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src/cpu/arm/vm/jniFastGetField_arm.cpp
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rev 12692 : 8176100: [REDO][REDO] G1 Needs pre barrier on dereference of weak JNI handles
Reviewed-by:
@@ -1,7 +1,7 @@
/*
- * Copyright (c) 2008, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2017, 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.
@@ -117,10 +117,18 @@
#endif // !AARCH64
__ ldr_s32(Rsafept_cnt, Address(Rsafepoint_counter_addr));
__ tbnz(Rsafept_cnt, 0, slow_case);
+#ifdef AARCH64
+ // If mask changes we need to ensure that the inverse is still encodable as an immediate
+ STATIC_ASSERT(JNIHandles::weak_tag_mask == 1);
+ __ andr(R1, R1, ~JNIHandles::weak_tag_mask);
+#else
+ __ bic(R1, R1, JNIHandles::weak_tag_mask);
+#endif
+
if (os::is_MP()) {
// Address dependency restricts memory access ordering. It's cheaper than explicit LoadLoad barrier
__ andr(Rtmp1, Rsafept_cnt, (unsigned)1);
__ ldr(Robj, Address(R1, Rtmp1));
} else {
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