[8833] | 1 | /* Language-level data type conversion for GNU C. |
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| 2 | Copyright (C) 1987, 1988, 1991 Free Software Foundation, Inc. |
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| 3 | |
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| 4 | This file is part of GNU CC. |
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| 5 | |
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| 6 | GNU CC is free software; you can redistribute it and/or modify |
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| 7 | it under the terms of the GNU General Public License as published by |
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| 8 | the Free Software Foundation; either version 2, or (at your option) |
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| 9 | any later version. |
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| 10 | |
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| 11 | GNU CC is distributed in the hope that it will be useful, |
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 14 | GNU General Public License for more details. |
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| 15 | |
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| 16 | You should have received a copy of the GNU General Public License |
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| 17 | along with GNU CC; see the file COPYING. If not, write to |
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| 18 | the Free Software Foundation, 59 Temple Place - Suite 330, |
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| 19 | Boston, MA 02111-1307, USA. */ |
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| 20 | |
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| 21 | |
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| 22 | /* This file contains the functions for converting C expressions |
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| 23 | to different data types. The only entry point is `convert'. |
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| 24 | Every language front end must have a `convert' function |
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| 25 | but what kind of conversions it does will depend on the language. */ |
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| 26 | |
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| 27 | #include "config.h" |
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| 28 | #include "tree.h" |
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| 29 | #include "flags.h" |
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| 30 | #include "convert.h" |
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| 31 | |
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| 32 | /* Change of width--truncation and extension of integers or reals-- |
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| 33 | is represented with NOP_EXPR. Proper functioning of many things |
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| 34 | assumes that no other conversions can be NOP_EXPRs. |
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| 35 | |
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| 36 | Conversion between integer and pointer is represented with CONVERT_EXPR. |
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| 37 | Converting integer to real uses FLOAT_EXPR |
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| 38 | and real to integer uses FIX_TRUNC_EXPR. |
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| 39 | |
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| 40 | Here is a list of all the functions that assume that widening and |
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| 41 | narrowing is always done with a NOP_EXPR: |
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| 42 | In convert.c, convert_to_integer. |
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| 43 | In c-typeck.c, build_binary_op (boolean ops), and truthvalue_conversion. |
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| 44 | In expr.c: expand_expr, for operands of a MULT_EXPR. |
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| 45 | In fold-const.c: fold. |
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| 46 | In tree.c: get_narrower and get_unwidened. */ |
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| 47 | |
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| 48 | /* Subroutines of `convert'. */ |
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| 49 | |
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| 50 | |
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| 51 | |
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| 52 | /* Create an expression whose value is that of EXPR, |
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| 53 | converted to type TYPE. The TREE_TYPE of the value |
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| 54 | is always TYPE. This function implements all reasonable |
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| 55 | conversions; callers should filter out those that are |
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| 56 | not permitted by the language being compiled. */ |
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| 57 | |
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| 58 | tree |
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| 59 | convert (type, expr) |
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| 60 | tree type, expr; |
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| 61 | { |
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| 62 | register tree e = expr; |
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| 63 | register enum tree_code code = TREE_CODE (type); |
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| 64 | |
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| 65 | if (type == TREE_TYPE (expr) |
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| 66 | || TREE_CODE (expr) == ERROR_MARK) |
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| 67 | return expr; |
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| 68 | if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))) |
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| 69 | return fold (build1 (NOP_EXPR, type, expr)); |
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| 70 | if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK) |
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| 71 | return error_mark_node; |
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| 72 | if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE) |
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| 73 | { |
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| 74 | error ("void value not ignored as it ought to be"); |
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| 75 | return error_mark_node; |
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| 76 | } |
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| 77 | if (code == VOID_TYPE) |
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| 78 | return build1 (CONVERT_EXPR, type, e); |
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| 79 | #if 0 |
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| 80 | /* This is incorrect. A truncation can't be stripped this way. |
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| 81 | Extensions will be stripped by the use of get_unwidened. */ |
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| 82 | if (TREE_CODE (expr) == NOP_EXPR) |
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| 83 | return convert (type, TREE_OPERAND (expr, 0)); |
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| 84 | #endif |
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| 85 | if (code == INTEGER_TYPE || code == ENUMERAL_TYPE) |
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| 86 | return fold (convert_to_integer (type, e)); |
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| 87 | if (code == POINTER_TYPE) |
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| 88 | return fold (convert_to_pointer (type, e)); |
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| 89 | if (code == REAL_TYPE) |
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| 90 | return fold (convert_to_real (type, e)); |
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| 91 | if (code == COMPLEX_TYPE) |
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| 92 | return fold (convert_to_complex (type, e)); |
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| 93 | |
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| 94 | error ("conversion to non-scalar type requested"); |
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| 95 | return error_mark_node; |
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| 96 | } |
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