path: root/gas/config/tc-riscv.c

/* tc-riscv.c -- RISC-V assembler
   Copyright 2011-2016 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 "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

static const char default_arch[] = DEFAULT_ARCH;

unsigned xlen = 0; /* width of an x-register */

#define LOAD_ADDRESS_INSN (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.  */
};

static struct riscv_set_options riscv_opts =
{
  0,	/* pic */
  0,	/* rvc */
};

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

  riscv_opts.rvc = rvc_value;
}

struct riscv_subset
{
  const char *name;

  struct riscv_subset *next;
};

static struct riscv_subset *riscv_subsets;

static bfd_boolean
riscv_subset_supports (const char *feature)
{
  struct riscv_subset *s;
  char *p;
  unsigned xlen_required = strtoul (feature, &p, 10);

  if (xlen_required && xlen != xlen_required)
    return FALSE;

  for (s = riscv_subsets; s != NULL; s = s->next)
    if (strcasecmp (s->name, p) == 0)
      return TRUE;

  return FALSE;
}

static void
riscv_add_subset (const char *subset)
{
  struct riscv_subset *s = xmalloc (sizeof *s);

  s->name = xstrdup (subset);
  s->next = riscv_subsets;
  riscv_subsets = s;
}

/* Set which ISA and extensions are available.  Formally, ISA strings must
   begin with RV32 or RV64, but we allow the prefix to be omitted.

   FIXME: Version numbers are not supported yet.  */
static void
riscv_set_arch (const char *p)
{
  const char *all_subsets = "IMAFDC";
  const char *extension = NULL;
  int rvc = 0;
  int i;

  if (strncasecmp (p, "RV32", 4) == 0)
    {
      xlen = 32;
      p += 4;
    }
  else if (strncasecmp (p, "RV64", 4) == 0)
    {
      xlen = 64;
      p += 4;
    }
  else if (strncasecmp (p, "RV", 2) == 0)
    p += 2;

  switch (TOUPPER(*p))
    {
      case 'I':
	break;

      case 'G':
	p++;
	/* Fall through.  */

      case '\0':
	for (i = 0; all_subsets[i] != '\0'; i++)
	  {
	    const char subset[] = {all_subsets[i], '\0'};
	    riscv_add_subset (subset);
	  }
	break;

      default:
	as_fatal ("`I' must be the first ISA subset name specified (got %c)",
		  *p);
    }

  while (*p)
    {
      if (TOUPPER(*p) == 'X')
	{
	  char *subset = xstrdup (p), *q = subset;

	  while (*++q != '\0' && *q != '_')
	    ;
	  *q = '\0';

	  if (extension)
	    as_fatal ("only one eXtension is supported (found %s and %s)",
		      extension, subset);
	  extension = subset;
	  riscv_add_subset (subset);
	  p += strlen (subset);
	  free (subset);
	}
      else if (*p == '_')
	p++;
      else if ((all_subsets = strchr (all_subsets, *p)) != NULL)
	{
	  const char subset[] = {*p, 0};
	  riscv_add_subset (subset);
	  if (TOUPPER(*p) == 'C')
	    rvc = 1;
	  all_subsets++;
	  p++;
	}
      else
	as_fatal ("unsupported ISA subset %c", *p);
    }

  if (rvc)
    {
      /* Override -m[no-]rvc setting if C was explicitly listed.  */
      riscv_set_rvc (TRUE);
    }
  else
    {
      /* Add RVC anyway.  -m[no-]rvc toggles its availability.  */
      riscv_add_subset ("C");
    }
}

/* Handle of the OPCODE hash table.  */
static struct hash_control *op_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";

/* 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)
      && 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;
}

struct regname
{
  const char *name;
  unsigned int num;
};

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

static struct hash_control *reg_names_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);
}

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

  if (r == NULL || DECODE_REG_CLASS (r) != class)
    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);

  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.  */
static bfd_boolean
validate_riscv_insn (const struct riscv_opcode *opc)
{
  const char *p = opc->args;
  char c;
  insn_t used_bits = opc->mask;
  int insn_width = 8 * riscv_insn_length (opc->match);
  insn_t 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 '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 '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 'T': USE_BITS (OP_MASK_CRS2, OP_SH_CRS2); break;
	  case 'D': USE_BITS (OP_MASK_CRS2S, OP_SH_CRS2S); 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 '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 '[': break;
      case ']': break;
      case '0': 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;
};

