src/hotspot/cpu/aarch64/jniFastGetField_aarch64.cpp

rev 55759 : 8227680: FastJNIAccessors: Check for JVMTI field access event requests at runtime
Summary: Check JvmtiExport::_field_access_count != 0 at runtime
Reviewed-by:

*** 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
--- 1,7 ----
  /*
!  * Copyright (c) 2004, 2019, 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
*** 77,91 ****
--- 77,110 ----
    __ adrp(rcounter_addr,
            SafepointSynchronize::safepoint_counter_addr(), offset);
    Address safepoint_counter_addr(rcounter_addr, offset);
    __ ldrw(rcounter, safepoint_counter_addr);
    __ tbnz(rcounter, 0, slow);
+ 
+   if (JvmtiExport::can_post_field_access()) {
+     // Using barrier to order wrt. JVMTI check and load of result.
+     __ membar(Assembler::LoadLoad);
+ 
+     // Check to see if a field access watch has been set before we
+     // take the fast path.
+     unsigned long offset2;
+     __ adrp(result,
+             ExternalAddress((address) JvmtiExport::get_field_access_count_addr()),
+             offset2);
+     __ ldrw(result, Address(result, offset2));
+     __ cbnzw(result, slow);
+ 
+     __ mov(robj, c_rarg1);
+   } else {
+     // Using address dependency to order wrt. load of result.
      __ eor(robj, c_rarg1, rcounter);
      __ eor(robj, robj, rcounter);         // obj, since
                                            // robj ^ rcounter ^ rcounter == robj
                                            // robj is address dependent on rcounter.
+   }
  
+   // Both robj and rscratch1 are clobbered by try_resolve_jobject_in_native.
    BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
    bs->try_resolve_jobject_in_native(masm, c_rarg0, robj, rscratch1, slow);
  
    __ lsr(roffset, c_rarg2, 2);                // offset
  
*** 101,113 ****
--- 120,138 ----
      case T_DOUBLE:
      case T_LONG:    __ ldr     (result, Address(robj, roffset)); break;
      default:        ShouldNotReachHere();
    }
  
+   if (JvmtiExport::can_post_field_access()) {
+     // Order JVMTI check and load of result wrt. succeeding check.
+     __ membar(Assembler::LoadLoad);
+   } else {
      // counter_addr is address dependent on result.
      __ eor(rcounter_addr, rcounter_addr, result);
      __ eor(rcounter_addr, rcounter_addr, result);
+   }
+ 
    __ ldrw(rscratch1, safepoint_counter_addr);
    __ cmpw(rcounter, rscratch1);
    __ br (Assembler::NE, slow);
  
    switch (type) {