8161720: Better byte behavior for off-heap data
Summary: Normalize boolean values read with Unsafe.
Reviewed-by: aph, simonis, jrose, psandoz
--- a/hotspot/src/share/vm/c1/c1_LIRGenerator.cpp Mon Aug 29 17:15:20 2016 +0000
+++ b/hotspot/src/share/vm/c1/c1_LIRGenerator.cpp Tue Aug 30 09:30:16 2016 +0200
@@ -2410,6 +2410,15 @@
#endif // INCLUDE_ALL_GCS
if (x->is_volatile() && os::is_MP()) __ membar_acquire();
+
+ /* Normalize boolean value returned by unsafe operation, i.e., value != 0 ? value = true : value false. */
+ if (type == T_BOOLEAN) {
+ LabelObj* equalZeroLabel = new LabelObj();
+ __ cmp(lir_cond_equal, value, 0);
+ __ branch(lir_cond_equal, T_BOOLEAN, equalZeroLabel->label());
+ __ move(LIR_OprFact::intConst(1), value);
+ __ branch_destination(equalZeroLabel->label());
+ }
}
--- a/hotspot/src/share/vm/opto/library_call.cpp Mon Aug 29 17:15:20 2016 +0000
+++ b/hotspot/src/share/vm/opto/library_call.cpp Tue Aug 30 09:30:16 2016 +0200
@@ -2471,6 +2471,28 @@
// load value
switch (type) {
case T_BOOLEAN:
+ {
+ // Normalize the value returned by getBoolean in the following cases
+ if (mismatched ||
+ heap_base_oop == top() || // - heap_base_oop is NULL or
+ (can_access_non_heap && alias_type->field() == NULL) // - heap_base_oop is potentially NULL
+ // and the unsafe access is made to large offset
+ // (i.e., larger than the maximum offset necessary for any
+ // field access)
+ ) {
+ IdealKit ideal = IdealKit(this);
+#define __ ideal.
+ IdealVariable normalized_result(ideal);
+ __ declarations_done();
+ __ set(normalized_result, p);
+ __ if_then(p, BoolTest::ne, ideal.ConI(0));
+ __ set(normalized_result, ideal.ConI(1));
+ ideal.end_if();
+ final_sync(ideal);
+ p = __ value(normalized_result);
+#undef __
+ }
+ }
case T_CHAR:
case T_BYTE:
case T_SHORT:
--- a/hotspot/src/share/vm/prims/unsafe.cpp Mon Aug 29 17:15:20 2016 +0000
+++ b/hotspot/src/share/vm/prims/unsafe.cpp Tue Aug 30 09:30:16 2016 +0200
@@ -150,14 +150,23 @@
}
template <typename T>
- T normalize(T x) {
+ T normalize_for_write(T x) {
return x;
}
- jboolean normalize(jboolean x) {
+ jboolean normalize_for_write(jboolean x) {
return x & 1;
}
+ template <typename T>
+ T normalize_for_read(T x) {
+ return x;
+ }
+
+ jboolean normalize_for_read(jboolean x) {
+ return x != 0;
+ }
+
/**
* Helper class to wrap memory accesses in JavaThread::doing_unsafe_access()
*/
@@ -196,7 +205,7 @@
T* p = (T*)addr();
- T x = *p;
+ T x = normalize_for_read(*p);
return x;
}
@@ -207,7 +216,7 @@
T* p = (T*)addr();
- *p = normalize(x);
+ *p = normalize_for_write(x);
}
@@ -223,7 +232,7 @@
T x = OrderAccess::load_acquire((volatile T*)p);
- return x;
+ return normalize_for_read(x);
}
template <typename T>
@@ -232,7 +241,7 @@
T* p = (T*)addr();
- OrderAccess::release_store_fence((volatile T*)p, normalize(x));
+ OrderAccess::release_store_fence((volatile T*)p, normalize_for_write(x));
}
@@ -256,7 +265,7 @@
jlong* p = (jlong*)addr();
- Atomic::store(normalize(x), p);
+ Atomic::store(normalize_for_write(x), p);
}
#endif
};
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/unsafe/UnsafeOffHeapBooleanTest.java Tue Aug 30 09:30:16 2016 +0200
@@ -0,0 +1,92 @@
+/*
+ * 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.
