1/* Language-level data type conversion for GNU C. 2 Copyright (C) 1987-2015 Free Software Foundation, Inc. 3 4This file is part of GCC. 5 6GCC is free software; you can redistribute it and/or modify it under 7the terms of the GNU General Public License as published by the Free 8Software Foundation; either version 3, or (at your option) any later 9version. 10 11GCC is distributed in the hope that it will be useful, but WITHOUT ANY 12WARRANTY; without even the implied warranty of MERCHANTABILITY or 13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14for more details. 15 16You should have received a copy of the GNU General Public License 17along 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 "tm.h" 30#include "hash-set.h" 31#include "vec.h" 32#include "symtab.h" 33#include "input.h" 34#include "alias.h" 35#include "double-int.h" 36#include "machmode.h" 37#include "inchash.h" 38#include "tree.h" 39#include "flags.h" 40#include "convert.h" 41#include "c-family/c-common.h" 42#include "c-tree.h" 43#include "langhooks.h" 44#include "target.h" 45#include "ubsan.h" 46 47/* Change of width--truncation and extension of integers or reals-- 48 is represented with NOP_EXPR. Proper functioning of many things 49 assumes that no other conversions can be NOP_EXPRs. 50 51 Conversion between integer and pointer is represented with CONVERT_EXPR. 52 Converting integer to real uses FLOAT_EXPR 53 and real to integer uses FIX_TRUNC_EXPR. 54 55 Here is a list of all the functions that assume that widening and 56 narrowing is always done with a NOP_EXPR: 57 In convert.c, convert_to_integer. 58 In c-typeck.c, build_binary_op (boolean ops), and 59 c_common_truthvalue_conversion. 60 In expr.c: expand_expr, for operands of a MULT_EXPR. 61 In fold-const.c: fold. 62 In tree.c: get_narrower and get_unwidened. */ 63 64/* Subroutines of `convert'. */ 65 66 67 68/* Create an expression whose value is that of EXPR, 69 converted to type TYPE. The TREE_TYPE of the value 70 is always TYPE. This function implements all reasonable 71 conversions; callers should filter out those that are 72 not permitted by the language being compiled. */ 73 74tree 75convert (tree type, tree expr) 76{ 77 tree e = expr; 78 enum tree_code code = TREE_CODE (type); 79 const char *invalid_conv_diag; 80 tree ret; 81 location_t loc = EXPR_LOCATION (expr); 82 83 if (type == error_mark_node 84 || error_operand_p (expr)) 85 return error_mark_node; 86 87 if ((invalid_conv_diag 88 = targetm.invalid_conversion (TREE_TYPE (expr), type))) 89 { 90 error (invalid_conv_diag); 91 return error_mark_node; 92 } 93 94 if (type == TREE_TYPE (expr)) 95 return expr; 96 ret = targetm.convert_to_type (type, expr); 97 if (ret) 98 return ret; 99 100 STRIP_TYPE_NOPS (e); 101 102 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)) 103 && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE 104 || TREE_CODE (e) == COMPLEX_EXPR)) 105 return fold_convert_loc (loc, type, expr); 106 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) 107 return error_mark_node; 108 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) 109 { 110 error ("void value not ignored as it ought to be"); 111 return error_mark_node; 112 } 113 114 switch (code) 115 { 116 case VOID_TYPE: 117 return fold_convert_loc (loc, type, e); 118 119 case INTEGER_TYPE: 120 case ENUMERAL_TYPE: 121 if (flag_sanitize & SANITIZE_FLOAT_CAST 122 && TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE 123 && COMPLETE_TYPE_P (type) 124 && do_ubsan_in_current_function ()) 125 { 126 tree arg; 127 if (in_late_binary_op) 128 { 129 expr = save_expr (expr); 130 arg = expr; 131 } 132 else 133 { 134 expr = c_save_expr (expr); 135 arg = c_fully_fold (expr, false, NULL); 136 } 137 tree check = ubsan_instrument_float_cast (loc, type, expr, arg); 138 expr = fold_build1 (FIX_TRUNC_EXPR, type, expr); 139 if (check == NULL) 140 return expr; 141 return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr); 142 } 143 ret = convert_to_integer (type, e); 144 goto maybe_fold; 145 146 case BOOLEAN_TYPE: 147 return fold_convert_loc 148 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr)); 149 150 case POINTER_TYPE: 151 case REFERENCE_TYPE: 152 ret = convert_to_pointer (type, e); 153 goto maybe_fold; 154 155 case REAL_TYPE: 156 ret = convert_to_real (type, e); 157 goto maybe_fold; 158 159 case FIXED_POINT_TYPE: 160 ret = convert_to_fixed (type, e); 161 goto maybe_fold; 162 163 case COMPLEX_TYPE: 164 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE 165 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr, 166 but for the C FE c_save_expr needs to be called instead. */ 167 if (TREE_CODE (TREE_TYPE (e)) == COMPLEX_TYPE) 168 { 169 if (TREE_CODE (e) != COMPLEX_EXPR) 170 { 171 tree subtype = TREE_TYPE (type); 172 tree elt_type = TREE_TYPE (TREE_TYPE (e)); 173 174 if (in_late_binary_op) 175 e = save_expr (e); 176 else 177 e = c_save_expr (e); 178 ret 179 = fold_build2_loc (loc, COMPLEX_EXPR, type, 180 convert (subtype, 181 fold_build1 (REALPART_EXPR, 182 elt_type, e)), 183 convert (subtype, 184 fold_build1 (IMAGPART_EXPR, 185 elt_type, e))); 186 goto maybe_fold; 187 } 188 } 189 ret = convert_to_complex (type, e); 190 goto maybe_fold; 191 192 case VECTOR_TYPE: 193 ret = convert_to_vector (type, e); 194 goto maybe_fold; 195 196 case RECORD_TYPE: 197 case UNION_TYPE: 198 if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr))) 199 return e; 200 break; 201 202 default: 203 break; 204 205 maybe_fold: 206 if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR) 207 ret = fold (ret); 208 return ret; 209 } 210 211 error ("conversion to non-scalar type requested"); 212 return error_mark_node; 213} 214