/* d-target.cc -- Target interface for the D front end.
   Copyright (C) 2013-2020 Free Software Foundation, Inc.

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/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"

#include "dmd/aggregate.h"
#include "dmd/declaration.h"
#include "dmd/expression.h"
#include "dmd/mangle.h"
#include "dmd/mtype.h"
#include "dmd/tokens.h"
#include "dmd/target.h"

#include "tree.h"
#include "memmodel.h"
#include "fold-const.h"
#include "diagnostic.h"
#include "stor-layout.h"
#include "tm.h"
#include "tm_p.h"
#include "target.h"

#include "d-tree.h"
#include "d-target.h"

/* Implements the Target interface defined by the front end.
   Used for retrieving target-specific information.  */

Target target;


/* Initialize the floating-point constants for TYPE.  */

template <typename T>
static void
define_float_constants (T &f, tree type)
{
  const double log10_2 = 0.30102999566398119521;
  char buf[128];

  /* Get back-end real mode format.  */
  const machine_mode mode = TYPE_MODE (type);
  const real_format *fmt = REAL_MODE_FORMAT (mode);

  /* The largest representable value that's not infinity.  */
  get_max_float (fmt, buf, sizeof (buf), false);
  real_from_string (&f.max.rv (), buf);

  /* The smallest representable normalized value that's not 0.  */
  snprintf (buf, sizeof (buf), "0x1p%d", fmt->emin - 1);
  real_from_string (&f.min_normal.rv (), buf);

  /* Floating-point NaN.  */
  real_nan (&f.nan.rv (), "", 1, mode);

  /* Signalling floating-point NaN.  */
  real_nan (&f.snan.rv (), "", 0, mode);

  /* Floating-point +Infinity if the target supports infinities.  */
  real_inf (&f.infinity.rv ());

  /* The smallest increment to the value 1.  */
  if (fmt->pnan < fmt->p)
    snprintf (buf, sizeof (buf), "0x1p%d", fmt->emin - fmt->p);
  else
    snprintf (buf, sizeof (buf), "0x1p%d", 1 - fmt->p);
  real_from_string (&f.epsilon.rv (), buf);

  /* The number of decimal digits of precision.  */
  f.dig = (fmt->p - 1) * log10_2;

  /* The number of bits in mantissa.  */
  f.mant_dig = fmt->p;

  /* The maximum int value such that 2** (value-1) is representable.  */
  f.max_exp = fmt->emax;

  /* The minimum int value such that 2** (value-1) is representable as a
     normalized value.  */
  f.min_exp = fmt->emin;

  /* The maximum int value such that 10**value is representable.  */
  f.max_10_exp = fmt->emax * log10_2;

  /* The minimum int value such that 10**value is representable as a
     normalized value.  */
  f.min_10_exp = (fmt->emin - 1) * log10_2;
}

/* Initialize all variables of the Target structure.  */

void
Target::_init (const Param &)
{
  /* Map D frontend type and sizes to GCC back-end types.  */
  this->ptrsize = (POINTER_SIZE / BITS_PER_UNIT);
  this->realsize = int_size_in_bytes (long_double_type_node);
  this->realpad = (this->realsize -
		   (TYPE_PRECISION (long_double_type_node) / BITS_PER_UNIT));
  this->realalignsize = TYPE_ALIGN_UNIT (long_double_type_node);

  /* Much of the dmd front-end uses ints for sizes and offsets, and cannot
     handle any larger data type without some pervasive rework.  */
  this->maxStaticDataSize = tree_to_shwi (TYPE_MAX_VALUE (integer_type_node));

  /* Define what type to use for size_t, ptrdiff_t.  */
  if (this->ptrsize == 8)
    {
      global.params.isLP64 = true;
      Type::tsize_t = Type::basic[Tuns64];
      Type::tptrdiff_t = Type::basic[Tint64];
    }
  else if (this->ptrsize == 4)
    {
      Type::tsize_t = Type::basic[Tuns32];
      Type::tptrdiff_t = Type::basic[Tint32];
    }
  else if (this->ptrsize == 2)
    {
      Type::tsize_t = Type::basic[Tuns16];
      Type::tptrdiff_t = Type::basic[Tint16];
    }
  else
    sorry ("D does not support pointers on this target.");

