/* Native CPU detection for aarch64.
   Copyright (C) 2015-2019 Free Software Foundation, Inc.

   This file is part of GCC.

   GCC 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.

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

#define IN_TARGET_CODE 1

#include "config.h"
#define INCLUDE_STRING
#include "system.h"
#include "coretypes.h"
#include "tm.h"

/* Defined in common/config/aarch64/aarch64-common.c.  */
std::string aarch64_get_extension_string_for_isa_flags (unsigned long,
							unsigned long);

struct aarch64_arch_extension
{
  const char *ext;
  unsigned int flag;
  const char *feat_string;
};

#define AARCH64_OPT_EXTENSION(EXT_NAME, FLAG_CANONICAL, FLAGS_ON, FLAGS_OFF, \
			      SYNTHETIC, FEATURE_STRING) \
  { EXT_NAME, FLAG_CANONICAL, FEATURE_STRING },
static struct aarch64_arch_extension aarch64_extensions[] =
{
#include "aarch64-option-extensions.def"
};


struct aarch64_core_data
{
  const char* name;
  const char* arch;
  unsigned char implementer_id; /* Exactly 8 bits */
  unsigned int part_no; /* 12 bits + 12 bits */
  unsigned variant;
  const unsigned long flags;
};

#define AARCH64_BIG_LITTLE(BIG, LITTLE) \
  (((BIG)&0xFFFu) << 12 | ((LITTLE) & 0xFFFu))
#define INVALID_IMP ((unsigned char) -1)
#define INVALID_CORE ((unsigned)-1)
#define ALL_VARIANTS ((unsigned)-1)

#define AARCH64_CORE(CORE_NAME, CORE_IDENT, SCHED, ARCH, FLAGS, COSTS, IMP, PART, VARIANT) \
  { CORE_NAME, #ARCH, IMP, PART, VARIANT, FLAGS },

static struct aarch64_core_data aarch64_cpu_data[] =
{
#include "aarch64-cores.def"
  { NULL, NULL, INVALID_IMP, INVALID_CORE, ALL_VARIANTS, 0 }
};


struct aarch64_arch_driver_info
{
  const char* id;
  const char* name;
  const unsigned long flags;
};

#define AARCH64_ARCH(NAME, CORE, ARCH_IDENT, ARCH_REV, FLAGS) \
  { #ARCH_IDENT, NAME, FLAGS },

static struct aarch64_arch_driver_info aarch64_arches[] =
{
#include "aarch64-arches.def"
  {NULL, NULL, 0}
};


/* Return an aarch64_arch_driver_info for the architecture described
   by ID, or NULL if ID describes something we don't know about.  */

static struct aarch64_arch_driver_info*
get_arch_from_id (const char* id)
{
  unsigned int i = 0;

  for (i = 0; aarch64_arches[i].id != NULL; i++)
    {
      if (strcmp (id, aarch64_arches[i].id) == 0)
	return &aarch64_arches[i];
    }

  return NULL;
}

/* Check wether the CORE array is the same as the big.LITTLE BL_CORE.
   For an example CORE={0xd08, 0xd03} and
   BL_CORE=AARCH64_BIG_LITTLE (0xd08, 0xd03) will return true.  */

static bool
valid_bL_core_p (unsigned int *core, unsigned int bL_core)
{
  return AARCH64_BIG_LITTLE (core[0], core[1]) == bL_core
         || AARCH64_BIG_LITTLE (core[1], core[0]) == bL_core;
}

/* Returns the hex integer that is after ':' for the FIELD.
   Returns -1 is returned if there was problem parsing the integer. */
static unsigned
parse_field (const char *field)
{
  const char *rest = strchr (field, ':');
  char *after;
  unsigned fint = strtol (rest + 1, &after, 16);
  if (after == rest + 1)
    return -1;
  return fint;
}

/*  Return true iff ARR contains CORE, in either of the two elements. */

static bool
contains_core_p (unsigned *arr, unsigned core)
{
  if (arr[0] != INVALID_CORE)
    {
      if (arr[0] == core)
        return true;

      if (arr[1] != INVALID_CORE)
        return arr[1] == core;
    }

  return false;
}

/* This will be called by the spec parser in gcc.c when it sees
   a %:local_cpu_detect(args) construct.  Currently it will be called
   with either "arch", "cpu" or "tune" as argument depending on if
   -march=native, -mcpu=native or -mtune=native is to be substituted.

   It returns a string containing new command line parameters to be
   put at the place of the above two options, depending on what CPU
   this is executed.  E.g. "-march=armv8-a" on a Cortex-A57 for
   -march=native.  If the routine can't detect a known processor,
   the -march or -mtune option is discarded.

