1/* Language-level data type conversion for GNU C. 2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005, 2007, 2008, 3 2009 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 3, 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 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#include "config.h" 28#include "system.h" 29#include "coretypes.h" 30#include "tm.h" 31#include "tree.h" 32#include "flags.h" 33#include "convert.h" 34#include "c-common.h" 35#include "c-tree.h" 36#include "langhooks.h" 37#include "toplev.h" 38#include "target.h" 39 40/* Change of width--truncation and extension of integers or reals-- 41 is represented with NOP_EXPR. Proper functioning of many things 42 assumes that no other conversions can be NOP_EXPRs. 43 44 Conversion between integer and pointer is represented with CONVERT_EXPR. 45 Converting integer to real uses FLOAT_EXPR 46 and real to integer uses FIX_TRUNC_EXPR. 47 48 Here is a list of all the functions that assume that widening and 49 narrowing is always done with a NOP_EXPR: 50 In convert.c, convert_to_integer. 51 In c-typeck.c, build_binary_op (boolean ops), and 52 c_common_truthvalue_conversion. 53 In expr.c: expand_expr, for operands of a MULT_EXPR. 54 In fold-const.c: fold. 55 In tree.c: get_narrower and get_unwidened. */ 56 57/* Subroutines of `convert'. */ 58 59 60 61/* Create an expression whose value is that of EXPR, 62 converted to type TYPE. The TREE_TYPE of the value 63 is always TYPE. This function implements all reasonable 64 conversions; callers should filter out those that are 65 not permitted by the language being compiled. */ 66 67tree 68convert (tree type, tree expr) 69{ 70 tree e = expr; 71 enum tree_code code = TREE_CODE (type); 72 const char *invalid_conv_diag; 73 tree ret; 74 location_t loc = EXPR_LOCATION (expr); 75 76 if (type == error_mark_node 77 || expr == error_mark_node 78 || TREE_TYPE (expr) == error_mark_node) 79 return error_mark_node; 80 81 if ((invalid_conv_diag 82 = targetm.invalid_conversion (TREE_TYPE (expr), type))) 83 { 84 error (invalid_conv_diag); 85 return error_mark_node; 86 } 87 88 if (type == TREE_TYPE (expr)) 89 return expr; 90 ret = targetm.convert_to_type (type, expr); 91 if (ret) 92 return ret; 93 94 STRIP_TYPE_NOPS (e); 95 96 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))) 97 return fold_convert_loc (loc, type, expr); 98 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) 99 return error_mark_node; 100 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) 101 { 102 error ("void value not ignored as it ought to be"); 103 return error_mark_node; 104 } 105 106 switch (code) 107 { 108 case VOID_TYPE: 109 return fold_convert_loc (loc, type, e); 110 111 case INTEGER_TYPE: 112 case ENUMERAL_TYPE: 113 ret = convert_to_integer (type, e); 114 goto maybe_fold; 115 116 case BOOLEAN_TYPE: 117 return fold_convert_loc 118 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr)); 119 120 case POINTER_TYPE: 121 case REFERENCE_TYPE: 122 ret = convert_to_pointer (type, e); 123 goto maybe_fold; 124 125 case REAL_TYPE: 126 ret = convert_to_real (type, e); 127 goto maybe_fold; 128 129 case FIXED_POINT_TYPE: 130 ret = convert_to_fixed (type, e); 131 goto maybe_fold; 132 133 case COMPLEX_TYPE: 134 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE 135 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr, 136 but for the C FE c_save_expr needs to be called instead. */ 137 if (TREE_CODE (TREE_TYPE (e)) == COMPLEX_TYPE) 138 { 139 tree subtype = TREE_TYPE (type); 140 tree elt_type = TREE_TYPE (TREE_TYPE (e)); 141 142 if (TYPE_MAIN_VARIANT (elt_type) != TYPE_MAIN_VARIANT (subtype) 143 && TREE_CODE (e) != COMPLEX_EXPR) 144 { 145 if (in_late_binary_op) 146 e = save_expr (e); 147 else 148 e = c_save_expr (e); 149 ret 150 = fold_build2 (COMPLEX_EXPR, type, 151 convert (subtype, 152 fold_build1 (REALPART_EXPR, 153 elt_type, e)), 154 convert (subtype, 155 fold_build1 (IMAGPART_EXPR, 156 elt_type, e))); 157 goto maybe_fold; 158 } 159 } 160 ret = convert_to_complex (type, e); 161 goto maybe_fold; 162 163 case VECTOR_TYPE: 164 ret = convert_to_vector (type, e); 165 goto maybe_fold; 166 167 case RECORD_TYPE: 168 case UNION_TYPE: 169 if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr))) 170 return e; 171 break; 172 173 default: 174 break; 175 176 maybe_fold: 177 if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR) 178 ret = fold (ret); 179 return ret; 180 } 181 182 error ("conversion to non-scalar type requested"); 183 return error_mark_node; 184} 185