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[thirdparty/binutils-gdb.git] / gas / config / tc-riscv.c

/* tc-riscv.c -- RISC-V assembler
   Copyright (C) 2011-2020 Free Software Foundation, Inc.

   Contributed by Andrew Waterman (andrew@sifive.com).
   Based on MIPS target.

   This file is part of GAS.

   GAS 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, or (at your option)
   any later version.

   GAS 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; see the file COPYING3. If not,
   see <http://www.gnu.org/licenses/>.  */

#include "as.h"
#include "config.h"
#include "subsegs.h"
#include "safe-ctype.h"

#include "itbl-ops.h"
#include "dwarf2dbg.h"
#include "dw2gencfi.h"

#include "bfd/elfxx-riscv.h"
#include "elf/riscv.h"
#include "opcode/riscv.h"

#include <stdint.h>

/* Information about an instruction, including its format, operands
   and fixups.  */
struct riscv_cl_insn
{
  /* The opcode's entry in riscv_opcodes.  */
  const struct riscv_opcode *insn_mo;

  /* The encoded instruction bits.  */
  insn_t insn_opcode;

  /* The frag that contains the instruction.  */
  struct frag *frag;

  /* The offset into FRAG of the first instruction byte.  */
  long where;

  /* The relocs associated with the instruction, if any.  */
  fixS *fixp;
};

#ifndef DEFAULT_ARCH
#define DEFAULT_ARCH "riscv64"
#endif

#ifndef DEFAULT_RISCV_ATTR
#define DEFAULT_RISCV_ATTR 0
#endif

static const char default_arch[] = DEFAULT_ARCH;

static unsigned xlen = 0; /* width of an x-register */
static unsigned abi_xlen = 0; /* width of a pointer in the ABI */
static bfd_boolean rve_abi = FALSE;

#define LOAD_ADDRESS_INSN (abi_xlen == 64 ? "ld" : "lw")
#define ADD32_INSN (xlen == 64 ? "addiw" : "addi")

static unsigned elf_flags = 0;

/* This is the set of options which the .option pseudo-op may modify.  */

struct riscv_set_options
{
  int pic; /* Generate position-independent code.  */
  int rvc; /* Generate RVC code.  */
  int rve; /* Generate RVE code.  */
  int relax; /* Emit relocs the linker is allowed to relax.  */
  int arch_attr; /* Emit arch attribute.  */
  int csr_check; /* Enable the CSR checking.  */
};

static struct riscv_set_options riscv_opts =
{
  0,    /* pic */
  0,    /* rvc */
  0,    /* rve */
  1,    /* relax */
  DEFAULT_RISCV_ATTR, /* arch_attr */
  0.    /* csr_check */
};

static void
riscv_set_rvc (bfd_boolean rvc_value)
{
  if (rvc_value)
    elf_flags |= EF_RISCV_RVC;

  riscv_opts.rvc = rvc_value;
}

static void
riscv_set_rve (bfd_boolean rve_value)
{
  riscv_opts.rve = rve_value;
}

static riscv_subset_list_t riscv_subsets;

static bfd_boolean
riscv_subset_supports (const char *feature)
{
  if (riscv_opts.rvc && (strcasecmp (feature, "c") == 0))
    return TRUE;

  return riscv_lookup_subset (&riscv_subsets, feature) != NULL;
}

static bfd_boolean
riscv_multi_subset_supports (enum riscv_insn_class insn_class)
{
  switch (insn_class)
    {
    case INSN_CLASS_I: return riscv_subset_supports ("i");
    case INSN_CLASS_C: return riscv_subset_supports ("c");
    case INSN_CLASS_A: return riscv_subset_supports ("a");
    case INSN_CLASS_M: return riscv_subset_supports ("m");
    case INSN_CLASS_F: return riscv_subset_supports ("f");
    case INSN_CLASS_D: return riscv_subset_supports ("d");
    case INSN_CLASS_D_AND_C:
      return riscv_subset_supports ("d") && riscv_subset_supports ("c");

    case INSN_CLASS_F_AND_C:
      return riscv_subset_supports ("f") && riscv_subset_supports ("c");

    case INSN_CLASS_Q: return riscv_subset_supports ("q");

    default:
      as_fatal ("Unreachable");
      return FALSE;
    }
}

/* Set which ISA and extensions are available.  */

static void
riscv_set_arch (const char *s)
{
  riscv_parse_subset_t rps;
  rps.subset_list = &riscv_subsets;
  rps.error_handler = as_fatal;
  rps.xlen = &xlen;

  riscv_release_subset_list (&riscv_subsets);
  riscv_parse_subset (&rps, s);
}

/* Handle of the OPCODE hash table.  */
static struct hash_control *op_hash = NULL;

/* Handle of the type of .insn hash table.  */
static struct hash_control *insn_type_hash = NULL;

/* This array holds the chars that always start a comment.  If the
    pre-processor is disabled, these aren't very useful */
const char comment_chars[] = "#";

/* This array holds the chars that only start a comment at the beginning of
   a line.  If the line seems to have the form '# 123 filename'
   .line and .file directives will appear in the pre-processed output */
/* Note that input_file.c hand checks for '#' at the beginning of the
   first line of the input file.  This is because the compiler outputs
   #NO_APP at the beginning of its output.  */
/* Also note that C style comments are always supported.  */
const char line_comment_chars[] = "#";

/* This array holds machine specific line separator characters.  */
const char line_separator_chars[] = ";";

/* Chars that can be used to separate mant from exp in floating point nums */
const char EXP_CHARS[] = "eE";

/* Chars that mean this number is a floating point constant */
/* As in 0f12.456 */
/* or    0d1.2345e12 */
const char FLT_CHARS[] = "rRsSfFdDxXpP";

/* Indicate we are already assemble any instructions or not.  */
static bfd_boolean start_assemble = FALSE;

/* Indicate arch attribute is explictly set.  */
static bfd_boolean explicit_arch_attr = FALSE;

/* Macros for encoding relaxation state for RVC branches and far jumps.  */
#define RELAX_BRANCH_ENCODE(uncond, rvc, length)        \
  ((relax_substateT)                                    \
   (0xc0000000                                          \
    | ((uncond) ? 1 : 0)                                \
    | ((rvc) ? 2 : 0)                                   \
    | ((length) << 2)))
#define RELAX_BRANCH_P(i) (((i) & 0xf0000000) == 0xc0000000)
#define RELAX_BRANCH_LENGTH(i) (((i) >> 2) & 0xF)
#define RELAX_BRANCH_RVC(i) (((i) & 2) != 0)
#define RELAX_BRANCH_UNCOND(i) (((i) & 1) != 0)

/* Is the given value a sign-extended 32-bit value?  */
#define IS_SEXT_32BIT_NUM(x)                                            \
  (((x) &~ (offsetT) 0x7fffffff) == 0                                   \
   || (((x) &~ (offsetT) 0x7fffffff) == ~ (offsetT) 0x7fffffff))

/* Is the given value a zero-extended 32-bit value?  Or a negated one?  */
#define IS_ZEXT_32BIT_NUM(x)                                            \
  (((x) &~ (offsetT) 0xffffffff) == 0                                   \
   || (((x) &~ (offsetT) 0xffffffff) == ~ (offsetT) 0xffffffff))

/* Change INSN's opcode so that the operand given by FIELD has value VALUE.
   INSN is a riscv_cl_insn structure and VALUE is evaluated exactly once.  */
#define INSERT_OPERAND(FIELD, INSN, VALUE) \
  INSERT_BITS ((INSN).insn_opcode, VALUE, OP_MASK_##FIELD, OP_SH_##FIELD)

/* Determine if an instruction matches an opcode.  */
#define OPCODE_MATCHES(OPCODE, OP) \
  (((OPCODE) & MASK_##OP) == MATCH_##OP)

static char *expr_end;

/* The default target format to use.  */

const char *
riscv_target_format (void)
{
  return xlen == 64 ? "elf64-littleriscv" : "elf32-littleriscv";
}

/* Return the length of instruction INSN.  */

static inline unsigned int
insn_length (const struct riscv_cl_insn *insn)
{
  return riscv_insn_length (insn->insn_opcode);
}

/* Initialise INSN from opcode entry MO.  Leave its position unspecified.  */

static void
create_insn (struct riscv_cl_insn *insn, const struct riscv_opcode *mo)
{
  insn->insn_mo = mo;
  insn->insn_opcode = mo->match;
  insn->frag = NULL;
  insn->where = 0;
  insn->fixp = NULL;
}

/* Install INSN at the location specified by its "frag" and "where" fields.  */

static void
install_insn (const struct riscv_cl_insn *insn)
{
  char *f = insn->frag->fr_literal + insn->where;
  md_number_to_chars (f, insn->insn_opcode, insn_length (insn));
}

/* Move INSN to offset WHERE in FRAG.  Adjust the fixups accordingly
   and install the opcode in the new location.  */

static void
move_insn (struct riscv_cl_insn *insn, fragS *frag, long where)
{
  insn->frag = frag;
  insn->where = where;
  if (insn->fixp != NULL)
    {
      insn->fixp->fx_frag = frag;
      insn->fixp->fx_where = where;
    }
  install_insn (insn);
}

/* Add INSN to the end of the output.  */

static void
add_fixed_insn (struct riscv_cl_insn *insn)
{
  char *f = frag_more (insn_length (insn));
  move_insn (insn, frag_now, f - frag_now->fr_literal);
}

static void
add_relaxed_insn (struct riscv_cl_insn *insn, int max_chars, int var,
      relax_substateT subtype, symbolS *symbol, offsetT offset)
{
  frag_grow (max_chars);
  move_insn (insn, frag_now, frag_more (0) - frag_now->fr_literal);
  frag_var (rs_machine_dependent, max_chars, var,
            subtype, symbol, offset, NULL);
}

/* Compute the length of a branch sequence, and adjust the stored length
   accordingly.  If FRAGP is NULL, the worst-case length is returned.  */

static unsigned
relaxed_branch_length (fragS *fragp, asection *sec, int update)
{
  int jump, rvc, length = 8;

  if (!fragp)
    return length;

  jump = RELAX_BRANCH_UNCOND (fragp->fr_subtype);
  rvc = RELAX_BRANCH_RVC (fragp->fr_subtype);
  length = RELAX_BRANCH_LENGTH (fragp->fr_subtype);

  /* Assume jumps are in range; the linker will catch any that aren't.  */
  length = jump ? 4 : 8;

  if (fragp->fr_symbol != NULL
      && S_IS_DEFINED (fragp->fr_symbol)
      && !S_IS_WEAK (fragp->fr_symbol)
      && sec == S_GET_SEGMENT (fragp->fr_symbol))
    {
      offsetT val = S_GET_VALUE (fragp->fr_symbol) + fragp->fr_offset;
      bfd_vma rvc_range = jump ? RVC_JUMP_REACH : RVC_BRANCH_REACH;
      val -= fragp->fr_address + fragp->fr_fix;

      if (rvc && (bfd_vma)(val + rvc_range/2) < rvc_range)
        length = 2;
      else if ((bfd_vma)(val + RISCV_BRANCH_REACH/2) < RISCV_BRANCH_REACH)
        length = 4;
      else if (!jump && rvc)
        length = 6;
    }

  if (update)
    fragp->fr_subtype = RELAX_BRANCH_ENCODE (jump, rvc, length);

  return length;
}

/* Information about an opcode name, mnemonics and its value.  */
struct opcode_name_t
{
  const char *name;
  unsigned int val;
};

/* List for all supported opcode name.  */
static const struct opcode_name_t opcode_name_list[] =
{
  {"C0",        0x0},
  {"C1",        0x1},
  {"C2",        0x2},

  {"LOAD",      0x03},
  {"LOAD_FP",   0x07},
  {"CUSTOM_0",  0x0b},
  {"MISC_MEM",  0x0f},
  {"OP_IMM",    0x13},
  {"AUIPC",     0x17},
  {"OP_IMM_32", 0x1b},
  /* 48b        0x1f.  */

  {"STORE",     0x23},
  {"STORE_FP",  0x27},
  {"CUSTOM_1",  0x2b},
  {"AMO",       0x2f},
  {"OP",        0x33},
  {"LUI",       0x37},
  {"OP_32",     0x3b},
  /* 64b        0x3f.  */

  {"MADD",      0x43},
  {"MSUB",      0x47},
  {"NMADD",     0x4f},
  {"NMSUB",     0x4b},
  {"OP_FP",     0x53},
  /*reserved    0x57.  */
  {"CUSTOM_2",  0x5b},
  /* 48b        0x5f.  */

  {"BRANCH",    0x63},
  {"JALR",      0x67},
  /*reserved    0x5b.  */
  {"JAL",       0x6f},
  {"SYSTEM",    0x73},
  /*reserved    0x77.  */
  {"CUSTOM_3",  0x7b},
  /* >80b       0x7f.  */

  {NULL, 0}
};

/* Hash table for lookup opcode name.  */
static struct hash_control *opcode_names_hash = NULL;

/* Initialization for hash table of opcode name.  */
static void
init_opcode_names_hash (void)
{
  const char *retval;
  const struct opcode_name_t *opcode;

  for (opcode = &opcode_name_list[0]; opcode->name != NULL; ++opcode)
    {
      retval = hash_insert (opcode_names_hash, opcode->name, (void *)opcode);

      if (retval != NULL)
        as_fatal (_("internal error: can't hash `%s': %s"),
                  opcode->name, retval);
    }
}

/* Find `s` is a valid opcode name or not,
   return the opcode name info if found.  */
static const struct opcode_name_t *
opcode_name_lookup (char **s)
{
  char *e;
  char save_c;
  struct opcode_name_t *o;

  /* Find end of name.  */
  e = *s;
  if (is_name_beginner (*e))
    ++e;
  while (is_part_of_name (*e))
    ++e;

