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8282045: When loop strip mining fails, safepoints are removed from loop anyway
Reviewed-by: thartmann, chagedorn
This commit is contained in:
Roland Westrelin
parent
341c8bd7f2
commit
2c5d266f9f
@ -690,8 +690,7 @@ SafePointNode* PhaseIdealLoop::find_safepoint(Node* back_control, Node* x, Ideal
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Node* mem = safepoint->in(TypeFunc::Memory);
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// We can only use that safepoint if there's not side effect
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// between the backedge and the safepoint.
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// We can only use that safepoint if there's no side effect between the backedge and the safepoint.
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// mm is used for book keeping
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MergeMemNode* mm = NULL;
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@ -1621,16 +1620,6 @@ bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_
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return false;
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}
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if (x->in(LoopNode::LoopBackControl)->Opcode() == Op_SafePoint &&
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((iv_bt == T_INT && LoopStripMiningIter != 0) ||
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iv_bt == T_LONG)) {
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// Leaving the safepoint on the backedge and creating a
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// CountedLoop will confuse optimizations. We can't move the
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// safepoint around because its jvm state wouldn't match a new
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// location. Give up on that loop.
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return false;
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}
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Node* iftrue = back_control;
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uint iftrue_op = iftrue->Opcode();
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Node* iff = iftrue->in(0);
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@ -1859,6 +1848,37 @@ bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_
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}
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}
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Node* sfpt = NULL;
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if (loop->_child == NULL) {
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sfpt = find_safepoint(back_control, x, loop);
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} else {
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sfpt = iff->in(0);
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if (sfpt->Opcode() != Op_SafePoint) {
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sfpt = NULL;
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}
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}
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if (x->in(LoopNode::LoopBackControl)->Opcode() == Op_SafePoint) {
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Node* backedge_sfpt = x->in(LoopNode::LoopBackControl);
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if (((iv_bt == T_INT && LoopStripMiningIter != 0) ||
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iv_bt == T_LONG) &&
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sfpt == NULL) {
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// Leaving the safepoint on the backedge and creating a
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// CountedLoop will confuse optimizations. We can't move the
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// safepoint around because its jvm state wouldn't match a new
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// location. Give up on that loop.
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return false;
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}
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if (is_deleteable_safept(backedge_sfpt)) {
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lazy_replace(backedge_sfpt, iftrue);
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if (loop->_safepts != NULL) {
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loop->_safepts->yank(backedge_sfpt);
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}
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loop->_tail = iftrue;
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}
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}
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#ifdef ASSERT
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if (iv_bt == T_INT &&
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!x->as_Loop()->is_loop_nest_inner_loop() &&
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@ -1897,18 +1917,6 @@ bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_
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}
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set_subtree_ctrl(adjusted_limit, false);
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if (iv_bt == T_INT && LoopStripMiningIter == 0) {
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// Check for SafePoint on backedge and remove
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Node *sfpt = x->in(LoopNode::LoopBackControl);
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if (sfpt->Opcode() == Op_SafePoint && is_deleteable_safept(sfpt)) {
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lazy_replace( sfpt, iftrue );
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if (loop->_safepts != NULL) {
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loop->_safepts->yank(sfpt);
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}
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loop->_tail = iftrue;
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}
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}
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// Build a canonical trip test.
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// Clone code, as old values may be in use.
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incr = incr->clone();
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@ -1980,13 +1988,11 @@ bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_
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assert(iff->outcnt() == 0, "should be dead now");
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lazy_replace( iff, le ); // fix 'get_ctrl'
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Node *sfpt2 = le->in(0);
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Node* entry_control = init_control;
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bool strip_mine_loop = iv_bt == T_INT &&
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LoopStripMiningIter > 1 &&
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loop->_child == NULL &&
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sfpt2->Opcode() == Op_SafePoint &&
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sfpt != NULL &&
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!loop->_has_call;
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IdealLoopTree* outer_ilt = NULL;
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if (strip_mine_loop) {
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@ -2012,30 +2018,30 @@ bool PhaseIdealLoop::is_counted_loop(Node* x, IdealLoopTree*&loop, BasicType iv_
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if (iv_bt == T_INT && (LoopStripMiningIter == 0 || strip_mine_loop)) {
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// Check for immediately preceding SafePoint and remove
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if (sfpt2->Opcode() == Op_SafePoint && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt2))) {
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if (sfpt != NULL && (LoopStripMiningIter != 0 || is_deleteable_safept(sfpt))) {
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if (strip_mine_loop) {
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Node* outer_le = outer_ilt->_tail->in(0);
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Node* sfpt = sfpt2->clone();
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sfpt->set_req(0, iffalse);
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outer_le->set_req(0, sfpt);
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Node* sfpt_clone = sfpt->clone();
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sfpt_clone->set_req(0, iffalse);
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outer_le->set_req(0, sfpt_clone);
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Node* polladdr = sfpt->in(TypeFunc::Parms);
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Node* polladdr = sfpt_clone->in(TypeFunc::Parms);
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if (polladdr != nullptr && polladdr->is_Load()) {
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// Polling load should be pinned outside inner loop.
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Node* new_polladdr = polladdr->clone();
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new_polladdr->set_req(0, iffalse);
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_igvn.register_new_node_with_optimizer(new_polladdr, polladdr);
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set_ctrl(new_polladdr, iffalse);
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sfpt->set_req(TypeFunc::Parms, new_polladdr);
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sfpt_clone->set_req(TypeFunc::Parms, new_polladdr);
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}
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// When this code runs, loop bodies have not yet been populated.
