1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
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
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
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/>. */
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. */
28 #include "coretypes.h"
35 #include "double-int.h"
41 #include "c-family/c-common.h"
43 #include "langhooks.h"
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.
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.
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. */
64 /* Subroutines of `convert'. */
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. */
75 convert (tree type, tree expr)
78 enum tree_code code = TREE_CODE (type);
79 const char *invalid_conv_diag;
81 location_t loc = EXPR_LOCATION (expr);
83 if (type == error_mark_node
84 || error_operand_p (expr))
85 return error_mark_node;
87 if ((invalid_conv_diag
88 = targetm.invalid_conversion (TREE_TYPE (expr), type)))
90 error (invalid_conv_diag);
91 return error_mark_node;
94 if (type == TREE_TYPE (expr))
96 ret = targetm.convert_to_type (type, expr);
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)
110 error ("void value not ignored as it ought to be");
111 return error_mark_node;
117 return fold_convert_loc (loc, type, e);
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 ())
127 if (in_late_binary_op)
129 expr = save_expr (expr);
134 expr = c_save_expr (expr);
135 arg = c_fully_fold (expr, false, NULL);
137 tree check = ubsan_instrument_float_cast (loc, type, expr, arg);
138 expr = fold_build1 (FIX_TRUNC_EXPR, type, expr);
141 return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
143 ret = convert_to_integer (type, e);
147 return fold_convert_loc
148 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr));
152 ret = convert_to_pointer (type, e);
156 ret = convert_to_real (type, e);
159 case FIXED_POINT_TYPE:
160 ret = convert_to_fixed (type, e);
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)
169 if (TREE_CODE (e) != COMPLEX_EXPR)
171 tree subtype = TREE_TYPE (type);
172 tree elt_type = TREE_TYPE (TREE_TYPE (e));
174 if (in_late_binary_op)
179 = fold_build2_loc (loc, COMPLEX_EXPR, type,
181 fold_build1 (REALPART_EXPR,
184 fold_build1 (IMAGPART_EXPR,
189 ret = convert_to_complex (type, e);
193 ret = convert_to_vector (type, e);
198 if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
206 if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR)
211 error ("conversion to non-scalar type requested");
212 return error_mark_node;