  /* Terminate name.  */
  save_c = *e;
  *e = '\0';

  o = (struct opcode_name_t *) hash_find (opcode_names_hash, *s);

  /* Advance to next token if one was recognized.  */
  if (o)
    *s = e;

  *e = save_c;
  expr_end = e;

  return o;
}

enum reg_class
{
  RCLASS_GPR,
  RCLASS_FPR,
  RCLASS_CSR,
  RCLASS_MAX
};

static struct hash_control *reg_names_hash = NULL;
static struct hash_control *csr_extra_hash = NULL;

#define ENCODE_REG_HASH(cls, n) \
  ((void *)(uintptr_t)((n) * RCLASS_MAX + (cls) + 1))
#define DECODE_REG_CLASS(hash) (((uintptr_t)(hash) - 1) % RCLASS_MAX)
#define DECODE_REG_NUM(hash) (((uintptr_t)(hash) - 1) / RCLASS_MAX)

static void
hash_reg_name (enum reg_class class, const char *name, unsigned n)
{
  void *hash = ENCODE_REG_HASH (class, n);
  const char *retval = hash_insert (reg_names_hash, name, hash);

  if (retval != NULL)
    as_fatal (_("internal error: can't hash `%s': %s"), name, retval);
}

static void
hash_reg_names (enum reg_class class, const char * const names[], unsigned n)
{
  unsigned i;

  for (i = 0; i < n; i++)
    hash_reg_name (class, names[i], i);
}

/* All RISC-V CSRs belong to one of these classes.  */

enum riscv_csr_class
{
  CSR_CLASS_NONE,

  CSR_CLASS_I,
  CSR_CLASS_I_32,       /* rv32 only */
  CSR_CLASS_F,          /* f-ext only */
};

/* This structure holds all restricted conditions for a CSR.  */

struct riscv_csr_extra
{
  /* Class to which this CSR belongs.  Used to decide whether or
     not this CSR is legal in the current -march context.  */
  enum riscv_csr_class csr_class;
};

/* Init two hashes, csr_extra_hash and reg_names_hash, for CSR.  */

static void
riscv_init_csr_hashes (const char *name,
                       unsigned address,
                       enum riscv_csr_class class)
{
  struct riscv_csr_extra *entry = XNEW (struct riscv_csr_extra);
  entry->csr_class = class;

  const char *hash_error =
    hash_insert (csr_extra_hash, name, (void *) entry);
  if (hash_error != NULL)
    {
      fprintf (stderr, _("internal error: can't hash `%s': %s\n"),
                      name, hash_error);
      /* Probably a memory allocation problem?  Give up now.  */
        as_fatal (_("Broken assembler.  No assembly attempted."));
    }

  hash_reg_name (RCLASS_CSR, name, address);
}

/* Check wether the CSR is valid according to the ISA.  */

static bfd_boolean
riscv_csr_class_check (enum riscv_csr_class csr_class)
{
  switch (csr_class)
    {
    case CSR_CLASS_I: return riscv_subset_supports ("i");
    case CSR_CLASS_F: return riscv_subset_supports ("f");
    case CSR_CLASS_I_32:
      return (xlen == 32 && riscv_subset_supports ("i"));

    default:
      return FALSE;
    }
}

/* If the CSR is defined, then we call `riscv_csr_class_check` to do the
   further checking.  Return FALSE if the CSR is not defined.  Otherwise,
   return TRUE.  */

static bfd_boolean
reg_csr_lookup_internal (const char *s)
{
  struct riscv_csr_extra *r =
    (struct riscv_csr_extra *) hash_find (csr_extra_hash, s);

  if (r == NULL)
    return FALSE;

  /* We just report the warning when the CSR is invalid.  */
  if (!riscv_csr_class_check (r->csr_class))
    as_warn (_("Invalid CSR `%s' for the current ISA"), s);

  return TRUE;
}

static unsigned int
reg_lookup_internal (const char *s, enum reg_class class)
{
  void *r = hash_find (reg_names_hash, s);

  if (r == NULL || DECODE_REG_CLASS (r) != class)
    return -1;

  if (riscv_opts.rve && class == RCLASS_GPR && DECODE_REG_NUM (r) > 15)
    return -1;

  if (class == RCLASS_CSR
      && riscv_opts.csr_check
      && !reg_csr_lookup_internal (s))
    return -1;

  return DECODE_REG_NUM (r);
}

static bfd_boolean
reg_lookup (char **s, enum reg_class class, unsigned int *regnop)
{
  char *e;
  char save_c;
  int reg = -1;

  /* Find end of name.  */
  e = *s;
  if (is_name_beginner (*e))
    ++e;
  while (is_part_of_name (*e))
    ++e;

  /* Terminate name.  */
  save_c = *e;
  *e = '\0';

  /* Look for the register.  Advance to next token if one was recognized.  */
  if ((reg = reg_lookup_internal (*s, class)) >= 0)
    *s = e;

  *e = save_c;
  if (regnop)
    *regnop = reg;
  return reg >= 0;
}

static bfd_boolean
arg_lookup (char **s, const char *const *array, size_t size, unsigned *regnop)
{
  const char *p = strchr (*s, ',');
  size_t i, len = p ? (size_t)(p - *s) : strlen (*s);

  if (len == 0)
    return FALSE;

  for (i = 0; i < size; i++)
    if (array[i] != NULL && strncmp (array[i], *s, len) == 0)
      {
        *regnop = i;
        *s += len;
        return TRUE;
      }

  return FALSE;
}

/* For consistency checking, verify that all bits are specified either
   by the match/mask part of the instruction definition, or by the
   operand list.

   `length` could be 0, 4 or 8, 0 for auto detection.  */
static bfd_boolean
validate_riscv_insn (const struct riscv_opcode *opc, int length)
{
  const char *p = opc->args;
  char c;
  insn_t used_bits = opc->mask;
  int insn_width;
  insn_t required_bits;

  if (length == 0)
    insn_width = 8 * riscv_insn_length (opc->match);
  else
    insn_width = 8 * length;

  required_bits = ~0ULL >> (64 - insn_width);

  if ((used_bits & opc->match) != (opc->match & required_bits))
    {
      as_bad (_("internal: bad RISC-V opcode (mask error): %s %s"),
              opc->name, opc->args);
      return FALSE;
    }

#define USE_BITS(mask,shift)    (used_bits |= ((insn_t)(mask) << (shift)))
  while (*p)
    switch (c = *p++)
      {
      case 'C': /* RVC */
        switch (c = *p++)
          {
          case 'a': used_bits |= ENCODE_RVC_J_IMM (-1U); break;
          case 'c': break; /* RS1, constrained to equal sp */
          case 'i': used_bits |= ENCODE_RVC_SIMM3(-1U); break;
          case 'j': used_bits |= ENCODE_RVC_IMM (-1U); break;
          case 'o': used_bits |= ENCODE_RVC_IMM (-1U); break;
          case 'k': used_bits |= ENCODE_RVC_LW_IMM (-1U); break;
          case 'l': used_bits |= ENCODE_RVC_LD_IMM (-1U); break;
          case 'm': used_bits |= ENCODE_RVC_LWSP_IMM (-1U); break;
          case 'n': used_bits |= ENCODE_RVC_LDSP_IMM (-1U); break;
          case 'p': used_bits |= ENCODE_RVC_B_IMM (-1U); break;
          case 's': USE_BITS (OP_MASK_CRS1S, OP_SH_CRS1S); break;
          case 't': USE_BITS (OP_MASK_CRS2S, OP_SH_CRS2S); break;
          case 'u': used_bits |= ENCODE_RVC_IMM (-1U); break;
          case 'v': used_bits |= ENCODE_RVC_IMM (-1U); break;
          case 'w': break; /* RS1S, constrained to equal RD */
          case 'x': break; /* RS2S, constrained to equal RD */
          case 'z': break; /* RS2S, contrained to be x0 */
          case 'K': used_bits |= ENCODE_RVC_ADDI4SPN_IMM (-1U); break;
          case 'L': used_bits |= ENCODE_RVC_ADDI16SP_IMM (-1U); break;
          case 'M': used_bits |= ENCODE_RVC_SWSP_IMM (-1U); break;
          case 'N': used_bits |= ENCODE_RVC_SDSP_IMM (-1U); break;
          case 'U': break; /* RS1, constrained to equal RD */
          case 'V': USE_BITS (OP_MASK_CRS2, OP_SH_CRS2); break;
          case '<': used_bits |= ENCODE_RVC_IMM (-1U); break;
          case '>': used_bits |= ENCODE_RVC_IMM (-1U); break;
          case '8': used_bits |= ENCODE_RVC_UIMM8 (-1U); break;
          case 'S': USE_BITS (OP_MASK_CRS1S, OP_SH_CRS1S); break;
          case 'T': USE_BITS (OP_MASK_CRS2, OP_SH_CRS2); break;
          case 'D': USE_BITS (OP_MASK_CRS2S, OP_SH_CRS2S); break;
          case 'F': /* funct */
            switch (c = *p++)
              {
                case '6': USE_BITS (OP_MASK_CFUNCT6, OP_SH_CFUNCT6); break;
                case '4': USE_BITS (OP_MASK_CFUNCT4, OP_SH_CFUNCT4); break;
                case '3': USE_BITS (OP_MASK_CFUNCT3, OP_SH_CFUNCT3); break;
                case '2': USE_BITS (OP_MASK_CFUNCT2, OP_SH_CFUNCT2); break;
                default:
                  as_bad (_("internal: bad RISC-V opcode"
                            " (unknown operand type `CF%c'): %s %s"),
                          c, opc->name, opc->args);
                  return FALSE;
              }
            break;
          default:
            as_bad (_("internal: bad RISC-V opcode (unknown operand type `C%c'): %s %s"),
                    c, opc->name, opc->args);
            return FALSE;
          }
        break;
      case ',': break;
      case '(': break;
      case ')': break;
      case '<': USE_BITS (OP_MASK_SHAMTW,       OP_SH_SHAMTW);  break;
      case '>': USE_BITS (OP_MASK_SHAMT,        OP_SH_SHAMT);   break;
      case 'A': break;
      case 'D': USE_BITS (OP_MASK_RD,           OP_SH_RD);      break;
      case 'Z': USE_BITS (OP_MASK_RS1,          OP_SH_RS1);     break;
      case 'E': USE_BITS (OP_MASK_CSR,          OP_SH_CSR);     break;
      case 'I': break;
      case 'R': USE_BITS (OP_MASK_RS3,          OP_SH_RS3);     break;
      case 'S': USE_BITS (OP_MASK_RS1,          OP_SH_RS1);     break;
      case 'U': USE_BITS (OP_MASK_RS1,          OP_SH_RS1);     /* fallthru */
      case 'T': USE_BITS (OP_MASK_RS2,          OP_SH_RS2);     break;
      case 'd': USE_BITS (OP_MASK_RD,           OP_SH_RD);      break;
      case 'm': USE_BITS (OP_MASK_RM,           OP_SH_RM);      break;
      case 's': USE_BITS (OP_MASK_RS1,          OP_SH_RS1);     break;
      case 't': USE_BITS (OP_MASK_RS2,          OP_SH_RS2);     break;
      case 'r': USE_BITS (OP_MASK_RS3,          OP_SH_RS3);     break;
      case 'P': USE_BITS (OP_MASK_PRED,         OP_SH_PRED); break;
      case 'Q': USE_BITS (OP_MASK_SUCC,         OP_SH_SUCC); break;
      case 'o':
      case 'j': used_bits |= ENCODE_ITYPE_IMM (-1U); break;
      case 'a': used_bits |= ENCODE_UJTYPE_IMM (-1U); break;
      case 'p': used_bits |= ENCODE_SBTYPE_IMM (-1U); break;
      case 'q': used_bits |= ENCODE_STYPE_IMM (-1U); break;
      case 'u': used_bits |= ENCODE_UTYPE_IMM (-1U); break;
      case 'z': break;
      case '[': break;
      case ']': break;
      case '0': break;
      case '1': break;
      case 'F': /* funct */
        switch (c = *p++)
          {
            case '7': USE_BITS (OP_MASK_FUNCT7, OP_SH_FUNCT7); break;
            case '3': USE_BITS (OP_MASK_FUNCT3, OP_SH_FUNCT3); break;
            case '2': USE_BITS (OP_MASK_FUNCT2, OP_SH_FUNCT2); break;
            default:
              as_bad (_("internal: bad RISC-V opcode"
                        " (unknown operand type `F%c'): %s %s"),
                      c, opc->name, opc->args);
            return FALSE;
          }
        break;
      case 'O': /* opcode */
        switch (c = *p++)
          {
            case '4': USE_BITS (OP_MASK_OP, OP_SH_OP); break;
            case '2': USE_BITS (OP_MASK_OP2, OP_SH_OP2); break;
            default:
              as_bad (_("internal: bad RISC-V opcode"
                        " (unknown operand type `F%c'): %s %s"),
                      c, opc->name, opc->args);
             return FALSE;
          }
        break;
      default:
        as_bad (_("internal: bad RISC-V opcode "
                  "(unknown operand type `%c'): %s %s"),
                c, opc->name, opc->args);
        return FALSE;
      }
#undef USE_BITS
  if (used_bits != required_bits)
    {
      as_bad (_("internal: bad RISC-V opcode (bits 0x%lx undefined): %s %s"),
              ~(unsigned long)(used_bits & required_bits),
              opc->name, opc->args);
      return FALSE;
    }
  return TRUE;
}

struct percent_op_match
{
  const char *str;
  bfd_reloc_code_real_type reloc;
};