/* 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)
{
  int i = 0;

  if (! bfd_set_arch_mach (stdoutput, bfd_arch_riscv, 0))
    as_warn (_("Could not set architecture and machine"));

  op_hash = hash_new ();

  while (riscv_opcodes[i].name)
    {
      const char *name = riscv_opcodes[i].name;
      const char *hash_error =
	hash_insert (op_hash, name, (void *) &riscv_opcodes[i]);

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

      do
	{
	  if (riscv_opcodes[i].pinfo != INSN_MACRO)
	    {
	      if (!validate_riscv_insn (&riscv_opcodes[i]))
		as_fatal (_("Broken assembler.  No assembly attempted."));
	    }
	  ++i;
	}
      while (riscv_opcodes[i].name && !strcmp (riscv_opcodes[i].name, name));
    }

  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);

#define DECLARE_CSR(name, num) hash_reg_name (RCLASS_CSR, #name, num);
#include "opcode/riscv-opc.h"
#undef DECLARE_CSR

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

/* 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 if (address_expr->X_op == O_constant)
	{
	  switch (reloc_type)
	    {
	    case BFD_RELOC_32:
	      ip->insn_opcode |= address_expr->X_add_number;
	      goto append;

	    case BFD_RELOC_RISCV_HI20:
	      {
		insn_t imm = RISCV_CONST_HIGH_PART (address_expr->X_add_number);
		ip->insn_opcode |= ENCODE_UTYPE_IMM (imm);
		goto append;
	      }

	    case BFD_RELOC_RISCV_LO12_S:
	      ip->insn_opcode |= ENCODE_STYPE_IMM (address_expr->X_add_number);
	      goto append;

	    case BFD_RELOC_RISCV_LO12_I:
	      ip->insn_opcode |= ENCODE_ITYPE_IMM (address_expr->X_add_number);
	      goto append;

	    default:
	      break;
	    }
	}

	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);
    }

append:
  add_fixed_insn (ip);
  install_insn (ip);
}

/* 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);
}

/* 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 is not a constant.  */

static void
check_absolute_expr (struct riscv_cl_insn *ip, expressionS *ex)
{
  if (ex->X_op == O_big)
    as_bad (_("unsupported large constant"));
  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;
  expressionS upper = *ep, lower = *ep;
  lower.X_add_number = (int32_t) ep->X_add_number << (32-shift) >> (32-shift);
  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);

      macro_build (NULL, "slli", "d,s,>", reg, reg, shift);
      if (lower.X_add_number != 0)
	macro_build (&lower, "addi", "d,s,j", reg, reg, BFD_RELOC_RISCV_LO12_I);
    }
  else
    {
      /* Simply emit LUI and/or ADDI to build a 32-bit signed constant.  */
      int hi_reg = 0;

      if (upper.X_add_number != 0)
	{
	  macro_build (ep, "lui", "d,u", reg, BFD_RELOC_RISCV_HI20);
	  hi_reg = reg;
	}

      if (lower.X_add_number != 0 || hi_reg == 0)
	macro_build (ep, ADD32_INSN, "d,s,j", reg, hi_reg,
		     BFD_RELOC_RISCV_LO12_I);
    }
}

/* 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}
};

/* 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 (!bfd_reloc_type_lookup (stdoutput, percent_op->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.  */
  if (reg_lookup (&str, RCLASS_GPR, &regno))
    {
      ep->X_op = O_register;
      ep->X_add_number = regno;
      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;
}

/* 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)
{
  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";

  /* 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 (op_hash, str);

