gcc/ada/gcc-interface/cuintp.c

   1 /****************************************************************************
   2  *                                                                          *
   3  *                        GNAT COMPILER COMPONENTS                          *
   4  *                                                                          *
   5  *                               C U I N T P                                *
   6  *                                                                          *
   7  *                          C Implementation File                           *
   8  *                                                                          *
   9  *          Copyright (C) 1992-2014, Free Software Foundation, Inc.         *
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  11  * GNAT is free software;  you can  redistribute it  and/or modify it under *
  12  * terms of the  GNU General Public License as published  by the Free Soft- *
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  14  * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
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  17  * for  more details.  You should have received a copy of the GNU General   *
  18  * Public License along with GCC; see the file COPYING3.  If not see        *
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  20  *                                                                          *
  21  * GNAT was originally developed  by the GNAT team at  New York University. *
  22  * Extensive contributions were provided by Ada Core Technologies Inc.      *
  23  *                                                                          *
  24  ****************************************************************************/
  25
  26 /* This file corresponds to the Ada package body Uintp.  It was created
  27    manually from the files uintp.ads and uintp.adb.  */
  28
  29 #include "config.h"
  30 #include "system.h"
  31 #include "coretypes.h"
  32 #include "tm.h"
  33 #include "tree.h"
  34
  35 #include "ada.h"
  36 #include "types.h"
  37 #include "uintp.h"
  38 #include "ada-tree.h"
  39 #include "gigi.h"
  40
  41 /* Universal integers are represented by the Uint type which is an index into
  42    the Uints_Ptr table containing Uint_Entry values.  A Uint_Entry contains an
  43    index and length for getting the "digits" of the universal integer from the
  44    Udigits_Ptr table.
  45
  46    For efficiency, this method is used only for integer values larger than the
  47    constant Uint_Bias.  If a Uint is less than this constant, then it contains
  48    the integer value itself.  The origin of the Uints_Ptr table is adjusted so
  49    that a Uint value of Uint_Bias indexes the first element.
  50
  51    First define a utility function that operates like build_int_cst_type for
  52    integral types and does a conversion for floating-point types.  */
  53
  54 static tree
  55 build_cst_from_int (tree type, HOST_WIDE_INT low)
  56 {
  57   if (SCALAR_FLOAT_TYPE_P (type))
  58     return convert (type, build_int_cst (gnat_type_for_size (32, 0), low));
  59   else
  60     return build_int_cst_type (type, low);
  61 }
  62
  63 /* Similar to UI_To_Int, but return a GCC INTEGER_CST or REAL_CST node,
  64    depending on whether TYPE is an integral or real type.  Overflow is tested
  65    by the constant-folding used to build the node.  TYPE is the GCC type of
  66    the resulting node.  */
  67
  68 tree
  69 UI_To_gnu (Uint Input, tree type)
  70 {
  71   /* We might have a TYPE with biased representation and be passed an unbiased
  72      value that doesn't fit.  We always use an unbiased type to be able to hold
  73      any such possible value for intermediate computations and then rely on a
  74      conversion back to TYPE to perform the bias adjustment when need be.  */
  75   tree comp_type
  76     = TREE_CODE (type) == INTEGER_TYPE && TYPE_BIASED_REPRESENTATION_P (type)
  77       ? get_base_type (type) : type;
  78   tree gnu_ret;
  79
  80   if (Input <= Uint_Direct_Last)
  81     gnu_ret = build_cst_from_int (comp_type, Input - Uint_Direct_Bias);
  82   else
  83     {
  84       Int Idx = Uints_Ptr[Input].Loc;
  85       Pos Length = Uints_Ptr[Input].Length;
  86       Int First = Udigits_Ptr[Idx];