/* Common hash table initialization function for
   instruction and .insn directive.  */
static struct hash_control *
init_opcode_hash (const struct riscv_opcode *opcodes,
                  bfd_boolean insn_directive_p)
{
  int i = 0;
  int length;
  struct hash_control *hash = hash_new ();
  while (opcodes[i].name)
    {
      const char *name = opcodes[i].name;
      const char *hash_error =
        hash_insert (hash, name, (void *) &opcodes[i]);

      if (hash_error != NULL)
        {
          fprintf (stderr, _("internal error: can't hash `%s': %s\n"),
                   opcodes[i].name, hash_error);
          /* Probably a memory allocation problem?  Give up now.  */
          as_fatal (_("Broken assembler.  No assembly attempted."));
        }

      do
        {
          if (opcodes[i].pinfo != INSN_MACRO)
            {
              if (insn_directive_p)
                length = ((name[0] == 'c') ? 2 : 4);
              else
                length = 0; /* Let assembler determine the length. */
              if (!validate_riscv_insn (&opcodes[i], length))
                as_fatal (_("Broken assembler.  No assembly attempted."));
            }
          else
            gas_assert (!insn_directive_p);
          ++i;
        }
      while (opcodes[i].name && !strcmp (opcodes[i].name, name));
    }

  return hash;
}

/* This function is called once, at assembler startup time.  It should set up
   all the tables, etc. that the MD part of the assembler will need.  */

void
md_begin (void)
{
  unsigned long mach = xlen == 64 ? bfd_mach_riscv64 : bfd_mach_riscv32;

  if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, mach))
    as_warn (_("Could not set architecture and machine"));

  op_hash = init_opcode_hash (riscv_opcodes, FALSE);
  insn_type_hash = init_opcode_hash (riscv_insn_types, TRUE);

  reg_names_hash = hash_new ();
  hash_reg_names (RCLASS_GPR, riscv_gpr_names_numeric, NGPR);
  hash_reg_names (RCLASS_GPR, riscv_gpr_names_abi, NGPR);
  hash_reg_names (RCLASS_FPR, riscv_fpr_names_numeric, NFPR);
  hash_reg_names (RCLASS_FPR, riscv_fpr_names_abi, NFPR);
  /* Add "fp" as an alias for "s0".  */
  hash_reg_name (RCLASS_GPR, "fp", 8);

  /* Create and insert CSR hash tables.  */
  csr_extra_hash = hash_new ();
#define DECLARE_CSR(name, num, class) riscv_init_csr_hashes (#name, num, class);
#define DECLARE_CSR_ALIAS(name, num, class) DECLARE_CSR(name, num, class);
#include "opcode/riscv-opc.h"
#undef DECLARE_CSR

  opcode_names_hash = hash_new ();
  init_opcode_names_hash ();

  /* Set the default alignment for the text section.  */
  record_alignment (text_section, riscv_opts.rvc ? 1 : 2);
}

static insn_t
riscv_apply_const_reloc (bfd_reloc_code_real_type reloc_type, bfd_vma value)
{
  switch (reloc_type)
    {
    case BFD_RELOC_32:
      return value;

    case BFD_RELOC_RISCV_HI20:
      return ENCODE_UTYPE_IMM (RISCV_CONST_HIGH_PART (value));

    case BFD_RELOC_RISCV_LO12_S:
      return ENCODE_STYPE_IMM (value);

    case BFD_RELOC_RISCV_LO12_I:
      return ENCODE_ITYPE_IMM (value);

    default:
      abort ();
    }
}

/* Output an instruction.  IP is the instruction information.
   ADDRESS_EXPR is an operand of the instruction to be used with
   RELOC_TYPE.  */

static void
append_insn (struct riscv_cl_insn *ip, expressionS *address_expr,
             bfd_reloc_code_real_type reloc_type)
{
  dwarf2_emit_insn (0);

  if (reloc_type != BFD_RELOC_UNUSED)
    {
      reloc_howto_type *howto;

      gas_assert (address_expr);
      if (reloc_type == BFD_RELOC_12_PCREL
          || reloc_type == BFD_RELOC_RISCV_JMP)
        {
          int j = reloc_type == BFD_RELOC_RISCV_JMP;
          int best_case = riscv_insn_length (ip->insn_opcode);
          unsigned worst_case = relaxed_branch_length (NULL, NULL, 0);
          add_relaxed_insn (ip, worst_case, best_case,
                            RELAX_BRANCH_ENCODE (j, best_case == 2, worst_case),
                            address_expr->X_add_symbol,
                            address_expr->X_add_number);
          return;
        }
      else
        {
          howto = bfd_reloc_type_lookup (stdoutput, reloc_type);
          if (howto == NULL)
            as_bad (_("Unsupported RISC-V relocation number %d"), reloc_type);

          ip->fixp = fix_new_exp (ip->frag, ip->where,
                                  bfd_get_reloc_size (howto),
                                  address_expr, FALSE, reloc_type);

          ip->fixp->fx_tcbit = riscv_opts.relax;
        }
    }

  add_fixed_insn (ip);
  install_insn (ip);

  /* We need to start a new frag after any instruction that can be
     optimized away or compressed by the linker during relaxation, to prevent
     the assembler from computing static offsets across such an instruction.
     This is necessary to get correct EH info.  */
  if (reloc_type == BFD_RELOC_RISCV_CALL
      || reloc_type == BFD_RELOC_RISCV_CALL_PLT
      || reloc_type == BFD_RELOC_RISCV_HI20
      || reloc_type == BFD_RELOC_RISCV_PCREL_HI20
      || reloc_type == BFD_RELOC_RISCV_TPREL_HI20
      || reloc_type == BFD_RELOC_RISCV_TPREL_ADD)
    {
      frag_wane (frag_now);
      frag_new (0);
    }
}

/* Build an instruction created by a macro expansion.  This is passed
   a pointer to the count of instructions created so far, an
   expression, the name of the instruction to build, an operand format
   string, and corresponding arguments.  */

static void
macro_build (expressionS *ep, const char *name, const char *fmt, ...)
{
  const struct riscv_opcode *mo;
  struct riscv_cl_insn insn;
  bfd_reloc_code_real_type r;
  va_list args;

  va_start (args, fmt);

  r = BFD_RELOC_UNUSED;
  mo = (struct riscv_opcode *) hash_find (op_hash, name);
  gas_assert (mo);

  /* Find a non-RVC variant of the instruction.  append_insn will compress
     it if possible.  */
  while (riscv_insn_length (mo->match) < 4)
    mo++;
  gas_assert (strcmp (name, mo->name) == 0);

  create_insn (&insn, mo);
  for (;;)
    {
      switch (*fmt++)
        {
        case 'd':
          INSERT_OPERAND (RD, insn, va_arg (args, int));
          continue;

        case 's':
          INSERT_OPERAND (RS1, insn, va_arg (args, int));
          continue;

        case 't':
          INSERT_OPERAND (RS2, insn, va_arg (args, int));
          continue;

        case '>':
          INSERT_OPERAND (SHAMT, insn, va_arg (args, int));
          continue;

        case 'j':
        case 'u':
        case 'q':
          gas_assert (ep != NULL);
          r = va_arg (args, int);
          continue;

        case '\0':
          break;
        case ',':
          continue;
        default:
          as_fatal (_("internal error: invalid macro"));
        }
      break;
    }
  va_end (args);
  gas_assert (r == BFD_RELOC_UNUSED ? ep == NULL : ep != NULL);

  append_insn (&insn, ep, r);
}

/* Build an instruction created by a macro expansion.  Like md_assemble but
   accept a printf-style format string and arguments.  */

static void
md_assemblef (const char *format, ...)
{
  char *buf = NULL;
  va_list ap;
  int r;

  va_start (ap, format);

  r = vasprintf (&buf, format, ap);

  if (r < 0)
    as_fatal (_("internal error: vasprintf failed"));

  md_assemble (buf);
  free(buf);

  va_end (ap);
}

/* Sign-extend 32-bit mode constants that have bit 31 set and all higher bits
   unset.  */
static void
normalize_constant_expr (expressionS *ex)
{
  if (xlen > 32)
    return;
  if ((ex->X_op == O_constant || ex->X_op == O_symbol)
      && IS_ZEXT_32BIT_NUM (ex->X_add_number))
    ex->X_add_number = (((ex->X_add_number & 0xffffffff) ^ 0x80000000)
                        - 0x80000000);
}

/* Fail if an expression EX is not a constant.  IP is the instruction using EX.
   MAYBE_CSR is true if the symbol may be an unrecognized CSR name.  */

static void
check_absolute_expr (struct riscv_cl_insn *ip, expressionS *ex,
                     bfd_boolean maybe_csr)
{
  if (ex->X_op == O_big)
    as_bad (_("unsupported large constant"));
  else if (maybe_csr && ex->X_op == O_symbol)
    as_bad (_("unknown CSR `%s'"),
            S_GET_NAME (ex->X_add_symbol));
  else if (ex->X_op != O_constant)
    as_bad (_("Instruction %s requires absolute expression"),
            ip->insn_mo->name);
  normalize_constant_expr (ex);
}

static symbolS *
make_internal_label (void)
{
  return (symbolS *) local_symbol_make (FAKE_LABEL_NAME, now_seg,
                                        (valueT) frag_now_fix (), frag_now);
}

/* Load an entry from the GOT.  */
static void
pcrel_access (int destreg, int tempreg, expressionS *ep,
              const char *lo_insn, const char *lo_pattern,
              bfd_reloc_code_real_type hi_reloc,
              bfd_reloc_code_real_type lo_reloc)
{
  expressionS ep2;
  ep2.X_op = O_symbol;
  ep2.X_add_symbol = make_internal_label ();
  ep2.X_add_number = 0;

  macro_build (ep, "auipc", "d,u", tempreg, hi_reloc);
  macro_build (&ep2, lo_insn, lo_pattern, destreg, tempreg, lo_reloc);
}

static void
pcrel_load (int destreg, int tempreg, expressionS *ep, const char *lo_insn,
            bfd_reloc_code_real_type hi_reloc,
            bfd_reloc_code_real_type lo_reloc)
{
  pcrel_access (destreg, tempreg, ep, lo_insn, "d,s,j", hi_reloc, lo_reloc);
}

static void
pcrel_store (int srcreg, int tempreg, expressionS *ep, const char *lo_insn,
             bfd_reloc_code_real_type hi_reloc,
             bfd_reloc_code_real_type lo_reloc)
{
  pcrel_access (srcreg, tempreg, ep, lo_insn, "t,s,q", hi_reloc, lo_reloc);
}

/* PC-relative function call using AUIPC/JALR, relaxed to JAL.  */
static void
riscv_call (int destreg, int tempreg, expressionS *ep,
            bfd_reloc_code_real_type reloc)
{
  macro_build (ep, "auipc", "d,u", tempreg, reloc);
  macro_build (NULL, "jalr", "d,s", destreg, tempreg);
}

/* Load an integer constant into a register.  */

static void
load_const (int reg, expressionS *ep)
{
  int shift = RISCV_IMM_BITS;
  bfd_vma upper_imm, sign = (bfd_vma) 1 << (RISCV_IMM_BITS - 1);
  expressionS upper = *ep, lower = *ep;
  lower.X_add_number = ((ep->X_add_number & (sign + sign - 1)) ^ sign) - sign;
  upper.X_add_number -= lower.X_add_number;

  if (ep->X_op != O_constant)
    {
      as_bad (_("unsupported large constant"));
      return;
    }

  if (xlen > 32 && !IS_SEXT_32BIT_NUM (ep->X_add_number))
    {
      /* Reduce to a signed 32-bit constant using SLLI and ADDI.  */
      while (((upper.X_add_number >> shift) & 1) == 0)
        shift++;

      upper.X_add_number = (int64_t) upper.X_add_number >> shift;
      load_const (reg, &upper);

      md_assemblef ("slli x%d, x%d, 0x%x", reg, reg, shift);
      if (lower.X_add_number != 0)
        md_assemblef ("addi x%d, x%d, %" BFD_VMA_FMT "d", reg, reg,
                      lower.X_add_number);
    }
  else
    {
      /* Simply emit LUI and/or ADDI to build a 32-bit signed constant.  */
      int hi_reg = 0;

      if (upper.X_add_number != 0)
        {
          /* Discard low part and zero-extend upper immediate.  */
          upper_imm = ((uint32_t)upper.X_add_number >> shift);

          md_assemblef ("lui x%d, 0x%" BFD_VMA_FMT "x", reg, upper_imm);
          hi_reg = reg;
        }

      if (lower.X_add_number != 0 || hi_reg == 0)
        md_assemblef ("%s x%d, x%d, %" BFD_VMA_FMT "d", ADD32_INSN, reg, hi_reg,
                      lower.X_add_number);
    }
}

