src/hotspot/cpu/aarch64/c1_MacroAssembler_aarch64.cpp

/*
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 * Copyright (c) 2014, 2021, Red Hat Inc. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
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 * 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.
 *
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#include "c1/c1_MacroAssembler.hpp"
#include "c1/c1_Runtime1.hpp"
#include "gc/shared/barrierSetAssembler.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "gc/shared/tlab_globals.hpp"
#include "interpreter/interpreter.hpp"
#include "oops/arrayOop.hpp"
#include "oops/markWord.hpp"
#include "runtime/basicLock.hpp"
#include "runtime/os.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/stubRoutines.hpp"

void C1_MacroAssembler::float_cmp(bool is_float, int unordered_result,
                                  FloatRegister f0, FloatRegister f1,
                                  Register result)
{
  Label done;
  if (is_float) {
    fcmps(f0, f1);
  } else {
    fcmpd(f0, f1);
  }
  if (unordered_result < 0) {
    // we want -1 for unordered or less than, 0 for equal and 1 for
    // greater than.
    cset(result, NE);  // Not equal or unordered
    cneg(result, result, LT);  // Less than or unordered
  } else {
    // we want -1 for less than, 0 for equal and 1 for unordered or
    // greater than.
    cset(result, NE);  // Not equal or unordered
    cneg(result, result, LO);  // Less than
  }
}

int C1_MacroAssembler::lock_object(Register hdr, Register obj, Register disp_hdr, Register temp, Label& slow_case) {
  const int aligned_mask = BytesPerWord -1;
  const int hdr_offset = oopDesc::mark_offset_in_bytes();
  assert_different_registers(hdr, obj, disp_hdr, temp, rscratch2);
  int null_check_offset = -1;

  verify_oop(obj);

  // save object being locked into the BasicObjectLock
  str(obj, Address(disp_hdr, BasicObjectLock::obj_offset()));

  null_check_offset = offset();

  if (LockingMode == LM_LIGHTWEIGHT) {
    lightweight_lock(disp_hdr, obj, hdr, temp, rscratch2, slow_case);
  } else if (LockingMode == LM_LEGACY) {

    if (DiagnoseSyncOnValueBasedClasses != 0) {
      load_klass(hdr, obj);
      ldrb(hdr, Address(hdr, Klass::misc_flags_offset()));
      tst(hdr, KlassFlags::_misc_is_value_based_class);
      br(Assembler::NE, slow_case);
    }

    Label done;
    // Load object header
    ldr(hdr, Address(obj, hdr_offset));
    // and mark it as unlocked
    orr(hdr, hdr, markWord::unlocked_value);
    // save unlocked object header into the displaced header location on the stack
    str(hdr, Address(disp_hdr, 0));
    // test if object header is still the same (i.e. unlocked), and if so, store the
    // displaced header address in the object header - if it is not the same, get the
    // object header instead
    lea(rscratch2, Address(obj, hdr_offset));
    cmpxchgptr(hdr, disp_hdr, rscratch2, rscratch1, done, /*fallthough*/nullptr);
    // if the object header was the same, we're done
    // if the object header was not the same, it is now in the hdr register
    // => test if it is a stack pointer into the same stack (recursive locking), i.e.:
    //
    // 1) (hdr & aligned_mask) == 0
    // 2) sp <= hdr
    // 3) hdr <= sp + page_size
    //
    // these 3 tests can be done by evaluating the following expression:
    //
    // (hdr - sp) & (aligned_mask - page_size)
    //
    // assuming both the stack pointer and page_size have their least
    // significant 2 bits cleared and page_size is a power of 2
    mov(rscratch1, sp);
    sub(hdr, hdr, rscratch1);
    ands(hdr, hdr, aligned_mask - (int)os::vm_page_size());
    // for recursive locking, the result is zero => save it in the displaced header
    // location (null in the displaced hdr location indicates recursive locking)
    str(hdr, Address(disp_hdr, 0));
    // otherwise we don't care about the result and handle locking via runtime call
    cbnz(hdr, slow_case);
    // done
    bind(done);
    inc_held_monitor_count(rscratch1);
  }
  return null_check_offset;
}


void C1_MacroAssembler::unlock_object(Register hdr, Register obj, Register disp_hdr, Register temp, Label& slow_case) {
  const int aligned_mask = BytesPerWord -1;
  const int hdr_offset = oopDesc::mark_offset_in_bytes();
  assert_different_registers(hdr, obj, disp_hdr, temp, rscratch2);
  Label done;

  if (LockingMode != LM_LIGHTWEIGHT) {
    // load displaced header
    ldr(hdr, Address(disp_hdr, 0));
    // if the loaded hdr is null we had recursive locking
    // if we had recursive locking, we are done
    cbz(hdr, done);
  }

