gcc/ada/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) 1992-2003 Free Software Foundation, Inc.          *
  10  *                                                                          *
  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- *
  13  * ware  Foundation;  either version 2,  or (at your option) any later ver- *
  14  * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
  15  * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
  16  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License *
  17  * for  more details.  You should have  received  a copy of the GNU General *
  18  * Public License  distributed with GNAT;  see file COPYING.  If not, write *
  19  * to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, *
  20  * MA 02111-1307, USA.                                                      *
  21  *                                                                          *
  22  * GNAT was originally developed  by the GNAT team at  New York University. *
  23  * Extensive contributions were provided by Ada Core Technologies Inc.      *
  24  *                                                                          *
  25  ****************************************************************************/
  26
  27 /* This file corresponds to the Ada package body Uintp. It was created
  28    manually from the files uintp.ads and uintp.adb. */
  29
  30 #include "config.h"
  31 #include "system.h"
  32 #include "coretypes.h"
  33 #include "tm.h"
  34 #include "tree.h"
  35 #include "ada.h"
  36 #include "types.h"
  37 #include "uintp.h"
  38 #include "atree.h"
  39 #include "elists.h"
  40 #include "nlists.h"
  41 #include "stringt.h"
  42 #include "fe.h"
  43 #include "gigi.h"
  44
  45 /* Universal integers are represented by the Uint type which is an index into
  46    the Uints_Ptr table containing Uint_Entry values.  A Uint_Entry contains an
  47    index and length for getting the "digits" of the universal integer from the
  48    Udigits_Ptr table.
  49
  50    For efficiency, this method is used only for integer values larger than the
  51    constant Uint_Bias.  If a Uint is less than this constant, then it contains
  52    the integer value itself.  The origin of the Uints_Ptr table is adjusted so
  53    that a Uint value of Uint_Bias indexes the first element.  */
  54
  55 /* Similarly to UI_To_Int, but return a GCC INTEGER_CST.  Overflow is tested
  56    by the constant-folding used to build the node.  TYPE is the GCC type of the
  57    resulting node.  */
  58
  59 tree
  60 UI_To_gnu (Uint Input, tree type)
  61 {
  62   tree gnu_ret;
  63
  64   if (Input <= Uint_Direct_Last)
  65     gnu_ret = convert (type, build_int_2 (Input - Uint_Direct_Bias,
  66                                           Input < Uint_Direct_Bias ? -1 : 0));
  67   else
  68     {
  69       Int Idx =    Uints_Ptr[Input].Loc;
  70       Pos Length = Uints_Ptr[Input].Length;
  71       Int First = Udigits_Ptr[Idx];
  72       /* Do computations in integer type or TYPE whichever is wider, then
  73          convert later.  This avoid overflow if type is short integer.  */
  74       tree comp_type
  75         = (TYPE_PRECISION (type) >= TYPE_PRECISION (integer_type_node)
  76            ? type : integer_type_node);
  77       tree gnu_base = convert (comp_type, build_int_2 (Base, 0));
  78
  79       if (Length <= 0)
  80         gigi_abort (601);
  81
  82       gnu_ret = convert (comp_type, build_int_2 (First, First < 0 ? -1 : 0));
  83       if (First < 0)
  84         for (Idx++, Length--; Length; Idx++, Length--)
  85           gnu_ret = fold (build (MINUS_EXPR, comp_type,
  86                                  fold (build (MULT_EXPR, comp_type,
  87                                               gnu_ret, gnu_base)),
  88                                  convert (comp_type,
  89                                           build_int_2 (Udigits_Ptr[Idx], 0))));
  90       else
  91         for (Idx++, Length--; Length; Idx++, Length--)
  92           gnu_ret = fold (build (PLUS_EXPR, comp_type,
  93                                  fold (build (MULT_EXPR, comp_type,
  94                                               gnu_ret, gnu_base)),
  95                                  convert (comp_type,
  96                                           build_int_2 (Udigits_Ptr[Idx], 0))));
  97     }
  98
  99   gnu_ret = convert (type, gnu_ret);
 100
 101   /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on GNU_RET.  */
 102   while ((TREE_CODE (gnu_ret) == NOP_EXPR
 103           || TREE_CODE (gnu_ret) == NON_LVALUE_EXPR)
 104          && TREE_TYPE (TREE_OPERAND (gnu_ret, 0)) == TREE_TYPE (gnu_ret))
 105     gnu_ret = TREE_OPERAND (gnu_ret, 0);
 106
 107   return gnu_ret;
 108 }