8301489: C1: ShortLoopOptimizer might lift instructions before their inputs
Reviewed-by: thartmann, rcastanedalo
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@ -359,6 +359,33 @@ LoopInvariantCodeMotion::LoopInvariantCodeMotion(ShortLoopOptimizer *slo, Global
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}
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}
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class CheckInsertionPoint : public ValueVisitor {
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private:
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Value _insert;
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bool _valid = true;
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void visit(Value* vp) {
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assert(*vp != nullptr, "value should not be null");
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if (_insert->dominator_depth() < (*vp)->dominator_depth()) {
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_valid = false;
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}
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}
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public:
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bool is_valid() { return _valid; }
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CheckInsertionPoint(Value insert)
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: _insert(insert) {
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assert(insert != nullptr, "insertion point should not be null");
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}
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};
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// Check that insertion point has higher dom depth than all inputs to cur
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static bool is_dominated_by_inputs(Instruction* insertion_point, Instruction* cur) {
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CheckInsertionPoint v(insertion_point);
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cur->input_values_do(&v);
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return v.is_valid();
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}
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void LoopInvariantCodeMotion::process_block(BlockBegin* block) {
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TRACE_VALUE_NUMBERING(tty->print_cr("processing block B%d", block->block_id()));
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@ -394,7 +421,7 @@ void LoopInvariantCodeMotion::process_block(BlockBegin* block) {
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cur_invariant = is_invariant(cvt->value());
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}
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if (cur_invariant) {
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if (cur_invariant && is_dominated_by_inputs(_insertion_point, cur)) {
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// perform value numbering and mark instruction as loop-invariant
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_gvn->substitute(cur);
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116
test/hotspot/jtreg/compiler/c1/Test8301489.java
Normal file
116
test/hotspot/jtreg/compiler/c1/Test8301489.java
Normal file
@ -0,0 +1,116 @@
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/*
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* Copyright (c) 2023, 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 8301489
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* @summary ShortLoopOptimizer might lift instructions before their inputs
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* @requires vm.compiler1.enabled
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* @run main/othervm -Xcomp -XX:TieredStopAtLevel=1
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* -XX:CompileOnly=compiler.c1.Test8301489::*
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* compiler.c1.Test8301489
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*/
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package compiler.c1;
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public class Test8301489 {
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static int c = 0;
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static int[] arr = {};
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static void op2Test(int a, int b) {
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// Implicit edges created during dom calculation to exception handler
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if (a < 0) {
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b = 0;
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}
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// Create two branches into next loop header block
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try {
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int l = arr.length;
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for (int i = 0; i < l; i++) {
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int d = arr[i] + arr[i];
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}
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}
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// Exception handler as predecessor of the next loop header block
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catch (ArithmeticException e) {}
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// op2(a, b) as candidate for hoisting: operands are loop invariant
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while (a + b < b) {}
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// op2(a, b) should not be hoisted above 'if (a < 0) {...}' block
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}
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static void arrayLengthTest() {
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float [] newArr = new float[c];
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try {
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for (float f : newArr) {}
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}
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catch (ArrayIndexOutOfBoundsException e) {}
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while (54321 < newArr.length) {
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newArr[c] = 123.45f;
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}
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}
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static void negateTest(int a) {
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if (a <= 111) {
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a = -111;
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}
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int f = 0;
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try {
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int l = arr.length;
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f--;
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}
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catch (NegativeArraySizeException e) {}
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while (-a < f) {
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f--;
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}
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}
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static void convertTest(int a) {
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if (c == 0) {
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a = 0;
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}
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long tgt = 10;
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try {
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String s = String.valueOf(c);
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}
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catch (NumberFormatException e) {}
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while ((long)a != tgt) {
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tgt--;
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}
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}
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public static void main(String[] args) {
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for (int i = 0; i < 3; i++) {
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op2Test(12, 34);
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arrayLengthTest();
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negateTest(-778);
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convertTest(4812);
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}
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}
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}
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