Quelle vtableStubs_x86_64.cpp Sprache: C

/*
* Copyright (c) 2003, 2021, 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/compiledICHolder.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) {
  // Read "A word on VtableStub sizing" in share/code/vtableStubs.hpp for details on stub sizing.
  const int stub_code_length = code_size_limit(true);
  VtableStub* s = new(stub_code_length) VtableStub(true, vtable_index);
  // Can be NULL if there is no free space in the code cache.
  if (s == NULL) {
    return NULL;
  }

  // Count unused bytes in instruction sequences of variable size.
  // We add them to the computed buffer size in order to avoid
  // overflow in subsequently generated stubs.
  address   start_pc;
  int       slop_bytes = 0;
  int       slop_delta = 0;
  // No variance was detected in vtable stub sizes. Setting index_dependent_slop == 0 will unveil any deviation from this observation.
  const int index_dependent_slop     = 0;

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

#if (!defined(PRODUCT) && defined(COMPILER2))
  if (CountCompiledCalls) {
    __ incrementq(ExternalAddress(SharedRuntime::nof_megamorphic_calls_addr()), rscratch1);
  }
#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, rscratch1);

#ifndef PRODUCT
  if (DebugVtables) {
    Label L;
    start_pc = __ pc();
    // check offset vs vtable length
    __ cmpl(Address(rax, Klass::vtable_length_offset()), vtable_index*vtableEntry::size());
    slop_delta  = 12 - (__ pc() - start_pc);  // cmpl varies in length, depending on data
    slop_bytes += slop_delta;
    assert(slop_delta >= 0, "negative slop(%d) encountered, adjust code size estimate!", slop_delta);

    __ jcc(Assembler::greater, L);
    __ movl(rbx, vtable_index);
    // VTABLE TODO: find upper bound for call_VM length.
    start_pc = __ pc();
    __ call_VM(noreg, CAST_FROM_FN_PTR(address, bad_compiled_vtable_index), j_rarg0, rbx);
    slop_delta  = 550 - (__ pc() - start_pc);
    slop_bytes += slop_delta;
    assert(slop_delta >= 0, "negative slop(%d) encountered, adjust code size estimate!", slop_delta);
    __ bind(L);
  }
#endif // PRODUCT

  const Register method = rbx;

  // load Method* and target address
  start_pc = __ pc();
  __ lookup_virtual_method(rax, vtable_index, method);
  slop_delta  = 8 - (int)(__ pc() - start_pc);
  slop_bytes += slop_delta;
  assert(slop_delta >= 0, "negative slop(%d) encountered, adjust code size estimate!", slop_delta);

#ifndef PRODUCT
  if (DebugVtables) {
    Label L;
    __ cmpptr(method, NULL_WORD);
    __ jcc(Assembler::equal, L);
    __ cmpptr(Address(method, Method::from_compiled_offset()), NULL_WORD);
    __ jcc(Assembler::notZero, L);
    __ stop("Vtable entry is NULL");
    __ bind(L);
  }
#endif // PRODUCT

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

  masm->flush();
  slop_bytes += index_dependent_slop; // add'l slop for size variance due to large itable offsets
  bookkeeping(masm, tty, s, npe_addr, ame_addr, true, vtable_index, slop_bytes, index_dependent_slop);

  return s;
}

VtableStub* VtableStubs::create_itable_stub(int itable_index) {
  // Read "A word on VtableStub sizing" in share/code/vtableStubs.hpp for details on stub sizing.
  const int stub_code_length = code_size_limit(false);
  VtableStub* s = new(stub_code_length) VtableStub(false, itable_index);
  // Can be NULL if there is no free space in the code cache.
  if (s == NULL) {
    return NULL;
  }

  // Count unused bytes in instruction sequences of variable size.
  // We add them to the computed buffer size in order to avoid
  // overflow in subsequently generated stubs.
  address   start_pc;
  int       slop_bytes = 0;
  int       slop_delta = 0;
  const int index_dependent_slop = (itable_index == 0) ? 4 :     // code size change with transition from 8-bit to 32-bit constant (@index == 16).
                                   (itable_index < 16) ? 3 : 0;  // index == 0 generates even shorter code.

