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113 lines
3.9 KiB
C
113 lines
3.9 KiB
C
/* Language-level data type conversion for GNU C.
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Copyright (C) 1987, 1988, 1991, 1998 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, 59 Temple Place - Suite 330, Boston, MA
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02111-1307, 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 "tree.h"
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#include "flags.h"
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#include "convert.h"
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#include "toplev.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 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 (type, expr)
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tree type, 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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if (type == TREE_TYPE (expr)
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|| TREE_CODE (expr) == ERROR_MARK
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|| code == ERROR_MARK || TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
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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 (build1 (NOP_EXPR, 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 build1 (CONVERT_EXPR, type, e);
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#if 0
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/* This is incorrect. A truncation can't be stripped this way.
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Extensions will be stripped by the use of get_unwidened. */
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if (TREE_CODE (expr) == NOP_EXPR)
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return convert (type, TREE_OPERAND (expr, 0));
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#endif
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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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{
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tree t = truthvalue_conversion (expr);
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/* If truthvalue_conversion returns a NOP_EXPR, we must fold it here
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to avoid infinite recursion between fold () and convert (). */
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if (TREE_CODE (t) == NOP_EXPR)
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return fold (build1 (NOP_EXPR, type, TREE_OPERAND (t, 0)));
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else
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return fold (build1 (NOP_EXPR, type, t));
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}
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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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error ("conversion to non-scalar type requested");
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return error_mark_node;
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}
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