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8150186: Folding mismatched accesses with @Stable is incorrect

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Reviewed-by: kvn, jrose, shade
This commit is contained in:
Vladimir Ivanov 2016-02-26 01:58:26 +03:00
parent 88575c5de7
commit abebc2da5c
3 changed files with 81 additions and 4 deletions
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3
hotspot/src/share/vm/ci/ciArray.cpp
View File

@ -107,8 +107,9 @@ ciConstant ciArray::element_value_by_offset(intptr_t element_offset) {
intptr_t header = arrayOopDesc::base_offset_in_bytes(elembt);
intptr_t index = (element_offset - header) >> shift;
intptr_t offset = header + ((intptr_t)index << shift);
if (offset != element_offset || index != (jint)index)
if (offset != element_offset || index != (jint)index || index < 0 || index >= length()) {
return ciConstant();
}
return element_value((jint) index);
}

14
hotspot/src/share/vm/opto/memnode.cpp
View File

@ -1582,6 +1582,15 @@ LoadNode::load_array_final_field(const TypeKlassPtr *tkls,
return NULL;
}
static bool is_mismatched_access(ciConstant con, BasicType loadbt) {
BasicType conbt = con.basic_type();
assert(conbt != T_NARROWOOP, "sanity");
if (loadbt == T_NARROWOOP || loadbt == T_ARRAY) {
loadbt = T_OBJECT;
}
return (conbt != loadbt);
}
// Try to constant-fold a stable array element.
static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicType loadbt) {
assert(ary->const_oop(), "array should be constant");
@ -1590,8 +1599,7 @@ static const Type* fold_stable_ary_elem(const TypeAryPtr* ary, int off, BasicTyp
// Decode the results of GraphKit::array_element_address.
ciArray* aobj = ary->const_oop()->as_array();
ciConstant con = aobj->element_value_by_offset(off);
if (con.basic_type() != T_ILLEGAL && !con.is_null_or_zero()) {
if (con.basic_type() != T_ILLEGAL && !is_mismatched_access(con, loadbt) && !con.is_null_or_zero()) {
const Type* con_type = Type::make_from_constant(con);
if (con_type != NULL) {
if (con_type->isa_aryptr()) {
@ -1642,7 +1650,7 @@ const Type* LoadNode::Value(PhaseGVN* phase) const {
const bool off_beyond_header = ((uint)off >= (uint)min_base_off);
// Try to constant-fold a stable array element.
if (FoldStableValues && ary->is_stable() && ary->const_oop() != NULL) {
if (FoldStableValues && !is_mismatched_access() && ary->is_stable() && ary->const_oop() != NULL) {
// Make sure the reference is not into the header and the offset is constant
if (off_beyond_header && adr->is_AddP() && off != Type::OffsetBot) {
const Type* con_type = fold_stable_ary_elem(ary, off, memory_type());

68
hotspot/test/compiler/unsafe/UnsafeGetStableArrayElement.java Normal file
View File

@ -0,0 +1,68 @@
/*
* Copyright (c) 2016, 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. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* 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
* @summary tests on constant folding of unsafe get operations
* @library /testlibrary /test/lib
*
* @run main/bootclasspath -XX:+UnlockDiagnosticVMOptions
* -Xbatch -XX:-TieredCompilation
* -XX:+FoldStableValues
* UnsafeGetStableArrayElement
*
* @run main/bootclasspath -XX:+UnlockDiagnosticVMOptions
* -Xbatch -XX:+TieredCompilation -XX:TieredStopAtLevel=1
* -XX:+FoldStableValues
* UnsafeGetStableArrayElement
*/
import jdk.internal.misc.Unsafe;
import jdk.internal.vm.annotation.Stable;
import java.util.concurrent.Callable;
import static jdk.internal.misc.Unsafe.*;
import static jdk.test.lib.Asserts.*;
public class UnsafeGetStableArrayElement {
@Stable static final byte[] STABLE_BYTE_ARRAY = new byte[] { 0, 1, -128, 127};
static final Unsafe U = Unsafe.getUnsafe();
static int testChar() {
return U.getChar(STABLE_BYTE_ARRAY, ARRAY_BYTE_BASE_OFFSET + 0 * ARRAY_CHAR_INDEX_SCALE) +
U.getChar(STABLE_BYTE_ARRAY, ARRAY_BYTE_BASE_OFFSET + 1 * ARRAY_CHAR_INDEX_SCALE);
}
static void run(Callable c) throws Exception {
Object first = c.call();
for (int i = 0; i < 20_000; i++) {
assertEQ(first, c.call());
}
}
public static void main(String[] args) throws Exception {
run(UnsafeGetStableArrayElement::testChar);
}
}