  // load object
  ldr(obj, Address(disp_hdr, BasicObjectLock::obj_offset()));
  verify_oop(obj);

  if (LockingMode == LM_LIGHTWEIGHT) {
    lightweight_unlock(obj, hdr, temp, rscratch2, slow_case);
  } else if (LockingMode == LM_LEGACY) {
    // test if object header is pointing to the displaced header, and if so, restore
    // the displaced header in the object - if the object header is not pointing to
    // the displaced header, get the object header instead
    // if the object header was not pointing to the displaced header,
    // we do unlocking via runtime call
    if (hdr_offset) {
      lea(rscratch1, Address(obj, hdr_offset));
      cmpxchgptr(disp_hdr, hdr, rscratch1, rscratch2, done, &slow_case);
    } else {
      cmpxchgptr(disp_hdr, hdr, obj, rscratch2, done, &slow_case);
    }
    // done
    bind(done);
    dec_held_monitor_count(rscratch1);
  }
}


// Defines obj, preserves var_size_in_bytes
void C1_MacroAssembler::try_allocate(Register obj, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, Label& slow_case) {
  if (UseTLAB) {
    tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
  } else {
    b(slow_case);
  }
}

void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
  assert_different_registers(obj, klass, len);

  if (UseCompactObjectHeaders) {
    ldr(t1, Address(klass, Klass::prototype_header_offset()));
    str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
  } else {
    mov(t1, checked_cast<int32_t>(markWord::prototype().value()));
    str(t1, Address(obj, oopDesc::mark_offset_in_bytes()));
    if (UseCompressedClassPointers) { // Take care not to kill klass
      encode_klass_not_null(t1, klass);
      strw(t1, Address(obj, oopDesc::klass_offset_in_bytes()));
    } else {
      str(klass, Address(obj, oopDesc::klass_offset_in_bytes()));
    }
  }

  if (len->is_valid()) {
    strw(len, Address(obj, arrayOopDesc::length_offset_in_bytes()));
    int base_offset = arrayOopDesc::length_offset_in_bytes() + BytesPerInt;
    if (!is_aligned(base_offset, BytesPerWord)) {
      assert(is_aligned(base_offset, BytesPerInt), "must be 4-byte aligned");
      // Clear gap/first 4 bytes following the length field.
      strw(zr, Address(obj, base_offset));
    }
  } else if (UseCompressedClassPointers && !UseCompactObjectHeaders) {
    store_klass_gap(obj, zr);
  }
}

// preserves obj, destroys len_in_bytes
//
// Scratch registers: t1 = r10, t2 = r11
//
void C1_MacroAssembler::initialize_body(Register obj, Register len_in_bytes, int hdr_size_in_bytes, Register t1, Register t2) {
  assert(hdr_size_in_bytes >= 0, "header size must be positive or 0");
  assert(t1 == r10 && t2 == r11, "must be");

  Label done;

  // len_in_bytes is positive and ptr sized
  subs(len_in_bytes, len_in_bytes, hdr_size_in_bytes);
  br(Assembler::EQ, done);

  // zero_words() takes ptr in r10 and count in words in r11
  mov(rscratch1, len_in_bytes);
  lea(t1, Address(obj, hdr_size_in_bytes));
  lsr(t2, rscratch1, LogBytesPerWord);
  address tpc = zero_words(t1, t2);

  bind(done);
  if (tpc == nullptr) {
    Compilation::current()->bailout("no space for trampoline stub");
  }
}


void C1_MacroAssembler::allocate_object(Register obj, Register t1, Register t2, int header_size, int object_size, Register klass, Label& slow_case) {
  assert_different_registers(obj, t1, t2); // XXX really?
  assert(header_size >= 0 && object_size >= header_size, "illegal sizes");

  try_allocate(obj, noreg, object_size * BytesPerWord, t1, t2, slow_case);

  initialize_object(obj, klass, noreg, object_size * HeapWordSize, t1, t2, UseTLAB);
}

// Scratch registers: t1 = r10, t2 = r11
void C1_MacroAssembler::initialize_object(Register obj, Register klass, Register var_size_in_bytes, int con_size_in_bytes, Register t1, Register t2, bool is_tlab_allocated) {
  assert((con_size_in_bytes & MinObjAlignmentInBytesMask) == 0,
         "con_size_in_bytes is not multiple of alignment");
  const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;

  initialize_header(obj, klass, noreg, t1, t2);

