8238384: CTW: C2 compilation fails with "assert(store != load->find_exact_control(load->in(0))) failed: dependence cycle found"
Reviewed-by: vlivanov, thartmann
diff --git a/src/hotspot/share/opto/compile.cpp b/src/hotspot/share/opto/compile.cpp
index 8cb3818..8446266 100644
--- a/src/hotspot/share/opto/compile.cpp
+++ b/src/hotspot/share/opto/compile.cpp
@@ -1905,8 +1905,9 @@
bool Compile::can_alias(const TypePtr* adr_type, int alias_idx) {
if (alias_idx == AliasIdxTop) return false; // the empty category
if (adr_type == NULL) return false; // NULL serves as TypePtr::TOP
- if (alias_idx == AliasIdxBot) return true; // the universal category
- if (adr_type->base() == Type::AnyPtr) return true; // TypePtr::BOTTOM or its twins
+ // Known instance doesn't alias with bottom memory
+ if (alias_idx == AliasIdxBot) return !adr_type->is_known_instance(); // the universal category
+ if (adr_type->base() == Type::AnyPtr) return !C->get_adr_type(alias_idx)->is_known_instance(); // TypePtr::BOTTOM or its twins
// the only remaining possible overlap is identity
int adr_idx = get_alias_index(adr_type);
diff --git a/src/hotspot/share/opto/gcm.cpp b/src/hotspot/share/opto/gcm.cpp
index aebf8f9..15ba69e 100644
--- a/src/hotspot/share/opto/gcm.cpp
+++ b/src/hotspot/share/opto/gcm.cpp
@@ -707,19 +707,6 @@
// instead of control + memory.
if (mstore->ideal_Opcode() == Op_SafePoint)
continue;
-
- // Check if the store is a membar on which the load is control dependent.
- // Inserting an anti-dependency between that membar and the load would
- // create a cycle that causes local scheduling to fail.
- if (mstore->isa_MachMemBar()) {
- Node* dom = load->find_exact_control(load->in(0));
- while (dom != NULL && dom != dom->in(0) && dom != mstore) {
- dom = dom->in(0);
- }
- if (dom == mstore) {
- continue;
- }
- }
} else {
// Some raw memory, such as the load of "top" at an allocation,
// can be control dependent on the previous safepoint. See
diff --git a/src/hotspot/share/opto/loopnode.cpp b/src/hotspot/share/opto/loopnode.cpp
index a907f59..6a89476 100644
--- a/src/hotspot/share/opto/loopnode.cpp
+++ b/src/hotspot/share/opto/loopnode.cpp
@@ -31,6 +31,7 @@
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "opto/addnode.hpp"
+#include "opto/arraycopynode.hpp"
#include "opto/callnode.hpp"
#include "opto/connode.hpp"
#include "opto/convertnode.hpp"
@@ -4089,8 +4090,16 @@
}
} else {
Node *sctrl = has_ctrl(s) ? get_ctrl(s) : s->in(0);
+ const TypePtr* adr_type = s->adr_type();
+ if (s->is_ArrayCopy()) {
+ // Copy to known instance needs destination type to test for aliasing
+ const TypePtr* dest_type = s->as_ArrayCopy()->_dest_type;
+ if (dest_type != TypeOopPtr::BOTTOM) {
+ adr_type = dest_type;
+ }
+ }
assert(sctrl != NULL || !s->is_reachable_from_root(), "must have control");
- if (sctrl != NULL && !sctrl->is_top() && C->can_alias(s->adr_type(), load_alias_idx) && is_dominator(early, sctrl)) {
+ if (sctrl != NULL && !sctrl->is_top() && C->can_alias(adr_type, load_alias_idx) && is_dominator(early, sctrl)) {
LCA = dom_lca_for_get_late_ctrl(LCA, sctrl, n);
}
}
diff --git a/src/hotspot/share/opto/macro.hpp b/src/hotspot/share/opto/macro.hpp
index 7171c05..a9bd67d 100644
--- a/src/hotspot/share/opto/macro.hpp
+++ b/src/hotspot/share/opto/macro.hpp
@@ -119,7 +119,7 @@
void expand_unlock_node(UnlockNode *unlock);
// More helper methods modeled after GraphKit for array copy
- void insert_mem_bar(Node** ctrl, Node** mem, int opcode, Node* precedent = NULL);