  Type::thash_t = Type::tsize_t;

  /* Set-up target C ABI.  */
  this->c.longsize = int_size_in_bytes (long_integer_type_node);
  this->c.long_doublesize = int_size_in_bytes (long_double_type_node);

  /* Set-up target C++ ABI.  */
  this->cpp.reverseOverloads = false;
  this->cpp.exceptions = true;
  this->cpp.twoDtorInVtable = true;

  /* Set-up target Objective-C ABI.  */
  this->objc.supported = false;

  /* Initialize all compile-time properties for floating-point types.
     Should ensure that our real_t type is able to represent real_value.  */
  gcc_assert (sizeof (real_t) >= sizeof (real_value));

  define_float_constants (this->FloatProperties, float_type_node);
  define_float_constants (this->DoubleProperties, double_type_node);
  define_float_constants (this->RealProperties, long_double_type_node);

  /* Commonly used floating-point constants.  */
  const machine_mode mode = TYPE_MODE (long_double_type_node);
  real_convert (&CTFloat::zero.rv (), mode, &dconst0);
  real_convert (&CTFloat::one.rv (), mode, &dconst1);
  real_convert (&CTFloat::minusone.rv (), mode, &dconstm1);
  real_convert (&CTFloat::half.rv (), mode, &dconsthalf);
}

/* Return GCC memory alignment size for type TYPE.  */

unsigned
Target::alignsize (Type *type)
{
  gcc_assert (type->isTypeBasic ());
  return min_align_of_type (build_ctype (type));
}

/* Return GCC field alignment size for type TYPE.  */

unsigned
Target::fieldalign (Type *type)
{
  /* Work out the correct alignment for the field decl.  */
  unsigned int align = type->alignsize () * BITS_PER_UNIT;

#ifdef BIGGEST_FIELD_ALIGNMENT
  align = MIN (align, (unsigned) BIGGEST_FIELD_ALIGNMENT);
#endif

#ifdef ADJUST_FIELD_ALIGN
  if (type->isTypeBasic ())
    align = ADJUST_FIELD_ALIGN (NULL_TREE, build_ctype (type), align);
#endif

  /* Also controlled by -fpack-struct=  */
  if (maximum_field_alignment)
    align = MIN (align, maximum_field_alignment);

  return align / BITS_PER_UNIT;
}

/* Returns a Type for the va_list type of the target.  */

Type *
Target::va_listType (const Loc &, Scope *)
{
  if (this->tvalist)
    return this->tvalist;

  /* Build the "standard" abi va_list.  */
  this->tvalist = build_frontend_type (va_list_type_node);
  if (!this->tvalist)
    sorry ("cannot represent built-in %<va_list%> type in D");

  /* Map the va_list type to the D frontend Type.  This is to prevent both
     errors in gimplification or an ICE in targetm.canonical_va_list_type.  */
  this->tvalist->ctype = va_list_type_node;
  TYPE_LANG_SPECIFIC (va_list_type_node) = build_lang_type (this->tvalist);

  return this->tvalist;
}

/* Checks whether the target supports a vector type with total size SZ
   (in bytes) and element type TYPE.  */

int
Target::isVectorTypeSupported (int sz, Type *type)
{
  /* Size must be greater than zero, and a power of two.  */
  if (sz <= 0 || sz & (sz - 1))
    return 3;

  /* __vector(void[]) is treated same as __vector(ubyte[])  */
  if (type == Type::tvoid)
    type = Type::tuns8;

  /* No support for non-trivial types, complex types, or booleans.  */
  if (!type->isTypeBasic () || type->iscomplex () || type->ty == Tbool)
    return 2;

  /* In [simd/vector extensions], which vector types are supported depends on
     the target.  The implementation is expected to only support the vector
     types that are implemented in the target's hardware.  */
  unsigned HOST_WIDE_INT nunits = sz / type->size ();
  tree ctype = build_vector_type (build_ctype (type), nunits);

  if (!targetm.vector_mode_supported_p (TYPE_MODE (ctype)))
    return 2;

  return 0;
}

/* Checks whether the target supports operation OP for vectors of type TYPE.
   For binary ops T2 is the type of the right-hand operand.
   Returns true if the operation is supported or type is not a vector.  */

bool
Target::isVectorOpSupported (Type *type, TOK op, Type *)
{
  if (type->ty != Tvector)
    return true;

