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.          *
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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- *
  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 *
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  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    First define a utility function that operates like build_int_cst for
  56    integral types and does a conversion to floating-point for real types.  */
  57
  58 static tree
  59 build_cst_from_int (tree type, HOST_WIDE_INT low)
  60 {
  61   if (TREE_CODE (type) == REAL_TYPE)
  62     return convert (type, build_int_cst (NULL_TREE, low));
  63   else
  64     return force_fit_type (build_int_cst (type, low), false, false, false);
  65 }
  66
  67 /* Similar to UI_To_Int, but return a GCC INTEGER_CST or REAL_CST node,
  68    depending on whether TYPE is an integral or real type.  Overflow is tested
  69    by the constant-folding used to build the node.  TYPE is the GCC type of
  70    the resulting node.  */
  71
  72 tree
  73 UI_To_gnu (Uint Input, tree type)
  74 {
  75   tree gnu_ret;
  76
  77   if (Input <= Uint_Direct_Last)
  78     gnu_ret = build_cst_from_int (type, Input - Uint_Direct_Bias);
  79   else
  80     {
  81       Int Idx = Uints_Ptr[Input].Loc;
  82       Pos Length = Uints_Ptr[Input].Length;
  83       Int First = Udigits_Ptr[Idx];
  84       /* Do computations in integer type or TYPE whichever is wider, then
  85          convert later.  This avoid overflow if type is short integer.  */
  86       tree comp_type
  87         = ((TREE_CODE (type) == REAL_TYPE
  88             || TYPE_PRECISION (type) >= TYPE_PRECISION (integer_type_node))
  89            ? type : integer_type_node);
  90       tree gnu_base = build_cst_from_int (comp_type, Base);
  91
  92       if (Length <= 0)
  93         abort ();
  94
  95       gnu_ret = build_cst_from_int (comp_type, First);
  96       if (First < 0)
  97         for (Idx++, Length--; Length; Idx++, Length--)
  98           gnu_ret = fold (build (MINUS_EXPR, comp_type,
  99                                  fold (build (MULT_EXPR, comp_type,
 100                                               gnu_ret, gnu_base)),
 101                                  build_cst_from_int (comp_type,
 102                                                      Udigits_Ptr[Idx])));
 103       else
 104         for (Idx++, Length--; Length; Idx++, Length--)
 105           gnu_ret = fold (build (PLUS_EXPR, comp_type,
 106                                  fold (build (MULT_EXPR, comp_type,
 107                                               gnu_ret, gnu_base)),
 108                                  build_cst_from_int (comp_type,
 109                                                      Udigits_Ptr[Idx])));
 110     }
 111
 112   gnu_ret = convert (type, gnu_ret);
 113
 114   /* We don't need any NOP_EXPR or NON_LVALUE_EXPR on GNU_RET.  */
 115   while ((TREE_CODE (gnu_ret) == NOP_EXPR
 116           || TREE_CODE (gnu_ret) == NON_LVALUE_EXPR)
 117          && TREE_TYPE (TREE_OPERAND (gnu_ret, 0)) == TREE_TYPE (gnu_ret))
 118     gnu_ret = TREE_OPERAND (gnu_ret, 0);
 119
 120   return gnu_ret;
 121 }