115 lines
4.0 KiB
C
115 lines
4.0 KiB
C
/* Language-level data type conversion for GNU C.
|
||
Copyright (C) 1987, 1988, 1991, 1998, 2002 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 "tree.h"
|
||
#include "flags.h"
|
||
#include "convert.h"
|
||
#include "c-common.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 (type, expr)
|
||
tree type, 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_common_truthvalue_conversion (expr);
|
||
/* 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));
|
||
|
||
error ("conversion to non-scalar type requested");
|
||
return error_mark_node;
|
||
}
|