ppc-dis.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* ppc-dis.c -- Disassemble PowerPC instructions
   Copyright (C) 1994-2016 Free Software Foundation, Inc.
   Written by Ian Lance Taylor, Cygnus Support

This file is part of GDB, GAS, and the GNU binutils.

 */

#include <asm/cputable.h>
#include <asm/cpu_has_feature.h>
#include "nonstdio.h"
#include "ansidecl.h"
#include "ppc.h"
#include "dis-asm.h"

/* This file provides several disassembler functions, all of which use
   the disassembler interface defined in dis-asm.h.  Several functions
   are provided because this file handles disassembly for the PowerPC
   in both big and little endian mode and also for the POWER (RS/6000)
   chip.  */

/* Extract the operand value from the PowerPC or POWER instruction.  */

static long
operand_value_powerpc (const struct powerpc_operand *operand,
		       unsigned long insn, ppc_cpu_t dialect)
{
  long value;
  int invalid;
  /* Extract the value from the instruction.  */
  if (operand->extract)
    value = (*operand->extract) (insn, dialect, &invalid);
  else
    {
      if (operand->shift >= 0)
	value = (insn >> operand->shift) & operand->bitm;
      else
	value = (insn << -operand->shift) & operand->bitm;
      if ((operand->flags & PPC_OPERAND_SIGNED) != 0)
	{
	  /* BITM is always some number of zeros followed by some
	     number of ones, followed by some number of zeros.  */
	  unsigned long top = operand->bitm;
	  /* top & -top gives the rightmost 1 bit, so this
	     fills in any trailing zeros.  */
	  top |= (top & -top) - 1;
	  top &= ~(top >> 1);
	  value = (value ^ top) - top;
	}
    }

  return value;
}

/* Determine whether the optional operand(s) should be printed.  */

static int
skip_optional_operands (const unsigned char *opindex,
			unsigned long insn, ppc_cpu_t dialect)
{
  const struct powerpc_operand *operand;

  for (; *opindex != 0; opindex++)
    {
      operand = &powerpc_operands[*opindex];
      if ((operand->flags & PPC_OPERAND_NEXT) != 0
	  || ((operand->flags & PPC_OPERAND_OPTIONAL) != 0
	      && operand_value_powerpc (operand, insn, dialect) !=
		 ppc_optional_operand_value (operand)))
	return 0;
    }

  return 1;
}

/* Find a match for INSN in the opcode table, given machine DIALECT.
   A DIALECT of -1 is special, matching all machine opcode variations.  */

static const struct powerpc_opcode *
lookup_powerpc (unsigned long insn, ppc_cpu_t dialect)
{
  const struct powerpc_opcode *opcode;
  const struct powerpc_opcode *opcode_end;

  opcode_end = powerpc_opcodes + powerpc_num_opcodes;
  /* Find the first match in the opcode table for this major opcode.  */
  for (opcode = powerpc_opcodes; opcode < opcode_end; ++opcode)
    {
      const unsigned char *opindex;
      const struct powerpc_operand *operand;
      int invalid;

      if ((insn & opcode->mask) != opcode->opcode
	  || (dialect != (ppc_cpu_t) -1
	      && ((opcode->flags & dialect) == 0
		  || (opcode->deprecated & dialect) != 0)))
	continue;

      /* Check validity of operands.  */
      invalid = 0;
      for (opindex = opcode->operands; *opindex != 0; opindex++)
	{
	  operand = powerpc_operands + *opindex;
	  if (operand->extract)
	    (*operand->extract) (insn, dialect, &invalid);
	}
      if (invalid)
	continue;

      return opcode;
    }

  return NULL;
}

/* Print a PowerPC or POWER instruction.  */

int print_insn_powerpc (unsigned long insn, unsigned long memaddr)
{
  const struct powerpc_opcode *opcode;
  bool insn_is_short;
  ppc_cpu_t dialect;

  dialect = PPC_OPCODE_PPC | PPC_OPCODE_COMMON;

  if (IS_ENABLED(CONFIG_PPC64))
    dialect |= PPC_OPCODE_64 | PPC_OPCODE_POWER4 | PPC_OPCODE_CELL |
	PPC_OPCODE_POWER5 | PPC_OPCODE_POWER6 | PPC_OPCODE_POWER7 | PPC_OPCODE_POWER8 |
	PPC_OPCODE_POWER9;

  if (cpu_has_feature(CPU_FTR_TM))
    dialect |= PPC_OPCODE_HTM;

  if (cpu_has_feature(CPU_FTR_ALTIVEC))
    dialect |= PPC_OPCODE_ALTIVEC | PPC_OPCODE_ALTIVEC2;

  if (cpu_has_feature(CPU_FTR_VSX))
    dialect |= PPC_OPCODE_VSX | PPC_OPCODE_VSX3;

