/* Utility routines for data type conversion for GNU C. | |

Copyright (C) 1987, 88, 91-95, 97, 1998 Free Software Foundation, Inc. | |

This file is part of GNU C. | |

GNU CC 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. | |

GNU CC 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 GNU CC; see the file COPYING. If not, write to | |

the Free Software Foundation, 59 Temple Place - Suite 330, | |

Boston, MA 02111-1307, USA. */ | |

/* These routines are somewhat language-independent utility function | |

intended to be called by the language-specific convert () functions. */ | |

#include "config.h" | |

#include "tree.h" | |

#include "flags.h" | |

#include "convert.h" | |

#include "toplev.h" | |

/* Convert EXPR to some pointer or reference type TYPE. | |

EXPR must be pointer, reference, integer, enumeral, or literal zero; | |

in other cases error is called. */ | |

tree | |

convert_to_pointer (type, expr) | |

tree type, expr; | |

{ | |

if (integer_zerop (expr)) | |

{ | |

expr = build_int_2 (0, 0); | |

TREE_TYPE (expr) = type; | |

return expr; | |

} | |

switch (TREE_CODE (TREE_TYPE (expr))) | |

{ | |

case POINTER_TYPE: | |

case REFERENCE_TYPE: | |

return build1 (NOP_EXPR, type, expr); | |

case INTEGER_TYPE: | |

case ENUMERAL_TYPE: | |

case BOOLEAN_TYPE: | |

case CHAR_TYPE: | |

if (TYPE_PRECISION (TREE_TYPE (expr)) == POINTER_SIZE) | |

return build1 (CONVERT_EXPR, type, expr); | |

return | |

convert_to_pointer (type, | |

convert (type_for_size (POINTER_SIZE, 0), expr)); | |

default: | |

error ("cannot convert to a pointer type"); | |

return convert_to_pointer (type, integer_zero_node); | |

} | |

} | |

/* Convert EXPR to some floating-point type TYPE. | |

EXPR must be float, integer, or enumeral; | |

in other cases error is called. */ | |

tree | |

convert_to_real (type, expr) | |

tree type, expr; | |

{ | |

switch (TREE_CODE (TREE_TYPE (expr))) | |

{ | |

case REAL_TYPE: | |

return build1 (flag_float_store ? CONVERT_EXPR : NOP_EXPR, | |

type, expr); | |

case INTEGER_TYPE: | |

case ENUMERAL_TYPE: | |

case BOOLEAN_TYPE: | |

case CHAR_TYPE: | |

return build1 (FLOAT_EXPR, type, expr); | |

case COMPLEX_TYPE: | |

return convert (type, | |

fold (build1 (REALPART_EXPR, | |

TREE_TYPE (TREE_TYPE (expr)), expr))); | |

case POINTER_TYPE: | |

case REFERENCE_TYPE: | |

error ("pointer value used where a floating point value was expected"); | |

return convert_to_real (type, integer_zero_node); | |

default: | |

error ("aggregate value used where a float was expected"); | |

return convert_to_real (type, integer_zero_node); | |

} | |

} | |

/* Convert EXPR to some integer (or enum) type TYPE. | |

EXPR must be pointer, integer, discrete (enum, char, or bool), or float; | |

in other cases error is called. | |

The result of this is always supposed to be a newly created tree node | |

not in use in any existing structure. */ | |

tree | |

convert_to_integer (type, expr) | |

tree type, expr; | |

{ | |

enum tree_code ex_form = TREE_CODE (expr); | |

tree intype = TREE_TYPE (expr); | |

int inprec = TYPE_PRECISION (intype); | |

int outprec = TYPE_PRECISION (type); | |

switch (TREE_CODE (intype)) | |

{ | |

case POINTER_TYPE: | |

case REFERENCE_TYPE: | |

if (integer_zerop (expr)) | |

expr = integer_zero_node; | |

else | |

expr = fold (build1 (CONVERT_EXPR, | |

type_for_size (POINTER_SIZE, 0), expr)); | |

return convert_to_integer (type, expr); | |

case INTEGER_TYPE: | |

case ENUMERAL_TYPE: | |

case BOOLEAN_TYPE: | |

case CHAR_TYPE: | |

/* If this is a logical operation, which just returns 0 or 1, we can | |

change the type of the expression. For some logical operations, | |

we must also change the types of the operands to maintain type | |

correctness. */ | |

if (TREE_CODE_CLASS (ex_form) == '<') | |

{ | |

TREE_TYPE (expr) = type; | |

return expr; | |

} | |

else if (ex_form == TRUTH_AND_EXPR || ex_form == TRUTH_ANDIF_EXPR | |

|| ex_form == TRUTH_OR_EXPR || ex_form == TRUTH_ORIF_EXPR | |

|| ex_form == TRUTH_XOR_EXPR) | |

{ | |

TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0)); | |

TREE_OPERAND (expr, 1) = convert (type, TREE_OPERAND (expr, 1)); | |

TREE_TYPE (expr) = type; | |

return expr; | |

} | |

else if (ex_form == TRUTH_NOT_EXPR) | |

{ | |

TREE_OPERAND (expr, 0) = convert (type, TREE_OPERAND (expr, 0)); | |

TREE_TYPE (expr) = type; | |

return expr; | |

} | |

/* If we are widening the type, put in an explicit conversion. | |