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

#if (!defined(PRODUCT) && defined(COMPILER2))
  if (CountCompiledCalls) {
    __ incrementq(ExternalAddress(SharedRuntime::nof_megamorphic_calls_addr()), rscratch1);
  }
#endif // PRODUCT

  // Entry arguments:
  //  rax: CompiledICHolder
  //  j_rarg0: Receiver

  // 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)
  const Register recv_klass_reg     = r10;
  const Register holder_klass_reg   = rax; // declaring interface klass (DECC)
  const Register resolved_klass_reg = rbx; // resolved interface klass (REFC)
  const Register temp_reg           = r11;

  const Register icholder_reg = rax;
  __ movptr(resolved_klass_reg, Address(icholder_reg, CompiledICHolder::holder_klass_offset()));
  __ movptr(holder_klass_reg,   Address(icholder_reg, CompiledICHolder::holder_metadata_offset()));

  Label L_no_such_interface;

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

  start_pc = __ pc();

  // Receiver subtype check against REFC.
  // Destroys recv_klass_reg value.
  __ lookup_interface_method(// inputs: rec. class, interface
                             recv_klass_reg, resolved_klass_reg, noreg,
                             // outputs:  scan temp. reg1, scan temp. reg2
                             recv_klass_reg, temp_reg,
                             L_no_such_interface,
                             /*return_method=*/false);

  const ptrdiff_t  typecheckSize = __ pc() - start_pc;
  start_pc = __ pc();

  // Get selected method from declaring class and itable index
  const Register method = rbx;
  __ load_klass(recv_klass_reg, j_rarg0, temp_reg);   // restore recv_klass_reg
  __ lookup_interface_method(// inputs: rec. class, interface, itable index
                             recv_klass_reg, holder_klass_reg, itable_index,
                             // outputs: method, scan temp. reg
                             method, temp_reg,
                             L_no_such_interface);

  const ptrdiff_t  lookupSize = __ pc() - start_pc;

  // We expect we need index_dependent_slop extra bytes. Reason:
  // The emitted code in lookup_interface_method changes when itable_index exceeds 15.
  // For linux, a very narrow estimate would be 112, but Solaris requires some more space (130).
  const ptrdiff_t estimate = 136;
  const ptrdiff_t codesize = typecheckSize + lookupSize + index_dependent_slop;
  slop_delta  = (int)(estimate - codesize);
  slop_bytes += slop_delta;
  assert(slop_delta >= 0, "itable #%d: Code size estimate (%d) for lookup_interface_method too small, required: %d", itable_index, (int)estimate, (int)codesize);

  // 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...

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

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

  address ame_addr = __ pc();
  __ jmp(Address(method, Method::from_compiled_offset()));

  __ bind(L_no_such_interface);
  // Handle IncompatibleClassChangeError in itable stubs.
  // More detailed error message.
  // We force resolving of the call site by jumping to the "handle
  // wrong method" stub, and so let the interpreter runtime do all the
  // dirty work.
  __ jump(RuntimeAddress(SharedRuntime::get_handle_wrong_method_stub()));

  masm->flush();
  slop_bytes += index_dependent_slop; // add'l slop for size variance due to large itable offsets
  bookkeeping(masm, tty, s, npe_addr, ame_addr, false, itable_index, slop_bytes, index_dependent_slop);

  return s;
}

int VtableStub::pd_code_alignment() {
  // x86 cache line size is 64 bytes, but we want to limit alignment loss.
  const unsigned int icache_line_size = wordSize;
  return icache_line_size;
}

quality95%

¤ Dauer der Verarbeitung: 0.28 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.