+ void insert_mem_bar(Node** ctrl, Node** mem, int opcode, int alias_idx = Compile::AliasIdxBot, Node* precedent = NULL);
Node* array_element_address(Node* ary, Node* idx, BasicType elembt);
Node* ConvI2L(Node* offset);
diff --git a/src/hotspot/share/opto/macroArrayCopy.cpp b/src/hotspot/share/opto/macroArrayCopy.cpp
index 8706563..b98aedd 100644
--- a/src/hotspot/share/opto/macroArrayCopy.cpp
+++ b/src/hotspot/share/opto/macroArrayCopy.cpp
@@ -33,8 +33,8 @@
#include "utilities/align.hpp"
#include "utilities/powerOfTwo.hpp"
-void PhaseMacroExpand::insert_mem_bar(Node** ctrl, Node** mem, int opcode, Node* precedent) {
- MemBarNode* mb = MemBarNode::make(C, opcode, Compile::AliasIdxBot, precedent);
+void PhaseMacroExpand::insert_mem_bar(Node** ctrl, Node** mem, int opcode, int alias_idx, Node* precedent) {
+ MemBarNode* mb = MemBarNode::make(C, opcode, alias_idx, precedent);
mb->init_req(TypeFunc::Control, *ctrl);
mb->init_req(TypeFunc::Memory, *mem);
transform_later(mb);
@@ -706,7 +706,15 @@
// the membar also.
//
// Do not let reads from the cloned object float above the arraycopy.
- if (alloc != NULL && !alloc->initialization()->does_not_escape()) {
+ if (ac->_dest_type != TypeOopPtr::BOTTOM && adr_type != ac->_dest_type) {
+ // Known instance: add memory of the destination type
+ MergeMemNode* mm = out_mem->clone()->as_MergeMem();
+ transform_later(mm);
+ uint dest_idx = C->get_alias_index(ac->_dest_type);
+ insert_mem_bar(ctrl, &out_mem, Op_MemBarCPUOrder, dest_idx);
+ mm->set_memory_at(dest_idx, out_mem);
+ out_mem = mm;
+ } else if (alloc != NULL && !alloc->initialization()->does_not_escape()) {
// Do not let stores that initialize this object be reordered with
// a subsequent store that would make this object accessible by
// other threads.
diff --git a/src/hotspot/share/opto/type.hpp b/src/hotspot/share/opto/type.hpp
index eae613f..08c78c3 100644
--- a/src/hotspot/share/opto/type.hpp
+++ b/src/hotspot/share/opto/type.hpp
@@ -452,6 +452,7 @@
const Type* maybe_remove_speculative(bool include_speculative) const;
virtual bool maybe_null() const { return true; }
+ virtual bool is_known_instance() const { return false; }
private:
// support arrays
@@ -1397,6 +1398,10 @@
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/test/hotspot/jtreg/compiler/escapeAnalysis/TestCopyOfBrokenAntiDependency.java b/test/hotspot/jtreg/compiler/escapeAnalysis/TestCopyOfBrokenAntiDependency.java
new file mode 100644
index 0000000..508d507
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/escapeAnalysis/TestCopyOfBrokenAntiDependency.java
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2020, Red Hat, Inc. 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 8238384
+ * @summary CTW: C2 compilation fails with "assert(store != load->find_exact_control(load->in(0))) failed: dependence cycle found"
+ *
+ * @run main/othervm -XX:-BackgroundCompilation TestCopyOfBrokenAntiDependency
+ *
+ */
+
+import java.util.Arrays;
+
+public class TestCopyOfBrokenAntiDependency {
+
+ public static void main(String[] args) {
+ for (int i = 0; i < 20_000; i++) {
+ test(100);
+ }
+ }
+
+ private static Object test(int length) {
+ Object[] src = new Object[length]; // non escaping
+ final Object[] dst = Arrays.copyOf(src, 10); // can't be removed
+ final Object[] dst2 = Arrays.copyOf(dst, 100);
+ // load is control dependent on membar from previous copyOf
+ // but has memory edge to first copyOf.
+ final Object v = dst[0];
+ return v;
+ }
+}
