/*

 * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.

 *

 * 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.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled.hpp"

#include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"

#include "gc/shenandoah/shenandoahForwarding.hpp"

#include "gc/shenandoah/shenandoahHeap.hpp"

#include "gc/shenandoah/shenandoahHeapRegion.hpp"

#include "gc/shenandoah/shenandoahHeuristics.hpp"

#include "gc/shenandoah/shenandoahRuntime.hpp"

#include "gc/shenandoah/shenandoahThreadLocalData.hpp"

#include "interpreter/interpreter.hpp"

#include "interpreter/interp_masm.hpp"

#include "runtime/sharedRuntime.hpp"

#include "runtime/thread.hpp"

#ifdef COMPILER1

#include "c1/c1_LIRAssembler.hpp"

#include "c1/c1_MacroAssembler.hpp"

#include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"

#endif

#define __ masm->

address ShenandoahBarrierSetAssembler::_shenandoah_lrb = NULL;

void ShenandoahBarrierSetAssembler::arraycopy_prologue(MacroAssembler* masm, DecoratorSet decorators, bool is_oop,

                                                       Register src, Register dst, Register count, RegSet saved_regs) {

  if (is_oop) {

    bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;

    if (ShenandoahSATBBarrier && !dest_uninitialized) {

      Label done;

      // Avoid calling runtime if count == 0

      __ cbz(count, done);

      // Is marking active?

      Address gc_state(rthread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));

      __ ldrb(rscratch1, gc_state);

      __ tbz(rscratch1, ShenandoahHeap::MARKING_BITPOS, done);

      __ push(saved_regs, sp);

      if (count == c_rarg0) {

        if (dst == c_rarg1) {

          // exactly backwards!!

          __ mov(rscratch1, c_rarg0);

          __ mov(c_rarg0, c_rarg1);

          __ mov(c_rarg1, rscratch1);

        } else {

          __ mov(c_rarg1, count);

          __ mov(c_rarg0, dst);

        }

      } else {

        __ mov(c_rarg0, dst);

        __ mov(c_rarg1, count);

      }

      if (UseCompressedOops) {

        __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_pre_narrow_oop_entry), 2);

      } else {

        __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_pre_oop_entry), 2);

      }

      __ pop(saved_regs, sp);

      __ bind(done);

    }

  }

}

void ShenandoahBarrierSetAssembler::arraycopy_epilogue(MacroAssembler* masm, DecoratorSet decorators, bool is_oop,

                                                       Register start, Register count, Register scratch, RegSet saved_regs) {

  if (is_oop) {

      Label done;

      // Avoid calling runtime if count == 0

      __ cbz(count, done);

      // Is updating references?

      Address gc_state(rthread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));

      __ ldrb(rscratch1, gc_state);

      __ tbz(rscratch1, ShenandoahHeap::UPDATEREFS_BITPOS, done);

    __ push(saved_regs, sp);

    assert_different_registers(start, count, scratch);

    assert_different_registers(c_rarg0, count);

    __ mov(c_rarg0, start);

    __ mov(c_rarg1, count);

    __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_array_post_entry), 2);

    __ pop(saved_regs, sp);

    __ bind(done);

  }

}

void ShenandoahBarrierSetAssembler::shenandoah_write_barrier_pre(MacroAssembler* masm,

                                                                 Register obj,

                                                                 Register pre_val,

                                                                 Register thread,

                                                                 Register tmp,

                                                                 bool tosca_live,

                                                                 bool expand_call) {

  if (ShenandoahSATBBarrier) {

    satb_write_barrier_pre(masm, obj, pre_val, thread, tmp, tosca_live, expand_call);

  }

}

void ShenandoahBarrierSetAssembler::satb_write_barrier_pre(MacroAssembler* masm,

                                                           Register obj,

                                                           Register pre_val,

                                                           Register thread,

                                                           Register tmp,

                                                           bool tosca_live,

                                                           bool expand_call) {

  // If expand_call is true then we expand the call_VM_leaf macro

  // directly to skip generating the check by

  // InterpreterMacroAssembler::call_VM_leaf_base that checks _last_sp.

  assert(thread == rthread, "must be");

  Label done;

  Label runtime;

  assert_different_registers(obj, pre_val, tmp, rscratch1);

  assert(pre_val != noreg &&  tmp != noreg, "expecting a register");

  Address in_progress(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_active_offset()));

  Address index(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));

  Address buffer(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));

  // Is marking active?

  if (in_bytes(SATBMarkQueue::byte_width_of_active()) == 4) {

    __ ldrw(tmp, in_progress);

  } else {

    assert(in_bytes(SATBMarkQueue::byte_width_of_active()) == 1, "Assumption");

    __ ldrb(tmp, in_progress);

  }

  __ cbzw(tmp, done);

  // Do we need to load the previous value?

  if (obj != noreg) {

    __ load_heap_oop(pre_val, Address(obj, 0), noreg, noreg, AS_RAW);

  }

  // Is the previous value null?

