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120 lines
3.9 KiB
C
120 lines
3.9 KiB
C
/* Language-level data type conversion for GNU C.
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Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005
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Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License as published by the Free
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Software Foundation; either version 2, or (at your option) any later
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version.
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GCC is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to the Free
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Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA. */
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/* This file contains the functions for converting C expressions
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to different data types. The only entry point is `convert'.
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Every language front end must have a `convert' function
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but what kind of conversions it does will depend on the language. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "tree.h"
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#include "flags.h"
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#include "convert.h"
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#include "c-common.h"
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#include "c-tree.h"
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#include "langhooks.h"
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#include "toplev.h"
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#include "target.h"
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/* Change of width--truncation and extension of integers or reals--
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is represented with NOP_EXPR. Proper functioning of many things
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assumes that no other conversions can be NOP_EXPRs.
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Conversion between integer and pointer is represented with CONVERT_EXPR.
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Converting integer to real uses FLOAT_EXPR
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and real to integer uses FIX_TRUNC_EXPR.
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Here is a list of all the functions that assume that widening and
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narrowing is always done with a NOP_EXPR:
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In convert.c, convert_to_integer.
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In c-typeck.c, build_binary_op (boolean ops), and
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c_common_truthvalue_conversion.
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In expr.c: expand_expr, for operands of a MULT_EXPR.
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In fold-const.c: fold.
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In tree.c: get_narrower and get_unwidened. */
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/* Subroutines of `convert'. */
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/* Create an expression whose value is that of EXPR,
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converted to type TYPE. The TREE_TYPE of the value
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is always TYPE. This function implements all reasonable
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conversions; callers should filter out those that are
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not permitted by the language being compiled. */
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tree
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convert (tree type, tree expr)
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{
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tree e = expr;
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enum tree_code code = TREE_CODE (type);
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const char *invalid_conv_diag;
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if (type == error_mark_node
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|| expr == error_mark_node
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|| TREE_TYPE (expr) == error_mark_node)
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return error_mark_node;
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if ((invalid_conv_diag
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= targetm.invalid_conversion (TREE_TYPE (expr), type)))
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{
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error (invalid_conv_diag);
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return error_mark_node;
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}
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if (type == TREE_TYPE (expr))
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return expr;
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if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))
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return fold_convert (type, expr);
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if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
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return error_mark_node;
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if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
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{
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error ("void value not ignored as it ought to be");
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return error_mark_node;
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}
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if (code == VOID_TYPE)
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return fold_convert (type, e);
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if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
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return fold (convert_to_integer (type, e));
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if (code == BOOLEAN_TYPE)
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return fold_convert (type, c_objc_common_truthvalue_conversion (expr));
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if (code == POINTER_TYPE || code == REFERENCE_TYPE)
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return fold (convert_to_pointer (type, e));
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if (code == REAL_TYPE)
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return fold (convert_to_real (type, e));
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if (code == COMPLEX_TYPE)
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return fold (convert_to_complex (type, e));
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if (code == VECTOR_TYPE)
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return fold (convert_to_vector (type, e));
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if ((code == RECORD_TYPE || code == UNION_TYPE)
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&& lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
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return e;
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error ("conversion to non-scalar type requested");
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return error_mark_node;
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}
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