JDK14/Java14源码在线阅读

/*
 * Copyright (c) 1999, 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.
 *
 * 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
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 */

#include "precompiled.hpp"
#include "asm/macroAssembler.inline.hpp"
#include "c1/c1_MacroAssembler.hpp"
#include "c1/c1_Runtime1.hpp"
#include "classfile/systemDictionary.hpp"
#include "gc/shared/collectedHeap.hpp"
#include "interpreter/interpreter.hpp"
#include "oops/arrayOop.hpp"
#include "oops/markWord.hpp"
#include "runtime/basicLock.hpp"
#include "runtime/biasedLocking.hpp"
#include "runtime/os.hpp"
#include "runtime/sharedRuntime.hpp"
#include "runtime/stubRoutines.hpp"

void C1_MacroAssembler::inline_cache_check(Register receiver, Register iCache) {
  Label L;
  const Register temp_reg = G3_scratch;
  // Note: needs more testing of out-of-line vs. inline slow case
  verify_oop(receiver);
  load_klass(receiver, temp_reg);
  cmp_and_brx_short(temp_reg, iCache, Assembler::equal, Assembler::pt, L);
  AddressLiteral ic_miss(SharedRuntime::get_ic_miss_stub());
  jump_to(ic_miss, temp_reg);
  delayed()->nop();
  align(CodeEntryAlignment);
  bind(L);
}


void C1_MacroAssembler::explicit_null_check(Register base) {
  Unimplemented();
}


void C1_MacroAssembler::build_frame(int frame_size_in_bytes, int bang_size_in_bytes) {
  assert(bang_size_in_bytes >= frame_size_in_bytes, "stack bang size incorrect");
  generate_stack_overflow_check(bang_size_in_bytes);
  // Create the frame.
  save_frame_c1(frame_size_in_bytes);
}


void C1_MacroAssembler::verified_entry() {
  if (C1Breakpoint) {
    breakpoint_trap();
  }
}


void C1_MacroAssembler::lock_object(Register Rmark, Register Roop, Register Rbox, Register Rscratch, Label& slow_case) {
  assert_different_registers(Rmark, Roop, Rbox, Rscratch);

  Label done;

  Address mark_addr(Roop, oopDesc::mark_offset_in_bytes());

  // The following move must be the first instruction of emitted since debug
  // information may be generated for it.
  // Load object header
  ld_ptr(mark_addr, Rmark);

  verify_oop(Roop);

  // save object being locked into the BasicObjectLock
  st_ptr(Roop, Rbox, BasicObjectLock::obj_offset_in_bytes());

  if (UseBiasedLocking) {
    biased_locking_enter(Roop, Rmark, Rscratch, done, &slow_case);
  }

  // Save Rbox in Rscratch to be used for the cas operation
  mov(Rbox, Rscratch);

  // and mark it unlocked
  or3(Rmark, markWord::unlocked_value, Rmark);

  // save unlocked object header into the displaced header location on the stack
  st_ptr(Rmark, Rbox, BasicLock::displaced_header_offset_in_bytes());

  // compare object markWord with Rmark and if equal exchange Rscratch with object markWord
  assert(mark_addr.disp() == 0, "cas must take a zero displacement");
  cas_ptr(mark_addr.base(), Rmark, Rscratch);
  // if compare/exchange succeeded we found an unlocked object and we now have locked it
  // hence we are done
  cmp(Rmark, Rscratch);
  brx(Assembler::equal, false, Assembler::pt, done);
  delayed()->sub(Rscratch, SP, Rscratch);  //pull next instruction into delay slot
  // we did not find an unlocked object so see if this is a recursive case
  // sub(Rscratch, SP, Rscratch);
  assert(os::vm_page_size() > 0xfff, "page size too small - change the constant");
  andcc(Rscratch, 0xfffff003, Rscratch);
  brx(Assembler::notZero, false, Assembler::pn, slow_case);
  delayed()->st_ptr(Rscratch, Rbox, BasicLock::displaced_header_offset_in_bytes());
  bind(done);
}


void C1_MacroAssembler::unlock_object(Register Rmark, Register Roop, Register Rbox, Label& slow_case) {
  assert_different_registers(Rmark, Roop, Rbox);

  Label done;

