Java example source code file (vtableStubs_x86_64.cpp)

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Java - Java tags/keywords

codebuffer, countcompiledcalls, debugvtables, label, macroassembler, method\:\:from_compiled_offset, null, printmiscellaneous, product, register, vtablestub, vtablestub\:\:pd_code_size_limit

The vtableStubs_x86_64.cpp Java example source code

/*
 * Copyright (c) 2003, 2013, 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
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#include "precompiled.hpp"
#include "asm/macroAssembler.hpp"
#include "code/vtableStubs.hpp"
#include "interp_masm_x86.hpp"
#include "memory/resourceArea.hpp"
#include "oops/instanceKlass.hpp"
#include "oops/klassVtable.hpp"
#include "runtime/sharedRuntime.hpp"
#include "vmreg_x86.inline.hpp"
#ifdef COMPILER2
#include "opto/runtime.hpp"
#endif

// machine-dependent part of VtableStubs: create VtableStub of correct size and
// initialize its code

#define __ masm->

#ifndef PRODUCT
extern "C" void bad_compiled_vtable_index(JavaThread* thread,
                                          oop receiver,
                                          int index);
#endif

VtableStub* VtableStubs::create_vtable_stub(int vtable_index) {
  const int amd64_code_length = VtableStub::pd_code_size_limit(true);
  VtableStub* s = new(amd64_code_length) VtableStub(true, vtable_index);
  // Can be NULL if there is no free space in the code cache.
  if (s == NULL) {
    return NULL;
  }

  ResourceMark rm;
  CodeBuffer cb(s->entry_point(), amd64_code_length);
  MacroAssembler* masm = new MacroAssembler(&cb);

#ifndef PRODUCT
  if (CountCompiledCalls) {
    __ incrementl(ExternalAddress((address) SharedRuntime::nof_megamorphic_calls_addr()));
  }
#endif

  // get receiver (need to skip return address on top of stack)
  assert(VtableStub::receiver_location() == j_rarg0->as_VMReg(), "receiver expected in j_rarg0");

  // Free registers (non-args) are rax, rbx

  // get receiver klass
  address npe_addr = __ pc();
  __ load_klass(rax, j_rarg0);

#ifndef PRODUCT
  if (DebugVtables) {
    Label L;
    // check offset vs vtable length
    __ cmpl(Address(rax, InstanceKlass::vtable_length_offset() * wordSize),
            vtable_index * vtableEntry::size());
    __ jcc(Assembler::greater, L);
    __ movl(rbx, vtable_index);
    __ call_VM(noreg,
               CAST_FROM_FN_PTR(address, bad_compiled_vtable_index), j_rarg0, rbx);
    __ bind(L);
  }
#endif // PRODUCT

  // load Method* and target address
  const Register method = rbx;

  __ lookup_virtual_method(rax, vtable_index, method);

  if (DebugVtables) {
    Label L;
    __ cmpptr(method, (int32_t)NULL_WORD);
    __ jcc(Assembler::equal, L);
    __ cmpptr(Address(method, Method::from_compiled_offset()), (int32_t)NULL_WORD);
    __ jcc(Assembler::notZero, L);
    __ stop("Vtable entry is NULL");
    __ bind(L);
  }
  // rax: receiver klass
  // rbx: Method*
  // rcx: receiver
  address ame_addr = __ pc();
  __ jmp( Address(rbx, Method::from_compiled_offset()));

  __ flush();

  if (PrintMiscellaneous && (WizardMode || Verbose)) {
    tty->print_cr("vtable #%d at "PTR_FORMAT"[%d] left over: %d",
                  vtable_index, s->entry_point(),
                  (int)(s->code_end() - s->entry_point()),
                  (int)(s->code_end() - __ pc()));
  }
  guarantee(__ pc() <= s->code_end(), "overflowed buffer");
  // shut the door on sizing bugs
  int slop = 3;  // 32-bit offset is this much larger than an 8-bit one
  assert(vtable_index > 10 || __ pc() + slop <= s->code_end(), "room for 32-bit offset");

  s->set_exception_points(npe_addr, ame_addr);
  return s;
}


VtableStub* VtableStubs::create_itable_stub(int itable_index) {
  // Note well: pd_code_size_limit is the absolute minimum we can get
  // away with.  If you add code here, bump the code stub size
  // returned by pd_code_size_limit!
  const int amd64_code_length = VtableStub::pd_code_size_limit(false);
  VtableStub* s = new(amd64_code_length) VtableStub(false, itable_index);
  // Can be NULL if there is no free space in the code cache.
  if (s == NULL) {
    return NULL;
  }

  ResourceMark rm;
  CodeBuffer cb(s->entry_point(), amd64_code_length);
  MacroAssembler* masm = new MacroAssembler(&cb);

