/* 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; }