  Address mark_addr(Roop, oopDesc::mark_offset_in_bytes());
  assert(mark_addr.disp() == 0, "cas must take a zero displacement");

  if (UseBiasedLocking) {
    // load the object out of the BasicObjectLock
    ld_ptr(Rbox, BasicObjectLock::obj_offset_in_bytes(), Roop);
    verify_oop(Roop);
    biased_locking_exit(mark_addr, Rmark, done);
  }
  // Test first it it is a fast recursive unlock
  ld_ptr(Rbox, BasicLock::displaced_header_offset_in_bytes(), Rmark);
  br_null_short(Rmark, Assembler::pt, done);
  if (!UseBiasedLocking) {
    // load object
    ld_ptr(Rbox, BasicObjectLock::obj_offset_in_bytes(), Roop);
    verify_oop(Roop);
  }

  // Check if it is still a light weight lock, this is is true if we see
  // the stack address of the basicLock in the markWord of the object
  cas_ptr(mark_addr.base(), Rbox, Rmark);
  cmp(Rbox, Rmark);

  brx(Assembler::notEqual, false, Assembler::pn, slow_case);
  delayed()->nop();
  // Done
  bind(done);
}


void C1_MacroAssembler::try_allocate(
  Register obj,                        // result: pointer to object after successful allocation
  Register var_size_in_bytes,          // object size in bytes if unknown at compile time; invalid otherwise
  int      con_size_in_bytes,          // object size in bytes if   known at compile time
  Register t1,                         // temp register, must be global register for incr_allocated_bytes
  Register t2,                         // temp register
  Label&   slow_case                   // continuation point if fast allocation fails
) {
  RegisterOrConstant size_in_bytes = var_size_in_bytes->is_valid()
    ? RegisterOrConstant(var_size_in_bytes) : RegisterOrConstant(con_size_in_bytes);
  if (UseTLAB) {
    tlab_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, slow_case);
  } else {
    eden_allocate(obj, var_size_in_bytes, con_size_in_bytes, t1, t2, slow_case);
    incr_allocated_bytes(size_in_bytes, t1, t2);
  }
}


void C1_MacroAssembler::initialize_header(Register obj, Register klass, Register len, Register t1, Register t2) {
  assert_different_registers(obj, klass, len, t1, t2);
  if (UseBiasedLocking && !len->is_valid()) {
    ld_ptr(klass, in_bytes(Klass::prototype_header_offset()), t1);
  } else {
    set((intx)markWord::prototype().value(), t1);
  }
  st_ptr(t1, obj, oopDesc::mark_offset_in_bytes());
  if (UseCompressedClassPointers) {
    // Save klass
    mov(klass, t1);
    encode_klass_not_null(t1);
    stw(t1, obj, oopDesc::klass_offset_in_bytes());
  } else {
    st_ptr(klass, obj, oopDesc::klass_offset_in_bytes());
  }
  if (len->is_valid()) {
    st(len, obj, arrayOopDesc::length_offset_in_bytes());
  } else if (UseCompressedClassPointers) {
    // otherwise length is in the class gap
    store_klass_gap(G0, obj);
  }
}


void C1_MacroAssembler::initialize_body(Register base, Register index) {
  zero_memory(base, index);
}


void C1_MacroAssembler::allocate_object(
  Register obj,                        // result: pointer to object after successful allocation
  Register t1,                         // temp register
  Register t2,                         // temp register, must be a global register for try_allocate
  Register t3,                         // temp register
  int      hdr_size,                   // object header size in words
  int      obj_size,                   // object size in words
  Register klass,                      // object klass
  Label&   slow_case                   // continuation point if fast allocation fails
) {
  assert_different_registers(obj, t1, t2, t3, klass);
  assert(klass == G5, "must be G5");

  // allocate space & initialize header
  if (!is_simm13(obj_size * wordSize)) {
    // would need to use extra register to load
    // object size => go the slow case for now
    ba(slow_case);
    delayed()->nop();
    return;
  }
  try_allocate(obj, noreg, obj_size * wordSize, t2, t3, slow_case);

  initialize_object(obj, klass, noreg, obj_size * HeapWordSize, t1, t2, /* is_tlab_allocated */ UseTLAB);
}

void C1_MacroAssembler::initialize_object(
  Register obj,                        // result: pointer to object after successful allocation
  Register klass,                      // object klass
  Register var_size_in_bytes,          // object size in bytes if unknown at compile time; invalid otherwise
  int      con_size_in_bytes,          // object size in bytes if   known at compile time
  Register t1,                         // temp register
  Register t2,                         // temp register
  bool     is_tlab_allocated           // the object was allocated in a TLAB; relevant for the implementation of ZeroTLAB
  ) {
  const int hdr_size_in_bytes = instanceOopDesc::header_size() * HeapWordSize;