/* Expand RISC-V assembly macros into one or more instructions.  */
static void
macro (struct riscv_cl_insn *ip, expressionS *imm_expr,
       bfd_reloc_code_real_type *imm_reloc)
{
  int rd = (ip->insn_opcode >> OP_SH_RD) & OP_MASK_RD;
  int rs1 = (ip->insn_opcode >> OP_SH_RS1) & OP_MASK_RS1;
  int rs2 = (ip->insn_opcode >> OP_SH_RS2) & OP_MASK_RS2;
  int mask = ip->insn_mo->mask;

  switch (mask)
    {
    case M_LI:
      load_const (rd, imm_expr);
      break;

    case M_LA:
    case M_LLA:
      /* Load the address of a symbol into a register.  */
      if (!IS_SEXT_32BIT_NUM (imm_expr->X_add_number))
        as_bad (_("offset too large"));

      if (imm_expr->X_op == O_constant)
        load_const (rd, imm_expr);
      else if (riscv_opts.pic && mask == M_LA) /* Global PIC symbol */
        pcrel_load (rd, rd, imm_expr, LOAD_ADDRESS_INSN,
                    BFD_RELOC_RISCV_GOT_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      else /* Local PIC symbol, or any non-PIC symbol */
        pcrel_load (rd, rd, imm_expr, "addi",
                    BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LA_TLS_GD:
      pcrel_load (rd, rd, imm_expr, "addi",
                  BFD_RELOC_RISCV_TLS_GD_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LA_TLS_IE:
      pcrel_load (rd, rd, imm_expr, LOAD_ADDRESS_INSN,
                  BFD_RELOC_RISCV_TLS_GOT_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LB:
      pcrel_load (rd, rd, imm_expr, "lb",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LBU:
      pcrel_load (rd, rd, imm_expr, "lbu",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LH:
      pcrel_load (rd, rd, imm_expr, "lh",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LHU:
      pcrel_load (rd, rd, imm_expr, "lhu",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LW:
      pcrel_load (rd, rd, imm_expr, "lw",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LWU:
      pcrel_load (rd, rd, imm_expr, "lwu",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_LD:
      pcrel_load (rd, rd, imm_expr, "ld",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_FLW:
      pcrel_load (rd, rs1, imm_expr, "flw",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_FLD:
      pcrel_load (rd, rs1, imm_expr, "fld",
                  BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_I);
      break;

    case M_SB:
      pcrel_store (rs2, rs1, imm_expr, "sb",
                   BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_S);
      break;

    case M_SH:
      pcrel_store (rs2, rs1, imm_expr, "sh",
                   BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_S);
      break;

    case M_SW:
      pcrel_store (rs2, rs1, imm_expr, "sw",
                   BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_S);
      break;

    case M_SD:
      pcrel_store (rs2, rs1, imm_expr, "sd",
                   BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_S);
      break;

    case M_FSW:
      pcrel_store (rs2, rs1, imm_expr, "fsw",
                   BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_S);
      break;

    case M_FSD:
      pcrel_store (rs2, rs1, imm_expr, "fsd",
                   BFD_RELOC_RISCV_PCREL_HI20, BFD_RELOC_RISCV_PCREL_LO12_S);
      break;

    case M_CALL:
      riscv_call (rd, rs1, imm_expr, *imm_reloc);
      break;

    default:
      as_bad (_("Macro %s not implemented"), ip->insn_mo->name);
      break;
    }
}

static const struct percent_op_match percent_op_utype[] =
{
  {"%tprel_hi", BFD_RELOC_RISCV_TPREL_HI20},
  {"%pcrel_hi", BFD_RELOC_RISCV_PCREL_HI20},
  {"%tls_ie_pcrel_hi", BFD_RELOC_RISCV_TLS_GOT_HI20},
  {"%tls_gd_pcrel_hi", BFD_RELOC_RISCV_TLS_GD_HI20},
  {"%hi", BFD_RELOC_RISCV_HI20},
  {0, 0}
};

static const struct percent_op_match percent_op_itype[] =
{
  {"%lo", BFD_RELOC_RISCV_LO12_I},
  {"%tprel_lo", BFD_RELOC_RISCV_TPREL_LO12_I},
  {"%pcrel_lo", BFD_RELOC_RISCV_PCREL_LO12_I},
  {0, 0}
};

static const struct percent_op_match percent_op_stype[] =
{
  {"%lo", BFD_RELOC_RISCV_LO12_S},
  {"%tprel_lo", BFD_RELOC_RISCV_TPREL_LO12_S},
  {"%pcrel_lo", BFD_RELOC_RISCV_PCREL_LO12_S},
  {0, 0}
};

static const struct percent_op_match percent_op_rtype[] =
{
  {"%tprel_add", BFD_RELOC_RISCV_TPREL_ADD},
  {0, 0}
};

static const struct percent_op_match percent_op_null[] =
{
  {0, 0}
};

/* Return true if *STR points to a relocation operator.  When returning true,
   move *STR over the operator and store its relocation code in *RELOC.
   Leave both *STR and *RELOC alone when returning false.  */

static bfd_boolean
parse_relocation (char **str, bfd_reloc_code_real_type *reloc,
                  const struct percent_op_match *percent_op)
{
  for ( ; percent_op->str; percent_op++)
    if (strncasecmp (*str, percent_op->str, strlen (percent_op->str)) == 0)
      {
        int len = strlen (percent_op->str);

        if (!ISSPACE ((*str)[len]) && (*str)[len] != '(')
          continue;

        *str += strlen (percent_op->str);
        *reloc = percent_op->reloc;

        /* Check whether the output BFD supports this relocation.
           If not, issue an error and fall back on something safe.  */
        if (*reloc != BFD_RELOC_UNUSED
            && !bfd_reloc_type_lookup (stdoutput, *reloc))
          {
            as_bad ("relocation %s isn't supported by the current ABI",
                    percent_op->str);
            *reloc = BFD_RELOC_UNUSED;
          }
        return TRUE;
      }
  return FALSE;
}

static void
my_getExpression (expressionS *ep, char *str)
{
  char *save_in;

  save_in = input_line_pointer;
  input_line_pointer = str;
  expression (ep);
  expr_end = input_line_pointer;
  input_line_pointer = save_in;
}

/* Parse string STR as a 16-bit relocatable operand.  Store the
   expression in *EP and the relocation, if any, in RELOC.
   Return the number of relocation operators used (0 or 1).

   On exit, EXPR_END points to the first character after the expression.  */

static size_t
my_getSmallExpression (expressionS *ep, bfd_reloc_code_real_type *reloc,
                       char *str, const struct percent_op_match *percent_op)
{
  size_t reloc_index;
  unsigned crux_depth, str_depth, regno;
  char *crux;

  /* First, check for integer registers.  No callers can accept a reg, but
     we need to avoid accidentally creating a useless undefined symbol below,
     if this is an instruction pattern that can't match.  A glibc build fails
     if this is removed.  */
  if (reg_lookup (&str, RCLASS_GPR, &regno))
    {
      ep->X_op = O_register;
      ep->X_add_number = regno;
      expr_end = str;
      return 0;
    }

  /* Search for the start of the main expression.
     End the loop with CRUX pointing to the start
     of the main expression and with CRUX_DEPTH containing the number
     of open brackets at that point.  */
  reloc_index = -1;
  str_depth = 0;
  do
    {
      reloc_index++;
      crux = str;
      crux_depth = str_depth;

      /* Skip over whitespace and brackets, keeping count of the number
         of brackets.  */
      while (*str == ' ' || *str == '\t' || *str == '(')
        if (*str++ == '(')
          str_depth++;
    }
  while (*str == '%'
         && reloc_index < 1
         && parse_relocation (&str, reloc, percent_op));

  my_getExpression (ep, crux);
  str = expr_end;

  /* Match every open bracket.  */
  while (crux_depth > 0 && (*str == ')' || *str == ' ' || *str == '\t'))
    if (*str++ == ')')
      crux_depth--;

  if (crux_depth > 0)
    as_bad ("unclosed '('");

  expr_end = str;

  return reloc_index;
}

/* Parse opcode name, could be an mnemonics or number.  */
static size_t
my_getOpcodeExpression (expressionS *ep, bfd_reloc_code_real_type *reloc,
                        char *str, const struct percent_op_match *percent_op)
{
  const struct opcode_name_t *o = opcode_name_lookup (&str);

  if (o != NULL)
    {
      ep->X_op = O_constant;
      ep->X_add_number = o->val;
      return 0;
    }

  return my_getSmallExpression (ep, reloc, str, percent_op);
}

/* Detect and handle implicitly zero load-store offsets.  For example,
   "lw t0, (t1)" is shorthand for "lw t0, 0(t1)".  Return TRUE iff such
   an implicit offset was detected.  */

static bfd_boolean
riscv_handle_implicit_zero_offset (expressionS *ep, const char *s)
{
  /* Check whether there is only a single bracketed expression left.
     If so, it must be the base register and the constant must be zero.  */
  if (*s == '(' && strchr (s + 1, '(') == 0)
    {
      ep->X_op = O_constant;
      ep->X_add_number = 0;
      return TRUE;
    }

  return FALSE;
}

/* All RISC-V CSR instructions belong to one of these classes.  */

enum csr_insn_type
{
  INSN_NOT_CSR,
  INSN_CSRRW,
  INSN_CSRRS,
  INSN_CSRRC
};

/* Return which CSR instruction is checking.  */

static enum csr_insn_type
riscv_csr_insn_type (insn_t insn)
{
  if (((insn ^ MATCH_CSRRW) & MASK_CSRRW) == 0
      || ((insn ^ MATCH_CSRRWI) & MASK_CSRRWI) == 0)
    return INSN_CSRRW;
  else if (((insn ^ MATCH_CSRRS) & MASK_CSRRS) == 0
           || ((insn ^ MATCH_CSRRSI) & MASK_CSRRSI) == 0)
    return INSN_CSRRS;
  else if (((insn ^ MATCH_CSRRC) & MASK_CSRRC) == 0
           || ((insn ^ MATCH_CSRRCI) & MASK_CSRRCI) == 0)
    return INSN_CSRRC;
  else
    return INSN_NOT_CSR;
}

/* CSRRW and CSRRWI always write CSR.  CSRRS, CSRRC, CSRRSI and CSRRCI write
   CSR when RS1 isn't zero.  The CSR is read only if the [11:10] bits of
   CSR address is 0x3.  */

static bfd_boolean
riscv_csr_read_only_check (insn_t insn)
{
  int csr = (insn & (OP_MASK_CSR << OP_SH_CSR)) >> OP_SH_CSR;
  int rs1 = (insn & (OP_MASK_RS1 << OP_SH_RS1)) >> OP_SH_RS1;
  int readonly = (((csr & (0x3 << 10)) >> 10) == 0x3);
  enum csr_insn_type csr_insn = riscv_csr_insn_type (insn);

  if (readonly
      && (((csr_insn == INSN_CSRRS
            || csr_insn == INSN_CSRRC)
           && rs1 != 0)
          || csr_insn == INSN_CSRRW))
    return FALSE;

  return TRUE;
}

/* This routine assembles an instruction into its binary format.  As a
   side effect, it sets the global variable imm_reloc to the type of
   relocation to do if one of the operands is an address expression.  */

static const char *
riscv_ip (char *str, struct riscv_cl_insn *ip, expressionS *imm_expr,
          bfd_reloc_code_real_type *imm_reloc, struct hash_control *hash)
{
  char *s;
  const char *args;
  char c = 0;
  struct riscv_opcode *insn;
  char *argsStart;
  unsigned int regno;
  char save_c = 0;
  int argnum;
  const struct percent_op_match *p;
  const char *error = "unrecognized opcode";
  /* Indicate we are assembling instruction with CSR.  */
  bfd_boolean insn_with_csr = FALSE;

  /* Parse the name of the instruction.  Terminate the string if whitespace
     is found so that hash_find only sees the name part of the string.  */
  for (s = str; *s != '\0'; ++s)
    if (ISSPACE (*s))
      {
        save_c = *s;
        *s++ = '\0';
        break;
      }

  insn = (struct riscv_opcode *) hash_find (hash, str);

  argsStart = s;
  for ( ; insn && insn->name && strcmp (insn->name, str) == 0; insn++)
    {
      if ((insn->xlen_requirement != 0) && (xlen != insn->xlen_requirement))
        continue;

      if (!riscv_multi_subset_supports (insn->insn_class))
        continue;

      create_insn (ip, insn);
      argnum = 1;

      imm_expr->X_op = O_absent;
      *imm_reloc = BFD_RELOC_UNUSED;
      p = percent_op_itype;

      for (args = insn->args;; ++args)
        {
          s += strspn (s, " \t");
          switch (*args)
            {
            case '\0':  /* End of args.  */
              if (insn->pinfo != INSN_MACRO)
                {
                  if (!insn->match_func (insn, ip->insn_opcode))
                    break;

                  /* For .insn, insn->match and insn->mask are 0.  */
                  if (riscv_insn_length ((insn->match == 0 && insn->mask == 0)
                                         ? ip->insn_opcode
                                         : insn->match) == 2
                      && !riscv_opts.rvc)
                    break;