Similarly if we are not changing the width. After this, we know | |

we are truncating EXPR. */ | |

else if (outprec >= inprec) | |

return build1 (NOP_EXPR, type, expr); | |

/* If TYPE is an enumeral type or a type with a precision less | |

than the number of bits in its mode, do the conversion to the | |

type corresponding to its mode, then do a nop conversion | |

to TYPE. */ | |

else if (TREE_CODE (type) == ENUMERAL_TYPE | |

|| outprec != GET_MODE_BITSIZE (TYPE_MODE (type))) | |

return build1 (NOP_EXPR, type, | |

convert (type_for_mode (TYPE_MODE (type), | |

TREE_UNSIGNED (type)), | |

expr)); | |

/* Here detect when we can distribute the truncation down past some | |

arithmetic. For example, if adding two longs and converting to an | |

int, we can equally well convert both to ints and then add. | |

For the operations handled here, such truncation distribution | |

is always safe. | |

It is desirable in these cases: | |

1) when truncating down to full-word from a larger size | |

2) when truncating takes no work. | |

3) when at least one operand of the arithmetic has been extended | |

(as by C's default conversions). In this case we need two conversions | |

if we do the arithmetic as already requested, so we might as well | |

truncate both and then combine. Perhaps that way we need only one. | |

Note that in general we cannot do the arithmetic in a type | |

shorter than the desired result of conversion, even if the operands | |

are both extended from a shorter type, because they might overflow | |

if combined in that type. The exceptions to this--the times when | |

two narrow values can be combined in their narrow type even to | |

make a wider result--are handled by "shorten" in build_binary_op. */ | |

switch (ex_form) | |

{ | |

case RSHIFT_EXPR: | |

/* We can pass truncation down through right shifting | |

when the shift count is a nonpositive constant. */ | |

if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST | |

&& tree_int_cst_lt (TREE_OPERAND (expr, 1), | |

convert (TREE_TYPE (TREE_OPERAND (expr, 1)), | |

integer_one_node))) | |

goto trunc1; | |

break; | |

case LSHIFT_EXPR: | |

/* We can pass truncation down through left shifting | |

when the shift count is a nonnegative constant. */ | |

if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST | |

&& tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0 | |

&& TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST) | |

{ | |

/* If shift count is less than the width of the truncated type, | |

really shift. */ | |

if (tree_int_cst_lt (TREE_OPERAND (expr, 1), TYPE_SIZE (type))) | |

/* In this case, shifting is like multiplication. */ | |

goto trunc1; | |

else | |

{ | |

/* If it is >= that width, result is zero. | |

Handling this with trunc1 would give the wrong result: | |

(int) ((long long) a << 32) is well defined (as 0) | |

but (int) a << 32 is undefined and would get a | |

warning. */ | |

tree t = convert_to_integer (type, integer_zero_node); | |

/* If the original expression had side-effects, we must | |

preserve it. */ | |

if (TREE_SIDE_EFFECTS (expr)) | |

return build (COMPOUND_EXPR, type, expr, t); | |

else | |

return t; | |

} | |

} | |

break; | |

case MAX_EXPR: | |

case MIN_EXPR: | |

case MULT_EXPR: | |

{ | |

tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type); | |

tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type); | |

/* Don't distribute unless the output precision is at least as big | |

as the actual inputs. Otherwise, the comparison of the | |

truncated values will be wrong. */ | |

if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0)) | |

&& outprec >= TYPE_PRECISION (TREE_TYPE (arg1)) | |

/* If signedness of arg0 and arg1 don't match, | |

we can't necessarily find a type to compare them in. */ | |

&& (TREE_UNSIGNED (TREE_TYPE (arg0)) | |

== TREE_UNSIGNED (TREE_TYPE (arg1)))) | |

goto trunc1; | |

break; | |

} | |

case PLUS_EXPR: | |

case MINUS_EXPR: | |

case BIT_AND_EXPR: | |

case BIT_IOR_EXPR: | |

case BIT_XOR_EXPR: | |

case BIT_ANDTC_EXPR: | |

trunc1: | |

{ | |

tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type); | |

tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type); | |

if (outprec >= BITS_PER_WORD | |

|| TRULY_NOOP_TRUNCATION (outprec, inprec) | |

|| inprec > TYPE_PRECISION (TREE_TYPE (arg0)) | |

|| inprec > TYPE_PRECISION (TREE_TYPE (arg1))) | |

{ | |