  __ cbz(pre_val, done);

  // Can we store original value in the thread's buffer?

  // Is index == 0?

  // (The index field is typed as size_t.)

  __ ldr(tmp, index);                      // tmp := *index_adr

  __ cbz(tmp, runtime);                    // tmp == 0?

                                        // If yes, goto runtime

  __ sub(tmp, tmp, wordSize);              // tmp := tmp - wordSize

  __ str(tmp, index);                      // *index_adr := tmp

  __ ldr(rscratch1, buffer);

  __ add(tmp, tmp, rscratch1);             // tmp := tmp + *buffer_adr

  // Record the previous value

  __ str(pre_val, Address(tmp, 0));

  __ b(done);

  __ bind(runtime);

  // save the live input values

  RegSet saved = RegSet::of(pre_val);

  if (tosca_live) saved += RegSet::of(r0);

  if (obj != noreg) saved += RegSet::of(obj);

  __ push(saved, sp);

  // Calling the runtime using the regular call_VM_leaf mechanism generates

  // code (generated by InterpreterMacroAssember::call_VM_leaf_base)

  // that checks that the *(rfp+frame::interpreter_frame_last_sp) == NULL.

  //

  // If we care generating the pre-barrier without a frame (e.g. in the

  // intrinsified Reference.get() routine) then ebp might be pointing to

  // the caller frame and so this check will most likely fail at runtime.

  //

  // Expanding the call directly bypasses the generation of the check.

  // So when we do not have have a full interpreter frame on the stack

  // expand_call should be passed true.

  if (expand_call) {

    assert(pre_val != c_rarg1, "smashed arg");

    __ super_call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), pre_val, thread);

  } else {

    __ call_VM_leaf(CAST_FROM_FN_PTR(address, ShenandoahRuntime::write_ref_field_pre_entry), pre_val, thread);

  }

  __ pop(saved, sp);

  __ bind(done);

}

void ShenandoahBarrierSetAssembler::resolve_forward_pointer(MacroAssembler* masm, Register dst, Register tmp) {

  assert(ShenandoahLoadRefBarrier || ShenandoahCASBarrier, "Should be enabled");

  Label is_null;

  __ cbz(dst, is_null);

  resolve_forward_pointer_not_null(masm, dst, tmp);

  __ bind(is_null);

}

// IMPORTANT: This must preserve all registers, even rscratch1 and rscratch2, except those explicitely

// passed in.

void ShenandoahBarrierSetAssembler::resolve_forward_pointer_not_null(MacroAssembler* masm, Register dst, Register tmp) {

  assert(ShenandoahLoadRefBarrier || ShenandoahCASBarrier, "Should be enabled");

  // The below loads the mark word, checks if the lowest two bits are

  // set, and if so, clear the lowest two bits and copy the result

  // to dst. Otherwise it leaves dst alone.

  // Implementing this is surprisingly awkward. I do it here by:

  // - Inverting the mark word

  // - Test lowest two bits == 0

  // - If so, set the lowest two bits

  // - Invert the result back, and copy to dst

  bool borrow_reg = (tmp == noreg);

  if (borrow_reg) {

    // No free registers available. Make one useful.

    tmp = rscratch1;

    __ push(RegSet::of(tmp), sp);

  }

  Label done;

  __ ldr(tmp, Address(dst, oopDesc::mark_offset_in_bytes()));

  __ eon(tmp, tmp, zr);

  __ ands(zr, tmp, markOopDesc::lock_mask_in_place);

  __ br(Assembler::NE, done);

  __ orr(tmp, tmp, markOopDesc::marked_value);

  __ eon(dst, tmp, zr);

  __ bind(done);

  if (borrow_reg) {

    __ pop(RegSet::of(tmp), sp);

  }

}

void ShenandoahBarrierSetAssembler::load_reference_barrier_not_null(MacroAssembler* masm, Register dst, Register tmp) {

  assert(ShenandoahLoadRefBarrier, "Should be enabled");

  assert(dst != rscratch2, "need rscratch2");

  Label done;

  __ enter();

  Address gc_state(rthread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));

