gdb/arch/riscv.h

/* Common target-dependent functionality for RISC-V

   Copyright (C) 2018-2024 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/>.  */

#ifndef ARCH_RISCV_H
#define ARCH_RISCV_H

#include "gdbsupport/tdesc.h"

/* The set of RISC-V architectural features that we track that impact how
   we configure the actual gdbarch instance.  We hold one of these in the
   gdbarch_tdep structure, and use it to distinguish between different
   RISC-V gdbarch instances.

   The information in here ideally comes from the target description,
   however, if the target doesn't provide a target description then we will
   create a default target description by first populating one of these
   based on what we know about the binary being executed, and using that to
   drive default target description creation.  */

struct riscv_gdbarch_features
{
  /* The size of the x-registers in bytes.  This is either 4 (RV32), 8
     (RV64), or 16 (RV128).  No other value is valid.  Initialise to the
     invalid 0 value so we can spot if one of these is used
     uninitialised.  */
  int xlen = 0;

  /* The size of the f-registers in bytes.  This is either 4 (RV32), 8
     (RV64), or 16 (RV128).  This can also hold the value 0 to indicate
     that there are no f-registers.  No other value is valid.  */
  int flen = 0;

  /* The size of the v-registers in bytes.  The value 0 indicates a target
     with no vector registers.  The minimum value for a 'V'-extension compliant
     target should be 16 and 4 for an embedded subset compliant target (with
     'Zve32*' extension), but GDB doesn't currently mind, and will accept any
     vector size.  */
  int vlen = 0;

  /* When true this target is RV32E.  */
  bool embedded = false;

  /* Track if the target description has an fcsr, fflags, and frm
     registers.  Some targets provide all these in their target
     descriptions, while some only offer fcsr, while others don't even
     offer that register.  If a target provides fcsr but not fflags and/or
     frm, then we can emulate these registers as pseudo registers.  */
  bool has_fcsr_reg = false;
  bool has_fflags_reg = false;
  bool has_frm_reg = false;

  /* Equality operator.  */
  bool operator== (const struct riscv_gdbarch_features &rhs) const
  {
    return (xlen == rhs.xlen && flen == rhs.flen
	    && embedded == rhs.embedded && vlen == rhs.vlen
	    && has_fflags_reg == rhs.has_fflags_reg
	    && has_frm_reg == rhs.has_frm_reg
	    && has_fcsr_reg == rhs.has_fcsr_reg);
  }

  /* Inequality operator.  */
  bool operator!= (const struct riscv_gdbarch_features &rhs) const
  {
    return !((*this) == rhs);
  }

  /* Used by std::unordered_map to hash feature sets.  */
  std::size_t hash () const noexcept
  {
    std::size_t val = ((embedded ? 1 : 0) << 10
		       | (has_fflags_reg ? 1 : 0) << 11
		       | (has_frm_reg ? 1 : 0) << 12
		       | (has_fcsr_reg ? 1 : 0) << 13
		       | (xlen & 0x1f) << 5
		       | (flen & 0x1f) << 0
		       | (vlen & 0x3fff) << 14);
    return val;
  }
};

#ifdef GDBSERVER

/* Create and return a target description that is compatible with FEATURES.
   This is only used directly from the gdbserver where the created target
   description is modified after it is return.  */

target_desc_up riscv_create_target_description
	(const struct riscv_gdbarch_features features);

#else

/* Lookup an already existing target description matching FEATURES, or
   create a new target description if this is the first time we have seen
   FEATURES.  For the same FEATURES the same target_desc is always
   returned.  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 target_desc *riscv_lookup_target_description
	(const struct riscv_gdbarch_features features);

#endif /* GDBSERVER */


#endif /* ARCH_RISCV_H */