jdk

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/*
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 * Copyright (c) 2020, 2022, Oracle and/or its affiliates. All rights reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 */
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#include "precompiled.hpp"
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#include "foreignGlobals.hpp"
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#include "classfile/javaClasses.hpp"
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#include "memory/resourceArea.hpp"
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#include "prims/foreignGlobals.inline.hpp"
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#include "runtime/jniHandles.inline.hpp"
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#include "utilities/resourceHash.hpp"
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StubLocations::StubLocations() {
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  for (uint32_t i = 0; i < LOCATION_LIMIT; i++) {
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    _locs[i] = VMStorage::invalid();
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  }
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}
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void StubLocations::set(uint32_t loc, VMStorage storage) {
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  assert(loc < LOCATION_LIMIT, "oob");
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  _locs[loc] = storage;
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}
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void StubLocations::set_frame_data(uint32_t loc, int offset) {
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  set(loc, VMStorage(StorageType::FRAME_DATA, 8, offset));
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}
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VMStorage StubLocations::get(uint32_t loc) const {
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  assert(loc < LOCATION_LIMIT, "oob");
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  VMStorage storage = _locs[loc];
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  assert(storage.is_valid(), "not set");
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  return storage;
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}
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VMStorage StubLocations::get(VMStorage placeholder) const {
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  assert(placeholder.type() == StorageType::PLACEHOLDER, "must be");
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  return get(placeholder.index());
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}
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int StubLocations::data_offset(uint32_t loc) const {
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  VMStorage storage = get(loc);
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  assert(storage.type() == StorageType::FRAME_DATA, "must be");
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  return storage.offset();
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}
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#define FOREIGN_ABI "jdk/internal/foreign/abi/"
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const CallRegs ForeignGlobals::parse_call_regs(jobject jconv) {
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  oop conv_oop = JNIHandles::resolve_non_null(jconv);
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  objArrayOop arg_regs_oop = jdk_internal_foreign_abi_CallConv::argRegs(conv_oop);
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  objArrayOop ret_regs_oop = jdk_internal_foreign_abi_CallConv::retRegs(conv_oop);
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  int num_args = arg_regs_oop->length();
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  int num_rets = ret_regs_oop->length();
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  CallRegs result(num_args, num_rets);
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  for (int i = 0; i < num_args; i++) {
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    result._arg_regs.push(parse_vmstorage(arg_regs_oop->obj_at(i)));
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  }
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  for (int i = 0; i < num_rets; i++) {
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    result._ret_regs.push(parse_vmstorage(ret_regs_oop->obj_at(i)));
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  }
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  return result;
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}
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VMStorage ForeignGlobals::parse_vmstorage(oop storage) {
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  jbyte type = jdk_internal_foreign_abi_VMStorage::type(storage);
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  jshort segment_mask_or_size = jdk_internal_foreign_abi_VMStorage::segment_mask_or_size(storage);
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  jint index_or_offset = jdk_internal_foreign_abi_VMStorage::index_or_offset(storage);
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  return VMStorage(static_cast<StorageType>(type), segment_mask_or_size, index_or_offset);
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}
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int RegSpiller::compute_spill_area(const GrowableArray<VMStorage>& regs) {
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  int result_size = 0;
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  for (int i = 0; i < regs.length(); i++) {
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    result_size += pd_reg_size(regs.at(i));
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  }
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  return result_size;
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}
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void RegSpiller::generate(MacroAssembler* masm, int rsp_offset, bool spill) const {
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  assert(rsp_offset != -1, "rsp_offset should be set");
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  int offset = rsp_offset;
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  for (int i = 0; i < _regs.length(); i++) {
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    VMStorage reg = _regs.at(i);
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    if (spill) {
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      pd_store_reg(masm, offset, reg);
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    } else {
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      pd_load_reg(masm, offset, reg);
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    }
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    offset += pd_reg_size(reg);
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  }
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}
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void ArgumentShuffle::print_on(outputStream* os) const {
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  os->print_cr("Argument shuffle {");
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  for (int i = 0; i < _moves.length(); i++) {
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    Move move = _moves.at(i);
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    VMStorage from_reg = move.from;
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    VMStorage to_reg   = move.to;
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    os->print("Move from ");
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    from_reg.print_on(os);
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    os->print(" to ");
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    to_reg.print_on(os);
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    os->print_cr("");
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  }
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  os->print_cr("}");
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}
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int ForeignGlobals::compute_out_arg_bytes(const GrowableArray<VMStorage>& out_regs) {
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  uint32_t max_stack_offset = 0;
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  for (VMStorage reg : out_regs) {
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    if (reg.is_stack())
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      max_stack_offset = MAX2(max_stack_offset, reg.offset() + reg.stack_size());
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  }
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  return align_up(max_stack_offset, 8);
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}
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int ForeignGlobals::java_calling_convention(const BasicType* signature, int num_args, GrowableArray<VMStorage>& out_regs) {
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  VMRegPair* vm_regs = NEW_RESOURCE_ARRAY(VMRegPair, num_args);
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  int slots = align_up(SharedRuntime::java_calling_convention(signature, vm_regs, num_args), 2);
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  for (int i = 0; i < num_args; i++) {
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    VMRegPair pair = vm_regs[i];
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    // note, we ignore second here. Signature should consist of register-size values. So there should be
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    // no need for multi-register pairs.