                  /* Check if we write a read-only CSR by the CSR
                     instruction.  */
                  if (insn_with_csr
                      && riscv_opts.csr_check
                      && !riscv_csr_read_only_check (ip->insn_opcode))
                    {
                      /* Restore the character in advance, since we want to
                         report the detailed warning message here.  */
                      if (save_c)
                        *(argsStart - 1) = save_c;
                      as_warn (_("Read-only CSR is written `%s'"), str);
                      insn_with_csr = FALSE;
                    }
                }
              if (*s != '\0')
                break;
              /* Successful assembly.  */
              error = NULL;
              insn_with_csr = FALSE;
              goto out;

            case 'C': /* RVC */
              switch (*++args)
                {
                case 's': /* RS1 x8-x15 */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || !(regno >= 8 && regno <= 15))
                    break;
                  INSERT_OPERAND (CRS1S, *ip, regno % 8);
                  continue;
                case 'w': /* RS1 x8-x15, constrained to equal RD x8-x15.  */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || EXTRACT_OPERAND (CRS1S, ip->insn_opcode) + 8 != regno)
                    break;
                  continue;
                case 't': /* RS2 x8-x15 */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || !(regno >= 8 && regno <= 15))
                    break;
                  INSERT_OPERAND (CRS2S, *ip, regno % 8);
                  continue;
                case 'x': /* RS2 x8-x15, constrained to equal RD x8-x15.  */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || EXTRACT_OPERAND (CRS2S, ip->insn_opcode) + 8 != regno)
                    break;
                  continue;
                case 'U': /* RS1, constrained to equal RD.  */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || EXTRACT_OPERAND (RD, ip->insn_opcode) != regno)
                    break;
                  continue;
                case 'V': /* RS2 */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno))
                    break;
                  INSERT_OPERAND (CRS2, *ip, regno);
                  continue;
                case 'c': /* RS1, constrained to equal sp.  */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || regno != X_SP)
                    break;
                  continue;
                case 'z': /* RS2, contrained to equal x0.  */
                  if (!reg_lookup (&s, RCLASS_GPR, &regno)
                      || regno != 0)
                    break;
                  continue;
                case '>':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number <= 0
                      || imm_expr->X_add_number >= 64)
                    break;
                  ip->insn_opcode |= ENCODE_RVC_IMM (imm_expr->X_add_number);
                rvc_imm_done:
                  s = expr_end;
                  imm_expr->X_op = O_absent;
                  continue;
                case '<':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_IMM (imm_expr->X_add_number)
                      || imm_expr->X_add_number <= 0
                      || imm_expr->X_add_number >= 32)
                    break;
                  ip->insn_opcode |= ENCODE_RVC_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case '8':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_UIMM8 (imm_expr->X_add_number)
                      || imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= 256)
                    break;
                  ip->insn_opcode |= ENCODE_RVC_UIMM8 (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'i':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number == 0
                      || !VALID_RVC_SIMM3 (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |= ENCODE_RVC_SIMM3 (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'j':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number == 0
                      || !VALID_RVC_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |= ENCODE_RVC_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'k':
                  if (riscv_handle_implicit_zero_offset (imm_expr, s))
                    continue;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_LW_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |= ENCODE_RVC_LW_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'l':
                  if (riscv_handle_implicit_zero_offset (imm_expr, s))
                    continue;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_LD_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |= ENCODE_RVC_LD_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'm':
                  if (riscv_handle_implicit_zero_offset (imm_expr, s))
                    continue;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_LWSP_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |=
                    ENCODE_RVC_LWSP_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'n':
                  if (riscv_handle_implicit_zero_offset (imm_expr, s))
                    continue;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_LDSP_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |=
                    ENCODE_RVC_LDSP_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'o':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      /* C.addiw, c.li, and c.andi allow zero immediate.
                         C.addi allows zero immediate as hint.  Otherwise this
                         is same as 'j'.  */
                      || !VALID_RVC_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |= ENCODE_RVC_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'K':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_ADDI4SPN_IMM (imm_expr->X_add_number)
                      || imm_expr->X_add_number == 0)
                    break;
                  ip->insn_opcode |=
                    ENCODE_RVC_ADDI4SPN_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'L':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_ADDI16SP_IMM (imm_expr->X_add_number)
                      || imm_expr->X_add_number == 0)
                    break;
                  ip->insn_opcode |=
                    ENCODE_RVC_ADDI16SP_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'M':
                  if (riscv_handle_implicit_zero_offset (imm_expr, s))
                    continue;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_SWSP_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |=
                    ENCODE_RVC_SWSP_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'N':
                  if (riscv_handle_implicit_zero_offset (imm_expr, s))
                    continue;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || !VALID_RVC_SDSP_IMM (imm_expr->X_add_number))
                    break;
                  ip->insn_opcode |=
                    ENCODE_RVC_SDSP_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'u':
                  p = percent_op_utype;
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p))
                    break;
                rvc_lui:
                  if (imm_expr->X_op != O_constant
                      || imm_expr->X_add_number <= 0
                      || imm_expr->X_add_number >= RISCV_BIGIMM_REACH
                      || (imm_expr->X_add_number >= RISCV_RVC_IMM_REACH / 2
                          && (imm_expr->X_add_number <
                              RISCV_BIGIMM_REACH - RISCV_RVC_IMM_REACH / 2)))
                    break;
                  ip->insn_opcode |= ENCODE_RVC_IMM (imm_expr->X_add_number);
                  goto rvc_imm_done;
                case 'v':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || (imm_expr->X_add_number & (RISCV_IMM_REACH - 1))
                      || ((int32_t)imm_expr->X_add_number
                          != imm_expr->X_add_number))
                    break;
                  imm_expr->X_add_number =
                    ((uint32_t) imm_expr->X_add_number) >> RISCV_IMM_BITS;
                  goto rvc_lui;
                case 'p':
                  goto branch;
                case 'a':
                  goto jump;
                case 'S': /* Floating-point RS1 x8-x15.  */
                  if (!reg_lookup (&s, RCLASS_FPR, &regno)
                      || !(regno >= 8 && regno <= 15))
                    break;
                  INSERT_OPERAND (CRS1S, *ip, regno % 8);
                  continue;
                case 'D': /* Floating-point RS2 x8-x15.  */
                  if (!reg_lookup (&s, RCLASS_FPR, &regno)
                      || !(regno >= 8 && regno <= 15))
                    break;
                  INSERT_OPERAND (CRS2S, *ip, regno % 8);
                  continue;
                case 'T': /* Floating-point RS2.  */
                  if (!reg_lookup (&s, RCLASS_FPR, &regno))
                    break;
                  INSERT_OPERAND (CRS2, *ip, regno);
                  continue;
                case 'F':
                  switch (*++args)
                    {
                      case '6':
                        if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                            || imm_expr->X_op != O_constant
                            || imm_expr->X_add_number < 0
                            || imm_expr->X_add_number >= 64)
                          {
                            as_bad (_("bad value for funct6 field, "
                                      "value must be 0...64"));
                            break;
                          }

                        INSERT_OPERAND (CFUNCT6, *ip, imm_expr->X_add_number);
                        imm_expr->X_op = O_absent;
                        s = expr_end;
                        continue;
                      case '4':
                        if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                            || imm_expr->X_op != O_constant
                            || imm_expr->X_add_number < 0
                            || imm_expr->X_add_number >= 16)
                          {
                            as_bad (_("bad value for funct4 field, "
                                      "value must be 0...15"));
                            break;
                          }

                        INSERT_OPERAND (CFUNCT4, *ip, imm_expr->X_add_number);
                        imm_expr->X_op = O_absent;
                        s = expr_end;
                        continue;
                      case '3':
                        if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                            || imm_expr->X_op != O_constant
                            || imm_expr->X_add_number < 0
                            || imm_expr->X_add_number >= 8)
                          {
                            as_bad (_("bad value for funct3 field, "
                                      "value must be 0...7"));
                            break;
                          }
                        INSERT_OPERAND (CFUNCT3, *ip, imm_expr->X_add_number);
                        imm_expr->X_op = O_absent;
                        s = expr_end;
                        continue;
                      case '2':
                        if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                            || imm_expr->X_op != O_constant
                            || imm_expr->X_add_number < 0
                            || imm_expr->X_add_number >= 4)
                          {
                            as_bad (_("bad value for funct2 field, "
                                      "value must be 0...3"));
                            break;
                          }
                        INSERT_OPERAND (CFUNCT2, *ip, imm_expr->X_add_number);
                        imm_expr->X_op = O_absent;
                        s = expr_end;
                        continue;
                      default:
                        as_bad (_("bad compressed FUNCT field"
                                  " specifier 'CF%c'\n"),
                                *args);
                    }
                  break;

                default:
                  as_bad (_("bad RVC field specifier 'C%c'\n"), *args);
                }
              break;

            case ',':
              ++argnum;
              if (*s++ == *args)
                continue;
              s--;
              break;

            case '(':
            case ')':
            case '[':
            case ']':
              if (*s++ == *args)
                continue;
              break;

            case '<':           /* Shift amount, 0 - 31.  */
              my_getExpression (imm_expr, s);
              check_absolute_expr (ip, imm_expr, FALSE);
              if ((unsigned long) imm_expr->X_add_number > 31)
                as_bad (_("Improper shift amount (%lu)"),
                        (unsigned long) imm_expr->X_add_number);
              INSERT_OPERAND (SHAMTW, *ip, imm_expr->X_add_number);
              imm_expr->X_op = O_absent;
              s = expr_end;
              continue;

            case '>':           /* Shift amount, 0 - (XLEN-1).  */
              my_getExpression (imm_expr, s);
              check_absolute_expr (ip, imm_expr, FALSE);
              if ((unsigned long) imm_expr->X_add_number >= xlen)
                as_bad (_("Improper shift amount (%lu)"),
                        (unsigned long) imm_expr->X_add_number);
              INSERT_OPERAND (SHAMT, *ip, imm_expr->X_add_number);
              imm_expr->X_op = O_absent;
              s = expr_end;
              continue;

            case 'Z':           /* CSRRxI immediate.  */
              my_getExpression (imm_expr, s);
              check_absolute_expr (ip, imm_expr, FALSE);
              if ((unsigned long) imm_expr->X_add_number > 31)
                as_bad (_("Improper CSRxI immediate (%lu)"),
                        (unsigned long) imm_expr->X_add_number);
              INSERT_OPERAND (RS1, *ip, imm_expr->X_add_number);
              imm_expr->X_op = O_absent;
              s = expr_end;
              continue;

            case 'E':           /* Control register.  */
              insn_with_csr = TRUE;
              if (reg_lookup (&s, RCLASS_CSR, &regno))
                INSERT_OPERAND (CSR, *ip, regno);
              else
                {
                  my_getExpression (imm_expr, s);
                  check_absolute_expr (ip, imm_expr, TRUE);
                  if ((unsigned long) imm_expr->X_add_number > 0xfff)
                    as_bad (_("Improper CSR address (%lu)"),
                            (unsigned long) imm_expr->X_add_number);
                  INSERT_OPERAND (CSR, *ip, imm_expr->X_add_number);
                  imm_expr->X_op = O_absent;
                  s = expr_end;
                }
              continue;

            case 'm':           /* Rounding mode.  */
              if (arg_lookup (&s, riscv_rm, ARRAY_SIZE (riscv_rm), &regno))
                {
                  INSERT_OPERAND (RM, *ip, regno);
                  continue;
                }
              break;

            case 'P':
            case 'Q':           /* Fence predecessor/successor.  */
              if (arg_lookup (&s, riscv_pred_succ, ARRAY_SIZE (riscv_pred_succ),
                              &regno))
                {
                  if (*args == 'P')
                    INSERT_OPERAND (PRED, *ip, regno);
                  else
                    INSERT_OPERAND (SUCC, *ip, regno);
                  continue;
                }
              break;

            case 'd':           /* Destination register.  */
            case 's':           /* Source register.  */
            case 't':           /* Target register.  */
            case 'r':           /* rs3.  */
              if (reg_lookup (&s, RCLASS_GPR, &regno))
                {
                  c = *args;
                  if (*s == ' ')
                    ++s;

                  /* Now that we have assembled one operand, we use the args
                     string to figure out where it goes in the instruction.  */
                  switch (c)
                    {
                    case 's':
                      INSERT_OPERAND (RS1, *ip, regno);
                      break;
                    case 'd':
                      INSERT_OPERAND (RD, *ip, regno);
                      break;
                    case 't':
                      INSERT_OPERAND (RS2, *ip, regno);
                      break;
                    case 'r':
                      INSERT_OPERAND (RS3, *ip, regno);
                      break;
                    }
                  continue;
                }
              break;

            case 'D':           /* Floating point rd.  */
            case 'S':           /* Floating point rs1.  */
            case 'T':           /* Floating point rs2.  */
            case 'U':           /* Floating point rs1 and rs2.  */
            case 'R':           /* Floating point rs3.  */
              if (reg_lookup (&s, RCLASS_FPR, &regno))
                {
                  c = *args;
                  if (*s == ' ')
                    ++s;
                  switch (c)
                    {
                    case 'D':
                      INSERT_OPERAND (RD, *ip, regno);
                      break;
                    case 'S':
                      INSERT_OPERAND (RS1, *ip, regno);
                      break;
                    case 'U':
                      INSERT_OPERAND (RS1, *ip, regno);
                      /* fallthru */
                    case 'T':
                      INSERT_OPERAND (RS2, *ip, regno);
                      break;
                    case 'R':
                      INSERT_OPERAND (RS3, *ip, regno);
                      break;
                    }
                  continue;
                }

              break;

            case 'I':
              my_getExpression (imm_expr, s);
              if (imm_expr->X_op != O_big
                  && imm_expr->X_op != O_constant)
                break;
              normalize_constant_expr (imm_expr);
              s = expr_end;
              continue;

            case 'A':
              my_getExpression (imm_expr, s);
              normalize_constant_expr (imm_expr);
              /* The 'A' format specifier must be a symbol.  */
              if (imm_expr->X_op != O_symbol)
                break;
              *imm_reloc = BFD_RELOC_32;
              s = expr_end;
              continue;

            case 'B':
              my_getExpression (imm_expr, s);
              normalize_constant_expr (imm_expr);
              /* The 'B' format specifier must be a symbol or a constant.  */
              if (imm_expr->X_op != O_symbol && imm_expr->X_op != O_constant)
                break;
              if (imm_expr->X_op == O_symbol)
                *imm_reloc = BFD_RELOC_32;
              s = expr_end;
              continue;

            case 'j': /* Sign-extended immediate.  */
              p = percent_op_itype;
              *imm_reloc = BFD_RELOC_RISCV_LO12_I;
              goto alu_op;
            case 'q': /* Store displacement.  */
              p = percent_op_stype;
              *imm_reloc = BFD_RELOC_RISCV_LO12_S;
              goto load_store;
            case 'o': /* Load displacement.  */
              p = percent_op_itype;
              *imm_reloc = BFD_RELOC_RISCV_LO12_I;
              goto load_store;
            case '1': /* 4-operand add, must be %tprel_add.  */
              p = percent_op_rtype;
              goto alu_op;
            case '0': /* AMO "displacement," which must be zero.  */
              p = percent_op_null;
            load_store:
              if (riscv_handle_implicit_zero_offset (imm_expr, s))
                continue;
            alu_op:
              /* If this value won't fit into a 16 bit offset, then go
                 find a macro that will generate the 32 bit offset
                 code pattern.  */
              if (!my_getSmallExpression (imm_expr, imm_reloc, s, p))
                {
                  normalize_constant_expr (imm_expr);
                  if (imm_expr->X_op != O_constant
                      || (*args == '0' && imm_expr->X_add_number != 0)
                      || (*args == '1')
                      || imm_expr->X_add_number >= (signed)RISCV_IMM_REACH/2
                      || imm_expr->X_add_number < -(signed)RISCV_IMM_REACH/2)
                    break;
                }

              s = expr_end;
              continue;

            case 'p':           /* PC-relative offset.  */
            branch:
              *imm_reloc = BFD_RELOC_12_PCREL;
              my_getExpression (imm_expr, s);
              s = expr_end;
              continue;

            case 'u':           /* Upper 20 bits.  */
              p = percent_op_utype;
              if (!my_getSmallExpression (imm_expr, imm_reloc, s, p))
                {
                  if (imm_expr->X_op != O_constant)
                    break;

                  if (imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= (signed)RISCV_BIGIMM_REACH)
                    as_bad (_("lui expression not in range 0..1048575"));