#ifndef PRODUCT
  if (CountCompiledCalls) {
    __ incrementl(ExternalAddress((address) SharedRuntime::nof_megamorphic_calls_addr()));
  }
#endif

  // Entry arguments:
  //  rax: Interface
  //  j_rarg0: Receiver

  // Free registers (non-args) are rax (interface), rbx

  // get receiver (need to skip return address on top of stack)

  assert(VtableStub::receiver_location() == j_rarg0->as_VMReg(), "receiver expected in j_rarg0");
  // get receiver klass (also an implicit null-check)
  address npe_addr = __ pc();

  // Most registers are in use; we'll use rax, rbx, r10, r11
  // (various calling sequences use r[cd]x, r[sd]i, r[89]; stay away from them)
  __ load_klass(r10, j_rarg0);

  // If we take a trap while this arg is on the stack we will not
  // be able to walk the stack properly. This is not an issue except
  // when there are mistakes in this assembly code that could generate
  // a spurious fault. Ask me how I know...

  const Register method = rbx;
  Label throw_icce;

  // Get Method* and entrypoint for compiler
  __ lookup_interface_method(// inputs: rec. class, interface, itable index
                             r10, rax, itable_index,
                             // outputs: method, scan temp. reg
                             method, r11,
                             throw_icce);

  // method (rbx): Method*
  // j_rarg0: receiver

#ifdef ASSERT
  if (DebugVtables) {
    Label L2;
    __ cmpptr(method, (int32_t)NULL_WORD);
    __ jcc(Assembler::equal, L2);
    __ cmpptr(Address(method, Method::from_compiled_offset()), (int32_t)NULL_WORD);
    __ jcc(Assembler::notZero, L2);
    __ stop("compiler entrypoint is null");
    __ bind(L2);
  }
#endif // ASSERT

  // rbx: Method*
  // j_rarg0: receiver
  address ame_addr = __ pc();
  __ jmp(Address(method, Method::from_compiled_offset()));

  __ bind(throw_icce);
  __ jump(RuntimeAddress(StubRoutines::throw_IncompatibleClassChangeError_entry()));

  __ flush();

  if (PrintMiscellaneous && (WizardMode || Verbose)) {
    tty->print_cr("itable #%d at "PTR_FORMAT"[%d] left over: %d",
                  itable_index, s->entry_point(),
                  (int)(s->code_end() - s->entry_point()),
                  (int)(s->code_end() - __ pc()));
  }
  guarantee(__ pc() <= s->code_end(), "overflowed buffer");
  // shut the door on sizing bugs
  int slop = 3;  // 32-bit offset is this much larger than an 8-bit one
  assert(itable_index > 10 || __ pc() + slop <= s->code_end(), "room for 32-bit offset");

  s->set_exception_points(npe_addr, ame_addr);
  return s;
}

int VtableStub::pd_code_size_limit(bool is_vtable_stub) {
  if (is_vtable_stub) {
    // Vtable stub size
    return (DebugVtables ? 512 : 24) + (CountCompiledCalls ? 13 : 0) +
           (UseCompressedClassPointers ?  MacroAssembler::instr_size_for_decode_klass_not_null() : 0);
  } else {
    // Itable stub size
    return (DebugVtables ? 512 : 74) + (CountCompiledCalls ? 13 : 0) +
           (UseCompressedClassPointers ?  MacroAssembler::instr_size_for_decode_klass_not_null() : 0);
  }
  // In order to tune these parameters, run the JVM with VM options
  // +PrintMiscellaneous and +WizardMode to see information about
  // actual itable stubs.  Look for lines like this:
  //   itable #1 at 0x5551212[71] left over: 3
  // Reduce the constants so that the "left over" number is >=3
  // for the common cases.
  // Do not aim at a left-over number of zero, because a
  // large vtable or itable index (>= 32) will require a 32-bit
  // immediate displacement instead of an 8-bit one.
  //
  // The JVM98 app. _202_jess has a megamorphic interface call.
  // The itable code looks like this:
  // Decoding VtableStub itbl[1]@12
  //   mov    0x8(%rsi),%r10
  //   mov    0x198(%r10),%r11d
  //   lea    0x218(%r10,%r11,8),%r11
  //   lea    0x8(%r10),%r10
  //   mov    (%r11),%rbx
  //   cmp    %rbx,%rax
  //   je     success
  // loop:
  //   test   %rbx,%rbx
  //   je     throw_icce
  //   add    $0x10,%r11
  //   mov    (%r11),%rbx
  //   cmp    %rbx,%rax
  //   jne    loop
  // success:
  //   mov    0x8(%r11),%r11d
  //   mov    (%r10,%r11,1),%rbx
  //   jmpq   *0x60(%rbx)
  // throw_icce:
  //   jmpq   throw_ICCE_entry
}

int VtableStub::pd_code_alignment() {
  return wordSize;
}