src/cpu/aarch64/vm/jniFastGetField_aarch64.cpp

rev 12692 : 8176100: [REDO][REDO] G1 Needs pre barrier on dereference of weak JNI handles
Reviewed-by:

*** 1,7 ****
  /*
!  * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2014, Red Hat Inc. 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
--- 1,7 ----
  /*
!  * Copyright (c) 2004, 2017, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2014, Red Hat Inc. 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
*** 80,89 ****
--- 80,94 ----
    __ cbnzw(rscratch1, slow);
    __ eor(robj, c_rarg1, rcounter);
    __ eor(robj, robj, rcounter);               // obj, since
                                                // robj ^ rcounter ^ rcounter == robj
                                                // robj is address dependent on rcounter.
+ 
+   // If mask changes we need to ensure that the inverse is still encodable as an immediate
+   STATIC_ASSERT(JNIHandles::weak_tag_mask == 1);
+   __ andr(robj, robj, ~JNIHandles::weak_tag_mask);
+ 
    __ ldr(robj, Address(robj, 0));             // *obj
    __ lsr(roffset, c_rarg2, 2);                // offset
  
    assert(count < LIST_CAPACITY, "LIST_CAPACITY too small");
    speculative_load_pclist[count] = __ pc();   // Used by the segfault handler