                  *imm_reloc = BFD_RELOC_RISCV_HI20;
                  imm_expr->X_add_number <<= RISCV_IMM_BITS;
                }
              s = expr_end;
              continue;

            case 'a':           /* 20-bit PC-relative offset.  */
            jump:
              my_getExpression (imm_expr, s);
              s = expr_end;
              *imm_reloc = BFD_RELOC_RISCV_JMP;
              continue;

            case 'c':
              my_getExpression (imm_expr, s);
              s = expr_end;
              if (strcmp (s, "@plt") == 0)
                {
                  *imm_reloc = BFD_RELOC_RISCV_CALL_PLT;
                  s += 4;
                }
              else
                *imm_reloc = BFD_RELOC_RISCV_CALL;
              continue;
            case 'O':
              switch (*++args)
                {
                case '4':
                  if (my_getOpcodeExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= 128
                      || (imm_expr->X_add_number & 0x3) != 3)
                    {
                      as_bad (_("bad value for opcode field, "
                                "value must be 0...127 and "
                                "lower 2 bits must be 0x3"));
                      break;
                    }

                  INSERT_OPERAND (OP, *ip, imm_expr->X_add_number);
                  imm_expr->X_op = O_absent;
                  s = expr_end;
                  continue;
                case '2':
                  if (my_getOpcodeExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= 3)
                    {
                      as_bad (_("bad value for opcode field, "
                                "value must be 0...2"));
                      break;
                    }

                  INSERT_OPERAND (OP2, *ip, imm_expr->X_add_number);
                  imm_expr->X_op = O_absent;
                  s = expr_end;
                  continue;
                default:
                  as_bad (_("bad Opcode field specifier 'O%c'\n"), *args);
                }
              break;

            case 'F':
              switch (*++args)
                {
                case '7':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= 128)
                    {
                      as_bad (_("bad value for funct7 field, "
                                "value must be 0...127"));
                      break;
                    }

                  INSERT_OPERAND (FUNCT7, *ip, imm_expr->X_add_number);
                  imm_expr->X_op = O_absent;
                  s = expr_end;
                  continue;
                case '3':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= 8)
                    {
                      as_bad (_("bad value for funct3 field, "
                                "value must be 0...7"));
                      break;
                    }

                  INSERT_OPERAND (FUNCT3, *ip, imm_expr->X_add_number);
                  imm_expr->X_op = O_absent;
                  s = expr_end;
                  continue;
                case '2':
                  if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                      || imm_expr->X_op != O_constant
                      || imm_expr->X_add_number < 0
                      || imm_expr->X_add_number >= 4)
                    {
                      as_bad (_("bad value for funct2 field, "
                                "value must be 0...3"));
                      break;
                    }

                  INSERT_OPERAND (FUNCT2, *ip, imm_expr->X_add_number);
                  imm_expr->X_op = O_absent;
                  s = expr_end;
                  continue;

                default:
                  as_bad (_("bad FUNCT field specifier 'F%c'\n"), *args);
                }
              break;

            case 'z':
              if (my_getSmallExpression (imm_expr, imm_reloc, s, p)
                  || imm_expr->X_op != O_constant
                  || imm_expr->X_add_number != 0)
                break;
              s = expr_end;
              imm_expr->X_op = O_absent;
              continue;

            default:
              as_fatal (_("internal error: bad argument type %c"), *args);
            }
          break;
        }
      s = argsStart;
      error = _("illegal operands");
      insn_with_csr = FALSE;
    }

 out:
  /* Restore the character we might have clobbered above.  */
  if (save_c)
    *(argsStart - 1) = save_c;

  return error;
}

void
md_assemble (char *str)
{
  struct riscv_cl_insn insn;
  expressionS imm_expr;
  bfd_reloc_code_real_type imm_reloc = BFD_RELOC_UNUSED;

  const char *error = riscv_ip (str, &insn, &imm_expr, &imm_reloc, op_hash);

  start_assemble = TRUE;

  if (error)
    {
      as_bad ("%s `%s'", error, str);
      return;
    }

  if (insn.insn_mo->pinfo == INSN_MACRO)
    macro (&insn, &imm_expr, &imm_reloc);
  else
    append_insn (&insn, &imm_expr, imm_reloc);
}

const char *
md_atof (int type, char *litP, int *sizeP)
{
  return ieee_md_atof (type, litP, sizeP, TARGET_BYTES_BIG_ENDIAN);
}

void
md_number_to_chars (char *buf, valueT val, int n)
{
  number_to_chars_littleendian (buf, val, n);
}

const char *md_shortopts = "O::g::G:";

enum options
{
  OPTION_MARCH = OPTION_MD_BASE,
  OPTION_PIC,
  OPTION_NO_PIC,
  OPTION_MABI,
  OPTION_RELAX,
  OPTION_NO_RELAX,
  OPTION_ARCH_ATTR,
  OPTION_NO_ARCH_ATTR,
  OPTION_CSR_CHECK,
  OPTION_NO_CSR_CHECK,
  OPTION_END_OF_ENUM
};

struct option md_longopts[] =
{
  {"march", required_argument, NULL, OPTION_MARCH},
  {"fPIC", no_argument, NULL, OPTION_PIC},
  {"fpic", no_argument, NULL, OPTION_PIC},
  {"fno-pic", no_argument, NULL, OPTION_NO_PIC},
  {"mabi", required_argument, NULL, OPTION_MABI},
  {"mrelax", no_argument, NULL, OPTION_RELAX},
  {"mno-relax", no_argument, NULL, OPTION_NO_RELAX},
  {"march-attr", no_argument, NULL, OPTION_ARCH_ATTR},
  {"mno-arch-attr", no_argument, NULL, OPTION_NO_ARCH_ATTR},
  {"mcsr-check", no_argument, NULL, OPTION_CSR_CHECK},
  {"mno-csr-check", no_argument, NULL, OPTION_NO_CSR_CHECK},

  {NULL, no_argument, NULL, 0}
};
size_t md_longopts_size = sizeof (md_longopts);

enum float_abi {
  FLOAT_ABI_DEFAULT = -1,
  FLOAT_ABI_SOFT,
  FLOAT_ABI_SINGLE,
  FLOAT_ABI_DOUBLE,
  FLOAT_ABI_QUAD
};
static enum float_abi float_abi = FLOAT_ABI_DEFAULT;

static void
riscv_set_abi (unsigned new_xlen, enum float_abi new_float_abi, bfd_boolean rve)
{
  abi_xlen = new_xlen;
  float_abi = new_float_abi;
  rve_abi = rve;
}

int
md_parse_option (int c, const char *arg)
{
  switch (c)
    {
    case OPTION_MARCH:
      riscv_set_arch (arg);
      break;

    case OPTION_NO_PIC:
      riscv_opts.pic = FALSE;
      break;

    case OPTION_PIC:
      riscv_opts.pic = TRUE;
      break;

    case OPTION_MABI:
      if (strcmp (arg, "ilp32") == 0)
        riscv_set_abi (32, FLOAT_ABI_SOFT, FALSE);
      else if (strcmp (arg, "ilp32e") == 0)
        riscv_set_abi (32, FLOAT_ABI_SOFT, TRUE);
      else if (strcmp (arg, "ilp32f") == 0)
        riscv_set_abi (32, FLOAT_ABI_SINGLE, FALSE);
      else if (strcmp (arg, "ilp32d") == 0)
        riscv_set_abi (32, FLOAT_ABI_DOUBLE, FALSE);
      else if (strcmp (arg, "ilp32q") == 0)
        riscv_set_abi (32, FLOAT_ABI_QUAD, FALSE);
      else if (strcmp (arg, "lp64") == 0)
        riscv_set_abi (64, FLOAT_ABI_SOFT, FALSE);
      else if (strcmp (arg, "lp64f") == 0)
        riscv_set_abi (64, FLOAT_ABI_SINGLE, FALSE);
      else if (strcmp (arg, "lp64d") == 0)
        riscv_set_abi (64, FLOAT_ABI_DOUBLE, FALSE);
      else if (strcmp (arg, "lp64q") == 0)
        riscv_set_abi (64, FLOAT_ABI_QUAD, FALSE);
      else
        return 0;
      break;

    case OPTION_RELAX:
      riscv_opts.relax = TRUE;
      break;

    case OPTION_NO_RELAX:
      riscv_opts.relax = FALSE;
      break;

    case OPTION_ARCH_ATTR:
      riscv_opts.arch_attr = TRUE;
      break;

    case OPTION_NO_ARCH_ATTR:
      riscv_opts.arch_attr = FALSE;
      break;

    case OPTION_CSR_CHECK:
      riscv_opts.csr_check = TRUE;
      break;

    case OPTION_NO_CSR_CHECK:
      riscv_opts.csr_check = FALSE;
      break;

    default:
      return 0;
    }

  return 1;
}

void
riscv_after_parse_args (void)
{
  if (xlen == 0)
    {
      if (strcmp (default_arch, "riscv32") == 0)
        xlen = 32;
      else if (strcmp (default_arch, "riscv64") == 0)
        xlen = 64;
      else
        as_bad ("unknown default architecture `%s'", default_arch);
    }

  if (riscv_subsets.head == NULL)
    riscv_set_arch (xlen == 64 ? "rv64g" : "rv32g");

  /* Add the RVC extension, regardless of -march, to support .option rvc.  */
  riscv_set_rvc (FALSE);
  if (riscv_subset_supports ("c"))
    riscv_set_rvc (TRUE);

  /* Enable RVE if specified by the -march option.  */
  riscv_set_rve (FALSE);
  if (riscv_subset_supports ("e"))
    riscv_set_rve (TRUE);

  /* Infer ABI from ISA if not specified on command line.  */
  if (abi_xlen == 0)
    abi_xlen = xlen;
  else if (abi_xlen > xlen)
    as_bad ("can't have %d-bit ABI on %d-bit ISA", abi_xlen, xlen);
  else if (abi_xlen < xlen)
    as_bad ("%d-bit ABI not yet supported on %d-bit ISA", abi_xlen, xlen);

  if (float_abi == FLOAT_ABI_DEFAULT)
    {
      riscv_subset_t *subset;

      /* Assume soft-float unless D extension is present.  */
      float_abi = FLOAT_ABI_SOFT;

      for (subset = riscv_subsets.head; subset != NULL; subset = subset->next)
        {
          if (strcasecmp (subset->name, "D") == 0)
            float_abi = FLOAT_ABI_DOUBLE;
          if (strcasecmp (subset->name, "Q") == 0)
            float_abi = FLOAT_ABI_QUAD;
        }
    }

  if (rve_abi)
    elf_flags |= EF_RISCV_RVE;

  /* Insert float_abi into the EF_RISCV_FLOAT_ABI field of elf_flags.  */
  elf_flags |= float_abi * (EF_RISCV_FLOAT_ABI & ~(EF_RISCV_FLOAT_ABI << 1));

  /* If the CIE to be produced has not been overridden on the command line,
     then produce version 3 by default.  This allows us to use the full
     range of registers in a .cfi_return_column directive.  */
  if (flag_dwarf_cie_version == -1)
    flag_dwarf_cie_version = 3;
}

long
md_pcrel_from (fixS *fixP)
{
  return fixP->fx_where + fixP->fx_frag->fr_address;
}

/* Apply a fixup to the object file.  */

void
md_apply_fix (fixS *fixP, valueT *valP, segT seg ATTRIBUTE_UNUSED)
{
  unsigned int subtype;
  bfd_byte *buf = (bfd_byte *) (fixP->fx_frag->fr_literal + fixP->fx_where);
  bfd_boolean relaxable = FALSE;
  offsetT loc;
  segT sub_segment;

