--- a/src/hotspot/share/opto/callnode.cpp Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/callnode.cpp Fri Dec 07 17:56:51 2018 +0100
@@ -1271,6 +1271,14 @@
return (TypeFunc::Parms == idx);
}
+void SafePointNode::disconnect_from_root(PhaseIterGVN *igvn) {
+ assert(Opcode() == Op_SafePoint, "only value for safepoint in loops");
+ int nb = igvn->C->root()->find_prec_edge(this);
+ if (nb != -1) {
+ igvn->C->root()->rm_prec(nb);
+ }
+}
+
//============== SafePointScalarObjectNode ==============
SafePointScalarObjectNode::SafePointScalarObjectNode(const TypeOopPtr* tp,
--- a/src/hotspot/share/opto/callnode.hpp Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/callnode.hpp Fri Dec 07 17:56:51 2018 +0100
@@ -462,6 +462,8 @@
return !_replaced_nodes.is_empty();
}
+ void disconnect_from_root(PhaseIterGVN *igvn);
+
// Standard Node stuff
virtual int Opcode() const;
virtual bool pinned() const { return true; }
--- a/src/hotspot/share/opto/compile.cpp Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/compile.cpp Fri Dec 07 17:56:51 2018 +0100
@@ -2184,6 +2184,23 @@
return true;
}
+// Remove edges from "root" to each SafePoint at a backward branch.
+// They were inserted during parsing (see add_safepoint()) to make
+// infinite loops without calls or exceptions visible to root, i.e.,
+// useful.
+void Compile::remove_root_to_sfpts_edges() {
+ Node *r = root();
+ if (r != NULL) {
+ for (uint i = r->req(); i < r->len(); ++i) {
+ Node *n = r->in(i);
+ if (n != NULL && n->is_SafePoint()) {
+ r->rm_prec(i);
+ --i;
+ }
+ }
+ }
+}
+
//------------------------------Optimize---------------------------------------
// Given a graph, optimize it.
void Compile::Optimize() {
@@ -2244,6 +2261,10 @@
if (failing()) return;
}
+ // Now that all inlining is over, cut edge from root to loop
+ // safepoints
+ remove_root_to_sfpts_edges();
+
// Remove the speculative part of types and clean up the graph from
// the extra CastPP nodes whose only purpose is to carry them. Do
// that early so that optimizations are not disrupted by the extra
@@ -3248,8 +3269,10 @@
break;
}
}
- assert(proj != NULL, "must be found");
- p->subsume_by(proj, this);
+ assert(proj != NULL || p->_con == TypeFunc::I_O, "io may be dropped at an infinite loop");
+ if (proj != NULL) {
+ p->subsume_by(proj, this);
+ }
}
}
break;
--- a/src/hotspot/share/opto/compile.hpp Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/compile.hpp Fri Dec 07 17:56:51 2018 +0100
@@ -1088,6 +1088,7 @@
void inline_string_calls(bool parse_time);
void inline_boxing_calls(PhaseIterGVN& igvn);
bool optimize_loops(PhaseIterGVN& igvn, LoopOptsMode mode);
+ void remove_root_to_sfpts_edges();
// Matching, CFG layout, allocation, code generation
PhaseCFG* cfg() { return _cfg; }
--- a/src/hotspot/share/opto/node.cpp Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/node.cpp Fri Dec 07 17:56:51 2018 +0100
@@ -37,6 +37,7 @@
#include "opto/node.hpp"
#include "opto/opcodes.hpp"
#include "opto/regmask.hpp"
+#include "opto/rootnode.hpp"
#include "opto/type.hpp"
#include "utilities/copy.hpp"
#include "utilities/macros.hpp"
@@ -1310,6 +1311,9 @@
while (nstack.size() > 0) {
dead = nstack.pop();
+ if (dead->Opcode() == Op_SafePoint) {
+ dead->as_SafePoint()->disconnect_from_root(igvn);
+ }
if (dead->outcnt() > 0) {
// Keep dead node on stack until all uses are processed.
nstack.push(dead);
--- a/src/hotspot/share/opto/phaseX.cpp Wed Jan 09 00:25:41 2019 -0800
+++ b/src/hotspot/share/opto/phaseX.cpp Fri Dec 07 17:56:51 2018 +0100
@@ -430,20 +430,6 @@
// Disconnect 'useless' nodes that are adjacent to useful nodes
C->remove_useless_nodes(_useful);
-
- // Remove edges from "root" to each SafePoint at a backward branch.
- // They were inserted during parsing (see add_safepoint()) to make infinite
- // loops without calls or exceptions visible to root, i.e., useful.
- Node *root = C->root();
- if( root != NULL ) {
- for( uint i = root->req(); i < root->len(); ++i ) {
- Node *n = root->in(i);
- if( n != NULL && n->is_SafePoint() ) {
- root->rm_prec(i);
- --i;
- }
- }
- }
}
//=============================================================================
@@ -1354,6 +1340,9 @@
while (_stack.is_nonempty()) {
dead = _stack.node();
+ if (dead->Opcode() == Op_SafePoint) {
+ dead->as_SafePoint()->disconnect_from_root(this);
+ }
uint progress_state = _stack.index();
assert(dead != C->root(), "killing root, eh?");
assert(!dead->is_top(), "add check for top when pushing");
@@ -1456,6 +1445,9 @@
//------------------------------subsume_node-----------------------------------
// Remove users from node 'old' and add them to node 'nn'.
void PhaseIterGVN::subsume_node( Node *old, Node *nn ) {
+ if (old->Opcode() == Op_SafePoint) {
+ old->as_SafePoint()->disconnect_from_root(this);
+ }
assert( old != hash_find(old), "should already been removed" );
assert( old != C->top(), "cannot subsume top node");
// Copy debug or profile information to the new version:
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/compiler/inlining/StringConcatInfiniteLoop.java Fri Dec 07 17:56:51 2018 +0100
@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2018, 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 8214862
+ * @summary Multiple passes of PhaseRemoveUseless causes infinite loop to be optimized out
+ *
+ * @run main/othervm -XX:-TieredCompilation -Xcomp -XX:CompileOnly=StringConcatInfiniteLoop::test -XX:CompileCommand=dontinline,*StringBuilder::* StringConcatInfiniteLoop
+ *
+ */
+
+public class StringConcatInfiniteLoop {
+ public static void main(String[] args) {
+ StringBuilder sb = new StringBuilder();
+ test(sb, "foo", "bar", true);
+ }
+
+ private static void test(Object v, String s1, String s2, boolean flag) {
+ if (flag) {
+ return;
+ }
+ int i = 0;
+ for (; i < 10; i++);
+ if (i == 10) {
+ v = null;
+ }
+ StringBuilder sb = new StringBuilder(s1);
+ sb.append(s2);
+ while (v == null);
+ }
+
+ private static class A {
+ }
+}