1/* Language-level data type conversion for GNU C. 2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005 3 Free Software Foundation, Inc. 4 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify it under 8the terms of the GNU General Public License as published by the Free 9Software Foundation; either version 2, or (at your option) any later 10version. 11 12GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13WARRANTY; without even the implied warranty of MERCHANTABILITY or 14FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15for more details. 16 17You should have received a copy of the GNU General Public License 18along with GCC; see the file COPYING. If not, write to the Free 19Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 2002110-1301, USA. */ 21 22 23/* This file contains the functions for converting C expressions 24 to different data types. The only entry point is `convert'. 25 Every language front end must have a `convert' function 26 but what kind of conversions it does will depend on the language. */ 27 28#include "config.h" 29#include "system.h" 30#include "coretypes.h" 31#include "tm.h" 32#include "tree.h" 33#include "flags.h" 34#include "convert.h" 35#include "c-common.h" 36#include "c-tree.h" 37#include "langhooks.h" 38#include "toplev.h" 39#include "target.h" 40 41/* Change of width--truncation and extension of integers or reals-- 42 is represented with NOP_EXPR. Proper functioning of many things 43 assumes that no other conversions can be NOP_EXPRs. 44 45 Conversion between integer and pointer is represented with CONVERT_EXPR. 46 Converting integer to real uses FLOAT_EXPR 47 and real to integer uses FIX_TRUNC_EXPR. 48 49 Here is a list of all the functions that assume that widening and 50 narrowing is always done with a NOP_EXPR: 51 In convert.c, convert_to_integer. 52 In c-typeck.c, build_binary_op (boolean ops), and 53 c_common_truthvalue_conversion. 54 In expr.c: expand_expr, for operands of a MULT_EXPR. 55 In fold-const.c: fold. 56 In tree.c: get_narrower and get_unwidened. */ 57 58/* Subroutines of `convert'. */ 59 60 61 62/* Create an expression whose value is that of EXPR, 63 converted to type TYPE. The TREE_TYPE of the value 64 is always TYPE. This function implements all reasonable 65 conversions; callers should filter out those that are 66 not permitted by the language being compiled. */ 67 68tree 69convert (tree type, tree expr) 70{ 71 tree e = expr; 72 enum tree_code code = TREE_CODE (type); 73 const char *invalid_conv_diag; 74 75 if (type == error_mark_node 76 || expr == error_mark_node 77 || TREE_TYPE (expr) == error_mark_node) 78 return error_mark_node; 79 80 if ((invalid_conv_diag 81 = targetm.invalid_conversion (TREE_TYPE (expr), type))) 82 { 83 error (invalid_conv_diag); 84 return error_mark_node; 85 } 86 87 if (type == TREE_TYPE (expr)) 88 return expr; 89 90 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))) 91 return fold_convert (type, expr); 92 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) 93 return error_mark_node; 94 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) 95 { 96 error ("void value not ignored as it ought to be"); 97 return error_mark_node; 98 } 99 if (code == VOID_TYPE) 100 return fold_convert (type, e); 101 if (code == INTEGER_TYPE || code == ENUMERAL_TYPE) 102 return fold (convert_to_integer (type, e)); 103 if (code == BOOLEAN_TYPE) 104 return fold_convert (type, c_objc_common_truthvalue_conversion (expr)); 105 if (code == POINTER_TYPE || code == REFERENCE_TYPE) 106 return fold (convert_to_pointer (type, e)); 107 if (code == REAL_TYPE) 108 return fold (convert_to_real (type, e)); 109 if (code == COMPLEX_TYPE) 110 return fold (convert_to_complex (type, e)); 111 if (code == VECTOR_TYPE) 112 return fold (convert_to_vector (type, e)); 113 if ((code == RECORD_TYPE || code == UNION_TYPE) 114 && lang_hooks.types_compatible_p (type, TREE_TYPE (expr))) 115 return e; 116 117 error ("conversion to non-scalar type requested"); 118 return error_mark_node; 119} 120