  /* Remember value for tc_gen_reloc.  */
  fixP->fx_addnumber = *valP;

  switch (fixP->fx_r_type)
    {
    case BFD_RELOC_RISCV_HI20:
    case BFD_RELOC_RISCV_LO12_I:
    case BFD_RELOC_RISCV_LO12_S:
      bfd_putl32 (riscv_apply_const_reloc (fixP->fx_r_type, *valP)
                  | bfd_getl32 (buf), buf);
      if (fixP->fx_addsy == NULL)
        fixP->fx_done = TRUE;
      relaxable = TRUE;
      break;

    case BFD_RELOC_RISCV_GOT_HI20:
    case BFD_RELOC_RISCV_ADD8:
    case BFD_RELOC_RISCV_ADD16:
    case BFD_RELOC_RISCV_ADD32:
    case BFD_RELOC_RISCV_ADD64:
    case BFD_RELOC_RISCV_SUB6:
    case BFD_RELOC_RISCV_SUB8:
    case BFD_RELOC_RISCV_SUB16:
    case BFD_RELOC_RISCV_SUB32:
    case BFD_RELOC_RISCV_SUB64:
    case BFD_RELOC_RISCV_RELAX:
      break;

    case BFD_RELOC_RISCV_TPREL_HI20:
    case BFD_RELOC_RISCV_TPREL_LO12_I:
    case BFD_RELOC_RISCV_TPREL_LO12_S:
    case BFD_RELOC_RISCV_TPREL_ADD:
      relaxable = TRUE;
      /* Fall through.  */

    case BFD_RELOC_RISCV_TLS_GOT_HI20:
    case BFD_RELOC_RISCV_TLS_GD_HI20:
    case BFD_RELOC_RISCV_TLS_DTPREL32:
    case BFD_RELOC_RISCV_TLS_DTPREL64:
      if (fixP->fx_addsy != NULL)
        S_SET_THREAD_LOCAL (fixP->fx_addsy);
      else
        as_bad_where (fixP->fx_file, fixP->fx_line,
                      _("TLS relocation against a constant"));
      break;

    case BFD_RELOC_32:
      /* Use pc-relative relocation for FDE initial location.
         The symbol address in .eh_frame may be adjusted in
         _bfd_elf_discard_section_eh_frame, and the content of
         .eh_frame will be adjusted in _bfd_elf_write_section_eh_frame.
         Therefore, we cannot insert a relocation whose addend symbol is
         in .eh_frame. Othrewise, the value may be adjusted twice.*/
      if (fixP->fx_addsy && fixP->fx_subsy
          && (sub_segment = S_GET_SEGMENT (fixP->fx_subsy))
          && strcmp (sub_segment->name, ".eh_frame") == 0
          && S_GET_VALUE (fixP->fx_subsy)
             == fixP->fx_frag->fr_address + fixP->fx_where)
        {
          fixP->fx_r_type = BFD_RELOC_RISCV_32_PCREL;
          fixP->fx_subsy = NULL;
          break;
        }
      /* Fall through.  */
    case BFD_RELOC_64:
    case BFD_RELOC_16:
    case BFD_RELOC_8:
    case BFD_RELOC_RISCV_CFA:
      if (fixP->fx_addsy && fixP->fx_subsy)
        {
          fixP->fx_next = xmemdup (fixP, sizeof (*fixP), sizeof (*fixP));
          fixP->fx_next->fx_addsy = fixP->fx_subsy;
          fixP->fx_next->fx_subsy = NULL;
          fixP->fx_next->fx_offset = 0;
          fixP->fx_subsy = NULL;

          switch (fixP->fx_r_type)
            {
            case BFD_RELOC_64:
              fixP->fx_r_type = BFD_RELOC_RISCV_ADD64;
              fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB64;
              break;

            case BFD_RELOC_32:
              fixP->fx_r_type = BFD_RELOC_RISCV_ADD32;
              fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB32;
              break;

            case BFD_RELOC_16:
              fixP->fx_r_type = BFD_RELOC_RISCV_ADD16;
              fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB16;
              break;

            case BFD_RELOC_8:
              fixP->fx_r_type = BFD_RELOC_RISCV_ADD8;
              fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB8;
              break;

            case BFD_RELOC_RISCV_CFA:
              /* Load the byte to get the subtype.  */
              subtype = bfd_get_8 (NULL, &((fragS *) (fixP->fx_frag->fr_opcode))->fr_literal[fixP->fx_where]);
              loc = fixP->fx_frag->fr_fix - (subtype & 7);
              switch (subtype)
                {
                case DW_CFA_advance_loc1:
                  fixP->fx_where = loc + 1;
                  fixP->fx_next->fx_where = loc + 1;
                  fixP->fx_r_type = BFD_RELOC_RISCV_SET8;
                  fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB8;
                  break;

                case DW_CFA_advance_loc2:
                  fixP->fx_size = 2;
                  fixP->fx_next->fx_size = 2;
                  fixP->fx_where = loc + 1;
                  fixP->fx_next->fx_where = loc + 1;
                  fixP->fx_r_type = BFD_RELOC_RISCV_SET16;
                  fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB16;
                  break;

                case DW_CFA_advance_loc4:
                  fixP->fx_size = 4;
                  fixP->fx_next->fx_size = 4;
                  fixP->fx_where = loc;
                  fixP->fx_next->fx_where = loc;
                  fixP->fx_r_type = BFD_RELOC_RISCV_SET32;
                  fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB32;
                  break;

                default:
                  if (subtype < 0x80 && (subtype & 0x40))
                    {
                      /* DW_CFA_advance_loc */
                      fixP->fx_frag = (fragS *) fixP->fx_frag->fr_opcode;
                      fixP->fx_next->fx_frag = fixP->fx_frag;
                      fixP->fx_r_type = BFD_RELOC_RISCV_SET6;
                      fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_SUB6;
                    }
                  else
                    as_fatal (_("internal error: bad CFA value #%d"), subtype);
                  break;
                }
              break;

            default:
              /* This case is unreachable.  */
              abort ();
            }
        }
      /* Fall through.  */

    case BFD_RELOC_RVA:
      /* If we are deleting this reloc entry, we must fill in the
         value now.  This can happen if we have a .word which is not
         resolved when it appears but is later defined.  */
      if (fixP->fx_addsy == NULL)
        {
          gas_assert (fixP->fx_size <= sizeof (valueT));
          md_number_to_chars ((char *) buf, *valP, fixP->fx_size);
          fixP->fx_done = 1;
        }
      break;

    case BFD_RELOC_RISCV_JMP:
      if (fixP->fx_addsy)
        {
          /* Fill in a tentative value to improve objdump readability.  */
          bfd_vma target = S_GET_VALUE (fixP->fx_addsy) + *valP;
          bfd_vma delta = target - md_pcrel_from (fixP);
          bfd_putl32 (bfd_getl32 (buf) | ENCODE_UJTYPE_IMM (delta), buf);
        }
      break;

    case BFD_RELOC_12_PCREL:
      if (fixP->fx_addsy)
        {
          /* Fill in a tentative value to improve objdump readability.  */
          bfd_vma target = S_GET_VALUE (fixP->fx_addsy) + *valP;
          bfd_vma delta = target - md_pcrel_from (fixP);
          bfd_putl32 (bfd_getl32 (buf) | ENCODE_SBTYPE_IMM (delta), buf);
        }
      break;

    case BFD_RELOC_RISCV_RVC_BRANCH:
      if (fixP->fx_addsy)
        {
          /* Fill in a tentative value to improve objdump readability.  */
          bfd_vma target = S_GET_VALUE (fixP->fx_addsy) + *valP;
          bfd_vma delta = target - md_pcrel_from (fixP);
          bfd_putl16 (bfd_getl16 (buf) | ENCODE_RVC_B_IMM (delta), buf);
        }
      break;

    case BFD_RELOC_RISCV_RVC_JUMP:
      if (fixP->fx_addsy)
        {
          /* Fill in a tentative value to improve objdump readability.  */
          bfd_vma target = S_GET_VALUE (fixP->fx_addsy) + *valP;
          bfd_vma delta = target - md_pcrel_from (fixP);
          bfd_putl16 (bfd_getl16 (buf) | ENCODE_RVC_J_IMM (delta), buf);
        }
      break;

    case BFD_RELOC_RISCV_CALL:
    case BFD_RELOC_RISCV_CALL_PLT:
      relaxable = TRUE;
      break;

    case BFD_RELOC_RISCV_PCREL_HI20:
    case BFD_RELOC_RISCV_PCREL_LO12_S:
    case BFD_RELOC_RISCV_PCREL_LO12_I:
      relaxable = riscv_opts.relax;
      break;

    case BFD_RELOC_RISCV_ALIGN:
      break;

    default:
      /* We ignore generic BFD relocations we don't know about.  */
      if (bfd_reloc_type_lookup (stdoutput, fixP->fx_r_type) != NULL)
        as_fatal (_("internal error: bad relocation #%d"), fixP->fx_r_type);
    }

  if (fixP->fx_subsy != NULL)
    as_bad_where (fixP->fx_file, fixP->fx_line,
                  _("unsupported symbol subtraction"));

  /* Add an R_RISCV_RELAX reloc if the reloc is relaxable.  */
  if (relaxable && fixP->fx_tcbit && fixP->fx_addsy != NULL)
    {
      fixP->fx_next = xmemdup (fixP, sizeof (*fixP), sizeof (*fixP));
      fixP->fx_next->fx_addsy = fixP->fx_next->fx_subsy = NULL;
      fixP->fx_next->fx_r_type = BFD_RELOC_RISCV_RELAX;
    }
}

/* Because the value of .cfi_remember_state may changed after relaxation,
   we insert a fix to relocate it again in link-time.  */

void
riscv_pre_output_hook (void)
{
  const frchainS *frch;
  const asection *s;

  for (s = stdoutput->sections; s; s = s->next)
    for (frch = seg_info (s)->frchainP; frch; frch = frch->frch_next)
      {
        fragS *frag;

        for (frag = frch->frch_root; frag; frag = frag->fr_next)
          {
            if (frag->fr_type == rs_cfa)
              {
                expressionS exp;
                expressionS *symval;

                symval = symbol_get_value_expression (frag->fr_symbol);
                exp.X_op = O_subtract;
                exp.X_add_symbol = symval->X_add_symbol;
                exp.X_add_number = 0;
                exp.X_op_symbol = symval->X_op_symbol;

                fix_new_exp (frag, (int) frag->fr_offset, 1, &exp, 0,
                             BFD_RELOC_RISCV_CFA);
              }
          }
      }
}


/* This structure is used to hold a stack of .option values.  */

struct riscv_option_stack
{
  struct riscv_option_stack *next;
  struct riscv_set_options options;
};

static struct riscv_option_stack *riscv_opts_stack;

/* Handle the .option pseudo-op.  */

static void
s_riscv_option (int x ATTRIBUTE_UNUSED)
{
  char *name = input_line_pointer, ch;

  while (!is_end_of_line[(unsigned char) *input_line_pointer])
    ++input_line_pointer;
  ch = *input_line_pointer;
  *input_line_pointer = '\0';

  if (strcmp (name, "rvc") == 0)
    riscv_set_rvc (TRUE);
  else if (strcmp (name, "norvc") == 0)
    riscv_set_rvc (FALSE);
  else if (strcmp (name, "pic") == 0)
    riscv_opts.pic = TRUE;
  else if (strcmp (name, "nopic") == 0)
    riscv_opts.pic = FALSE;
  else if (strcmp (name, "relax") == 0)
    riscv_opts.relax = TRUE;
  else if (strcmp (name, "norelax") == 0)
    riscv_opts.relax = FALSE;
  else if (strcmp (name, "csr-check") == 0)
    riscv_opts.csr_check = TRUE;
  else if (strcmp (name, "no-csr-check") == 0)
    riscv_opts.csr_check = FALSE;
  else if (strcmp (name, "push") == 0)
    {
      struct riscv_option_stack *s;

      s = (struct riscv_option_stack *) xmalloc (sizeof *s);
      s->next = riscv_opts_stack;
      s->options = riscv_opts;
      riscv_opts_stack = s;
    }
  else if (strcmp (name, "pop") == 0)
    {
      struct riscv_option_stack *s;

      s = riscv_opts_stack;
      if (s == NULL)
        as_bad (_(".option pop with no .option push"));
      else
        {
          riscv_opts = s->options;
          riscv_opts_stack = s->next;
          free (s);
        }
    }
  else
    {
      as_warn (_("Unrecognized .option directive: %s\n"), name);
    }
  *input_line_pointer = ch;
  demand_empty_rest_of_line ();
}

/* Handle the .dtprelword and .dtpreldword pseudo-ops.  They generate
   a 32-bit or 64-bit DTP-relative relocation (BYTES says which) for
   use in DWARF debug information.  */

static void
s_dtprel (int bytes)
{
  expressionS ex;
  char *p;

  expression (&ex);

  if (ex.X_op != O_symbol)
    {
      as_bad (_("Unsupported use of %s"), (bytes == 8
                                           ? ".dtpreldword"
                                           : ".dtprelword"));
      ignore_rest_of_line ();
    }

  p = frag_more (bytes);
  md_number_to_chars (p, 0, bytes);
  fix_new_exp (frag_now, p - frag_now->fr_literal, bytes, &ex, FALSE,
               (bytes == 8
                ? BFD_RELOC_RISCV_TLS_DTPREL64
                : BFD_RELOC_RISCV_TLS_DTPREL32));

  demand_empty_rest_of_line ();
}

/* Handle the .bss pseudo-op.  */

static void
s_bss (int ignore ATTRIBUTE_UNUSED)
{
  subseg_set (bss_section, 0);
  demand_empty_rest_of_line ();
}

static void
riscv_make_nops (char *buf, bfd_vma bytes)
{
  bfd_vma i = 0;

  /* RISC-V instructions cannot begin or end on odd addresses, so this case
     means we are not within a valid instruction sequence.  It is thus safe
     to use a zero byte, even though that is not a valid instruction.  */
  if (bytes % 2 == 1)
    buf[i++] = 0;

  /* Use at most one 2-byte NOP.  */
  if ((bytes - i) % 4 == 2)
    {
      md_number_to_chars (buf + i, RVC_NOP, 2);
      i += 2;
    }

  /* Fill the remainder with 4-byte NOPs.  */
  for ( ; i < bytes; i += 4)
    md_number_to_chars (buf + i, RISCV_NOP, 4);
}

/* Called from md_do_align.  Used to create an alignment frag in a
   code section by emitting a worst-case NOP sequence that the linker
   will later relax to the correct number of NOPs.  We can't compute
   the correct alignment now because of other linker relaxations.  */

bfd_boolean
riscv_frag_align_code (int n)
{
  bfd_vma bytes = (bfd_vma) 1 << n;
  bfd_vma insn_alignment = riscv_opts.rvc ? 2 : 4;
  bfd_vma worst_case_bytes = bytes - insn_alignment;
  char *nops;
  expressionS ex;

  /* If we are moving to a smaller alignment than the instruction size, then no
     alignment is required. */
  if (bytes <= insn_alignment)
    return TRUE;