  /* Get the major opcode of the insn.  */
  opcode = NULL;
  insn_is_short = false;

  if (opcode == NULL)
    opcode = lookup_powerpc (insn, dialect);
  if (opcode == NULL && (dialect & PPC_OPCODE_ANY) != 0)
    opcode = lookup_powerpc (insn, (ppc_cpu_t) -1);

  if (opcode != NULL)
    {
      const unsigned char *opindex;
      const struct powerpc_operand *operand;
      int need_comma;
      int need_paren;
      int skip_optional;

      if (opcode->operands[0] != 0)
	printf("%-7s ", opcode->name);
      else
	printf("%s", opcode->name);

      if (insn_is_short)
        /* The operands will be fetched out of the 16-bit instruction.  */
        insn >>= 16;

      /* Now extract and print the operands.  */
      need_comma = 0;
      need_paren = 0;
      skip_optional = -1;
      for (opindex = opcode->operands; *opindex != 0; opindex++)
	{
	  long value;

	  operand = powerpc_operands + *opindex;

	  /* Operands that are marked FAKE are simply ignored.  We
	     already made sure that the extract function considered
	     the instruction to be valid.  */
	  if ((operand->flags & PPC_OPERAND_FAKE) != 0)
	    continue;

	  /* If all of the optional operands have the value zero,
	     then don't print any of them.  */
	  if ((operand->flags & PPC_OPERAND_OPTIONAL) != 0)
	    {
	      if (skip_optional < 0)
		skip_optional = skip_optional_operands (opindex, insn,
							dialect);
	      if (skip_optional)
		continue;
	    }

	  value = operand_value_powerpc (operand, insn, dialect);

	  if (need_comma)
	    {
	      printf(",");
	      need_comma = 0;
	    }

	  /* Print the operand as directed by the flags.  */
	  if ((operand->flags & PPC_OPERAND_GPR) != 0
	      || ((operand->flags & PPC_OPERAND_GPR_0) != 0 && value != 0))
	    printf("r%ld", value);
	  else if ((operand->flags & PPC_OPERAND_FPR) != 0)
	    printf("f%ld", value);
	  else if ((operand->flags & PPC_OPERAND_VR) != 0)
	    printf("v%ld", value);
	  else if ((operand->flags & PPC_OPERAND_VSR) != 0)
	    printf("vs%ld", value);
	  else if ((operand->flags & PPC_OPERAND_RELATIVE) != 0)
	    print_address(memaddr + value);
	  else if ((operand->flags & PPC_OPERAND_ABSOLUTE) != 0)
	    print_address(value & 0xffffffff);
	  else if ((operand->flags & PPC_OPERAND_FSL) != 0)
	    printf("fsl%ld", value);
	  else if ((operand->flags & PPC_OPERAND_FCR) != 0)
	    printf("fcr%ld", value);
	  else if ((operand->flags & PPC_OPERAND_UDI) != 0)
	    printf("%ld", value);
	  else if ((operand->flags & PPC_OPERAND_CR_REG) != 0
		   && (((dialect & PPC_OPCODE_PPC) != 0)
		       || ((dialect & PPC_OPCODE_VLE) != 0)))
	    printf("cr%ld", value);
	  else if (((operand->flags & PPC_OPERAND_CR_BIT) != 0)
		   && (((dialect & PPC_OPCODE_PPC) != 0)
		       || ((dialect & PPC_OPCODE_VLE) != 0)))
	    {
	      static const char *cbnames[4] = { "lt", "gt", "eq", "so" };
	      int cr;
	      int cc;

	      cr = value >> 2;
	      if (cr != 0)
		printf("4*cr%d+", cr);
	      cc = value & 3;
	      printf("%s", cbnames[cc]);
	    }
	  else
	    printf("%d", (int) value);

	  if (need_paren)
	    {
	      printf(")");
	      need_paren = 0;
	    }

	  if ((operand->flags & PPC_OPERAND_PARENS) == 0)
	    need_comma = 1;
	  else
	    {
	      printf("(");
	      need_paren = 1;
	    }
	}

      /* We have found and printed an instruction.
         If it was a short VLE instruction we have more to do.  */
      if (insn_is_short)
        {
          memaddr += 2;
          return 2;
        }
      else
        /* Otherwise, return.  */
        return 4;
    }

  /* We could not find a match.  */
  printf(".long 0x%lx", insn);

  return 4;
}