   For -mtune and -mcpu arguments it attempts to detect the CPU or
   a big.LITTLE system.
   ARGC and ARGV are set depending on the actual arguments given
   in the spec.  */

const char *
host_detect_local_cpu (int argc, const char **argv)
{
  const char *res = NULL;
  static const int num_exts = ARRAY_SIZE (aarch64_extensions);
  char buf[128];
  FILE *f = NULL;
  bool arch = false;
  bool tune = false;
  bool cpu = false;
  unsigned int i = 0;
  unsigned char imp = INVALID_IMP;
  unsigned int cores[2] = { INVALID_CORE, INVALID_CORE };
  unsigned int n_cores = 0;
  unsigned int variants[2] = { ALL_VARIANTS, ALL_VARIANTS };
  unsigned int n_variants = 0;
  bool processed_exts = false;
  unsigned long extension_flags = 0;
  unsigned long default_flags = 0;

  gcc_assert (argc);

  if (!argv[0])
    goto not_found;

  /* Are we processing -march, mtune or mcpu?  */
  arch = strcmp (argv[0], "arch") == 0;
  if (!arch)
    tune = strcmp (argv[0], "tune") == 0;

  if (!arch && !tune)
    cpu = strcmp (argv[0], "cpu") == 0;

  if (!arch && !tune && !cpu)
    goto not_found;

  f = fopen ("/proc/cpuinfo", "r");

  if (f == NULL)
    goto not_found;

  /* Look through /proc/cpuinfo to determine the implementer
     and then the part number that identifies a particular core.  */
  while (fgets (buf, sizeof (buf), f) != NULL)
    {
      if (strstr (buf, "implementer") != NULL)
	{
	  unsigned cimp = parse_field (buf);
	  if (cimp == INVALID_IMP)
	    goto not_found;

	  if (imp == INVALID_IMP)
	    imp = cimp;
	  /* FIXME: BIG.little implementers are always equal. */
	  else if (imp != cimp)
	    goto not_found;
	}

      if (strstr (buf, "variant") != NULL)
	{
	  unsigned cvariant = parse_field (buf);
	  if (!contains_core_p (variants, cvariant))
	    {
              if (n_variants == 2)
                goto not_found;

              variants[n_variants++] = cvariant;
	    }
          continue;
        }

      if (strstr (buf, "part") != NULL)
	{
	  unsigned ccore = parse_field (buf);
	  if (!contains_core_p (cores, ccore))
	    {
	      if (n_cores == 2)
		goto not_found;

	      cores[n_cores++] = ccore;
	    }
	  continue;
	}
      if (!tune && !processed_exts && strstr (buf, "Features") != NULL)
	{
	  for (i = 0; i < num_exts; i++)
	    {
	      const char *p = aarch64_extensions[i].feat_string;

	      /* If the feature contains no HWCAPS string then ignore it for the
		 auto detection.  */
	      if (*p == '\0')
		continue;

	      bool enabled = true;

	      /* This may be a multi-token feature string.  We need
		 to match all parts, which could be in any order.  */
	      size_t len = strlen (buf);
	      do
		{
		  const char *end = strchr (p, ' ');
		  if (end == NULL)
		    end = strchr (p, '\0');
		  if (memmem (buf, len, p, end - p) == NULL)
		    {
		      /* Failed to match this token.  Turn off the
			 features we'd otherwise enable.  */
		      enabled = false;
		      break;
		    }
		  if (*end == '\0')
		    break;
		  p = end + 1;
		}
	      while (1);

	      if (enabled)
		extension_flags |= aarch64_extensions[i].flag;
	      else
		extension_flags &= ~(aarch64_extensions[i].flag);
	    }

	  processed_exts = true;
	}
    }

  fclose (f);
  f = NULL;

  /* Weird cpuinfo format that we don't know how to handle.  */
  if (n_cores == 0
      || n_cores > 2
      || (n_cores == 1 && n_variants != 1)
      || imp == INVALID_IMP)
    goto not_found;

  /* Simple case, one core type or just looking for the arch. */
  if (n_cores == 1 || arch)
    {
      /* Search for one of the cores in the list. */
      for (i = 0; aarch64_cpu_data[i].name != NULL; i++)
	if (aarch64_cpu_data[i].implementer_id == imp
            && cores[0] == aarch64_cpu_data[i].part_no
            && (aarch64_cpu_data[i].variant == ALL_VARIANTS
                || variants[0] == aarch64_cpu_data[i].variant))
	  break;
      if (aarch64_cpu_data[i].name == NULL)
        goto not_found;

      if (arch)
	{
	  const char *arch_id = aarch64_cpu_data[i].arch;
	  aarch64_arch_driver_info* arch_info = get_arch_from_id (arch_id);

	  /* We got some arch indentifier that's not in aarch64-arches.def?  */
	  if (!arch_info)
	    goto not_found;

	  res = concat ("-march=", arch_info->name, NULL);
	  default_flags = arch_info->flags;
	}
      else
	{
	  default_flags = aarch64_cpu_data[i].flags;
	  res = concat ("-m",
			cpu ? "cpu" : "tune", "=",
			aarch64_cpu_data[i].name,
			NULL);
	}
    }
  /* We have big.LITTLE.  */
  else
    {
      for (i = 0; aarch64_cpu_data[i].name != NULL; i++)
	{
	  if (aarch64_cpu_data[i].implementer_id == imp
	      && valid_bL_core_p (cores, aarch64_cpu_data[i].part_no))
	    {
	      res = concat ("-m",
			    cpu ? "cpu" : "tune", "=",
			    aarch64_cpu_data[i].name,
			    NULL);
	      default_flags = aarch64_cpu_data[i].flags;
	      break;
	    }
	}
      if (!res)
	goto not_found;
    }

  if (tune)
    return res;

  {
    std::string extension
      = aarch64_get_extension_string_for_isa_flags (extension_flags,
						    default_flags);
    res = concat (res, extension.c_str (), NULL);
  }

  return res;

not_found:
  {
   /* If detection fails we ignore the option.
      Clean up and return NULL.  */

    if (f)
      fclose (f);

    return NULL;
  }
}