src/hotspot/cpu/arm/jniFastGetField_arm.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) 2008, 2018, 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.
--- 1,7 ----
  /*
!  * Copyright (c) 2008, 2019, 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.
*** 97,122 ****
    ResourceMark rm;
    BufferBlob* blob = BufferBlob::create(name, BUFFER_SIZE);
    CodeBuffer cbuf(blob);
    MacroAssembler* masm = new MacroAssembler(&cbuf);
    fast_entry = __ pc();
  
    // Safepoint check
    InlinedAddress safepoint_counter_addr(SafepointSynchronize::safepoint_counter_addr());
-   Label slow_case;
    __ ldr_literal(Rsafepoint_counter_addr, safepoint_counter_addr);
  
    __ push(RegisterSet(R0, R3));  // save incoming arguments for slow case
  
    __ ldr_s32(Rsafept_cnt, Address(Rsafepoint_counter_addr));
    __ tbnz(Rsafept_cnt, 0, slow_case);
  
    __ bic(R1, R1, JNIHandles::weak_tag_mask);
  
    // Address dependency restricts memory access ordering. It's cheaper than explicit LoadLoad barrier
    __ andr(Rtmp1, Rsafept_cnt, (unsigned)1);
    __ ldr(Robj, Address(R1, Rtmp1));
  
    Address field_addr;
    if (type != T_BOOLEAN
        && type != T_INT
  #ifndef __ABI_HARD__
--- 97,134 ----
    ResourceMark rm;
    BufferBlob* blob = BufferBlob::create(name, BUFFER_SIZE);
    CodeBuffer cbuf(blob);
    MacroAssembler* masm = new MacroAssembler(&cbuf);
    fast_entry = __ pc();
+   Label slow_case;
  
    // Safepoint check
    InlinedAddress safepoint_counter_addr(SafepointSynchronize::safepoint_counter_addr());
    __ ldr_literal(Rsafepoint_counter_addr, safepoint_counter_addr);
  
    __ push(RegisterSet(R0, R3));  // save incoming arguments for slow case
  
    __ ldr_s32(Rsafept_cnt, Address(Rsafepoint_counter_addr));
    __ tbnz(Rsafept_cnt, 0, slow_case);
  
    __ bic(R1, R1, JNIHandles::weak_tag_mask);
  
+   if (JvmtiExport::can_post_field_access()) {
+     // Using barrier to order wrt. JVMTI check and load of result.
+     __ membar(Assembler::LoadLoad, Rtmp1);
+ 
+     // Check to see if a field access watch has been set before we
+     // take the fast path.
+     __ ldr_global_s32(Rtmp1, (address)JvmtiExport::get_field_access_count_addr());
+     __ cbnz(Rtmp1, slow_case);
+ 
+     __ ldr(Robj, Address(R1));
+   } else {
      // Address dependency restricts memory access ordering. It's cheaper than explicit LoadLoad barrier
      __ andr(Rtmp1, Rsafept_cnt, (unsigned)1);
      __ ldr(Robj, Address(R1, Rtmp1));
+   }
  
    Address field_addr;
    if (type != T_BOOLEAN
        && type != T_INT
  #ifndef __ABI_HARD__
*** 168,191 ****
  #endif // __ABI_HARD__
      default:
        ShouldNotReachHere();
    }
  
!   // Address dependency restricts memory access ordering. It's cheaper than explicit LoadLoad barrier
  #ifdef __ABI_HARD__
    if (type == T_FLOAT || type == T_DOUBLE) {
-     __ ldr_literal(Rsafepoint_counter_addr, safepoint_counter_addr);
      __ fmrrd(Rres, Rres_hi, D0);
!     __ eor(Rtmp2, Rres, Rres);
!     __ ldr_s32(Rsafept_cnt2, Address(Rsafepoint_counter_addr, Rtmp2));
!   } else
  #endif // __ABI_HARD__
!   {
!     __ ldr_literal(Rsafepoint_counter_addr, safepoint_counter_addr);
      __ eor(Rtmp2, Rres, Rres);
      __ ldr_s32(Rsafept_cnt2, Address(Rsafepoint_counter_addr, Rtmp2));
    }
    __ cmp(Rsafept_cnt2, Rsafept_cnt);
    // discards saved R0 R1 R2 R3
    __ add(SP, SP, 4 * wordSize, eq);
    __ bx(LR, eq);
  
--- 180,206 ----
  #endif // __ABI_HARD__
      default:
        ShouldNotReachHere();
    }
  
!   __ ldr_literal(Rsafepoint_counter_addr, safepoint_counter_addr);
  #ifdef __ABI_HARD__
    if (type == T_FLOAT || type == T_DOUBLE) {
      __ fmrrd(Rres, Rres_hi, D0);
!   }
  #endif // __ABI_HARD__
! 
!   if (JvmtiExport::can_post_field_access()) {
!     // Order JVMTI check and load of result wrt. succeeding check.
!     __ membar(Assembler::LoadLoad, Rtmp2);
!     __ ldr_s32(Rsafept_cnt2, Address(Rsafepoint_counter_addr));
!   } else {
!     // Address dependency restricts memory access ordering. It's cheaper than explicit LoadLoad barrier
      __ eor(Rtmp2, Rres, Rres);
      __ ldr_s32(Rsafept_cnt2, Address(Rsafepoint_counter_addr, Rtmp2));
    }
+ 
    __ cmp(Rsafept_cnt2, Rsafept_cnt);
    // discards saved R0 R1 R2 R3
    __ add(SP, SP, 4 * wordSize, eq);
    __ bx(LR, eq);