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8308749: C2 failed: regular loops only (counted loop inside infinite loop)

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Reviewed-by: kvn, chagedorn
This commit is contained in:
Emanuel Peter 2023-06-12 07:40:58 +00:00
parent f5cbe53fdd
commit 6c3e621f98
3 changed files with 114 additions and 0 deletions
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15
src/hotspot/share/opto/loopnode.cpp
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@ -1745,6 +1745,21 @@ bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_
// =================================================
// ---- SUCCESS! Found A Trip-Counted Loop! -----
//
if (x->Opcode() == Op_Region) {
// x has not yet been transformed to Loop or LongCountedLoop.
// This should only happen if we are inside an infinite loop.
// It happens like this:
// build_loop_tree -> do not attach infinite loop and nested loops
// beautify_loops -> does not transform the infinite and nested loops to LoopNode, because not attached yet
// build_loop_tree -> find and attach infinite and nested loops
// counted_loop -> nested Regions are not yet transformed to LoopNodes, we land here
assert(x->as_Region()->is_in_infinite_subgraph(),
"x can only be a Region and not Loop if inside infinite loop");
// Come back later when Region is transformed to LoopNode
return false;
}
assert(x->Opcode() == Op_Loop || x->Opcode() == Op_LongCountedLoop, "regular loops only");
C->print_method(PHASE_BEFORE_CLOOPS, 3);

60
test/hotspot/jtreg/compiler/loopopts/TestCountedLoopInsideInfiniteLoop.jasm Normal file
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@ -0,0 +1,60 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. 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.
*/
super public class TestCountedLoopInsideInfiniteLoop
{
public Method "<init>":"()V"
stack 2 locals 1
{
aload_0;
invokespecial Method java/lang/Object."<init>":"()V";
return;
}
static Method test:"(IIII)V"
stack 200 locals 4
{
iload 0; // arg0 == 0
ifeq LEND;
LOOP1: // counted loop to kick off beautify_loops
iload 1;
ifeq LOOP1;
iload 2;
ifle LOOP1;
LOOP2: // infinite loop (still Region)
goto LOOP2b;
LOOP2b: // counted loop (still Region)
iinc 3, -1;
iload 3;
ifgt LOOP2b;
iconst_0;
ifeq LOOP2; // always true
goto LOOP2b;
LEND:
return;
}
}

39
test/hotspot/jtreg/compiler/loopopts/TestCountedLoopInsideInfiniteLoopMain.java Normal file
View File

@ -0,0 +1,39 @@
/*
* Copyright (c) 2023, Oracle and/or its affiliates. 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 8308749
* @compile TestCountedLoopInsideInfiniteLoop.jasm
* @summary Counted Loops inside infinite loops are only detected later,
* and may still be a Region and not a LoopNode as expected.
* @run main/othervm -Xcomp -XX:-TieredCompilation -XX:PerMethodTrapLimit=0
* -XX:CompileCommand=compileonly,TestCountedLoopInsideInfiniteLoop::test
* TestCountedLoopInsideInfiniteLoopMain
*/
public class TestCountedLoopInsideInfiniteLoopMain {
public static void main (String[] args) {
TestCountedLoopInsideInfiniteLoop.test(0, 0, 0, 0);
}
}