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	clang warns:
  ../sysdeps/x86/fpu/powl_helper.c:233:3: error: absolute value function
  '__builtin_fabsf' given an argument of type 'typeof (res)' (aka 'long
  double') but has parameter of type 'float' which may cause truncation of
  value [-Werror,-Wabsolute-value]
    math_check_force_underflow (res);
    ^
  ./math-underflow.h:45:11: note: expanded from macro
  'math_check_force_underflow'
        if (fabs_tg (force_underflow_tmp)                         \
            ^
  ./math-underflow.h:27:20: note: expanded from macro 'fabs_tg'
  #define fabs_tg(x) __MATH_TG ((x), (__typeof (x)) __builtin_fabs, (x))
                     ^
  ../math/math.h:899:16: note: expanded from macro '__MATH_TG'
                 float: FUNC ## f ARGS,           \
                        ^
  <scratch space>:73:1: note: expanded from here
  __builtin_fabsf
  ^
Due the use of _Generic from TG_MATH.
Reviewed-by: Sam James <sam@gentoo.org>
		
	
		
			
				
	
	
		
			89 lines
		
	
	
		
			3.1 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			89 lines
		
	
	
		
			3.1 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/* Check for underflow and force underflow exceptions.
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   Copyright (C) 2015-2025 Free Software Foundation, Inc.
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   This file is part of the GNU C Library.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <https://www.gnu.org/licenses/>.  */
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#ifndef _MATH_UNDERFLOW_H
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#define _MATH_UNDERFLOW_H	1
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#include <float.h>
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#include <math.h>
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#include <math-barriers.h>
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#include <libc-diag.h>
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#define fabs_tg(x) __MATH_TG ((x), (__typeof (x)) __builtin_fabs, (x))
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/* These must be function-like macros because some __MATH_TG
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   implementations macro-expand the function-name argument before
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   concatenating a suffix to it.  */
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#define min_of_type_f() FLT_MIN
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#define min_of_type_() DBL_MIN
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#define min_of_type_l() LDBL_MIN
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#define min_of_type_f128() FLT128_MIN
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#define min_of_type(x) __MATH_TG ((x), (__typeof (x)) min_of_type_, ())
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/* If X (which is not a NaN) is subnormal, force an underflow
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   exception.
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   clang issues a warning where _Generic is using a non expected
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   builtin which may cause truncation of value.
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   clang warns the value might be truncated due the use of _Generics. */
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#define math_check_force_underflow(x)				\
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  do								\
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    {								\
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      DIAG_PUSH_NEEDS_COMMENT_CLANG;				\
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      DIAG_IGNORE_NEEDS_COMMENT_CLANG (18, "-Wabsolute-value"); \
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      __typeof (x) force_underflow_tmp = (x);			\
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      if (fabs_tg (force_underflow_tmp)				\
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	  < min_of_type (force_underflow_tmp))			\
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	{							\
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	  __typeof (force_underflow_tmp) force_underflow_tmp2	\
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	    = force_underflow_tmp * force_underflow_tmp;	\
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	  math_force_eval (force_underflow_tmp2);		\
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	}							\
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      DIAG_POP_NEEDS_COMMENT_CLANG;				\
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    }								\
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  while (0)
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/* Likewise, but X is also known to be nonnegative.  */
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#define math_check_force_underflow_nonneg(x)			\
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  do								\
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    {								\
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      __typeof (x) force_underflow_tmp = (x);			\
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      if (force_underflow_tmp					\
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	  < min_of_type (force_underflow_tmp))			\
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	{							\
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	  __typeof (force_underflow_tmp) force_underflow_tmp2	\
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	    = force_underflow_tmp * force_underflow_tmp;	\
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	  math_force_eval (force_underflow_tmp2);		\
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	}							\
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    }								\
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  while (0)
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/* Likewise, for both real and imaginary parts of a complex
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   result.  */
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#define math_check_force_underflow_complex(x)				\
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  do									\
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    {									\
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      __typeof (x) force_underflow_complex_tmp = (x);			\
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      math_check_force_underflow (__real__ force_underflow_complex_tmp); \
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      math_check_force_underflow (__imag__ force_underflow_complex_tmp); \
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    }									\
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  while (0)
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#endif /* math-underflow.h */
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