  87       tree gnu_base;
  88
  89       gcc_assert (Length > 0);
  90
  91       /* The computations we perform below always require a type at least as
  92          large as an integer not to overflow.  FP types are always fine, but
  93          INTEGER or ENUMERAL types we are handed may be too short.  We use a
  94          base integer type node for the computations in this case and will
  95          convert the final result back to the incoming type later on.  */
  96       if (!SCALAR_FLOAT_TYPE_P (comp_type) && TYPE_PRECISION (comp_type) < 32)
  97         comp_type = gnat_type_for_size (32, 0);
  98
  99       gnu_base = build_cst_from_int (comp_type, Base);
 100
 101       gnu_ret = build_cst_from_int (comp_type, First);
 102       if (First < 0)
 103         for (Idx++, Length--; Length; Idx++, Length--)
 104           gnu_ret = fold_build2 (MINUS_EXPR, comp_type,
 105                                  fold_build2 (MULT_EXPR, comp_type,
 106                                               gnu_ret, gnu_base),
 107                                  build_cst_from_int (comp_type,
 108                                                      Udigits_Ptr[Idx]));
 109       else
 110         for (Idx++, Length--; Length; Idx++, Length--)
 111           gnu_ret = fold_build2 (PLUS_EXPR, comp_type,
 112                                  fold_build2 (MULT_EXPR, comp_type,
 113                                               gnu_ret, gnu_base),
 114                                  build_cst_from_int (comp_type,
 115                                                      Udigits_Ptr[Idx]));
 116     }
 117
 118   gnu_ret = convert (type, gnu_ret);
 119
 120   /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on GNU_RET.  */
 121   while ((TREE_CODE (gnu_ret) == NOP_EXPR
 122           || TREE_CODE (gnu_ret) == NON_LVALUE_EXPR)
 123          && TREE_TYPE (TREE_OPERAND (gnu_ret, 0)) == TREE_TYPE (gnu_ret))
 124     gnu_ret = TREE_OPERAND (gnu_ret, 0);
 125
 126   return gnu_ret;
 127 }
 128
 129 /* Similar to UI_From_Int, but take a GCC INTEGER_CST.  We use UI_From_Int
 130    when possible, i.e. for a 32-bit signed value, to take advantage of its
 131    built-in caching mechanism.  For values of larger magnitude, we compute
 132    digits into a vector and call Vector_To_Uint.  */
 133
 134 Uint
 135 UI_From_gnu (tree Input)
 136 {
 137   tree gnu_type = TREE_TYPE (Input), gnu_base, gnu_temp;
 138   /* UI_Base is defined so that 5 Uint digits is sufficient to hold the
 139      largest possible signed 64-bit value.  */
 140   const int Max_For_Dint = 5;
 141   int v[Max_For_Dint], i;
 142   Vector_Template temp;
 143   Int_Vector vec;
 144
 145 #if HOST_BITS_PER_WIDE_INT == 64
 146   /* On 64-bit hosts, tree_fits_shwi_p tells whether the input fits in a
 147      signed 64-bit integer.  Then a truncation tells whether it fits
 148      in a signed 32-bit integer.  */
 149   if (tree_fits_shwi_p (Input))
 150     {
 151       HOST_WIDE_INT hw_input = tree_to_shwi (Input);
 152       if (hw_input == (int) hw_input)
 153         return UI_From_Int (hw_input);
 154     }
 155   else
 156     return No_Uint;
 157 #else
 158   /* On 32-bit hosts, tree_fits_shwi_p tells whether the input fits in a
 159      signed 32-bit integer.  Then a sign test tells whether it fits
 160      in a signed 64-bit integer.  */
 161   if (tree_fits_shwi_p (Input))
 162     return UI_From_Int (tree_to_shwi (Input));
 163
 164   gcc_assert (TYPE_PRECISION (gnu_type) <= 64);
 165   if (TYPE_UNSIGNED (gnu_type)
 166       && TYPE_PRECISION (gnu_type) == 64
 167       && wi::neg_p (Input, SIGNED))
 168     return No_Uint;
 169 #endif
 170
 171   gnu_base = build_int_cst (gnu_type, UI_Base);
 172   gnu_temp = Input;
 173
 174   for (i = Max_For_Dint - 1; i >= 0; i--)
 175     {
 176       v[i] = tree_to_shwi (fold_build1 (ABS_EXPR, gnu_type,
 177                                         fold_build2 (TRUNC_MOD_EXPR, gnu_type,
 178                                                      gnu_temp, gnu_base)));
 179       gnu_temp = fold_build2 (TRUNC_DIV_EXPR, gnu_type, gnu_temp, gnu_base);
 180     }
 181
 182   temp.Low_Bound = 1;
 183   temp.High_Bound = Max_For_Dint;
 184   vec.Bounds = &temp;
 185   vec.Array = v;
 186   return Vector_To_Uint (vec, tree_int_cst_sgn (Input) < 0);
 187 }