gcc/fortran/convert.c

   1 /* Language-level data type conversion for GNU C.
   2    Copyright (C) 1987, 1988, 1991, 1998, 2002, 2007, 2008, 2010
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21
  22 /* This file contains the functions for converting C expressions
  23    to different data types.  The only entry point is `convert'.
  24    Every language front end must have a `convert' function
  25    but what kind of conversions it does will depend on the language.  */
  26
  27 /* copied from the f77 frontend I think */
  28
  29 /* copied from c-convert.c without significant modification*/
  30 /* Change of width--truncation and extension of integers or reals--
  31    is represented with NOP_EXPR.  Proper functioning of many things
  32    assumes that no other conversions can be NOP_EXPRs.
  33 */
  34
  35 /* I've added support for WITH_RECORD_EXPR.  */
  36
  37 #include "config.h"
  38 #include "system.h"
  39 #include "coretypes.h"
  40 #include "tree.h"
  41 #include "flags.h"
  42 #include "convert.h"
  43 #include "diagnostic-core.h"    /* For error.  */
  44 #include "gfortran.h"
  45 #include "trans.h"
  46
  47 /*
  48    Conversion between integer and pointer is represented with CONVERT_EXPR.
  49    Converting integer to real uses FLOAT_EXPR
  50    and real to integer uses FIX_TRUNC_EXPR.
  51
  52    Here is a list of all the functions that assume that widening and
  53    narrowing is always done with a NOP_EXPR:
  54      In convert.c, convert_to_integer.
  55      In c-typeck.c, build_binary_op (boolean ops), and
  56         c_common_truthvalue_conversion.
  57      In expr.c: expand_expr, for operands of a MULT_EXPR.
  58      In fold-const.c: fold.
  59      In tree.c: get_narrower and get_unwidened.  */
  60
  61 /* Subroutines of `convert'.  */
  62
  63
  64 /* Create an expression whose value is that of EXPR,
  65    converted to type TYPE.  The TREE_TYPE of the value
  66    is always TYPE.  This function implements all reasonable
  67    conversions; callers should filter out those that are
  68    not permitted by the language being compiled.  */
  69 /* We are assuming that given a SIMPLE val, the result will be a SIMPLE rhs.
  70    If this is not the case, we will abort with an internal error.  */
  71 tree
  72 convert (tree type, tree expr)
  73 {
  74   tree e = expr;
  75   enum tree_code code = TREE_CODE (type);
  76
  77   if (type == TREE_TYPE (expr)
  78       || TREE_CODE (expr) == ERROR_MARK
  79       || code == ERROR_MARK || TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
  80     return expr;
  81
  82   if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))
  83     return fold_build1_loc (input_location, NOP_EXPR, type, expr);
  84   if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
  85     return error_mark_node;
  86   if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
  87     {
  88       error ("void value not ignored as it ought to be");
  89       return error_mark_node;
  90     }
  91   if (code == VOID_TYPE)
  92     return fold_build1_loc (input_location, CONVERT_EXPR, type, e);
  93 #if 0
  94   /* This is incorrect.  A truncation can't be stripped this way.
  95      Extensions will be stripped by the use of get_unwidened.  */
  96   if (TREE_CODE (expr) == NOP_EXPR)
  97     return convert (type, TREE_OPERAND (expr, 0));
  98 #endif
  99   if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
 100     return fold (convert_to_integer (type, e));
 101   if (code == BOOLEAN_TYPE)
 102     {
 103       e = gfc_truthvalue_conversion (e);
 104
 105       /* If we have a NOP_EXPR, we must fold it here to avoid
 106          infinite recursion between fold () and convert ().  */
 107       if (TREE_CODE (e) == NOP_EXPR)
 108         return fold_build1_loc (input_location, NOP_EXPR, type,
 109                                 TREE_OPERAND (e, 0));
 110       else
 111         return fold_build1_loc (input_location, NOP_EXPR, type, e);
 112     }
 113   if (code == POINTER_TYPE || code == REFERENCE_TYPE)
 114     return fold (convert_to_pointer (type, e));
 115   if (code == REAL_TYPE)
 116     return fold (convert_to_real (type, e));
 117   if (code == COMPLEX_TYPE)
 118     return fold (convert_to_complex (type, e));
 119   if (code == VECTOR_TYPE)
 120     return fold (convert_to_vector (type, e));
 121
 122   error ("conversion to non-scalar type requested");
 123   return error_mark_node;
 124 }