  __ ldrb(rscratch2, gc_state);

  // Check for heap stability

  __ tbz(rscratch2, ShenandoahHeap::HAS_FORWARDED_BITPOS, done);

  RegSet to_save = RegSet::of(r0);

  if (dst != r0) {

    __ push(to_save, sp);

    __ mov(r0, dst);

  }

  __ far_call(RuntimeAddress(CAST_FROM_FN_PTR(address, ShenandoahBarrierSetAssembler::shenandoah_lrb())));

  if (dst != r0) {

    __ mov(dst, r0);

    __ pop(to_save, sp);

  }

  __ bind(done);

  __ leave();

}

void ShenandoahBarrierSetAssembler::storeval_barrier(MacroAssembler* masm, Register dst, Register tmp) {

  if (ShenandoahStoreValEnqueueBarrier) {

    // Save possibly live regs.

    RegSet live_regs = RegSet::range(r0, r4) - dst;

    __ push(live_regs, sp);

    __ strd(v0, __ pre(sp, 2 * -wordSize));

    satb_write_barrier_pre(masm, noreg, dst, rthread, tmp, true, false);

    // Restore possibly live regs.

    __ ldrd(v0, __ post(sp, 2 * wordSize));

    __ pop(live_regs, sp);

  }

}

void ShenandoahBarrierSetAssembler::load_reference_barrier(MacroAssembler* masm, Register dst, Register tmp) {

  if (ShenandoahLoadRefBarrier) {

    Label is_null;

    __ cbz(dst, is_null);

    load_reference_barrier_not_null(masm, dst, tmp);

    __ bind(is_null);

  }

}

void ShenandoahBarrierSetAssembler::load_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,

                                            Register dst, Address src, Register tmp1, Register tmp_thread) {

  bool on_oop = type == T_OBJECT || type == T_ARRAY;

  bool on_weak = (decorators & ON_WEAK_OOP_REF) != 0;

  bool on_phantom = (decorators & ON_PHANTOM_OOP_REF) != 0;

  bool on_reference = on_weak || on_phantom;

  BarrierSetAssembler::load_at(masm, decorators, type, dst, src, tmp1, tmp_thread);

  if (on_oop) {

    load_reference_barrier(masm, dst, tmp1);

    if (ShenandoahKeepAliveBarrier && on_reference) {

      __ enter();

      satb_write_barrier_pre(masm /* masm */,

                             noreg /* obj */,

                             dst /* pre_val */,

                             rthread /* thread */,

                             tmp1 /* tmp */,

                             true /* tosca_live */,

                             true /* expand_call */);

      __ leave();

    }

  }

}

void ShenandoahBarrierSetAssembler::store_at(MacroAssembler* masm, DecoratorSet decorators, BasicType type,

                                             Address dst, Register val, Register tmp1, Register tmp2) {

  bool on_oop = type == T_OBJECT || type == T_ARRAY;

  if (!on_oop) {

    BarrierSetAssembler::store_at(masm, decorators, type, dst, val, tmp1, tmp2);

    return;

  }

  // flatten object address if needed

  if (dst.index() == noreg && dst.offset() == 0) {

    if (dst.base() != r3) {

      __ mov(r3, dst.base());

    }

  } else {

    __ lea(r3, dst);

  }

  shenandoah_write_barrier_pre(masm,

                               r3 /* obj */,

                               tmp2 /* pre_val */,

                               rthread /* thread */,

                               tmp1  /* tmp */,

                               val != noreg /* tosca_live */,

                               false /* expand_call */);

  if (val == noreg) {

    BarrierSetAssembler::store_at(masm, decorators, type, Address(r3, 0), noreg, noreg, noreg);

  } else {

    storeval_barrier(masm, val, tmp1);

    // G1 barrier needs uncompressed oop for region cross check.

    Register new_val = val;

    if (UseCompressedOops) {

      new_val = rscratch2;

      __ mov(new_val, val);

    }

    BarrierSetAssembler::store_at(masm, decorators, type, Address(r3, 0), val, noreg, noreg);

  }

}

void ShenandoahBarrierSetAssembler::cmpxchg_oop(MacroAssembler* masm, Register addr, Register expected, Register new_val,

                                                bool acquire, bool release, bool weak, bool is_cae,

                                                Register result) {

  Register tmp1 = rscratch1;

  Register tmp2 = rscratch2;

  bool is_narrow = UseCompressedOops;

  Assembler::operand_size size = is_narrow ? Assembler::word : Assembler::xword;

  assert_different_registers(addr, expected, new_val, tmp1, tmp2);

  Label retry, done, fail;

  // CAS, using LL/SC pair.

