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8301489: C1: ShortLoopOptimizer might lift instructions before their …
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…inputs

Backport-of: 73d7aa1d2cb037fed69263a1990258866333664d
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GoeLin committed Oct 6, 2023
1 parent 9dc5ff0 commit 273872c
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29 changes: 28 additions & 1 deletion src/hotspot/share/c1/c1_ValueMap.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -359,6 +359,33 @@ LoopInvariantCodeMotion::LoopInvariantCodeMotion(ShortLoopOptimizer *slo, Global
}
}

class CheckInsertionPoint : public ValueVisitor {
private:
Value _insert;
bool _valid = true;

void visit(Value* vp) {
assert(*vp != nullptr, "value should not be null");
if (_insert->dominator_depth() < (*vp)->dominator_depth()) {
_valid = false;
}
}

public:
bool is_valid() { return _valid; }
CheckInsertionPoint(Value insert)
: _insert(insert) {
assert(insert != nullptr, "insertion point should not be null");
}
};

// Check that insertion point has higher dom depth than all inputs to cur
static bool is_dominated_by_inputs(Instruction* insertion_point, Instruction* cur) {
CheckInsertionPoint v(insertion_point);
cur->input_values_do(&v);
return v.is_valid();
}

void LoopInvariantCodeMotion::process_block(BlockBegin* block) {
TRACE_VALUE_NUMBERING(tty->print_cr("processing block B%d", block->block_id()));

Expand Down Expand Up @@ -394,7 +421,7 @@ void LoopInvariantCodeMotion::process_block(BlockBegin* block) {
cur_invariant = is_invariant(cvt->value());
}

if (cur_invariant) {
if (cur_invariant && is_dominated_by_inputs(_insertion_point, cur)) {
// perform value numbering and mark instruction as loop-invariant
_gvn->substitute(cur);

Expand Down
116 changes: 116 additions & 0 deletions test/hotspot/jtreg/compiler/c1/Test8301489.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,116 @@
/*
* 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 8301489
* @summary ShortLoopOptimizer might lift instructions before their inputs
* @requires vm.compiler1.enabled
* @run main/othervm -Xcomp -XX:TieredStopAtLevel=1
* -XX:CompileOnly=compiler.c1.Test8301489::*
* compiler.c1.Test8301489
*/


package compiler.c1;

public class Test8301489 {
static int c = 0;
static int[] arr = {};

static void op2Test(int a, int b) {
// Implicit edges created during dom calculation to exception handler
if (a < 0) {
b = 0;
}
// Create two branches into next loop header block
try {
int l = arr.length;
for (int i = 0; i < l; i++) {
int d = arr[i] + arr[i];
}
}
// Exception handler as predecessor of the next loop header block
catch (ArithmeticException e) {}

// op2(a, b) as candidate for hoisting: operands are loop invariant
while (a + b < b) {}
// op2(a, b) should not be hoisted above 'if (a < 0) {...}' block
}

static void arrayLengthTest() {
float [] newArr = new float[c];

try {
for (float f : newArr) {}
}
catch (ArrayIndexOutOfBoundsException e) {}

while (54321 < newArr.length) {
newArr[c] = 123.45f;
}
}

static void negateTest(int a) {
if (a <= 111) {
a = -111;
}

int f = 0;
try {
int l = arr.length;
f--;
}
catch (NegativeArraySizeException e) {}

while (-a < f) {
f--;
}
}

static void convertTest(int a) {
if (c == 0) {
a = 0;
}

long tgt = 10;

try {
String s = String.valueOf(c);
}
catch (NumberFormatException e) {}

while ((long)a != tgt) {
tgt--;
}
}

public static void main(String[] args) {
for (int i = 0; i < 3; i++) {
op2Test(12, 34);
arrayLengthTest();
negateTest(-778);
convertTest(4812);
}
}
}

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