Fix a bug in the register allocator around pair allocation.
We may get hints that do not work with the current implementation
of register pairs, which forces the allocation of (low + 1)
for the high register. For example, if the hint is EBX, we will
allocate ESP for the high register.
bug:23043730
Change-Id: I371ebb0c61568f09d12eb9ab815c0bf0ea02d49b
diff --git a/compiler/optimizing/register_allocator.cc b/compiler/optimizing/register_allocator.cc
index de62530..60f5ab2 100644
--- a/compiler/optimizing/register_allocator.cc
+++ b/compiler/optimizing/register_allocator.cc
@@ -782,7 +782,10 @@
} else {
DCHECK(!current->IsHighInterval());
int hint = current->FindFirstRegisterHint(free_until, liveness_);
- if (hint != kNoRegister) {
+ if ((hint != kNoRegister)
+ // For simplicity, if the hint we are getting for a pair cannot be used,
+ // we are just going to allocate a new pair.
+ && !(current->IsLowInterval() && IsBlocked(GetHighForLowRegister(hint)))) {
DCHECK(!IsBlocked(hint));
reg = hint;
} else if (current->IsLowInterval()) {
diff --git a/test/528-long-hint/expected.txt b/test/528-long-hint/expected.txt
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test/528-long-hint/expected.txt
diff --git a/test/528-long-hint/info.txt b/test/528-long-hint/info.txt
new file mode 100644
index 0000000..6a9cfae
--- /dev/null
+++ b/test/528-long-hint/info.txt
@@ -0,0 +1,2 @@
+Regression test for optimizing that used to crash on x86 when
+allocating a wrong register pair.
diff --git a/test/528-long-hint/src/Main.java b/test/528-long-hint/src/Main.java
new file mode 100644
index 0000000..ca1a114
--- /dev/null
+++ b/test/528-long-hint/src/Main.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import sun.misc.Unsafe;
+import java.lang.reflect.Field;
+
+public class Main {
+
+ long instanceField;
+ static long myLongField1;
+ static long myLongField2;
+
+ public static void main(String[] args) throws Exception {
+ Unsafe unsafe = getUnsafe();
+ Main f = new Main();
+ long offset = unsafe.objectFieldOffset(Main.class.getDeclaredField("instanceField"));
+ getUnsafe(); // spill offset
+ long a = myLongField1;
+ // We used the hinted register for the low part of b, which is EBX, as requested
+ // by the intrinsic below. Allocating EBX for the low part, would put ESP as the high
+ // part, and we did not check that ESP was blocked.
+ long b = myLongField2;
+ unsafe.compareAndSwapLong(f, offset, a, b);
+ }
+
+
+ private static Unsafe getUnsafe() throws Exception {
+ Field f = Unsafe.class.getDeclaredField("theUnsafe");
+ f.setAccessible(true);
+ return (Unsafe) f.get(null);
+ }
+}
