8296412: Special case infinite loops with unmerged backedges in IdealLoopTree::check_safepts
Reviewed-by: chagedorn, kvn, thartmann
This commit is contained in:
Emanuel Peter
parent
8e49fcdde4
commit
da38d43fcc
src/hotspot/share/opto
test/hotspot/jtreg/compiler/loopopts
@ -3632,6 +3632,17 @@ void IdealLoopTree::check_safepts(VectorSet &visited, Node_List &stack) {
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// Skip to head of inner loop
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assert(_phase->is_dominator(_head, nlpt->_head), "inner head dominated by outer head");
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n = nlpt->_head;
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if (_head == n) {
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// this and nlpt (inner loop) have the same loop head. This should not happen because
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// during beautify_loops we call merge_many_backedges. However, infinite loops may not
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// have been attached to the loop-tree during build_loop_tree before beautify_loops,
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// but then attached in the build_loop_tree afterwards, and so still have unmerged
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// backedges. Check if we are indeed in an infinite subgraph, and terminate the scan,
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// since we have reached the loop head of this.
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assert(_head->as_Region()->is_in_infinite_subgraph(),
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"only expect unmerged backedges in infinite loops");
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break;
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}
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}
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}
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}
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@ -0,0 +1,200 @@
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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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super public class TestInfiniteLoopWithUnmergedBackedges
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{
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public Method "<init>":"()V"
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stack 2 locals 1
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{
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aload_0;
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invokespecial Method java/lang/Object."<init>":"()V";
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return;
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}
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static Method test_001:"(IIIII)V"
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stack 5 locals 10
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{
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iload_0;
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ifgt LOOP;
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// below is dominated by the one above
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iload_0;
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ifle BACK;
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goto HEAD;
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HEAD:
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iload_3;
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ifeq BACK;
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BACK:
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goto HEAD;
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LOOP:
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iload_1;
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iflt LOOP;
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iload_2;
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iflt LOOP;
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return;
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}
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static Method test_002:"(IIIII)V"
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stack 5 locals 30
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{
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iload_0;
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ifgt LOOP;
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iconst_0;
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istore 9;
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goto HEAD;
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TAIL:
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iload_3;
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iload 9;
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if_icmpeq HEAD;
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iinc 9, 1;
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HEAD:
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goto TAIL;
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LOOP:
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iload_1;
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iflt LOOP;
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iload_2;
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iflt LOOP;
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return;
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}
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static Method test_003:"(IIIII)I"
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stack 5 locals 30
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{
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iload_0;
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ifgt SKIP;
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iconst_0;
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istore 9;
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goto HEAD;
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TAIL:
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iload_3;
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iload 9;
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if_icmpeq HEAD;
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iinc 9, 1;
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// Two paths lead to HEAD, so we have an inner and outer loop
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// But no SafePoint is placed here, because we go forward in bci
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HEAD:
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// SafePoint is placed here, because we go from here back in bci
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goto TAIL;
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SKIP:
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iconst_0;
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istore 8;
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iconst_0;
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istore 9;
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// loop with two backedges, which calls
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// merge_many_backedges and then recomputes
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// build_loop_tree
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LOOP:
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iinc 9, 1;
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iinc 8, -1;
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iload 9;
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ldc 7;
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irem;
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ifeq LOOP;
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iload 9;
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ldc 10001;
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if_icmple LOOP;
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iload 8;
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ireturn;
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}
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static Method test_004:"(IIIII)I"
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stack 5 locals 30
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{
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iload_0;
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ifgt SKIP;
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iconst_0;
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istore 9;
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goto HEAD;
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TAIL:
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iload_3;
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iload 9;
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if_icmpeq HEAD;
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iinc 9, 1;
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iload 9;
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ldc 10001;
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if_icmpeq HEAD; // a second one
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iinc 9, 1;
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HEAD:
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goto TAIL;
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SKIP:
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iconst_0;
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istore 8;
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iconst_0;
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istore 9;
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LOOP:
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iinc 9, 1;
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iinc 8, -1;
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iload 9;
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ldc 7;
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irem;
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ifeq LOOP;
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iload 9;
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ldc 10001;
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if_icmple LOOP;
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iload 8;
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ireturn;
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}
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static Method test_005:"(IIIII)I"
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stack 5 locals 30
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{
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iload_0;
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ifgt SKIP;
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iconst_0;
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istore 9;
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goto HEAD;
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TAIL:
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iload_3;
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iload 9;
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if_icmpeq HEAD;
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iinc 9, 1;
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iload 9;
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ldc 10001;
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if_icmpeq HEAD; // a second one
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iinc 9, 1;
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HEAD:
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goto TAIL;
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SKIP:
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iconst_0;
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istore 8;
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iconst_0;
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istore 9;
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LOOP:
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iinc 9, 1;
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iinc 8, -1;
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iload 9;
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ldc 7;
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irem;
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ifeq LOOP;
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iload 9;
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ldc 10001;
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if_icmple LOOP;
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iload 8;
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ireturn;
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}
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}
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@ -0,0 +1,41 @@
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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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* @bug 8296412
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* @compile TestInfiniteLoopWithUnmergedBackedges.jasm
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* @summary Infinite loops may not have the backedges merged, before we call IdealLoopTree::check_safepts
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* @run main/othervm -Xcomp -XX:-TieredCompilation -XX:-LoopUnswitching
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* -XX:CompileCommand=compileonly,TestInfiniteLoopWithUnmergedBackedges::test*
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* TestInfiniteLoopWithUnmergedBackedgesMain
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*/
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public class TestInfiniteLoopWithUnmergedBackedgesMain {
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public static void main (String[] args) {
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TestInfiniteLoopWithUnmergedBackedges.test_001(1, 0, 0, 0, 0);
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TestInfiniteLoopWithUnmergedBackedges.test_002(1, 0, 0, 0, 0);
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TestInfiniteLoopWithUnmergedBackedges.test_003(1, 0, 0, 0, 0);
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TestInfiniteLoopWithUnmergedBackedges.test_004(1, 0, 0, 0, 0);
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}
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}
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