8280123: C2: Infinite loop in CMoveINode::Ideal during IGVN
Reviewed-by: kvn, thartmann, chagedorn
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@ -75,21 +75,25 @@
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// Return a node which is more "ideal" than the current node.
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// Move constants to the right.
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Node *CMoveNode::Ideal(PhaseGVN *phase, bool can_reshape) {
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if( in(0) && remove_dead_region(phase, can_reshape) ) return this;
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if (in(0) != NULL && remove_dead_region(phase, can_reshape)) {
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return this;
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}
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// Don't bother trying to transform a dead node
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if( in(0) && in(0)->is_top() ) return NULL;
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if (in(0) != NULL && in(0)->is_top()) {
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return NULL;
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}
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assert(in(Condition) != this &&
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in(IfFalse) != this &&
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in(IfTrue) != this, "dead loop in CMoveNode::Ideal" );
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if( phase->type(in(Condition)) == Type::TOP )
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return NULL; // return NULL when Condition is dead
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if( in(IfFalse)->is_Con() && !in(IfTrue)->is_Con() ) {
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if( in(Condition)->is_Bool() ) {
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BoolNode* b = in(Condition)->as_Bool();
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BoolNode* b2 = b->negate(phase);
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return make(in(Control), phase->transform(b2), in(IfTrue), in(IfFalse), _type);
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}
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in(IfFalse) != this &&
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in(IfTrue) != this, "dead loop in CMoveNode::Ideal");
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if (phase->type(in(Condition)) == Type::TOP ||
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phase->type(in(IfFalse)) == Type::TOP ||
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phase->type(in(IfTrue)) == Type::TOP) {
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return NULL;
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}
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// Canonicalize the node by moving constants to the right input.
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if (in(Condition)->is_Bool() && phase->type(in(IfFalse))->singleton() && !phase->type(in(IfTrue))->singleton()) {
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BoolNode* b = in(Condition)->as_Bool()->negate(phase);
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return make(in(Control), phase->transform(b), in(IfTrue), in(IfFalse), _type);
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}
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return NULL;
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}
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@ -191,14 +195,10 @@ Node *CMoveINode::Ideal(PhaseGVN *phase, bool can_reshape) {
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// If zero is on the left (false-case, no-move-case) it must mean another
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// constant is on the right (otherwise the shared CMove::Ideal code would
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// have moved the constant to the right). This situation is bad for Intel
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// and a don't-care for Sparc. It's bad for Intel because the zero has to
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// be manifested in a register with a XOR which kills flags, which are live
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// on input to the CMoveI, leading to a situation which causes excessive
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// spilling on Intel. For Sparc, if the zero in on the left the Sparc will
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// zero a register via G0 and conditionally-move the other constant. If the
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// zero is on the right, the Sparc will load the first constant with a
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// 13-bit set-lo and conditionally move G0. See bug 4677505.
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// have moved the constant to the right). This situation is bad for x86 because
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// the zero has to be manifested in a register with a XOR which kills flags,
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// which are live on input to the CMoveI, leading to a situation which causes
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// excessive spilling. See bug 4677505.
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if( phase->type(in(IfFalse)) == TypeInt::ZERO && !(phase->type(in(IfTrue)) == TypeInt::ZERO) ) {
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if( in(Condition)->is_Bool() ) {
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BoolNode* b = in(Condition)->as_Bool();
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68
test/hotspot/jtreg/compiler/c2/TestCMoveInfiniteGVN.java
Normal file
68
test/hotspot/jtreg/compiler/c2/TestCMoveInfiniteGVN.java
Normal file
@ -0,0 +1,68 @@
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/*
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* Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @key stress randomness
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* @bug 8280123
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* @run main/othervm -Xcomp -XX:-TieredCompilation
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* -XX:CompileCommand=compileonly,compiler.c2.TestCMoveInfiniteGVN::test
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* -XX:+UnlockDiagnosticVMOptions -XX:+StressIGVN -XX:StressSeed=43739875
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* compiler.c2.TestCMoveInfiniteGVN
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* @run main/othervm -Xcomp -XX:-TieredCompilation
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* -XX:CompileCommand=compileonly,compiler.c2.TestCMoveInfiniteGVN::test
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* -XX:+UnlockDiagnosticVMOptions -XX:+StressIGVN
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* compiler.c2.TestCMoveInfiniteGVN
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*/
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package compiler.c2;
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public class TestCMoveInfiniteGVN {
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static int test(boolean b, int i) {
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int iArr[] = new int[2];
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double d = Math.max(i, i);
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for (int i1 = 1; i1 < 2; i1++) {
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if (i1 != 0) {
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return (b ? 1 : 0); // CMoveI
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}
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for (int i2 = 1; i2 < 2; i2++) {
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switch (i2) {
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case 1: d -= Math.max(i1, i2); break;
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}
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d -= iArr[i1 - 1];
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}
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}
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return 0;
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}
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static void test() {
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test(true, 234);
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}
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public static void main(String[] strArr) {
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test(); // compilation, then nmethod invalidation during execution
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test(); // trigger crashing recompilation
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}
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}
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