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    if (signature[i] != T_VOID) {
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      out_regs.push(as_VMStorage(pair.first(), signature[i]));
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    }
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  }
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  return slots << LogBytesPerInt;
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}
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GrowableArray<VMStorage> ForeignGlobals::replace_place_holders(const GrowableArray<VMStorage>& regs, const StubLocations& locs) {
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  GrowableArray<VMStorage> result(regs.length());
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  for (VMStorage reg : regs) {
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    result.push(reg.type() == StorageType::PLACEHOLDER ? locs.get(reg) : reg);
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  }
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  return result;
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}
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GrowableArray<VMStorage> ForeignGlobals::upcall_filter_receiver_reg(const GrowableArray<VMStorage>& unfiltered_regs) {
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  GrowableArray<VMStorage> out(unfiltered_regs.length() - 1);
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  // drop first arg reg
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  for (int i = 1; i < unfiltered_regs.length(); i++) {
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    out.push(unfiltered_regs.at(i));
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  }
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  return out;
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}
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GrowableArray<VMStorage> ForeignGlobals::downcall_filter_offset_regs(const GrowableArray<VMStorage>& regs,
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                                                                     BasicType* signature, int num_args,
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                                                                     bool& has_objects) {
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  GrowableArray<VMStorage> result(regs.length());
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  int reg_idx = 0;
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  for (int sig_idx = 0; sig_idx < num_args; sig_idx++) {
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    if (signature[sig_idx] == T_VOID) {
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      continue; // ignore upper halves
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    }
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    result.push(regs.at(reg_idx++));
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    if (signature[sig_idx] == T_OBJECT) {
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      has_objects = true;
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      sig_idx++; // skip offset
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      reg_idx++;
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    }
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  }
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  return result;
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}
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class ArgumentShuffle::ComputeMoveOrder: public StackObj {
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  class MoveOperation;
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  // segment_mask_or_size is not taken into account since
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  // VMStorages that differ only in mask or size can still
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  // conflict
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  static inline unsigned hash(const VMStorage& vms) {
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    return static_cast<unsigned int>(vms.type()) ^ vms.index_or_offset();
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  }
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  static inline bool equals(const VMStorage& a, const VMStorage& b) {
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    return a.type() == b.type() && a.index_or_offset() == b.index_or_offset();
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  }
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  using KillerTable = ResourceHashtable<
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    VMStorage, MoveOperation*,
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    32, // doesn't need to be big. don't have that many argument registers (in known ABIs)
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    AnyObj::RESOURCE_AREA,
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    mtInternal,
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    ComputeMoveOrder::hash,
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    ComputeMoveOrder::equals
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    >;
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  class MoveOperation: public ResourceObj {
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    friend class ComputeMoveOrder;
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   private:
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    VMStorage       _src;
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    VMStorage       _dst;
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    bool            _processed;
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    MoveOperation*  _next;
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    MoveOperation*  _prev;
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   public:
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    MoveOperation(VMStorage src, VMStorage dst):
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      _src(src), _dst(dst), _processed(false), _next(nullptr), _prev(nullptr) {}
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    const VMStorage& src() const { return _src; }
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    const VMStorage& dst() const { return _dst; }
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    MoveOperation* next()  const { return _next; }
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    MoveOperation* prev()  const { return _prev; }
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    void set_processed()         { _processed = true; }
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    bool is_processed()    const { return _processed; }
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    // insert
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    void break_cycle(VMStorage temp_register) {
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      // create a new store following the last store
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      // to move from the temp_register to the original
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      MoveOperation* new_store = new MoveOperation(temp_register, _dst);
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      // break the cycle of links and insert new_store at the end
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      // break the reverse link.
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      MoveOperation* p = prev();
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      assert(p->next() == this, "must be");
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      _prev = nullptr;
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      p->_next = new_store;
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      new_store->_prev = p;
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      // change the original store to save it's value in the temp.
