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0e48b5a2 RS |
1 | /* Language-level data type conversion for GNU C. |
2 | Copyright (C) 1987, 1988, 1991 Free Software Foundation, Inc. | |
3 | ||
4 | This file is part of GNU CC. | |
5 | ||
6 | GNU CC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 2, or (at your option) | |
9 | any later version. | |
10 | ||
11 | GNU CC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with GNU CC; see the file COPYING. If not, write to | |
18 | the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ | |
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 "tree.h" | |
28 | #include "flags.h" | |
10055ae2 | 29 | #include "convert.h" |
0e48b5a2 RS |
30 | |
31 | /* Change of width--truncation and extension of integers or reals-- | |
32 | is represented with NOP_EXPR. Proper functioning of many things | |
33 | assumes that no other conversions can be NOP_EXPRs. | |
34 | ||
35 | Conversion between integer and pointer is represented with CONVERT_EXPR. | |
36 | Converting integer to real uses FLOAT_EXPR | |
37 | and real to integer uses FIX_TRUNC_EXPR. | |
38 | ||
39 | Here is a list of all the functions that assume that widening and | |
40 | narrowing is always done with a NOP_EXPR: | |
10055ae2 | 41 | In convert.c, convert_to_integer. |
0e48b5a2 RS |
42 | In c-typeck.c, build_binary_op (boolean ops), and truthvalue_conversion. |
43 | In expr.c: expand_expr, for operands of a MULT_EXPR. | |
44 | In fold-const.c: fold. | |
45 | In tree.c: get_narrower and get_unwidened. */ | |
46 | \f | |
47 | /* Subroutines of `convert'. */ | |
48 | ||
0e48b5a2 | 49 | |
0e48b5a2 RS |
50 | \f |
51 | /* Create an expression whose value is that of EXPR, | |
52 | converted to type TYPE. The TREE_TYPE of the value | |
53 | is always TYPE. This function implements all reasonable | |
54 | conversions; callers should filter out those that are | |
55 | not permitted by the language being compiled. */ | |
56 | ||
57 | tree | |
58 | convert (type, expr) | |
59 | tree type, expr; | |
60 | { | |
61 | register tree e = expr; | |
62 | register enum tree_code code = TREE_CODE (type); | |
63 | ||
412a4297 | 64 | if (type == TREE_TYPE (expr) |
dacaf84f | 65 | || TREE_CODE (expr) == ERROR_MARK) |
0e48b5a2 | 66 | return expr; |
412a4297 | 67 | if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))) |
542bc952 | 68 | return fold (build1 (NOP_EXPR, type, expr)); |
0e48b5a2 RS |
69 | if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) |
70 | return error_mark_node; | |
71 | if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) | |
72 | { | |
73 | error ("void value not ignored as it ought to be"); | |
74 | return error_mark_node; | |
75 | } | |
76 | if (code == VOID_TYPE) | |
77 | return build1 (CONVERT_EXPR, type, e); | |
78 | #if 0 | |
79 | /* This is incorrect. A truncation can't be stripped this way. | |
80 | Extensions will be stripped by the use of get_unwidened. */ | |
81 | if (TREE_CODE (expr) == NOP_EXPR) | |
82 | return convert (type, TREE_OPERAND (expr, 0)); | |
83 | #endif | |
84 | if (code == INTEGER_TYPE || code == ENUMERAL_TYPE) | |
85 | return fold (convert_to_integer (type, e)); | |
86 | if (code == POINTER_TYPE) | |
87 | return fold (convert_to_pointer (type, e)); | |
88 | if (code == REAL_TYPE) | |
89 | return fold (convert_to_real (type, e)); | |
c050422f RS |
90 | if (code == COMPLEX_TYPE) |
91 | return fold (convert_to_complex (type, e)); | |
0e48b5a2 RS |
92 | |
93 | error ("conversion to non-scalar type requested"); | |
94 | return error_mark_node; | |
95 | } |