1 /* Language-level data type conversion for GNU C. 2 Copyright (C) 1987-2018 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 #include "stringpool.h" 35 #include "attribs.h" 36 #include "asan.h" 37 38 /* Change of width--truncation and extension of integers or reals-- 39 is represented with NOP_EXPR. Proper functioning of many things 40 assumes that no other conversions can be NOP_EXPRs. 41 42 Conversion between integer and pointer is represented with CONVERT_EXPR. 43 Converting integer to real uses FLOAT_EXPR 44 and real to integer uses FIX_TRUNC_EXPR. 45 46 Here is a list of all the functions that assume that widening and 47 narrowing is always done with a NOP_EXPR: 48 In convert.c, convert_to_integer. 49 In c-typeck.c, build_binary_op (boolean ops), and 50 c_common_truthvalue_conversion. 51 In expr.c: expand_expr, for operands of a MULT_EXPR. 52 In fold-const.c: fold. 53 In tree.c: get_narrower and get_unwidened. */ 54 55 /* Subroutines of `convert'. */ 56 57 58 59 /* Create an expression whose value is that of EXPR, 60 converted to type TYPE. The TREE_TYPE of the value 61 is always TYPE. This function implements all reasonable 62 conversions; callers should filter out those that are 63 not permitted by the language being compiled. */ 64 65 tree 66 convert (tree type, tree expr) 67 { 68 tree e = expr; 69 enum tree_code code = TREE_CODE (type); 70 const char *invalid_conv_diag; 71 tree ret; 72 location_t loc = EXPR_LOCATION (expr); 73 74 if (type == error_mark_node 75 || error_operand_p (expr)) 76 return error_mark_node; 77 78 if ((invalid_conv_diag 79 = targetm.invalid_conversion (TREE_TYPE (expr), type))) 80 { 81 error (invalid_conv_diag); 82 return error_mark_node; 83 } 84 85 if (type == TREE_TYPE (expr)) 86 return expr; 87 ret = targetm.convert_to_type (type, expr); 88 if (ret) 89 return ret; 90 91 STRIP_TYPE_NOPS (e); 92 93 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)) 94 && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE 95 || TREE_CODE (e) == COMPLEX_EXPR)) 96 return fold_convert_loc (loc, type, expr); 97 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) 98 return error_mark_node; 99 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) 100 { 101 error ("void value not ignored as it ought to be"); 102 return error_mark_node; 103 } 104 105 switch (code) 106 { 107 case VOID_TYPE: 108 return fold_convert_loc (loc, type, e); 109 110 case INTEGER_TYPE: 111 case ENUMERAL_TYPE: 112 if (sanitize_flags_p (SANITIZE_FLOAT_CAST) 113 && current_function_decl != NULL_TREE 114 && TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE 115 && COMPLETE_TYPE_P (type)) 116 { 117 expr = save_expr (expr); 118 expr = c_fully_fold (expr, false, NULL); 119 tree check = ubsan_instrument_float_cast (loc, type, expr); 120 expr = fold_build1 (FIX_TRUNC_EXPR, type, expr); 121 if (check == NULL_TREE) 122 return expr; 123 return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr); 124 } 125 ret = convert_to_integer (type, e); 126 goto maybe_fold; 127 128 case BOOLEAN_TYPE: 129 return fold_convert_loc 130 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr)); 131 132 case POINTER_TYPE: 133 case REFERENCE_TYPE: 134 ret = convert_to_pointer (type, e); 135 goto maybe_fold; 136 137 case REAL_TYPE: 138 ret = convert_to_real (type, e); 139 goto maybe_fold; 140 141 case FIXED_POINT_TYPE: 142 ret = convert_to_fixed (type, e); 143 goto maybe_fold; 144 145 case COMPLEX_TYPE: 146 ret = convert_to_complex (type, e); 147 goto maybe_fold; 148 149 case VECTOR_TYPE: 150 ret = convert_to_vector (type, e); 151 goto maybe_fold; 152 153 case RECORD_TYPE: 154 case UNION_TYPE: 155 if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr))) 156 return e; 157 break; 158 159 default: 160 break; 161 162 maybe_fold: 163 if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR) 164 ret = fold (ret); 165 return ret; 166 } 167 168 error ("conversion to non-scalar type requested"); 169 return error_mark_node; 170 } 171