+ *
+ * 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 8161720
+ * @modules java.base/jdk.internal.misc
+ * @run main/othervm -Xint UnsafeOffHeapBooleanTest 1
+ * @run main/othervm -XX:+TieredCompilation -XX:TieredStopAtLevel=3 -Xbatch UnsafeOffHeapBooleanTest 20000
+ * @run main/othervm -XX:-TieredCompilation -Xbatch UnsafeOffHeapBooleanTest 20000
+ */
+
+
+import java.lang.reflect.Field;
+import jdk.internal.misc.Unsafe;
+
+public class UnsafeOffHeapBooleanTest {
+ static boolean bool0 = false, bool1 = false, result = false;
+ static Unsafe UNSAFE = Unsafe.getUnsafe();
+ static long offHeapMemory;
+
+ public static void test() {
+ // Write two bytes to the off-heap memory location, both
+ // bytes correspond to the boolean value 'true'.
+ UNSAFE.putShort(null, offHeapMemory, (short)0x0204);
+
+ // Read two bytes from the storage allocated above (as booleans).
+ bool0 = UNSAFE.getBoolean(null, offHeapMemory + 0);
+ bool1 = UNSAFE.getBoolean(null, offHeapMemory + 1);
+ result = bool0 & bool1;
+ }
+
+ public static void main(String args[]) {
+ System.out.println("### Test started");
+
+ if (args.length != 1) {
+ throw new RuntimeException("### Test failure: test called with incorrect number of arguments");
+ }
+
+ // Allocate two bytes of storage.
+ offHeapMemory = UNSAFE.allocateMemory(2);
+
+ try {
+ for (int i = 0; i < Integer.parseInt(args[0]); i++) {
+ test();
+ }
+
+ // Check if the two 'true' boolean values were normalized
+ // (i.e., reduced from the range 1...255 to 1).
+ if (!bool0 || !bool1 || !result) {
+ System.out.println("Some of the results below are wrong");
+ System.out.println("bool0 is: " + bool0);
+ System.out.println("bool1 is: " + bool1);
+ System.out.println("bool0 & bool1 is: " + result);
+ System.out.println("===================================");
+ throw new RuntimeException("### Test failed");
+ } else {
+ System.out.println("Test generated correct results");
+ System.out.println("bool0 is: " + bool0);
+ System.out.println("bool1 is: " + bool1);
+ System.out.println("bool0 & bool1 is: " + result);
+ System.out.println("===================================");
+ }
+ } catch (NumberFormatException e) {
+ throw new RuntimeException("### Test failure: test called with incorrectly formatted parameter");
+ }
+
+ UNSAFE.freeMemory(offHeapMemory);
+
+ System.out.println("### Test passed");
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/unsafe/UnsafeOnHeapBooleanTest.java Tue Aug 30 09:30:16 2016 +0200
@@ -0,0 +1,95 @@
+/*
+ * 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.
+ *
+ * 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 8161720
+ * @modules java.base/jdk.internal.misc
+ * @run main/othervm -Xint UnsafeOnHeapBooleanTest 1
+ * @run main/othervm -XX:-UseOnStackReplacement -XX:+TieredCompilation -XX:TieredStopAtLevel=3 -Xbatch UnsafeOnHeapBooleanTest 20000
+ * @run main/othervm -XX:-UseOnStackReplacement -XX:-TieredCompilation -Xbatch UnsafeOnHeapBooleanTest 20000
+ */
+
+import java.lang.reflect.Field;
+import jdk.internal.misc.Unsafe;
+
+public class UnsafeOnHeapBooleanTest {
+ static short static_v;
+ static boolean bool0 = false, bool1 = false, result = false;
+ static Unsafe UNSAFE = Unsafe.getUnsafe();
+
+ public static void test() {
+ try {
+ // Write two bytes into the static field
+ // UnsafeOnHeapBooleanTest.static_v write two values. Both
+ // bytes correspond to the boolean value 'true'.
