1 /* Language-level data type conversion for GNU C. 2 Copyright (C) 1987-2017 Free Software Foundation, Inc. 3 4 This file is part of GCC. 5 6 GCC is free software; you can redistribute it and/or modify it under 7 the terms of the GNU General Public License as published by the Free 8 Software Foundation; either version 3, or (at your option) any later 9 version. 10 11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12 WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GCC; see the file COPYING3. If not see 18 <http://www.gnu.org/licenses/>. */ 19 20 21 /* This file contains the functions for converting C expressions 22 to different data types. The only entry point is `convert'. 23 Every language front end must have a `convert' function 24 but what kind of conversions it does will depend on the language. */ 25 26 #include "config.h" 27 #include "system.h" 28 #include "coretypes.h" 29 #include "target.h" 30 #include "c-tree.h" 31 #include "convert.h" 32 #include "langhooks.h" 33 #include "ubsan.h" 34 35 /* Change of width--truncation and extension of integers or reals-- 36 is represented with NOP_EXPR. Proper functioning of many things 37 assumes that no other conversions can be NOP_EXPRs. 38 39 Conversion between integer and pointer is represented with CONVERT_EXPR. 40 Converting integer to real uses FLOAT_EXPR 41 and real to integer uses FIX_TRUNC_EXPR. 42 43 Here is a list of all the functions that assume that widening and 44 narrowing is always done with a NOP_EXPR: 45 In convert.c, convert_to_integer. 46 In c-typeck.c, build_binary_op (boolean ops), and 47 c_common_truthvalue_conversion. 48 In expr.c: expand_expr, for operands of a MULT_EXPR. 49 In fold-const.c: fold. 50 In tree.c: get_narrower and get_unwidened. */ 51 52 /* Subroutines of `convert'. */ 53 54 55 56 /* Create an expression whose value is that of EXPR, 57 converted to type TYPE. The TREE_TYPE of the value 58 is always TYPE. This function implements all reasonable 59 conversions; callers should filter out those that are 60 not permitted by the language being compiled. */ 61 62 tree 63 convert (tree type, tree expr) 64 { 65 tree e = expr; 66 enum tree_code code = TREE_CODE (type); 67 const char *invalid_conv_diag; 68 tree ret; 69 location_t loc = EXPR_LOCATION (expr); 70 71 if (type == error_mark_node 72 || error_operand_p (expr)) 73 return error_mark_node; 74 75 if ((invalid_conv_diag 76 = targetm.invalid_conversion (TREE_TYPE (expr), type))) 77 { 78 error (invalid_conv_diag); 79 return error_mark_node; 80 } 81 82 if (type == TREE_TYPE (expr)) 83 return expr; 84 ret = targetm.convert_to_type (type, expr); 85 if (ret) 86 return ret; 87 88 STRIP_TYPE_NOPS (e); 89 90 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)) 91 && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE 92 || TREE_CODE (e) == COMPLEX_EXPR)) 93 return fold_convert_loc (loc, type, expr); 94 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) 95 return error_mark_node; 96 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) 97 { 98 error ("void value not ignored as it ought to be"); 99 return error_mark_node; 100 } 101 102 switch (code) 103 { 104 case VOID_TYPE: 105 return fold_convert_loc (loc, type, e); 106 107 case INTEGER_TYPE: 108 case ENUMERAL_TYPE: 109 if (flag_sanitize & SANITIZE_FLOAT_CAST 110 && TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE 111 && COMPLETE_TYPE_P (type) 112 && do_ubsan_in_current_function ()) 113 { 114 if (in_late_binary_op) 115 expr = save_expr (expr); 116 else 117 { 118 expr = c_save_expr (expr); 119 expr = c_fully_fold (expr, false, NULL); 120 } 121 tree check = ubsan_instrument_float_cast (loc, type, expr); 122 expr = fold_build1 (FIX_TRUNC_EXPR, type, expr); 123 if (check == NULL_TREE) 124 return expr; 125 return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr); 126 } 127 ret = convert_to_integer (type, e); 128 goto maybe_fold; 129 130 case BOOLEAN_TYPE: 131 return fold_convert_loc 132 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr)); 133 134 case POINTER_TYPE: 135 case REFERENCE_TYPE: 136 ret = convert_to_pointer (type, e); 137 goto maybe_fold; 138 139 case REAL_TYPE: 140 ret = convert_to_real (type, e); 141 goto maybe_fold; 142 143 case FIXED_POINT_TYPE: 144 ret = convert_to_fixed (type, e); 145 goto maybe_fold; 146 147 case COMPLEX_TYPE: 148 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE 149 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr, 150 but for the C FE c_save_expr needs to be called instead. */ 151 if (TREE_CODE (TREE_TYPE (e)) == COMPLEX_TYPE) 152 { 153 if (TREE_CODE (e) != COMPLEX_EXPR) 154 { 155 tree subtype = TREE_TYPE (type); 156 tree elt_type = TREE_TYPE (TREE_TYPE (e)); 157 158 if (in_late_binary_op) 159 e = save_expr (e); 160 else 161 e = c_save_expr (e); 162 ret 163 = fold_build2_loc (loc, COMPLEX_EXPR, type, 164 convert (subtype, 165 fold_build1 (REALPART_EXPR, 166 elt_type, e)), 167 convert (subtype, 168 fold_build1 (IMAGPART_EXPR, 169 elt_type, e))); 170 goto maybe_fold; 171 } 172 } 173 ret = convert_to_complex (type, e); 174 goto maybe_fold; 175 176 case VECTOR_TYPE: 177 ret = convert_to_vector (type, e); 178 goto maybe_fold; 179 180 case RECORD_TYPE: 181 case UNION_TYPE: 182 if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr))) 183 return e; 184 break; 185 186 default: 187 break; 188 189 maybe_fold: 190 if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR) 191 ret = fold (ret); 192 return ret; 193 } 194 195 error ("conversion to non-scalar type requested"); 196 return error_mark_node; 197 } 198