  /* When not relaxing, riscv_handle_align handles code alignment.  */
  if (!riscv_opts.relax)
    return FALSE;

  nops = frag_more (worst_case_bytes);

  ex.X_op = O_constant;
  ex.X_add_number = worst_case_bytes;

  riscv_make_nops (nops, worst_case_bytes);

  fix_new_exp (frag_now, nops - frag_now->fr_literal, 0,
               &ex, FALSE, BFD_RELOC_RISCV_ALIGN);

  return TRUE;
}

/* Implement HANDLE_ALIGN.  */

void
riscv_handle_align (fragS *fragP)
{
  switch (fragP->fr_type)
    {
    case rs_align_code:
      /* When relaxing, riscv_frag_align_code handles code alignment.  */
      if (!riscv_opts.relax)
        {
          bfd_signed_vma bytes = (fragP->fr_next->fr_address
                                  - fragP->fr_address - fragP->fr_fix);
          /* We have 4 byte uncompressed nops.  */
          bfd_signed_vma size = 4;
          bfd_signed_vma excess = bytes % size;
          char *p = fragP->fr_literal + fragP->fr_fix;

          if (bytes <= 0)
            break;

          /* Insert zeros or compressed nops to get 4 byte alignment.  */
          if (excess)
            {
              riscv_make_nops (p, excess);
              fragP->fr_fix += excess;
              p += excess;
            }

          /* Insert variable number of 4 byte uncompressed nops.  */
          riscv_make_nops (p, size);
          fragP->fr_var = size;
        }
      break;

    default:
      break;
    }
}

int
md_estimate_size_before_relax (fragS *fragp, asection *segtype)
{
  return (fragp->fr_var = relaxed_branch_length (fragp, segtype, FALSE));
}

/* Translate internal representation of relocation info to BFD target
   format.  */

arelent *
tc_gen_reloc (asection *section ATTRIBUTE_UNUSED, fixS *fixp)
{
  arelent *reloc = (arelent *) xmalloc (sizeof (arelent));

  reloc->sym_ptr_ptr = (asymbol **) xmalloc (sizeof (asymbol *));
  *reloc->sym_ptr_ptr = symbol_get_bfdsym (fixp->fx_addsy);
  reloc->address = fixp->fx_frag->fr_address + fixp->fx_where;
  reloc->addend = fixp->fx_addnumber;

  reloc->howto = bfd_reloc_type_lookup (stdoutput, fixp->fx_r_type);
  if (reloc->howto == NULL)
    {
      if ((fixp->fx_r_type == BFD_RELOC_16 || fixp->fx_r_type == BFD_RELOC_8)
          && fixp->fx_addsy != NULL && fixp->fx_subsy != NULL)
        {
          /* We don't have R_RISCV_8/16, but for this special case,
             we can use R_RISCV_ADD8/16 with R_RISCV_SUB8/16.  */
          return reloc;
        }

      as_bad_where (fixp->fx_file, fixp->fx_line,
                    _("cannot represent %s relocation in object file"),
                    bfd_get_reloc_code_name (fixp->fx_r_type));
      return NULL;
    }

  return reloc;
}

int
riscv_relax_frag (asection *sec, fragS *fragp, long stretch ATTRIBUTE_UNUSED)
{
  if (RELAX_BRANCH_P (fragp->fr_subtype))
    {
      offsetT old_var = fragp->fr_var;
      fragp->fr_var = relaxed_branch_length (fragp, sec, TRUE);
      return fragp->fr_var - old_var;
    }

  return 0;
}

/* Expand far branches to multi-instruction sequences.  */

static void
md_convert_frag_branch (fragS *fragp)
{
  bfd_byte *buf;
  expressionS exp;
  fixS *fixp;
  insn_t insn;
  int rs1, reloc;

  buf = (bfd_byte *)fragp->fr_literal + fragp->fr_fix;

  exp.X_op = O_symbol;
  exp.X_add_symbol = fragp->fr_symbol;
  exp.X_add_number = fragp->fr_offset;

  gas_assert (fragp->fr_var == RELAX_BRANCH_LENGTH (fragp->fr_subtype));

  if (RELAX_BRANCH_RVC (fragp->fr_subtype))
    {
      switch (RELAX_BRANCH_LENGTH (fragp->fr_subtype))
        {
          case 8:
          case 4:
            /* Expand the RVC branch into a RISC-V one.  */
            insn = bfd_getl16 (buf);
            rs1 = 8 + ((insn >> OP_SH_CRS1S) & OP_MASK_CRS1S);
            if ((insn & MASK_C_J) == MATCH_C_J)
              insn = MATCH_JAL;
            else if ((insn & MASK_C_JAL) == MATCH_C_JAL)
              insn = MATCH_JAL | (X_RA << OP_SH_RD);
            else if ((insn & MASK_C_BEQZ) == MATCH_C_BEQZ)
              insn = MATCH_BEQ | (rs1 << OP_SH_RS1);
            else if ((insn & MASK_C_BNEZ) == MATCH_C_BNEZ)
              insn = MATCH_BNE | (rs1 << OP_SH_RS1);
            else
              abort ();
            bfd_putl32 (insn, buf);
            break;

          case 6:
            /* Invert the branch condition.  Branch over the jump.  */
            insn = bfd_getl16 (buf);
            insn ^= MATCH_C_BEQZ ^ MATCH_C_BNEZ;
            insn |= ENCODE_RVC_B_IMM (6);
            bfd_putl16 (insn, buf);
            buf += 2;
            goto jump;

          case 2:
            /* Just keep the RVC branch.  */
            reloc = RELAX_BRANCH_UNCOND (fragp->fr_subtype)
                    ? BFD_RELOC_RISCV_RVC_JUMP : BFD_RELOC_RISCV_RVC_BRANCH;
            fixp = fix_new_exp (fragp, buf - (bfd_byte *)fragp->fr_literal,
                                2, &exp, FALSE, reloc);
            buf += 2;
            goto done;

          default:
            abort ();
        }
    }

  switch (RELAX_BRANCH_LENGTH (fragp->fr_subtype))
    {
    case 8:
      gas_assert (!RELAX_BRANCH_UNCOND (fragp->fr_subtype));

      /* Invert the branch condition.  Branch over the jump.  */
      insn = bfd_getl32 (buf);
      insn ^= MATCH_BEQ ^ MATCH_BNE;
      insn |= ENCODE_SBTYPE_IMM (8);
      md_number_to_chars ((char *) buf, insn, 4);
      buf += 4;

    jump:
      /* Jump to the target.  */
      fixp = fix_new_exp (fragp, buf - (bfd_byte *)fragp->fr_literal,
                          4, &exp, FALSE, BFD_RELOC_RISCV_JMP);
      md_number_to_chars ((char *) buf, MATCH_JAL, 4);
      buf += 4;
      break;

    case 4:
      reloc = RELAX_BRANCH_UNCOND (fragp->fr_subtype)
              ? BFD_RELOC_RISCV_JMP : BFD_RELOC_12_PCREL;
      fixp = fix_new_exp (fragp, buf - (bfd_byte *)fragp->fr_literal,
                          4, &exp, FALSE, reloc);
      buf += 4;
      break;

    default:
      abort ();
    }

 done:
  fixp->fx_file = fragp->fr_file;
  fixp->fx_line = fragp->fr_line;

  gas_assert (buf == (bfd_byte *)fragp->fr_literal
              + fragp->fr_fix + fragp->fr_var);

  fragp->fr_fix += fragp->fr_var;
}

/* Relax a machine dependent frag.  This returns the amount by which
   the current size of the frag should change.  */

void
md_convert_frag (bfd *abfd ATTRIBUTE_UNUSED, segT asec ATTRIBUTE_UNUSED,
                 fragS *fragp)
{
  gas_assert (RELAX_BRANCH_P (fragp->fr_subtype));
  md_convert_frag_branch (fragp);
}

void
md_show_usage (FILE *stream)
{
  fprintf (stream, _("\
RISC-V options:\n\
  -fpic          generate position-independent code\n\
  -fno-pic       don't generate position-independent code (default)\n\
  -march=ISA     set the RISC-V architecture\n\
  -mabi=ABI      set the RISC-V ABI\n\
  -mrelax        enable relax (default)\n\
  -mno-relax     disable relax\n\
  -march-attr    generate RISC-V arch attribute\n\
  -mno-arch-attr don't generate RISC-V arch attribute\n\
"));
}

/* Standard calling conventions leave the CFA at SP on entry.  */
void
riscv_cfi_frame_initial_instructions (void)
{
  cfi_add_CFA_def_cfa_register (X_SP);
}

int
tc_riscv_regname_to_dw2regnum (char *regname)
{
  int reg;

  if ((reg = reg_lookup_internal (regname, RCLASS_GPR)) >= 0)
    return reg;

  if ((reg = reg_lookup_internal (regname, RCLASS_FPR)) >= 0)
    return reg + 32;

  /* CSRs are numbered 4096 -> 8191.  */
  if ((reg = reg_lookup_internal (regname, RCLASS_CSR)) >= 0)
    return reg + 4096;

  as_bad (_("unknown register `%s'"), regname);
  return -1;
}

void
riscv_elf_final_processing (void)
{
  elf_elfheader (stdoutput)->e_flags |= elf_flags;
}

/* Parse the .sleb128 and .uleb128 pseudos.  Only allow constant expressions,
   since these directives break relaxation when used with symbol deltas.  */

static void
s_riscv_leb128 (int sign)
{
  expressionS exp;
  char *save_in = input_line_pointer;

  expression (&exp);
  if (exp.X_op != O_constant)
    as_bad (_("non-constant .%cleb128 is not supported"), sign ? 's' : 'u');
  demand_empty_rest_of_line ();

  input_line_pointer = save_in;
  return s_leb128 (sign);
}

/* Parse the .insn directive.  */

static void
s_riscv_insn (int x ATTRIBUTE_UNUSED)
{
  char *str = input_line_pointer;
  struct riscv_cl_insn insn;
  expressionS imm_expr;
  bfd_reloc_code_real_type imm_reloc = BFD_RELOC_UNUSED;
  char save_c;

  while (!is_end_of_line[(unsigned char) *input_line_pointer])
    ++input_line_pointer;

  save_c = *input_line_pointer;
  *input_line_pointer = '\0';

  const char *error = riscv_ip (str, &insn, &imm_expr,
                                &imm_reloc, insn_type_hash);

  if (error)
    {
      as_bad ("%s `%s'", error, str);
    }
  else
    {
      gas_assert (insn.insn_mo->pinfo != INSN_MACRO);
      append_insn (&insn, &imm_expr, imm_reloc);
    }

  *input_line_pointer = save_c;
  demand_empty_rest_of_line ();
}

/* Update arch attributes.  */

static void
riscv_write_out_arch_attr (void)
{
  const char *arch_str = riscv_arch_str (xlen, &riscv_subsets);

  bfd_elf_add_proc_attr_string (stdoutput, Tag_RISCV_arch, arch_str);

  xfree ((void *)arch_str);
}

/* Add the default contents for the .riscv.attributes section.  */

static void
riscv_set_public_attributes (void)
{
  if (riscv_opts.arch_attr || explicit_arch_attr)
    /* Re-write arch attribute to normalize the arch string.  */
    riscv_write_out_arch_attr ();
}

/* Called after all assembly has been done.  */

void
riscv_md_end (void)
{
  riscv_set_public_attributes ();
}

/* Given a symbolic attribute NAME, return the proper integer value.
   Returns -1 if the attribute is not known.  */

int
riscv_convert_symbolic_attribute (const char *name)
{
  static const struct
  {
    const char * name;
    const int    tag;
  }
  attribute_table[] =
    {
      /* When you modify this table you should
         also modify the list in doc/c-riscv.texi.  */
#define T(tag) {#tag, Tag_RISCV_##tag},  {"Tag_RISCV_" #tag, Tag_RISCV_##tag}
      T(arch),
      T(priv_spec),
      T(priv_spec_minor),
      T(priv_spec_revision),
      T(unaligned_access),
      T(stack_align),
#undef T
    };

  unsigned int i;

  if (name == NULL)
    return -1;

  for (i = 0; i < ARRAY_SIZE (attribute_table); i++)
    if (strcmp (name, attribute_table[i].name) == 0)
      return attribute_table[i].tag;

  return -1;
}

/* Parse a .attribute directive.  */

static void
s_riscv_attribute (int ignored ATTRIBUTE_UNUSED)
{
  int tag = obj_elf_vendor_attribute (OBJ_ATTR_PROC);

  if (tag == Tag_RISCV_arch)
    {
      unsigned old_xlen = xlen;

      explicit_arch_attr = TRUE;
      obj_attribute *attr;
      attr = elf_known_obj_attributes_proc (stdoutput);
      if (!start_assemble)
        riscv_set_arch (attr[Tag_RISCV_arch].s);
      else
        as_fatal (_(".attribute arch must set before any instructions"));

      if (old_xlen != xlen)
        {
          /* We must re-init bfd again if xlen is changed.  */
          unsigned long mach = xlen == 64 ? bfd_mach_riscv64 : bfd_mach_riscv32;
          bfd_find_target (riscv_target_format (), stdoutput);

          if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, mach))
            as_warn (_("Could not set architecture and machine"));
        }
    }
}

/* Pseudo-op table.  */

static const pseudo_typeS riscv_pseudo_table[] =
{
  /* RISC-V-specific pseudo-ops.  */
  {"option", s_riscv_option, 0},
  {"half", cons, 2},
  {"word", cons, 4},
  {"dword", cons, 8},
  {"dtprelword", s_dtprel, 4},
  {"dtpreldword", s_dtprel, 8},
  {"bss", s_bss, 0},
  {"uleb128", s_riscv_leb128, 0},
  {"sleb128", s_riscv_leb128, 1},
  {"insn", s_riscv_insn, 0},
  {"attribute", s_riscv_attribute, 0},

  { NULL, NULL, 0 },
};

void
riscv_pop_insert (void)
{
  extern void pop_insert (const pseudo_typeS *);

  pop_insert (riscv_pseudo_table);
}