  argsStart = s;
  for ( ; insn && insn->name && strcmp (insn->name, str) == 0; insn++)
    {
      if (!riscv_subset_supports (insn->subset))
	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;
		  if (riscv_insn_length (insn->match) == 2 && !riscv_opts.rvc)
		    break;
		}
	      if (*s != '\0')
		break;
	      /* Successful assembly.  */
	      error = NULL;
	      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 '>':
		  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 '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 (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 (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 (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 (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 '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 (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 (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 '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;
		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);
	      if ((unsigned long) imm_expr->X_add_number > 31)
		as_warn (_("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);
	      if ((unsigned long) imm_expr->X_add_number >= xlen)
		as_warn (_("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);
	      if ((unsigned long) imm_expr->X_add_number > 31)
		as_warn (_("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.  */
	      if (reg_lookup (&s, RCLASS_CSR, &regno))
		INSERT_OPERAND (CSR, *ip, regno);
	      else
		{
		  my_getExpression (imm_expr, s);
		  check_absolute_expr (ip, imm_expr);
		  if ((unsigned long) imm_expr->X_add_number > 0xfff)
		    as_warn(_("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.  */
	      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;
		    }
		  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 'j': /* Sign-extended immediate.  */
	      *imm_reloc = BFD_RELOC_RISCV_LO12_I;
	      p = percent_op_itype;
	      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 '0': /* AMO "displacement," which must be zero.  */
	      p = percent_op_rtype;
	      *imm_reloc = BFD_RELOC_UNUSED;
load_store:
	      /* Check whether there is only a single bracketed expression
		 left.  If so, it must be the base register and the
		 constant must be zero.  */
	      imm_expr->X_op = O_constant;
	      imm_expr->X_add_number = 0;
	      if (*s == '(' && strchr (s + 1, '(') == 0)
		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)
		      || 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)
		  && imm_expr->X_op == O_constant)
		{
		  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;

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

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);

  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_M32 = OPTION_MD_BASE,
  OPTION_M64,
  OPTION_MARCH,
  OPTION_PIC,
  OPTION_NO_PIC,
  OPTION_MSOFT_FLOAT,
  OPTION_MHARD_FLOAT,
  OPTION_MRVC,
  OPTION_MNO_RVC,
  OPTION_END_OF_ENUM
};

struct option md_longopts[] =
{
  {"m32", no_argument, NULL, OPTION_M32},
  {"m64", no_argument, NULL, OPTION_M64},
  {"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},
  {"mrvc", no_argument, NULL, OPTION_MRVC},
  {"mno-rvc", no_argument, NULL, OPTION_MNO_RVC},
  {"msoft-float", no_argument, NULL, OPTION_MSOFT_FLOAT},
  {"mhard-float", no_argument, NULL, OPTION_MHARD_FLOAT},

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

enum float_mode
{
  FLOAT_MODE_DEFAULT,
  FLOAT_MODE_SOFT,
  FLOAT_MODE_HARD
};
static enum float_mode float_mode = FLOAT_MODE_DEFAULT;

int
md_parse_option (int c, const char *arg)
{
  switch (c)
    {
    case OPTION_MRVC:
      riscv_set_rvc (TRUE);
      break;

    case OPTION_MNO_RVC:
      riscv_set_rvc (FALSE);
      break;

    case OPTION_MSOFT_FLOAT:
      float_mode = FLOAT_MODE_SOFT;
      break;

    case OPTION_MHARD_FLOAT:
      float_mode = FLOAT_MODE_HARD;
      break;

    case OPTION_M32:
      xlen = 32;
      break;

    case OPTION_M64:
      xlen = 64;
      break;

    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;

    default:
      return 0;
    }

  return 1;
}

void
riscv_after_parse_args (void)
{
  if (riscv_subsets == NULL)
    riscv_set_arch ("RVIMAFD");

  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);
    }
}

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)
{
  bfd_byte *buf = (bfd_byte *) (fixP->fx_frag->fr_literal + fixP->fx_where);

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

  switch (fixP->fx_r_type)
    {
    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:
    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:
      S_SET_THREAD_LOCAL (fixP->fx_addsy);
      /* Fall through.  */

    case BFD_RELOC_RISCV_GOT_HI20:
    case BFD_RELOC_RISCV_PCREL_HI20:
    case BFD_RELOC_RISCV_HI20:
    case BFD_RELOC_RISCV_LO12_I:
    case BFD_RELOC_RISCV_LO12_S:
    case BFD_RELOC_RISCV_ADD8:
    case BFD_RELOC_RISCV_ADD16:
    case BFD_RELOC_RISCV_ADD32:
    case BFD_RELOC_RISCV_ADD64:
    case BFD_RELOC_RISCV_SUB8:
    case BFD_RELOC_RISCV_SUB16:
    case BFD_RELOC_RISCV_SUB32:
    case BFD_RELOC_RISCV_SUB64:
      gas_assert (fixP->fx_addsy != NULL);
      /* Nothing needed to do.  The value comes from the reloc entry.  */
      break;

    case BFD_RELOC_64:
    case BFD_RELOC_32:
    case BFD_RELOC_16:
    case BFD_RELOC_8:
      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;

