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8233032: assert(in_bb(n)) failed: must be

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Find first and last memory state of a load pack without relying on bb indices.

Co-authored-by: Roland Westrelin <rwestrel@redhat.com>
Reviewed-by: roland, kvn, thartmann
This commit is contained in:
Christian Hagedorn 2019-12-10 09:28:38 +01:00
parent 5fc46f3c50
commit 2ee7b9d3a0
2 changed files with 115 additions and 17 deletions
src/hotspot/share/opto
superword.cpp
test/hotspot/jtreg/compiler/loopopts/superword
CoLocatePack.java

42
src/hotspot/share/opto/superword.cpp

@ -2255,30 +2255,38 @@ void SuperWord::co_locate_pack(Node_List* pk) {
// we use the memory state of the last load. However, if any load could
// not be moved down due to the dependence constraint, we use the memory
// state of the first load.
Node* first_mem = pk->at(0)->in(MemNode::Memory);
Node* last_mem = first_mem;
for (uint i = 1; i < pk->size(); i++) {
Node* ld = pk->at(i);
Node* mem = ld->in(MemNode::Memory);
assert(in_bb(first_mem) || in_bb(mem) || mem == first_mem, "2 different memory state from outside the loop?");
if (in_bb(mem)) {
if (in_bb(first_mem) && bb_idx(mem) < bb_idx(first_mem)) {
first_mem = mem;
}
if (!in_bb(last_mem) || bb_idx(mem) > bb_idx(last_mem)) {
last_mem = mem;
Node* last_mem = pk->at(0)->in(MemNode::Memory);
Node* first_mem = last_mem;
// Walk the memory graph from the current first load until the
// start of the loop and check if nodes on the way are memory
// edges of loads in the pack. The last one we encounter is the
// first load.
for (Node* current = first_mem; in_bb(current); current = current->is_Phi() ? current->in(LoopNode::EntryControl) : current->in(MemNode::Memory)) {
assert(current->is_Mem() || (current->is_Phi() && current->in(0) == bb()), "unexpected memory");
for (uint i = 1; i < pk->size(); i++) {
Node* ld = pk->at(i);
if (ld->in(MemNode::Memory) == current) {
first_mem = current;
break;
}
}
}
// Find the last load by going over the pack again and walking
// the memory graph from the loads of the pack to the memory of
// the first load. If we encounter the memory of the current last
// load, then we started from further down in the memory graph and
// the load we started from is the last load. Check for dependence
// constraints in that loop as well.
bool schedule_last = true;
for (uint i = 0; i < pk->size(); i++) {
Node* ld = pk->at(i);
for (Node* current = last_mem; current != ld->in(MemNode::Memory);
current=current->in(MemNode::Memory)) {
assert(current != first_mem, "corrupted memory graph");
if(current->is_Mem() && !independent(current, ld)){
for (Node* current = ld->in(MemNode::Memory); current != first_mem; current = current->in(MemNode::Memory)) {
assert(current->is_Mem() && in_bb(current), "unexpected memory");
if (current->in(MemNode::Memory) == last_mem) {
last_mem = ld->in(MemNode::Memory);
}
if (!independent(current, ld)) {
schedule_last = false; // a later store depends on this load
break;
}
}
}

90
test/hotspot/jtreg/compiler/loopopts/superword/CoLocatePack.java Normal file

@ -0,0 +1,90 @@
/*
* Copyright (c) 2019, 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 8233032
* @summary Tests SuperWord::co_locate_pack() involving a load pack that relies on a sandwiched and moved StoreF node.
*
* @run main/othervm -Xbatch -XX:+IgnoreUnrecognizedVMOptions -XX:UseAVX=1
* -XX:CompileCommand=compileonly,compiler.loopopts.superword.CoLocatePack::test
* compiler.loopopts.superword.CoLocatePack
*/
package compiler.loopopts.superword;
public class CoLocatePack {
public static long lFld = 10;
public static float fFld = 11.2f;
public int iFld = 12;
public void test() {
int iArr[] = new int[200];
float fArr[] = new float[200];
/*
* The IR for this loop contains the following StoreF chain after unrolling once:
* StoreF 1 -> StoreF 2 -> StoreF 3 -> StoreF 4 -> StoreF 5 -> StoreF 6
*
* The superword algorithm creates a pack for [ StoreF 2 and 5 ] and one for [ StoreF 3 and 6 ]
* (The pack [ StoreF 1 and 4 ] is filtered out). As a result, StoreF 3 and 4 are sandwiched between
* StoreF 2 and 5. SuperWord::co_locate_pack() will move both after StoreF 5 to remove any dependencies
* within the pack:
* StoreF 1 -> [ StoreF 2 -> StoreF 5 ] -> StoreF 3 -> StoreF 4 -> StoreF 6
*
* Afterwards, StoreF 4 is moved before StoreF 3 to remove any dependency within [ StoreF 3 -> StoreF 6 ]
* The resulting chain looks like this:
* StoreF 1 -> [ StoreF 2 -> StoreF 5 ] -> StoreF 4 -> [ StoreF 3 -> StoreF 6 ]
*
* When later processing a load pack depending on StoreF 4 and 5, the first and last memory state of the load pack are
* determined by using the bb indices. However, those were not updated before when moving nodes around and
* bb_idx(4) < bb_idx(5) still holds even though they swapped positions in the IR. Therefore, it wrongly uses the memory
* state of the first load (StoreF 5) in the pack as the last memory state. As a result, the graph walk always starts
* following the input of StoreF 5 (which should actually be StoreF 4) and will move beyond a loop phi as the stop
* condition is never met for a node having another memory state than the first one of the load pack. Eventually a
* bb index for a node outside of the loop is read resulting in an assertion failure.
*
* The fix uses a different approach to find the first and last memory state of a load pack without depending on bb indices.
*/
for (int i = 5; i < 169; i++) {
fArr[i + 1] += ((long)(fFld) | 1); // StoreF 1/4
iFld += lFld;
fArr[i - 1] -= 20; // StoreF 2/5
fFld += i;
fArr[i + 1] -= -117; // StoreF 3/6
int j = 10;
do {
} while (--j > 0);
iArr[i] += 11;
}
}
public static void main(String[] strArr) {
CoLocatePack _instance = new CoLocatePack();
for (int i = 0; i < 1000; i++ ) {
_instance.test();
}
}
}