gdb/arch/riscv.c

/* Copyright (C) 2018-2020 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program 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 for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "gdbsupport/common-defs.h"
#include "riscv.h"
#include <stdlib.h>
#include <unordered_map>

#include "../features/riscv/32bit-cpu.c"
#include "../features/riscv/64bit-cpu.c"
#include "../features/riscv/32bit-fpu.c"
#include "../features/riscv/64bit-fpu.c"

/* Wrapper used by std::unordered_map to generate hash for feature set.  */
struct riscv_gdbarch_features_hasher
{
  std::size_t
  operator() (const riscv_gdbarch_features &features) const noexcept
  {
    return features.hash ();
  }
};

/* Cache of previously seen target descriptions, indexed by the feature set
   that created them.  */
static std::unordered_map<riscv_gdbarch_features,
                          target_desc *,
                          riscv_gdbarch_features_hasher> riscv_tdesc_cache;

/* See arch/riscv.h.  */

const target_desc *
riscv_create_target_description (struct riscv_gdbarch_features features)
{
  /* Have we seen this feature set before?  If we have return the same
     target description.  GDB expects that if two target descriptions are
     the same (in content terms) then they will actually be the same
     instance.  This is important when trying to lookup gdbarch objects as
     GDBARCH_LIST_LOOKUP_BY_INFO performs a pointer comparison on target
     descriptions to find candidate gdbarch objects.  */
  const auto it = riscv_tdesc_cache.find (features);
  if (it != riscv_tdesc_cache.end ())
    return it->second;

  /* Now we should create a new target description.  */
  target_desc *tdesc = allocate_target_description ();

#ifndef IN_PROCESS_AGENT
  std::string arch_name = "riscv";

  if (features.xlen == 4)
    arch_name.append (":rv32i");
  else if (features.xlen == 8)
    arch_name.append (":rv64i");
  else if (features.xlen == 16)
    arch_name.append (":rv128i");

  if (features.flen == 4)
    arch_name.append ("f");
  else if (features.flen == 8)
    arch_name.append ("d");
  else if (features.flen == 16)
    arch_name.append ("q");

  set_tdesc_architecture (tdesc, arch_name.c_str ());
#endif

  long regnum = 0;

  /* For now we only support creating 32-bit or 64-bit x-registers.  */
  if (features.xlen == 4)
    regnum = create_feature_riscv_32bit_cpu (tdesc, regnum);
  else if (features.xlen == 8)
    regnum = create_feature_riscv_64bit_cpu (tdesc, regnum);

  /* For now we only support creating 32-bit or 64-bit f-registers.  */
  if (features.flen == 4)
    regnum = create_feature_riscv_32bit_fpu (tdesc, regnum);
  else if (features.flen == 8)
    regnum = create_feature_riscv_64bit_fpu (tdesc, regnum);

  /* Add to the cache.  */
  riscv_tdesc_cache.emplace (features, tdesc);

  return tdesc;
}