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

#ifdef ASSERT
  {
    Label ok;
    ld(klass, in_bytes(Klass::layout_helper_offset()), t1);
    if (var_size_in_bytes != noreg) {
      cmp_and_brx_short(t1, var_size_in_bytes, Assembler::equal, Assembler::pt, ok);
    } else {
      cmp_and_brx_short(t1, con_size_in_bytes, Assembler::equal, Assembler::pt, ok);
    }
    stop("bad size in initialize_object");
    should_not_reach_here();

    bind(ok);
  }

#endif

  if (!(UseTLAB && ZeroTLAB && is_tlab_allocated)) {
    // initialize body
    const int threshold = 5 * HeapWordSize;              // approximate break even point for code size
    if (var_size_in_bytes != noreg) {
      // use a loop
      add(obj, hdr_size_in_bytes, t1);               // compute address of first element
      sub(var_size_in_bytes, hdr_size_in_bytes, t2); // compute size of body
      initialize_body(t1, t2);
    } else if (con_size_in_bytes <= threshold) {
      // use explicit NULL stores
      for (int i = hdr_size_in_bytes; i < con_size_in_bytes; i += HeapWordSize)     st_ptr(G0, obj, i);
    } else if (con_size_in_bytes > hdr_size_in_bytes) {
      // use a loop
      const Register base  = t1;
      const Register index = t2;
      add(obj, hdr_size_in_bytes, base);               // compute address of first element
      // compute index = number of words to clear
      set(con_size_in_bytes - hdr_size_in_bytes, index);
      initialize_body(base, index);
    }
  }

  if (CURRENT_ENV->dtrace_alloc_probes()) {
    assert(obj == O0, "must be");
    call(CAST_FROM_FN_PTR(address, Runtime1::entry_for(Runtime1::dtrace_object_alloc_id)),
         relocInfo::runtime_call_type);
    delayed()->nop();
  }

  verify_oop(obj);
}


void C1_MacroAssembler::allocate_array(
  Register obj,                        // result: pointer to array after successful allocation
  Register len,                        // array length
  Register t1,                         // temp register
  Register t2,                         // temp register
  Register t3,                         // temp register
  int      hdr_size,                   // object header size in words
  int      elt_size,                   // element size in bytes
  Register klass,                      // object klass
  Label&   slow_case                   // continuation point if fast allocation fails
) {
  assert_different_registers(obj, len, t1, t2, t3, klass);
  assert(klass == G5, "must be G5");
  assert(t1 == G1, "must be G1");

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

  // check for negative or excessive length
  // note: the maximum length allowed is chosen so that arrays of any
  //       element size with this length are always smaller or equal
  //       to the largest integer (i.e., array size computation will
  //       not overflow)
  set(max_array_allocation_length, t1);
  cmp(len, t1);
  br(Assembler::greaterUnsigned, false, Assembler::pn, slow_case);

  // compute array size
  // note: if 0 <= len <= max_length, len*elt_size + header + alignment is
  //       smaller or equal to the largest integer; also, since top is always
  //       aligned, we can do the alignment here instead of at the end address
  //       computation
  const Register arr_size = t1;
  switch (elt_size) {
    case  1: delayed()->mov(len,    arr_size); break;
    case  2: delayed()->sll(len, 1, arr_size); break;
    case  4: delayed()->sll(len, 2, arr_size); break;
    case  8: delayed()->sll(len, 3, arr_size); break;
    default: ShouldNotReachHere();
  }
  add(arr_size, hdr_size * wordSize + MinObjAlignmentInBytesMask, arr_size); // add space for header & alignment
  and3(arr_size, ~MinObjAlignmentInBytesMask, arr_size);                     // align array size

  // allocate space & initialize header
  if (UseTLAB) {
    tlab_allocate(obj, arr_size, 0, t2, slow_case);
  } else {
    eden_allocate(obj, arr_size, 0, t2, t3, slow_case);
  }
  initialize_header(obj, klass, len, t2, t3);

  // initialize body
  const Register base  = t2;
  const Register index = t3;

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