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8187822: C2 conditonal move optimization might create broken graph

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Reviewed-by: kvn
This commit is contained in:
Roland Westrelin 2017-09-27 16:17:47 +02:00
parent eed5d34c26
commit 844e594fec
2 changed files with 82 additions and 9 deletions
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24
src/hotspot/share/opto/loopopts.cpp
View File

@ -311,6 +311,7 @@ Node *PhaseIdealLoop::has_local_phi_input( Node *n ) {
}
return NULL;
}
assert(m->is_Phi() || is_dominator(get_ctrl(m), n_ctrl), "m has strange control");
}
return n_ctrl;
@ -615,6 +616,7 @@ Node *PhaseIdealLoop::conditional_move( Node *region ) {
// Now replace all Phis with CMOV's
Node *cmov_ctrl = iff->in(0);
uint flip = (lp->Opcode() == Op_IfTrue);
Node_List wq;
while (1) {
PhiNode* phi = NULL;
for (DUIterator_Fast imax, i = region->fast_outs(imax); i < imax; i++) {
@ -627,17 +629,21 @@ Node *PhaseIdealLoop::conditional_move( Node *region ) {
if (phi == NULL) break;
if (PrintOpto && VerifyLoopOptimizations) { tty->print_cr("CMOV"); }
// Move speculative ops
for (uint j = 1; j < region->req(); j++) {
Node *proj = region->in(j);
Node *inp = phi->in(j);
if (get_ctrl(inp) == proj) { // Found local op
wq.push(phi);
while (wq.size() > 0) {
Node *n = wq.pop();
for (uint j = 1; j < n->req(); j++) {
Node* m = n->in(j);
if (m != NULL && !is_dominator(get_ctrl(m), cmov_ctrl)) {
#ifndef PRODUCT
if (PrintOpto && VerifyLoopOptimizations) {
tty->print(" speculate: ");
inp->dump();
}
if (PrintOpto && VerifyLoopOptimizations) {
tty->print(" speculate: ");
m->dump();
}
#endif
set_ctrl(inp, cmov_ctrl);
set_ctrl(m, cmov_ctrl);
wq.push(m);
}
}
}
Node *cmov = CMoveNode::make(cmov_ctrl, iff->in(1), phi->in(1+flip), phi->in(2-flip), _igvn.type(phi));

67
test/hotspot/jtreg/compiler/loopopts/TestCMovSplitThruPhi.java Normal file
View File

@ -0,0 +1,67 @@
/*
* Copyright (c) 2017, Red Hat, Inc. 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 8187822
* @summary C2 conditonal move optimization might create broken graph
* @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:CompileCommand=dontinline,TestCMovSplitThruPhi::not_inlined -XX:CompileOnly=TestCMovSplitThruPhi::test -XX:-LoopUnswitching TestCMovSplitThruPhi
*
*/
public class TestCMovSplitThruPhi {
static int f;
static int test(boolean flag1, boolean flag2, boolean flag3, boolean flag4) {
int v3 = 0;
if (flag4) {
for (int i = 0; i < 10; i++) {
int v1 = 0;
if (flag1) {
v1 = not_inlined();
}
// AddI below will be candidate for split through Phi
int v2 = v1;
if (flag2) {
v2 = f + v1;
}
// test above will be converted to CMovI
if (flag3) {
v3 = v2 * 2;
break;
}
}
}
return v3;
}
private static int not_inlined() {
return 0;
}
public static void main(String[] args) {
for (int i = 0; i < 20000; i++) {
test((i % 2) == 0, (i % 2) == 0, (i % 100) == 1, (i % 1000) == 1);
}
}
}