+ Field staticVField = UnsafeOnHeapBooleanTest.class.getDeclaredField("static_v");
+ Object base = UNSAFE.staticFieldBase(staticVField);
+ long offset = UNSAFE.staticFieldOffset(staticVField);
+ UNSAFE.putShort(base, offset, (short)0x0204);
+
+ // Read two bytes from the static field
+ // UnsafeOnHeapBooleanTest.static_v (as booleans).
+ bool0 = UNSAFE.getBoolean(base, offset + 0);
+ bool1 = UNSAFE.getBoolean(base, offset + 1);
+ result = bool0 & bool1;
+ } catch (NoSuchFieldException e) {
+ throw new RuntimeException("### Test failure: static field UnsafeOnHeapBooleanTest.static_v was not found");
+ }
+ }
+
+ public static void main(String args[]) {
+ System.out.println("### Test started");
+
+ if (args.length != 1) {
+ throw new RuntimeException("### Test failure: test called with incorrect number of arguments");
+ }
+
+ try {
+ for (int i = 0; i < Integer.parseInt(args[0]); i++) {
+ test();
+ }
+
+ // Check if the two 'true' boolean values were normalized
+ // (i.e., reduced from the range 1...255 to 1).
+ if (!bool0 || !bool1 || !result) {
+ System.out.println("Some of the results below are wrong");
+ System.out.println("bool0 is: " + bool0);
+ System.out.println("bool1 is: " + bool1);
+ System.out.println("bool0 & bool1 is: " + result);
+ System.out.println("===================================");
+ throw new RuntimeException("### Test failed");
+ } else {
+ System.out.println("Test generated correct results");
+ System.out.println("bool0 is: " + bool0);
+ System.out.println("bool1 is: " + bool1);
+ System.out.println("bool0 & bool1 is: " + result);
+ System.out.println("===================================");
+ }
+ } catch (NumberFormatException e) {
+ throw new RuntimeException("### Test failure: test called with incorrectly formatted parameter");
+ }
+
+ System.out.println("### Test passed");
+ }
+}
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/unsafe/UnsafeSmallOffsetBooleanAccessTest.java Tue Aug 30 09:30:16 2016 +0200
@@ -0,0 +1,85 @@
+/*
+ * 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.
+ *
+ * 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 8161720
+ * @modules java.base/jdk.internal.misc
+ * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -Xbatch -XX:-TieredCompilation UnsafeSmallOffsetBooleanAccessTest
+ * @run main/othervm -Xbatch UnsafeSmallOffsetBooleanAccessTest
+ */
+
+import java.util.Random;
+import jdk.internal.misc.Unsafe;
+
+public class UnsafeSmallOffsetBooleanAccessTest {
+ static final Unsafe UNSAFE = Unsafe.getUnsafe();
+ static final long F_OFFSET;
+ static final Random random = new Random();
+
+ static {
+ try {
+ F_OFFSET = UNSAFE.objectFieldOffset(T.class.getDeclaredField("f"));
+ System.out.println("The offset is: " + F_OFFSET);
+ } catch (Exception e) {
+ throw new Error(e);
+ }
+ }
+
+ static class T {
+ boolean f;
+ }
+
+ // Always return false in a way that is not obvious to the compiler.
+ public static boolean myRandom() {
+ if (random.nextInt(101) > 134) {
+ return true;
+ } else {
+ return false;
+ }
+ }
+
+ public static boolean test(T t) {
+ boolean result = false;
+ for (int i = 0; i < 20000; i++) {
+ boolean random = myRandom();
+ // If myRandom() returns false, access t.f.
+ //
+ // If myRandom() returns true, access virtual address
+ // F_OFFSET. That address is most likely not mapped,
+ // therefore the access will most likely cause a
+ // crash. We're not concerned about that, though, because
+ // myRandom() always returns false. However, the C2
+ // compiler avoids normalization of the value returned by
+ // getBoolean in this case.
+ result = UNSAFE.getBoolean(myRandom() ? null : t, F_OFFSET);
+ }
+ return result;
+ }
+
+ public static void main(String[] args) {
+ T t = new T();
+ UNSAFE.putBoolean(t, F_OFFSET, true);
+ System.out.println("The result for t is: " + test(t));
+ }
+}