  /* Don't support if type is non-scalar, such as __vector(void[]).  */
  if (!type->isscalar ())
    return false;

  /* Don't support if expression cannot be represented.  */
  switch (op)
    {
    case TOKpow:
    case TOKpowass:
      /* pow() is lowered as a function call.  */
      return false;

    case TOKmod:
    case TOKmodass:
      /* fmod() is lowered as a function call.  */
      if (type->isfloating ())
	return false;
      break;

    case TOKandand:
    case TOKoror:
      /* Logical operators must have a result type of bool.  */
      return false;

    case TOKue:
    case TOKlg:
    case TOKule:
    case TOKul:
    case TOKuge:
    case TOKug:
    case TOKle:
    case TOKlt:
    case TOKge:
    case TOKgt:
    case TOKleg:
    case TOKunord:
    case TOKequal:
    case TOKnotequal:
    case TOKidentity:
    case TOKnotidentity:
      /* Comparison operators must have a result type of bool.  */
      return false;

    default:
      break;
    }

  return true;
}

/* Return the symbol mangling of S for C++ linkage.  */

const char *
TargetCPP::toMangle (Dsymbol *s)
{
  return toCppMangleItanium (s);
}

/* Return the symbol mangling of CD for C++ linkage.  */

const char *
TargetCPP::typeInfoMangle (ClassDeclaration *cd)
{
  return cppTypeInfoMangleItanium (cd);
}

/* Get mangle name of a this-adjusting thunk to the function declaration FD
   at call offset OFFSET for C++ linkage.  */

const char *
TargetCPP::thunkMangle (FuncDeclaration *fd, int offset)
{
  return cppThunkMangleItanium (fd, offset);
}

/* For a vendor-specific type, return a string containing the C++ mangling.
   In all other cases, return NULL.  */

const char *
TargetCPP::typeMangle (Type *type)
{
  if (type->isTypeBasic () || type->ty == Tvector || type->ty == Tstruct)
    {
      tree ctype = build_ctype (type);
      return targetm.mangle_type (ctype);
    }

  return NULL;
}

/* Return the type that will really be used for passing the given parameter
   ARG to an extern(C++) function.  */

Type *
TargetCPP::parameterType (Parameter *arg)
{
  Type *t = arg->type->merge2 ();
  if (arg->storageClass & (STCout | STCref))
    t = t->referenceTo ();
  else if (arg->storageClass & STClazy)
    {
      /* Mangle as delegate.  */
      Type *td = TypeFunction::create (NULL, t, VARARGnone, LINKd);
      td = TypeDelegate::create (td);
      t = t->merge2 ();
    }

  /* Could be a va_list, which we mangle as a pointer.  */
  Type *tvalist = target.va_listType (Loc (), NULL);
  if (t->ty == Tsarray && tvalist->ty == Tsarray)
    {
      Type *tb = t->toBasetype ()->mutableOf ();
      if (tb == tvalist)
	{
	  tb = t->nextOf ()->pointerTo ();
	  t = tb->castMod (t->mod);
	}
    }

  return t;
}

/* Checks whether TYPE is a vendor-specific fundamental type.  Stores the result
   in IS_FUNDAMENTAL and returns true if the parameter was set.  */

bool
TargetCPP::fundamentalType (const Type *, bool &)
{
  return false;
}

/* Return the default system linkage for the target.  */

LINK
Target::systemLinkage (void)
{
  return LINKc;
}

/* Generate a TypeTuple of the equivalent types used to determine if a
   function argument of the given type can be passed in registers.
   The results of this are highly platform dependent, and intended
   primarly for use in implementing va_arg() with RTTI.  */

TypeTuple *
Target::toArgTypes (Type *)
{
  /* Not implemented, however this is not currently used anywhere.  */
  return NULL;
}