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const bool body_populated = false;
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register_control(sfpt, outer_ilt, iffalse, body_populated);
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set_idom(outer_le, sfpt, dom_depth(sfpt));
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register_control(sfpt_clone, outer_ilt, iffalse, body_populated);
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set_idom(outer_le, sfpt_clone, dom_depth(sfpt_clone));
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}
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lazy_replace( sfpt2, sfpt2->in(TypeFunc::Control));
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lazy_replace(sfpt, sfpt->in(TypeFunc::Control));
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if (loop->_safepts != NULL) {
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loop->_safepts->yank(sfpt2);
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loop->_safepts->yank(sfpt);
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}
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}
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}
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@ -3663,7 +3669,7 @@ void IdealLoopTree::counted_loop( PhaseIdealLoop *phase ) {
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if (_head->is_CountedLoop() ||
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phase->is_counted_loop(_head, loop, T_INT)) {
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if (LoopStripMiningIter == 0 || (LoopStripMiningIter > 1 && _child == NULL)) {
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if (LoopStripMiningIter == 0 || _head->as_CountedLoop()->is_strip_mined()) {
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// Indicate we do not need a safepoint here
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_has_sfpt = 1;
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}
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@ -0,0 +1,132 @@
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/*
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* Copyright (c) 2022, Red Hat, Inc. 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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package compiler.c2.irTests;
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import compiler.lib.ir_framework.*;
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/*
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* @test
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* @bug 8282045
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* @summary When loop strip mining fails, safepoints are removed from loop anyway
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* @library /test/lib /
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* @run driver compiler.c2.irTests.TestStripMiningDropsSafepoint
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*/
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public class TestStripMiningDropsSafepoint {
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public static void main(String[] args) {
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TestFramework.runWithFlags("-XX:+UseCountedLoopSafepoints", "-XX:LoopStripMiningIter=1000", "-XX:LoopMaxUnroll=1", "-XX:-RangeCheckElimination");
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TestFramework.runWithFlags("-XX:+UseCountedLoopSafepoints", "-XX:LoopStripMiningIter=1000", "-XX:LoopMaxUnroll=1", "-XX:-RangeCheckElimination", "-XX:-PartialPeelLoop");
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}
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@Test
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@IR(applyIf = { "PartialPeelLoop", "true" }, counts = { IRNode.COUNTEDLOOP, "1", IRNode.OUTERSTRIPMINEDLOOP, "1", IRNode.SAFEPOINT, "1" })
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private static void test1(int[] dst, int[] src) {
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// Partial peel is applied. No side effect between exit and
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// safepoint.
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for (int i = 0; ; ) {
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// prevent ciTypeFlow from cloning head
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synchronized (new Object()) {}
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i++;
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if (i >= src.length) {
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break;
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}
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dst[i] = src[i];
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if (i / 2 >= 2000) {
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break;
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}
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}
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}
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@Run(test = "test1")
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private static void test1_runner() {
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int[] array1 = new int[1000];
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int[] array2 = new int[10000];
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test1(array1, array1);
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test1(array2, array2);
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}
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@Test
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@IR(applyIf = { "PartialPeelLoop", "true" }, counts = { IRNode.COUNTEDLOOP, "1", IRNode.SAFEPOINT, "1" })
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@IR(applyIf = { "PartialPeelLoop", "true" }, failOn = { IRNode.OUTERSTRIPMINEDLOOP })
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private static void test2(int[] dst, int[] src) {
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// Partial peel is applied. Some side effect between exit and
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// safepoint.
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int v = src[0];
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for (int i = 0; ; ) {
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synchronized (new Object()) {}
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dst[i] = v;
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i++;
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if (i >= src.length) {
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break;
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}
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v = src[i];
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if (i / 2 >= 2000) {
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break;
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}
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}
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}
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@Run(test = "test2")
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private static void test2_runner() {
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int[] array1 = new int[1000];
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int[] array2 = new int[10000];
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test2(array1, array1);
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test2(array2, array2);
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}
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@Test
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@IR(applyIf = { "PartialPeelLoop", "false" }, counts = { IRNode.COUNTEDLOOP, "1", IRNode.OUTERSTRIPMINEDLOOP, "1", IRNode.SAFEPOINT, "1" })
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private static void test3(int[] dst, int[] src) {
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int v = src[0];
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for (int i = 0; ; ) {
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synchronized (new Object()) {}
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dst[i] = v;
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int inc = test3_helper(2);
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v = src[i];
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i += (inc / 2);
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if (i >= src.length) {
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break;
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}
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for (int j = 0; j < 10; j++) {
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}
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// safepoint on backedge
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}
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}
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private static int test3_helper(int stop) {
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int i = 1;
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do {
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synchronized (new Object()) {}
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i *= 2;
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} while (i < stop);
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return i;
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}
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@Run(test = "test3")
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private static void test3_runner() {
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int[] array1 = new int[1000];
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test3(array1, array1);
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test3_helper(10);
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}
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}
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@ -115,6 +115,7 @@ public class IRNode {
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public static final String LOOP = START + "Loop" + MID + END;
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public static final String COUNTEDLOOP = START + "CountedLoop\\b" + MID + END;
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public static final String COUNTEDLOOP_MAIN = START + "CountedLoop\\b" + MID + "main" + END;
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public static final String OUTERSTRIPMINEDLOOP = START + "OuterStripMinedLoop\\b" + MID + END;
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public static final String IF = START + "If\\b" + MID + END;
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public static final String CALL = START + "Call.*Java" + MID + END;
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@ -136,6 +137,7 @@ public class IRNode {
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public static final String SCOPE_OBJECT = "(.*# ScObj.*" + END;
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public static final String MEMBAR = START + "MemBar" + MID + END;
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public static final String SAFEPOINT = START + "SafePoint" + MID + END;
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public static final String ABS_I = START + "AbsI" + MID + END;
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public static final String ABS_L = START + "AbsL" + MID + END;
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