  __ bind(retry);

  __ load_exclusive(tmp1, addr, size, acquire);

  if (is_narrow) {

    __ cmpw(tmp1, expected);

  } else {

    __ cmp(tmp1, expected);

  }

  __ br(Assembler::NE, fail);

  __ store_exclusive(tmp2, new_val, addr, size, release);

  if (weak) {

    __ cmpw(tmp2, 0u); // If the store fails, return NE to our caller

  } else {

    __ cbnzw(tmp2, retry);

  }

  __ b(done);

 __  bind(fail);

  // Check if rb(expected)==rb(tmp1)

  // Shuffle registers so that we have memory value ready for next expected.

  __ mov(tmp2, expected);

  __ mov(expected, tmp1);

  if (is_narrow) {

    __ decode_heap_oop(tmp1, tmp1);

    __ decode_heap_oop(tmp2, tmp2);

  }

  resolve_forward_pointer(masm, tmp1);

  resolve_forward_pointer(masm, tmp2);

  __ cmp(tmp1, tmp2);

  // Retry with expected now being the value we just loaded from addr.

  __ br(Assembler::EQ, retry);

  if (is_cae && is_narrow) {

    // For cmp-and-exchange and narrow oops, we need to restore

    // the compressed old-value. We moved it to 'expected' a few lines up.

    __ mov(tmp1, expected);

  }

  __ bind(done);

  if (is_cae) {

    __ mov(result, tmp1);

  } else {

    __ cset(result, Assembler::EQ);

  }

}

#undef __

#ifdef COMPILER1

#define __ ce->masm()->

void ShenandoahBarrierSetAssembler::gen_pre_barrier_stub(LIR_Assembler* ce, ShenandoahPreBarrierStub* stub) {

  ShenandoahBarrierSetC1* bs = (ShenandoahBarrierSetC1*)BarrierSet::barrier_set()->barrier_set_c1();

  // At this point we know that marking is in progress.

  // If do_load() is true then we have to emit the

  // load of the previous value; otherwise it has already

  // been loaded into _pre_val.

  __ bind(*stub->entry());

  assert(stub->pre_val()->is_register(), "Precondition.");

  Register pre_val_reg = stub->pre_val()->as_register();

  if (stub->do_load()) {

    ce->mem2reg(stub->addr(), stub->pre_val(), T_OBJECT, stub->patch_code(), stub->info(), false /*wide*/, false /*unaligned*/);

  }

  __ cbz(pre_val_reg, *stub->continuation());

  ce->store_parameter(stub->pre_val()->as_register(), 0);

  __ far_call(RuntimeAddress(bs->pre_barrier_c1_runtime_code_blob()->code_begin()));

  __ b(*stub->continuation());

}

void ShenandoahBarrierSetAssembler::gen_load_reference_barrier_stub(LIR_Assembler* ce, ShenandoahLoadReferenceBarrierStub* stub) {

  Register obj = stub->obj()->as_register();

  Register res = stub->result()->as_register();

  Label done;

  __ bind(*stub->entry());

  if (res != obj) {

    __ mov(res, obj);

  }

  // Check for null.

  if (stub->needs_null_check()) {

    __ cbz(res, done);

  }

  load_reference_barrier_not_null(ce->masm(), res, rscratch1);

  __ bind(done);

  __ b(*stub->continuation());

}

#undef __

#define __ sasm->

void ShenandoahBarrierSetAssembler::generate_c1_pre_barrier_runtime_stub(StubAssembler* sasm) {

  __ prologue("shenandoah_pre_barrier", false);

  // arg0 : previous value of memory

  BarrierSet* bs = BarrierSet::barrier_set();

  const Register pre_val = r0;

  const Register thread = rthread;

  const Register tmp = rscratch1;

  Address queue_index(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_index_offset()));

  Address buffer(thread, in_bytes(ShenandoahThreadLocalData::satb_mark_queue_buffer_offset()));

  Label done;

  Label runtime;

  // Is marking still active?

  Address gc_state(thread, in_bytes(ShenandoahThreadLocalData::gc_state_offset()));

  __ ldrb(tmp, gc_state);

  __ mov(rscratch2, ShenandoahHeap::MARKING | ShenandoahHeap::TRAVERSAL);

  __ tst(tmp, rscratch2);

  __ br(Assembler::EQ, done);

  // Can we store original value in the thread's buffer?

  __ ldr(tmp, queue_index);

  __ cbz(tmp, runtime);