1 /* Language-level data type conversion for GNU C. 2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005, 2007, 2008, 3 2009, 2010, 2011, 2012 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 #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-family/c-common.h" 35 #include "c-tree.h" 36 #include "langhooks.h" 37 #include "target.h" 38 39 /* Change of width--truncation and extension of integers or reals-- 40 is represented with NOP_EXPR. Proper functioning of many things 41 assumes that no other conversions can be NOP_EXPRs. 42 43 Conversion between integer and pointer is represented with CONVERT_EXPR. 44 Converting integer to real uses FLOAT_EXPR 45 and real to integer uses FIX_TRUNC_EXPR. 46 47 Here is a list of all the functions that assume that widening and 48 narrowing is always done with a NOP_EXPR: 49 In convert.c, convert_to_integer. 50 In c-typeck.c, build_binary_op (boolean ops), and 51 c_common_truthvalue_conversion. 52 In expr.c: expand_expr, for operands of a MULT_EXPR. 53 In fold-const.c: fold. 54 In tree.c: get_narrower and get_unwidened. */ 55 56 /* Subroutines of `convert'. */ 57 58 59 60 /* Create an expression whose value is that of EXPR, 61 converted to type TYPE. The TREE_TYPE of the value 62 is always TYPE. This function implements all reasonable 63 conversions; callers should filter out those that are 64 not permitted by the language being compiled. */ 65 66 tree 67 convert (tree type, tree expr) 68 { 69 tree e = expr; 70 enum tree_code code = TREE_CODE (type); 71 const char *invalid_conv_diag; 72 tree ret; 73 location_t loc = EXPR_LOCATION (expr); 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 ret = targetm.convert_to_type (type, expr); 90 if (ret) 91 return ret; 92 93 STRIP_TYPE_NOPS (e); 94 95 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)) 96 && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE 97 || TREE_CODE (e) == COMPLEX_EXPR)) 98 return fold_convert_loc (loc, type, expr); 99 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) 100 return error_mark_node; 101 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) 102 { 103 error ("void value not ignored as it ought to be"); 104 return error_mark_node; 105 } 106 107 switch (code) 108 { 109 case VOID_TYPE: 110 return fold_convert_loc (loc, type, e); 111 112 case INTEGER_TYPE: 113 case ENUMERAL_TYPE: 114 ret = convert_to_integer (type, e); 115 goto maybe_fold; 116 117 case BOOLEAN_TYPE: 118 return fold_convert_loc 119 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr)); 120 121 case POINTER_TYPE: 122 case REFERENCE_TYPE: 123 ret = convert_to_pointer (type, e); 124 goto maybe_fold; 125 126 case REAL_TYPE: 127 ret = convert_to_real (type, e); 128 goto maybe_fold; 129 130 case FIXED_POINT_TYPE: 131 ret = convert_to_fixed (type, e); 132 goto maybe_fold; 133 134 case COMPLEX_TYPE: 135 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE 136 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr, 137 but for the C FE c_save_expr needs to be called instead. */ 138 if (TREE_CODE (TREE_TYPE (e)) == COMPLEX_TYPE) 139 { 140 if (TREE_CODE (e) != COMPLEX_EXPR) 141 { 142 tree subtype = TREE_TYPE (type); 143 tree elt_type = TREE_TYPE (TREE_TYPE (e)); 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_loc (loc, 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