diff --git a/src/hotspot/share/opto/block.cpp b/src/hotspot/share/opto/block.cpp
index 56371e574f4..d4227df0b4f 100644
--- a/src/hotspot/share/opto/block.cpp
+++ b/src/hotspot/share/opto/block.cpp
@@ -1245,12 +1245,18 @@ void PhaseCFG::verify() const {
for (uint k = 0; k < n->req(); k++) {
Node *def = n->in(k);
if (def && def != n) {
- assert(get_block_for_node(def) || def->is_Con(), "must have block; constants for debug info ok");
- // Verify that instructions in the block is in correct order.
+ Block* def_block = get_block_for_node(def);
+ assert(def_block || def->is_Con(), "must have block; constants for debug info ok");
+ // Verify that all definitions dominate their uses (except for virtual
+ // instructions merging multiple definitions).
+ assert(n->is_Root() || n->is_Region() || n->is_Phi() || n->is_MachMerge() ||
+ def_block->dominates(block),
+ "uses must be dominated by definitions");
+ // Verify that instructions in the block are in correct order.
// Uses must follow their definition if they are at the same block.
// Mostly done to check that MachSpillCopy nodes are placed correctly
// when CreateEx node is moved in build_ifg_physical().
- if (get_block_for_node(def) == block && !(block->head()->is_Loop() && n->is_Phi()) &&
+ if (def_block == block && !(block->head()->is_Loop() && n->is_Phi()) &&
// See (+++) comment in reg_split.cpp
!(n->jvms() != NULL && n->jvms()->is_monitor_use(k))) {
bool is_loop = false;
@@ -1266,6 +1272,14 @@ void PhaseCFG::verify() const {
}
}
}
+ if (n->is_Proj()) {
+ assert(j >= 1, "a projection cannot be the first instruction in a block");
+ Node* pred = block->get_node(j - 1);
+ Node* parent = n->in(0);
+ assert(parent != NULL, "projections must have a parent");
+ assert(pred == parent || (pred->is_Proj() && pred->in(0) == parent),
+ "projections must follow their parents or other sibling projections");
+ }
}
j = block->end_idx();
diff --git a/src/hotspot/share/opto/lcm.cpp b/src/hotspot/share/opto/lcm.cpp
index cf45ff971f7..28116653f94 100644
--- a/src/hotspot/share/opto/lcm.cpp
+++ b/src/hotspot/share/opto/lcm.cpp
@@ -1390,14 +1390,40 @@ void PhaseCFG::call_catch_cleanup(Block* block) {
}
// If the successor blocks have a CreateEx node, move it back to the top
- for(uint i4 = 0; i4 < block->_num_succs; i4++ ) {
+ for (uint i4 = 0; i4 < block->_num_succs; i4++) {
Block *sb = block->_succs[i4];
uint new_cnt = end - beg;
- // Remove any newly created, but dead, nodes.
- for( uint j = new_cnt; j > 0; j-- ) {
+ // Remove any newly created, but dead, nodes by traversing their schedule
+ // backwards. Here, a dead node is a node whose only outputs (if any) are
+ // unused projections.
+ for (uint j = new_cnt; j > 0; j--) {
Node *n = sb->get_node(j);
- if (n->outcnt() == 0 &&
- (!n->is_Proj() || n->as_Proj()->in(0)->outcnt() == 1) ){
+ // Individual projections are examined together with all siblings when
+ // their parent is visited.
+ if (n->is_Proj()) {
+ continue;
+ }
+ bool dead = true;
+ for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+ Node* out = n->fast_out(i);
+ // n is live if it has a non-projection output or a used projection.
+ if (!out->is_Proj() || out->outcnt() > 0) {
+ dead = false;
+ break;
+ }
+ }
+ if (dead) {
+ // n's only outputs (if any) are unused projections scheduled next to n
+ // (see PhaseCFG::select()). Remove these projections backwards.
+ for (uint k = j + n->outcnt(); k > j; k--) {
+ Node* proj = sb->get_node(k);
+ assert(proj->is_Proj() && proj->in(0) == n,
+ "projection should correspond to dead node");
+ proj->disconnect_inputs(C);
+ sb->remove_node(k);
+ new_cnt--;
+ }
+ // Now remove the node itself.
n->disconnect_inputs(C);
sb->remove_node(j);
new_cnt--;
diff --git a/src/hotspot/share/opto/reg_split.cpp b/src/hotspot/share/opto/reg_split.cpp
index ca5c9eaf7f8..1d2717e7556 100644
--- a/src/hotspot/share/opto/reg_split.cpp
+++ b/src/hotspot/share/opto/reg_split.cpp
@@ -114,6 +114,8 @@ void PhaseChaitin::insert_proj( Block *b, uint i, Node *spill, uint maxlrg ) {
// Do not insert between a call and his Catch
if( b->get_node(i)->is_Catch() ) {
// Put the instruction at the top of the fall-thru block.
+ // This assumes that the instruction is not used in the other exception
+ // blocks. Global code motion is responsible for maintaining this invariant.
// Find the fall-thru projection
while( 1 ) {
const CatchProjNode *cp = b->get_node(++i)->as_CatchProj();
diff --git a/test/hotspot/jtreg/compiler/exceptions/TestSpilling.java b/test/hotspot/jtreg/compiler/exceptions/TestSpilling.java
new file mode 100644
index 00000000000..572e2384d56
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/exceptions/TestSpilling.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2021, 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.
+ */
+
+package compiler.exceptions;
+
+/**
+ * @test
+ * @bug 8263227
+ * @summary Tests that users of return values from exception-throwing method
+ * calls are not duplicated in the call's exception path. The second
+ * run with a variable seed is added for test robustness.
+ * @library /test/lib /
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions
+ * -XX:+UnlockDiagnosticVMOptions
+ * -Xbatch -XX:+StressGCM -XX:StressSeed=0
+ * -XX:+VerifyRegisterAllocator
+ * -XX:CompileCommand=dontinline,java.lang.Integer::*
+ * compiler.exceptions.TestSpilling
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions
+ * -XX:+UnlockDiagnosticVMOptions
+ * -Xbatch -XX:+StressGCM
+ * -XX:+VerifyRegisterAllocator
+ * -XX:CompileCommand=dontinline,java.lang.Integer::*
+ * compiler.exceptions.TestSpilling
+ */
+
+public class TestSpilling {
+
+ public static void test() {
+ int a = Integer.valueOf(42).intValue();
+ // After global code motion, the logic below should only be placed in
+ // the fall-through path of java.lang.Integer::intValue(). Otherwise,
+ // live range splitting might create uses without reaching definitions
+ // if 'a' is spilled.
+ int b = (((a & 0x0000F000)) + 1);
+ int c = a / b + ((a % b > 0) ? 1 : 0);
+ }
+
+ public static void main(String[] args) {
+ for (int i = 0; i < 10_000; i++) {
+ test();
+ }
+ }
+
+}