackgroundCompilation compiler.c2.TestReplaceEquivPhis
+ */
+
+package compiler.c2;
+
+public class TestReplaceEquivPhis {
+
+ public static final int N = 400;
+ public static volatile int instanceCount = 0;
+ public int iFld = 0;
+ public static int iArrFld[] = new int[N];
+
+ public int test() {
+ int v = 0;
+ boolean bArr[] = new boolean[N];
+
+ for (int i = 1; i < 344; i++) {
+ iFld = i;
+ for (int j = 2; j <177 ; j++) {
+ v = iFld;
+ iFld = TestReplaceEquivPhis.instanceCount;
+ TestReplaceEquivPhis.iArrFld[i] = 0;
+ iFld += TestReplaceEquivPhis.instanceCount;
+ TestReplaceEquivPhis.iArrFld[i] = 0;
+ bArr[j] = false;
+ TestReplaceEquivPhis.instanceCount = 1;
+
+ for (int k = 1; k < 3; k++) {
+ // do nothing
+ }
+ }
+ }
+ return v;
+ }
+
+ public static void main(String[] args) {
+ TestReplaceEquivPhis obj = new TestReplaceEquivPhis();
+ for (int i = 0; i < 5; i++) {
+ int result = obj.test();
+ if (result != 2) {
+ throw new RuntimeException("Test failed.");
+ }
+ }
+ System.out.println("Test passed.");
+ }
+
+}
--
2.19.0
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