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/* Language-level data type conversion for GNU C.
Copyright (C) 1987-2015 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 3, 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 COPYING3. If not see
<http://www.gnu.org/licenses/>. */
/* 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-family/c-common.h"
#include "c-tree.h"
#include "langhooks.h"
#include "target.h"
#include "ubsan.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);
const char *invalid_conv_diag;
tree ret;
location_t loc = EXPR_LOCATION (expr);
if (type == error_mark_node
|| error_operand_p (expr))
return error_mark_node;
if ((invalid_conv_diag
= targetm.invalid_conversion (TREE_TYPE (expr), type)))
{
error (invalid_conv_diag);
return error_mark_node;
}
if (type == TREE_TYPE (expr))
return expr;
ret = targetm.convert_to_type (type, expr);
if (ret)
return ret;
STRIP_TYPE_NOPS (e);
if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))
&& (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE
|| TREE_CODE (e) == COMPLEX_EXPR))
return fold_convert_loc (loc, 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;
}
switch (code)
{
case VOID_TYPE:
return fold_convert_loc (loc, type, e);
case INTEGER_TYPE:
case ENUMERAL_TYPE:
if (flag_sanitize & SANITIZE_FLOAT_CAST
&& TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE
&& COMPLETE_TYPE_P (type)
&& current_function_decl != NULL_TREE
&& !lookup_attribute ("no_sanitize_undefined",
DECL_ATTRIBUTES (current_function_decl)))
{
tree arg;
if (in_late_binary_op)
{
expr = save_expr (expr);
arg = expr;
}
else
{
expr = c_save_expr (expr);
arg = c_fully_fold (expr, false, NULL);
}
tree check = ubsan_instrument_float_cast (loc, type, expr, arg);
expr = fold_build1 (FIX_TRUNC_EXPR, type, expr);
if (check == NULL)
return expr;
return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
}
ret = convert_to_integer (type, e);
goto maybe_fold;
case BOOLEAN_TYPE:
return fold_convert_loc
(loc, type, c_objc_common_truthvalue_conversion (input_location, expr));
case POINTER_TYPE:
case REFERENCE_TYPE:
ret = convert_to_pointer (type, e);
goto maybe_fold;
case REAL_TYPE:
ret = convert_to_real (type, e);
goto maybe_fold;
case FIXED_POINT_TYPE:
ret = convert_to_fixed (type, e);
goto maybe_fold;
case COMPLEX_TYPE:
/* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE
and e is not COMPLEX_EXPR, convert_to_complex uses save_expr,
but for the C FE c_save_expr needs to be called instead. */
if (TREE_CODE (TREE_TYPE (e)) == COMPLEX_TYPE)
{
if (TREE_CODE (e) != COMPLEX_EXPR)
{
tree subtype = TREE_TYPE (type);
tree elt_type = TREE_TYPE (TREE_TYPE (e));
if (in_late_binary_op)
e = save_expr (e);
else
e = c_save_expr (e);
ret
= fold_build2_loc (loc, COMPLEX_EXPR, type,
convert (subtype,
fold_build1 (REALPART_EXPR,
elt_type, e)),
convert (subtype,
fold_build1 (IMAGPART_EXPR,
elt_type, e)));
goto maybe_fold;
}
}
ret = convert_to_complex (type, e);
goto maybe_fold;
case VECTOR_TYPE:
ret = convert_to_vector (type, e);
goto maybe_fold;
case RECORD_TYPE:
case UNION_TYPE:
if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
return e;
break;
default:
break;
maybe_fold:
if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR)
ret = fold (ret);
return ret;
}
error ("conversion to non-scalar type requested");
return error_mark_node;
}
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