81 lines
3.2 KiB
Java
81 lines
3.2 KiB
Java
/*
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* Copyright (c) 2024, 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 8343944
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* @summary Test that _widen is set correctly in MinL::add_ring() to prevent an endless widening in CCP.
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* @run main/othervm -Xcomp -XX:CompileCommand=compileonly,compiler.ccp.TestWrongMinLWiden::*
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* compiler.ccp.TestWrongMinLWiden
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*/
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package compiler.ccp;
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public class TestWrongMinLWiden {
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static long lFld;
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static short sFld;
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public static void main(String[] strArr) {
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Math.min(3,3); // Make sure Math class is loaded.
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test();
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testWithMathMin();
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}
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static long test() {
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long x = 50398;
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for (int i = 1; i < 100; i++) {
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long xMinus1 = x - 1; // x is a phi with type #long
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// Long comparison:
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// ConvI2L(sFld) <= xMinus1
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// First converted to
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// CMoveL(sFld <= xMinus1, sFld, xMinus1)
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// CMoveL(ConvI2L(sFld) <= long_phi, ConvI2L(sFld), long_phi)
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// with types
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// CMoveL(#short <= #long, #short, #long)
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// And then converted in CMoveNode::Ideal() to
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// MinL(sFld, xMinus1)
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// MinL(ConvI2L(sFld), long_phi)
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//
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// We wrongly set the _widen of the new type for MinL in MinL::add_ring() to the minimum of both types which
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// is always 0 because the _widen of sFld is 0. As a result, we will endlessly widen the involved types
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// because the new type for MinL keeps resetting _widen to 0.
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// Instead, we should choose the maximum of both _widen fields for the new type for MinL which will then
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// select the _widen of xMinus1 which will grow each time we set a new type for the long_phi. Eventually,
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// we will saturate the type of long_phi to min_long to avoid an endless widening.
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x = sFld <= xMinus1 ? sFld : xMinus1;
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}
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return x;
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}
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// Same as test() but with Math.min() which internally uses x <= y ? x : y which allows the CMoveL pattern to be
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// replaced with MinL.
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static long testWithMathMin() {
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long x = 50398;
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for (int i = 1; i < 100; i++) {
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x = Math.min(sFld, x - 1);
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}
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return x;
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}
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}
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