/* Language-level data type conversion for GNU C. | |

Copyright (C) 1987-2022 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 3, 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 COPYING3. If not see | |

<http://www.gnu.org/licenses/>. */ | |

/* 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 "coretypes.h" | |

#include "target.h" | |

#include "c-tree.h" | |

#include "convert.h" | |

#include "langhooks.h" | |

#include "ubsan.h" | |

#include "stringpool.h" | |

#include "attribs.h" | |

#include "asan.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.cc, convert_to_integer. | |

In c-typeck.cc, build_binary_op (boolean ops), and | |

c_common_truthvalue_conversion. | |

In expr.cc: expand_expr, for operands of a MULT_EXPR. | |

In fold-const.cc: fold. | |

In tree.cc: 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. | |

INIT_CONST is true if the conversion is for arithmetic types for a static | |

initializer and folding must apply accordingly (discarding floating-point | |

exceptions and assuming the default rounding mode is in effect). */ | |

static tree | |

c_convert (tree type, tree expr, bool init_const) | |

{ | |

tree e = expr; | |

enum tree_code code = TREE_CODE (type); | |

const char *invalid_conv_diag; | |

tree ret; | |

location_t loc = EXPR_LOCATION (expr); | |

if (type == error_mark_node | |

|| error_operand_p (expr)) | |

return error_mark_node; | |

if ((invalid_conv_diag | |

= targetm.invalid_conversion (TREE_TYPE (expr), type))) | |

{ | |

error (invalid_conv_diag); | |

return error_mark_node; | |

} | |

if (type == TREE_TYPE (expr)) | |

return expr; | |

ret = targetm.convert_to_type (type, expr); | |

if (ret) | |

return ret; | |

STRIP_TYPE_NOPS (e); | |

if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)) | |

&& (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE | |

|| TREE_CODE (e) == COMPLEX_EXPR)) | |

return fold_convert_loc (loc, 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; | |

} | |

switch (code) | |

{ | |

case VOID_TYPE: | |

return fold_convert_loc (loc, type, e); | |

case ENUMERAL_TYPE: | |

if (ENUM_UNDERLYING_TYPE (type) != NULL_TREE | |

&& TREE_CODE (ENUM_UNDERLYING_TYPE (type)) == BOOLEAN_TYPE) | |

goto convert_to_boolean; | |

gcc_fallthrough (); | |

case INTEGER_TYPE: | |

if (sanitize_flags_p (SANITIZE_FLOAT_CAST) | |

&& current_function_decl != NULL_TREE | |

&& TREE_CODE (TREE_TYPE (expr)) == REAL_TYPE | |

&& COMPLETE_TYPE_P (type)) | |

{ | |

expr = save_expr (expr); | |

expr = c_fully_fold (expr, init_const, NULL); | |

tree check = ubsan_instrument_float_cast (loc, type, expr); | |

expr = fold_build1 (FIX_TRUNC_EXPR, type, expr); | |

if (check == NULL_TREE) | |

return expr; | |

return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr); | |

} | |

ret = convert_to_integer (type, e); | |

goto maybe_fold; | |

case BOOLEAN_TYPE: | |

convert_to_boolean: | |

return fold_convert_loc | |

(loc, type, c_objc_common_truthvalue_conversion (input_location, expr)); | |

case POINTER_TYPE: | |

/* The type nullptr_t may be converted to a pointer type. The result is | |

a null pointer value. */ | |

if (NULLPTR_TYPE_P (TREE_TYPE (e))) | |

{ | |

/* To make sure that (void *)nullptr is not a null pointer constant, | |

build_c_cast will create an additional NOP_EXPR around the result | |

of this conversion. */ | |

if (TREE_SIDE_EFFECTS (e)) | |

ret = build2 (COMPOUND_EXPR, type, e, build_int_cst (type, 0)); | |

else | |

ret = build_int_cst (type, 0); | |

goto maybe_fold; | |

} | |

gcc_fallthrough (); | |

case REFERENCE_TYPE: | |

ret = convert_to_pointer (type, e); | |

goto maybe_fold; | |

case REAL_TYPE: | |

ret = convert_to_real (type, e); | |

goto maybe_fold; | |

case FIXED_POINT_TYPE: | |

ret = convert_to_fixed (type, e); | |

goto maybe_fold; | |

case COMPLEX_TYPE: | |

ret = convert_to_complex (type, e); | |

goto maybe_fold; | |

case VECTOR_TYPE: | |

if (gnu_vector_type_p (type) | |

|| gnu_vector_type_p (TREE_TYPE (e)) | |

/* Allow conversions between compatible non-GNU vector types | |

when -flax-vector-conversions is passed. The whole purpose | |

of the option is to bend the normal type rules and accept | |

nonconforming code. */ | |

|| (flag_lax_vector_conversions | |

&& VECTOR_TYPE_P (TREE_TYPE (e)) | |

&& vector_types_convertible_p (type, TREE_TYPE (e), false))) | |

{ | |

ret = convert_to_vector (type, e); | |

goto maybe_fold; | |

} | |

break; | |

case RECORD_TYPE: | |

case UNION_TYPE: | |

if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr))) | |

return e; | |

break; | |

default: | |

break; | |

maybe_fold: | |

if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR) | |

ret = init_const ? fold_init (ret) : fold (ret); | |

return ret; | |

} | |

/* If we are converting to nullptr_t, don't say "non-scalar type" because | |

the nullptr_t type is a scalar type. Only nullptr_t shall be converted | |

to nullptr_t. */ | |

if (code == NULLPTR_TYPE) | |

{ | |

error ("conversion from %qT to %qT", TREE_TYPE (e), type); | |

inform (input_location, "only %qT can be converted to %qT", type, type); | |

} | |

else | |

error ("conversion to non-scalar type requested"); | |

return error_mark_node; | |

} | |

/* 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 (tree type, tree expr) | |

{ | |

return c_convert (type, expr, false); | |

} | |

/* Create an expression whose value is that of EXPR, converted to type TYPE, in | |

a static initializer. 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_init (tree type, tree expr) | |

{ | |

return c_convert (type, expr, true); | |

} |