/* Do the arithmetic in type TYPEX, | |

then convert result to TYPE. */ | |

register tree typex = type; | |

/* Can't do arithmetic in enumeral types | |

so use an integer type that will hold the values. */ | |

if (TREE_CODE (typex) == ENUMERAL_TYPE) | |

typex = type_for_size (TYPE_PRECISION (typex), | |

TREE_UNSIGNED (typex)); | |

/* But now perhaps TYPEX is as wide as INPREC. | |

In that case, do nothing special here. | |

(Otherwise would recurse infinitely in convert. */ | |

if (TYPE_PRECISION (typex) != inprec) | |

{ | |

/* Don't do unsigned arithmetic where signed was wanted, | |

or vice versa. | |

Exception: if either of the original operands were | |

unsigned then can safely do the work as unsigned. | |

And we may need to do it as unsigned | |

if we truncate to the original size. */ | |

typex = ((TREE_UNSIGNED (TREE_TYPE (expr)) | |

|| TREE_UNSIGNED (TREE_TYPE (arg0)) | |

|| TREE_UNSIGNED (TREE_TYPE (arg1))) | |

? unsigned_type (typex) : signed_type (typex)); | |

return convert (type, | |

fold (build (ex_form, typex, | |

convert (typex, arg0), | |

convert (typex, arg1), | |

0))); | |

} | |

} | |

} | |

break; | |

case NEGATE_EXPR: | |

case BIT_NOT_EXPR: | |

/* This is not correct for ABS_EXPR, | |

since we must test the sign before truncation. */ | |

{ | |

register tree typex = type; | |

/* Can't do arithmetic in enumeral types | |

so use an integer type that will hold the values. */ | |

if (TREE_CODE (typex) == ENUMERAL_TYPE) | |

typex = type_for_size (TYPE_PRECISION (typex), | |

TREE_UNSIGNED (typex)); | |

/* But now perhaps TYPEX is as wide as INPREC. | |

In that case, do nothing special here. | |

(Otherwise would recurse infinitely in convert. */ | |

if (TYPE_PRECISION (typex) != inprec) | |

{ | |

/* Don't do unsigned arithmetic where signed was wanted, | |

or vice versa. */ | |

typex = (TREE_UNSIGNED (TREE_TYPE (expr)) | |

? unsigned_type (typex) : signed_type (typex)); | |

return convert (type, | |

fold (build1 (ex_form, typex, | |

convert (typex, | |

TREE_OPERAND (expr, 0))))); | |

} | |

} | |

case NOP_EXPR: | |

/* If truncating after truncating, might as well do all at once. | |

If truncating after extending, we may get rid of wasted work. */ | |

return convert (type, get_unwidened (TREE_OPERAND (expr, 0), type)); | |

case COND_EXPR: | |

/* It is sometimes worthwhile to push the narrowing down through | |

the conditional and never loses. */ | |

return fold (build (COND_EXPR, type, TREE_OPERAND (expr, 0), | |

convert (type, TREE_OPERAND (expr, 1)), | |

convert (type, TREE_OPERAND (expr, 2)))); | |

default: | |

break; | |

} | |

return build1 (NOP_EXPR, type, expr); | |

case REAL_TYPE: | |

return build1 (FIX_TRUNC_EXPR, type, expr); | |

case COMPLEX_TYPE: | |

return convert (type, | |

fold (build1 (REALPART_EXPR, | |

TREE_TYPE (TREE_TYPE (expr)), expr))); | |

default: | |

error ("aggregate value used where an integer was expected"); | |

return convert (type, integer_zero_node); | |

} | |

} | |

/* Convert EXPR to the complex type TYPE in the usual ways. */ | |

tree | |

convert_to_complex (type, expr) | |

tree type, expr; | |

{ | |

tree subtype = TREE_TYPE (type); | |

switch (TREE_CODE (TREE_TYPE (expr))) | |

{ | |

case REAL_TYPE: | |

case INTEGER_TYPE: | |

case ENUMERAL_TYPE: | |

case BOOLEAN_TYPE: | |

case CHAR_TYPE: | |

return build (COMPLEX_EXPR, type, convert (subtype, expr), | |

convert (subtype, integer_zero_node)); | |

case COMPLEX_TYPE: | |

{ | |

tree elt_type = TREE_TYPE (TREE_TYPE (expr)); | |

if (TYPE_MAIN_VARIANT (elt_type) == TYPE_MAIN_VARIANT (subtype)) | |

return expr; | |

else if (TREE_CODE (expr) == COMPLEX_EXPR) | |

return fold (build (COMPLEX_EXPR, | |

type, | |

convert (subtype, TREE_OPERAND (expr, 0)), | |

convert (subtype, TREE_OPERAND (expr, 1)))); | |

else | |

{ | |

expr = save_expr (expr); | |

return | |

fold (build (COMPLEX_EXPR, | |

type, convert (subtype, | |

fold (build1 (REALPART_EXPR, | |

TREE_TYPE (TREE_TYPE (expr)), | |

expr))), | |

convert (subtype, | |

fold (build1 (IMAGPART_EXPR, | |

TREE_TYPE (TREE_TYPE (expr)), | |

expr))))); | |

} | |

} | |

case POINTER_TYPE: | |

case REFERENCE_TYPE: | |

error ("pointer value used where a complex was expected"); | |

return convert_to_complex (type, integer_zero_node); | |

default: | |

error ("aggregate value used where a complex was expected"); | |

return convert_to_complex (type, integer_zero_node); | |

} | |

} |