1 /*
   2  * Copyright (c) 2015, 2018, Red Hat, Inc. All rights reserved.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #include "gc_implementation/shenandoah/shenandoahBarrierSet.inline.hpp"
  25 #include "gc_implementation/shenandoah/shenandoahBrooksPointer.hpp"
  26 
  27 #include "asm/macroAssembler.hpp"
  28 #include "interpreter/interpreter.hpp"
  29 
  30 #define __ masm->
  31 
  32 #ifndef CC_INTERP
  33 void ShenandoahBarrierSet::interpreter_read_barrier(MacroAssembler* masm, Register dst) {
  34   if (ShenandoahReadBarrier) {
  35     Label is_null;
  36     __ cbz(dst, is_null);
  37     interpreter_read_barrier_not_null(masm, dst);
  38     __ bind(is_null);
  39   }
  40 }
  41 
  42 void ShenandoahBarrierSet::interpreter_read_barrier_not_null(MacroAssembler* masm, Register dst) {
  43   if (ShenandoahReadBarrier) {
  44     __ ldr(dst, Address(dst, ShenandoahBrooksPointer::byte_offset()));
  45   }
  46 }
  47 
  48 void ShenandoahBarrierSet::interpreter_write_barrier(MacroAssembler* masm, Register dst) {
  49   if (! ShenandoahWriteBarrier) {
  50     return interpreter_read_barrier(masm, dst);
  51   }
  52 
  53   assert(dst != rscratch1, "different regs");
  54   assert(dst != rscratch2, "Need rscratch2");
  55 
  56   Label done;
  57 
  58   Address gc_state(rthread, in_bytes(JavaThread::gc_state_offset()));
  59   __ ldrb(rscratch1, gc_state);
  60 
  61   // Check for heap stability
  62   __ mov(rscratch2, ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::EVACUATION);
  63   __ tst(rscratch1, rscratch2);
  64   __ br(Assembler::EQ, done);
  65 
  66   // Heap is unstable, need to perform the read-barrier even if WB is inactive
  67   __ ldr(dst, Address(dst, ShenandoahBrooksPointer::byte_offset()));
  68 
  69   // Check for evacuation-in-progress and jump to WB slow-path if needed
  70   __ mov(rscratch2, ShenandoahHeap::EVACUATION);
  71   __ tst(rscratch1, rscratch2);
  72   __ br(Assembler::EQ, done);
  73 
  74   __ lsr(rscratch1, dst, ShenandoahHeapRegion::region_size_bytes_shift_jint());
  75   __ mov(rscratch2,  ShenandoahHeap::in_cset_fast_test_addr());
  76   __ ldrb(rscratch2, Address(rscratch2, rscratch1));
  77   __ tst(rscratch2, 0x1);
  78   __ br(Assembler::EQ, done);
  79 
  80   // Save possibly live regs.
  81   RegSet live_regs = RegSet::range(r0, r4) - dst;
  82   __ push(live_regs, sp);
  83   __ strd(v0, __ pre(sp, 2 * -wordSize));
  84 
  85   // Call into runtime
  86   __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahBarrierSet::write_barrier_IRT), dst);
  87 
  88   // Move result into dst reg.
  89   __ mov(dst, r0);
  90 
  91   // Restore possibly live regs.
  92   __ ldrd(v0, __ post(sp, 2 * wordSize));
  93   __ pop(live_regs, sp);
  94 
  95   __ bind(done);
  96 }
  97 
  98 void ShenandoahHeap::compile_prepare_oop(MacroAssembler* masm, Register obj) {
  99   __ add(obj, obj, ShenandoahBrooksPointer::byte_size());
 100   __ str(obj, Address(obj, -1 * HeapWordSize));
 101 }
 102 
 103 void ShenandoahBarrierSet::asm_acmp_barrier(MacroAssembler* masm,
 104                                             Register op1, Register op2) {
 105   assert(UseShenandoahGC, "Should be enabled");
 106   if (ShenandoahAcmpBarrier) {
 107     Label done;
 108     __ br(Assembler::EQ, done);
 109     // The object may have been evacuated, but we won't see it without a
 110     // membar here.
 111     __ membar(Assembler::LoadStore|Assembler::LoadLoad);
 112     interpreter_read_barrier(masm, op1);
 113     interpreter_read_barrier(masm, op2);
 114     __ cmp(op1, op2);
 115     __ bind(done);
 116   }
 117 }
 118 
 119 #endif