	    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_PCREL_LO12_S:
    case BFD_RELOC_RISCV_PCREL_LO12_I:
    case BFD_RELOC_RISCV_CALL:
    case BFD_RELOC_RISCV_CALL_PLT:
    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);
    }
}

/* 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, "soft-float") == 0)
    float_mode = FLOAT_MODE_SOFT;
  else if (strcmp (name, "hard-float") == 0)
    float_mode = FLOAT_MODE_HARD;
  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 ();
}

/* Align to a given power of two.  */

static void
s_align (int bytes_p)
{
  int fill_value = 0, fill_value_specified = 0;
  int min_text_alignment = riscv_opts.rvc ? 2 : 4;
  int alignment = get_absolute_expression(), bytes;

  if (bytes_p)
    {
      bytes = alignment;
      if (bytes < 1 || (bytes & (bytes-1)) != 0)
	as_bad (_("alignment not a power of 2: %d"), bytes);
      for (alignment = 0; bytes > 1; bytes >>= 1)
	alignment++;
    }

  bytes = 1 << alignment;

  if (alignment < 0 || alignment > 31)
    as_bad (_("unsatisfiable alignment: %d"), alignment);

  if (*input_line_pointer == ',')
    {
      ++input_line_pointer;
      fill_value = get_absolute_expression ();
      fill_value_specified = 1;
    }

  if (!fill_value_specified
      && subseg_text_p (now_seg)
      && bytes > min_text_alignment)
    {
      /* Emit the worst-case NOP string.  The linker will delete any
	 unnecessary NOPs.  This allows us to support code alignment
	 in spite of linker relaxations.  */
      bfd_vma i, worst_case_bytes = bytes - min_text_alignment;
      char *nops = frag_more (worst_case_bytes);
      for (i = 0; i < worst_case_bytes - 2; i += 4)
	md_number_to_chars (nops + i, RISCV_NOP, 4);
      if (i < worst_case_bytes)
	md_number_to_chars (nops + i, RVC_NOP, 2);

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

      fix_new_exp (frag_now, nops - frag_now->fr_literal, 0,
		   &ex, FALSE, BFD_RELOC_RISCV_ALIGN);
    }
  else if (alignment)
    frag_align (alignment, fill_value, 0);

  record_alignment (now_seg, alignment);

  demand_empty_rest_of_line ();
}

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\
  -m32           assemble RV32 code\n\
  -m64           assemble RV64 code (default)\n\
  -fpic          generate position-independent code\n\
  -fno-pic       don't generate position-independent code (default)\n\
  -msoft-float   don't use F registers for floating-point values\n\
  -mhard-float   use F registers for floating-point values (default)\n\
  -mno-rvc       disable the C extension for compressed instructions (default)\n\
  -mrvc          enable the C extension for compressed instructions\n\
  -march=ISA     set the RISC-V architecture, RV64IMAFD by default\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;

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

void
riscv_elf_final_processing (void)
{
  enum float_mode elf_float_mode = float_mode;

  elf_elfheader (stdoutput)->e_flags |= elf_flags;

  if (elf_float_mode == FLOAT_MODE_DEFAULT)
    {
      struct riscv_subset *subset;

      /* Assume soft-float unless D extension is present.  */
      elf_float_mode = FLOAT_MODE_SOFT;

      for (subset = riscv_subsets; subset != NULL; subset = subset->next)
	if (strcasecmp (subset->name, "D") == 0)
	  elf_float_mode = FLOAT_MODE_HARD;
    }

  if (elf_float_mode == FLOAT_MODE_SOFT)
    elf_elfheader (stdoutput)->e_flags |= EF_RISCV_SOFT_FLOAT;
}

/* 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);
}

/* 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},
  {"align", s_align, 0},
  {"p2align", s_align, 0},
  {"balign", s_align, 1},
  {"uleb128", s_riscv_leb128, 0},
  {"sleb128", s_riscv_leb128, 1},

  { NULL, NULL, 0 },
};

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

  pop_insert (riscv_pseudo_table);
}