  if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
     // clear rest of allocated space
     const Register index = t2;
     if (var_size_in_bytes != noreg) {
       mov(index, var_size_in_bytes);
       initialize_body(obj, index, hdr_size_in_bytes, t1, t2);
       if (Compilation::current()->bailed_out()) {
         return;
       }
     } else if (con_size_in_bytes > hdr_size_in_bytes) {
       con_size_in_bytes -= hdr_size_in_bytes;
       lea(t1, Address(obj, hdr_size_in_bytes));
       address tpc = zero_words(t1, con_size_in_bytes / BytesPerWord);
       if (tpc == nullptr) {
         Compilation::current()->bailout("no space for trampoline stub");
         return;
       }
     }
  }

  membar(StoreStore);

  if (CURRENT_ENV->dtrace_alloc_probes()) {
    assert(obj == r0, "must be");
    far_call(RuntimeAddress(Runtime1::entry_for(C1StubId::dtrace_object_alloc_id)));
  }

  verify_oop(obj);
}
void C1_MacroAssembler::allocate_array(Register obj, Register len, Register t1, Register t2, int base_offset_in_bytes, int f, Register klass, Label& slow_case, bool zero_array) {
  assert_different_registers(obj, len, t1, t2, klass);

  // determine alignment mask
  assert(!(BytesPerWord & 1), "must be a multiple of 2 for masking code to work");

  // check for negative or excessive length
  mov(rscratch1, (int32_t)max_array_allocation_length);
  cmp(len, rscratch1);
  br(Assembler::HS, slow_case);

  const Register arr_size = t2; // okay to be the same
  // align object end
  mov(arr_size, (int32_t)base_offset_in_bytes + MinObjAlignmentInBytesMask);
  add(arr_size, arr_size, len, ext::uxtw, f);
  andr(arr_size, arr_size, ~MinObjAlignmentInBytesMask);

  try_allocate(obj, arr_size, 0, t1, t2, slow_case);

  initialize_header(obj, klass, len, t1, t2);

  // Align-up to word boundary, because we clear the 4 bytes potentially
  // following the length field in initialize_header().
  int base_offset = align_up(base_offset_in_bytes, BytesPerWord);
  // clear rest of allocated space
  if (zero_array) {
    initialize_body(obj, arr_size, base_offset, t1, t2);
  }
  if (Compilation::current()->bailed_out()) {
    return;
  }

  membar(StoreStore);

  if (CURRENT_ENV->dtrace_alloc_probes()) {
    assert(obj == r0, "must be");
    far_call(RuntimeAddress(Runtime1::entry_for(C1StubId::dtrace_object_alloc_id)));
  }

  verify_oop(obj);
}

void C1_MacroAssembler::build_frame(int framesize, int bang_size_in_bytes) {
  assert(bang_size_in_bytes >= framesize, "stack bang size incorrect");
  // Make sure there is enough stack space for this method's activation.
  // Note that we do this before creating a frame.
  generate_stack_overflow_check(bang_size_in_bytes);
  MacroAssembler::build_frame(framesize);

  // Insert nmethod entry barrier into frame.
  BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();
  bs->nmethod_entry_barrier(this, nullptr /* slow_path */, nullptr /* continuation */, nullptr /* guard */);
}

void C1_MacroAssembler::remove_frame(int framesize) {
  MacroAssembler::remove_frame(framesize);
}


void C1_MacroAssembler::verified_entry(bool breakAtEntry) {
  // If we have to make this method not-entrant we'll overwrite its
  // first instruction with a jump.  For this action to be legal we
  // must ensure that this first instruction is a B, BL, NOP, BKPT,
  // SVC, HVC, or SMC.  Make it a NOP.
  nop();
}

void C1_MacroAssembler::load_parameter(int offset_in_words, Register reg) {
  // rfp, + 0: link
  //     + 1: return address
  //     + 2: argument with offset 0
  //     + 3: argument with offset 1
  //     + 4: ...

  ldr(reg, Address(rfp, (offset_in_words + 2) * BytesPerWord));
}

#ifndef PRODUCT

void C1_MacroAssembler::verify_stack_oop(int stack_offset) {
  if (!VerifyOops) return;
  verify_oop_addr(Address(sp, stack_offset));
}

void C1_MacroAssembler::verify_not_null_oop(Register r) {
  if (!VerifyOops) return;
  Label not_null;
  cbnz(r, not_null);
  stop("non-null oop required");
  bind(not_null);
  verify_oop(r);
}

void C1_MacroAssembler::invalidate_registers(bool inv_r0, bool inv_r19, bool inv_r2, bool inv_r3, bool inv_r4, bool inv_r5) {
#ifdef ASSERT
  static int nn;
  if (inv_r0) mov(r0, 0xDEAD);
  if (inv_r19) mov(r19, 0xDEAD);
  if (inv_r2) mov(r2, nn++);
  if (inv_r3) mov(r3, 0xDEAD);
  if (inv_r4) mov(r4, 0xDEAD);
  if (inv_r5) mov(r5, 0xDEAD);
#endif
}
#endif // ifndef PRODUCT