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      _dst = temp_register;
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    }
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    void link(KillerTable& killer) {
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      // link this store in front the store that it depends on
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      MoveOperation** n = killer.get(_src);
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      if (n != nullptr) {
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        MoveOperation* src_killer = *n;
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        assert(_next == nullptr && src_killer->_prev == nullptr, "shouldn't have been set yet");
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        _next = src_killer;
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        src_killer->_prev = this;
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      }
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    }
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    Move as_move() {
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      return {_src, _dst};
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    }
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  };
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 private:
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  const GrowableArray<VMStorage>& _in_regs;
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  const GrowableArray<VMStorage>& _out_regs;
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  VMStorage _tmp_vmreg;
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  GrowableArray<MoveOperation*> _edges;
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  GrowableArray<Move> _moves;
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 public:
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  ComputeMoveOrder(const GrowableArray<VMStorage>& in_regs,
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                   const GrowableArray<VMStorage>& out_regs,
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                   VMStorage tmp_vmreg) :
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      _in_regs(in_regs),
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      _out_regs(out_regs),
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      _tmp_vmreg(tmp_vmreg),
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      _edges(in_regs.length()),
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      _moves(in_regs.length()) {
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    assert(in_regs.length() == out_regs.length(),
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      "stray registers? %d != %d", in_regs.length(), out_regs.length());
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  }
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  void compute() {
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    for (int i = 0; i < _in_regs.length(); i++) {
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      VMStorage in_reg = _in_regs.at(i);
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      VMStorage out_reg = _out_regs.at(i);
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      if (out_reg.is_stack() || out_reg.is_frame_data()) {
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        // Move operations where the dest is the stack can all be
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        // scheduled first since they can't interfere with the other moves.
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        // The input and output stack spaces are distinct from each other.
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        Move move{in_reg, out_reg};
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        _moves.push(move);
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      } else if (in_reg == out_reg) {
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        // Can skip non-stack identity moves.
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        continue;
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      } else {
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        _edges.append(new MoveOperation(in_reg, out_reg));
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      }
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    }
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    // Break any cycles in the register moves and emit the in the
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    // proper order.
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    compute_store_order();
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  }
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  // Walk the edges breaking cycles between moves.  The result list
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  // can be walked in order to produce the proper set of loads
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  void compute_store_order() {
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    // Record which moves kill which registers
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    KillerTable killer; // a map of VMStorage -> MoveOperation*
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    for (int i = 0; i < _edges.length(); i++) {
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      MoveOperation* s = _edges.at(i);
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      assert(!killer.contains(s->dst()),
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             "multiple moves with the same register as destination");
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      killer.put(s->dst(), s);
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    }
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    assert(!killer.contains(_tmp_vmreg),
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           "make sure temp isn't in the registers that are killed");
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    // create links between loads and stores
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    for (int i = 0; i < _edges.length(); i++) {
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      _edges.at(i)->link(killer);
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    }
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    // at this point, all the move operations are chained together
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    // in one or more doubly linked lists.  Processing them backwards finds
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    // the beginning of the chain, forwards finds the end.  If there's
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    // a cycle it can be broken at any point,  so pick an edge and walk
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    // backward until the list ends or we end where we started.
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    for (int e = 0; e < _edges.length(); e++) {
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      MoveOperation* s = _edges.at(e);
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      if (!s->is_processed()) {
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        MoveOperation* start = s;
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        // search for the beginning of the chain or cycle
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        while (start->prev() != nullptr && start->prev() != s) {
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          start = start->prev();
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        }
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        if (start->prev() == s) {
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          start->break_cycle(_tmp_vmreg);
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        }
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        // walk the chain forward inserting to store list
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        while (start != nullptr) {
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          _moves.push(start->as_move());
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          start->set_processed();
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          start = start->next();
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        }
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      }
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    }
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  }
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public:
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  static GrowableArray<Move> compute_move_order(const GrowableArray<VMStorage>& in_regs,
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                                                const GrowableArray<VMStorage>& out_regs,
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                                                VMStorage tmp_vmreg) {
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    ComputeMoveOrder cmo(in_regs, out_regs, tmp_vmreg);
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    cmo.compute();
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    return cmo._moves;
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  }
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};
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ArgumentShuffle::ArgumentShuffle(
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    const GrowableArray<VMStorage>& in_regs,
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    const GrowableArray<VMStorage>& out_regs,
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    VMStorage shuffle_temp) {
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  _moves = ComputeMoveOrder::compute_move_order(in_regs, out_regs, shuffle_temp);
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}
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