1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
/* Language-level data type conversion for GNU C.
Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005
Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/* This file contains the functions for converting C expressions
to different data types. The only entry point is `convert'.
Every language front end must have a `convert' function
but what kind of conversions it does will depend on the language. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "flags.h"
#include "convert.h"
#include "c-common.h"
#include "c-tree.h"
#include "langhooks.h"
#include "toplev.h"
/* Change of width--truncation and extension of integers or reals--
is represented with NOP_EXPR. Proper functioning of many things
assumes that no other conversions can be NOP_EXPRs.
Conversion between integer and pointer is represented with CONVERT_EXPR.
Converting integer to real uses FLOAT_EXPR
and real to integer uses FIX_TRUNC_EXPR.
Here is a list of all the functions that assume that widening and
narrowing is always done with a NOP_EXPR:
In convert.c, convert_to_integer.
In c-typeck.c, build_binary_op (boolean ops), and
c_common_truthvalue_conversion.
In expr.c: expand_expr, for operands of a MULT_EXPR.
In fold-const.c: fold.
In tree.c: get_narrower and get_unwidened. */
/* Subroutines of `convert'. */
/* Create an expression whose value is that of EXPR,
converted to type TYPE. The TREE_TYPE of the value
is always TYPE. This function implements all reasonable
conversions; callers should filter out those that are
not permitted by the language being compiled. */
tree
convert (tree type, tree expr)
{
tree e = expr;
enum tree_code code = TREE_CODE (type);
if (type == TREE_TYPE (expr)
|| TREE_CODE (expr) == ERROR_MARK
|| code == ERROR_MARK || TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
return expr;
if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))
return fold (build1 (NOP_EXPR, type, expr));
if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
return error_mark_node;
if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
{
error ("void value not ignored as it ought to be");
return error_mark_node;
}
if (code == VOID_TYPE)
return build1 (CONVERT_EXPR, type, e);
#if 0
/* This is incorrect. A truncation can't be stripped this way.
Extensions will be stripped by the use of get_unwidened. */
if (TREE_CODE (expr) == NOP_EXPR)
return convert (type, TREE_OPERAND (expr, 0));
#endif
if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
return fold (convert_to_integer (type, e));
if (code == BOOLEAN_TYPE)
{
tree t = c_objc_common_truthvalue_conversion (expr);
if (TREE_CODE (t) == ERROR_MARK)
return t;
/* If it returns a NOP_EXPR, we must fold it here to avoid
infinite recursion between fold () and convert (). */
if (TREE_CODE (t) == NOP_EXPR)
return fold (build1 (NOP_EXPR, type, TREE_OPERAND (t, 0)));
else
return fold (build1 (NOP_EXPR, type, t));
}
if (code == POINTER_TYPE || code == REFERENCE_TYPE)
return fold (convert_to_pointer (type, e));
if (code == REAL_TYPE)
return fold (convert_to_real (type, e));
if (code == COMPLEX_TYPE)
return fold (convert_to_complex (type, e));
if (code == VECTOR_TYPE)
return fold (convert_to_vector (type, e));
if ((code == RECORD_TYPE || code == UNION_TYPE)
&& lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
return e;
error ("conversion to non-scalar type requested");
return error_mark_node;
}
|
