src/cpu/aarch64/vm/shenandoahBarrierSet_aarch64.cpp

rev 10555 : [backport] Micro-optimize AArch64 assembly write-barriers
rev 10557 : [backport] Assembler write barriers should consistently check for forwarded objects

*** 55,70 ****
  
    Label done;
  
    Address gc_state(rthread, in_bytes(JavaThread::gc_state_offset()));
    __ ldrb(rscratch1, gc_state);
-   __ membar(Assembler::LoadLoad);
  
!   // Now check if evacuation is in progress.
!   interpreter_read_barrier_not_null(masm, dst);
  
!   __ tbz(rscratch1, ShenandoahHeap::EVACUATION_BITPOS, done);
  
    __ lsr(rscratch1, dst, ShenandoahHeapRegion::region_size_bytes_shift_jint());
    __ mov(rscratch2,  ShenandoahHeap::in_cset_fast_test_addr());
    __ ldrb(rscratch2, Address(rscratch2, rscratch1));
    __ tst(rscratch2, 0x1);
--- 55,79 ----
  
    Label done;
  
    Address gc_state(rthread, in_bytes(JavaThread::gc_state_offset()));
    __ ldrb(rscratch1, gc_state);
  
!   // Check for heap stability
!   __ mov(rscratch2, ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION);
!   __ tst(rscratch1, rscratch2);
!   __ br(Assembler::EQ, done);
  
!   // Heap is unstable, need to perform the read-barrier even if WB is inactive
!   if (ShenandoahWriteBarrierRB) {
!     __ ldr(dst, Address(dst, BrooksPointer::byte_offset()));
!   }
! 
!   // Check for evacuation-in-progress and jump to WB slow-path if needed
!   __ mov(rscratch2, ShenandoahHeap::EVACUATION);
!   __ tst(rscratch1, rscratch2);
!   __ br(Assembler::EQ, done);
  
    __ lsr(rscratch1, dst, ShenandoahHeapRegion::region_size_bytes_shift_jint());
    __ mov(rscratch2,  ShenandoahHeap::in_cset_fast_test_addr());
    __ ldrb(rscratch2, Address(rscratch2, rscratch1));
    __ tst(rscratch2, 0x1);