gdb/arch/riscv.h

   1 /* Common target-dependent functionality for RISC-V
   2
   3    Copyright (C) 2018-2024 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef ARCH_RISCV_H
  21 #define ARCH_RISCV_H
  22
  23 #include "gdbsupport/tdesc.h"
  24
  25 /* The set of RISC-V architectural features that we track that impact how
  26    we configure the actual gdbarch instance.  We hold one of these in the
  27    gdbarch_tdep structure, and use it to distinguish between different
  28    RISC-V gdbarch instances.
  29
  30    The information in here ideally comes from the target description,
  31    however, if the target doesn't provide a target description then we will
  32    create a default target description by first populating one of these
  33    based on what we know about the binary being executed, and using that to
  34    drive default target description creation.  */
  35
  36 struct riscv_gdbarch_features
  37 {
  38   /* The size of the x-registers in bytes.  This is either 4 (RV32), 8
  39      (RV64), or 16 (RV128).  No other value is valid.  Initialise to the
  40      invalid 0 value so we can spot if one of these is used
  41      uninitialised.  */
  42   int xlen = 0;
  43
  44   /* The size of the f-registers in bytes.  This is either 4 (RV32), 8
  45      (RV64), or 16 (RV128).  This can also hold the value 0 to indicate
  46      that there are no f-registers.  No other value is valid.  */
  47   int flen = 0;
  48
  49   /* The size of the v-registers in bytes.  The value 0 indicates a target
  50      with no vector registers.  The minimum value for a 'V'-extension compliant
  51      target should be 16 and 4 for an embedded subset compliant target (with
  52      'Zve32*' extension), but GDB doesn't currently mind, and will accept any
  53      vector size.  */
  54   int vlen = 0;
  55
  56   /* When true this target is RV32E.  */
  57   bool embedded = false;
  58
  59   /* Track if the target description has an fcsr, fflags, and frm
  60      registers.  Some targets provide all these in their target
  61      descriptions, while some only offer fcsr, while others don't even
  62      offer that register.  If a target provides fcsr but not fflags and/or
  63      frm, then we can emulate these registers as pseudo registers.  */
  64   bool has_fcsr_reg = false;
  65   bool has_fflags_reg = false;
  66   bool has_frm_reg = false;
  67
  68   /* Equality operator.  */
  69   bool operator== (const struct riscv_gdbarch_features &rhs) const
  70   {
  71     return (xlen == rhs.xlen && flen == rhs.flen
  72             && embedded == rhs.embedded && vlen == rhs.vlen
  73             && has_fflags_reg == rhs.has_fflags_reg
  74             && has_frm_reg == rhs.has_frm_reg
  75             && has_fcsr_reg == rhs.has_fcsr_reg);
  76   }
  77
  78   /* Inequality operator.  */
  79   bool operator!= (const struct riscv_gdbarch_features &rhs) const
  80   {
  81     return !((*this) == rhs);
  82   }
  83
  84   /* Used by std::unordered_map to hash feature sets.  */
  85   std::size_t hash () const noexcept
  86   {
  87     std::size_t val = ((embedded ? 1 : 0) << 10
  88                        | (has_fflags_reg ? 1 : 0) << 11
  89                        | (has_frm_reg ? 1 : 0) << 12
  90                        | (has_fcsr_reg ? 1 : 0) << 13
  91                        | (xlen & 0x1f) << 5
  92                        | (flen & 0x1f) << 0
  93                        | (vlen & 0x3fff) << 14);
  94     return val;
  95   }
  96 };
  97
  98 #ifdef GDBSERVER
  99
 100 /* Create and return a target description that is compatible with FEATURES.
 101    This is only used directly from the gdbserver where the created target
 102    description is modified after it is return.  */
 103
 104 target_desc_up riscv_create_target_description
 105         (const struct riscv_gdbarch_features features);
 106
 107 #else
 108
 109 /* Lookup an already existing target description matching FEATURES, or
 110    create a new target description if this is the first time we have seen
 111    FEATURES.  For the same FEATURES the same target_desc is always
 112    returned.  This is important when trying to lookup gdbarch objects as
 113    GDBARCH_LIST_LOOKUP_BY_INFO performs a pointer comparison on target
 114    descriptions to find candidate gdbarch objects.  */
 115
 116 const target_desc *riscv_lookup_target_description
 117         (const struct riscv_gdbarch_features features);
 118
 119 #endif /* GDBSERVER */
 120
 121
 122 #endif /* ARCH_RISCV_H */