Re: [PATCH] Added Redirects to longdouble error functions [BZ #29033]

[Paul E Murphy <murphyp@linux.ibm.com>]

On 2/9/23 11:45 AM, Sachin Monga via Libc-alpha wrote:
> This patch redirects the error functions to the appropriate
> longdouble variants which enables the compiler to optimize
> for the abi ieeelongdouble.

This is a tricky patch. Are there tests to verify this functions as 
desired when redirecting long double? If practical, please add some.

> 
> Signed-off-by: Sachin Monga <smonga@linux.ibm.com>
> ---
>   misc/bits/error-ldbl.h | 53 ++++++++++++++++++++++++++++++++++++++++--
>   misc/sys/cdefs.h       |  6 +++++
>   2 files changed, 57 insertions(+), 2 deletions(-)
> 
> diff --git a/misc/bits/error-ldbl.h b/misc/bits/error-ldbl.h
> index 599a7d6e06..73ecbe7a10 100644
> --- a/misc/bits/error-ldbl.h
> +++ b/misc/bits/error-ldbl.h
> @@ -20,5 +20,54 @@
>   # error "Never include <bits/error-ldbl.h> directly; use <error.h> instead."
>   #endif
> 
> -__LDBL_REDIR_DECL (error)
> -__LDBL_REDIR_DECL (error_at_line)

Does this still return the expected function with usage like?

#include <error.h>
typedef void (error_func_t)(int,int,const char*,...);
error_func_t
get_error_func() {
   return &error;
}

> +
> +__LDBL_REDIRECT (__error_alias, (int __status, int __errnum,
> +					const char *__format, ...),
> +			error)
> +  __attribute__ ((__format__ (__printf__, 3, 4)));
> +__LDBL_REDIRECT (__error_noreturn, (int __status, int __errnum,
> +					   const char *__format, ...),
> +			error)
> +  __attribute__ ((__noreturn__, __format__ (__printf__, 3, 4)));
> +
> +
> +/* If we know the function will never return make sure the compiler
> +   realizes that, too.  */
> +__extern_always_inline void
> +error (int __status, int __errnum, const char *__format, ...)
> +{
> +  if (__builtin_constant_p (__status) && __status != 0)
> +    __error_noreturn (__status, __errnum, __format, __va_arg_pack ());
> +  else
> +    __error_alias (__status, __errnum, __format, __va_arg_pack ());
> +}
> +
> +
> +__LDBL_REDIRECT (__error_at_line_alias, (int __status, int __errnum,
> +						const char *__fname,
> +						unsigned int __line,
> +						const char *__format, ...),
> +			error_at_line)
> +  __attribute__ ((__format__ (__printf__, 5, 6)));
> +__LDBL_REDIRECT (__error_at_line_noreturn, (int __status, int __errnum,
> +						   const char *__fname,
> +						   unsigned int __line,
> +						   const char *__format,
> +						   ...),
> +			error_at_line)
> +  __attribute__ ((__noreturn__, __format__ (__printf__, 5, 6)));
> +
> +
> +/* If we know the function will never return make sure the compiler
> +   realizes that, too.  */
> +__extern_always_inline void
> +error_at_line (int __status, int __errnum, const char *__fname,
> +	       unsigned int __line, const char *__format, ...)
> +{
> +  if (__builtin_constant_p (__status) && __status != 0)
> +    __error_at_line_noreturn (__status, __errnum, __fname, __line, __format,
> +			      __va_arg_pack ());
> +  else
> +    __error_at_line_alias (__status, __errnum, __fname, __line,
> +			   __format, __va_arg_pack ());
> +}
> diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
> index 66d6702123..34fdd3c24a 100644
> --- a/misc/sys/cdefs.h
> +++ b/misc/sys/cdefs.h
> @@ -245,6 +245,7 @@
>   #if (defined __GNUC__ && __GNUC__ >= 2) || (__clang_major__ >= 4)
> 
>   # define __REDIRECT(name, proto, alias) name proto __asm__ (__ASMNAME (#alias))
> +
Trivial nit, this change seems unrelated.

>   # ifdef __cplusplus
>   #  define __REDIRECT_NTH(name, proto, alias) \
>        name proto __THROW __asm__ (__ASMNAME (#alias))
> @@ -567,6 +568,8 @@
>   #  define __LDBL_REDIR(name, proto) ... unused__ldbl_redir
>   #  define __LDBL_REDIR_DECL(name) \
>     extern __typeof (name) name __asm (__ASMNAME ("__" #name "ieee128"));
> +#  define __LDBL_REDIRECT(name, proto, alias) \
> +  extern void name proto __asm (__ASMNAME ("__" #alias "ieee128"))
Is it possible to use the existing __REDIRECT_LDBL macro instead of 
adding a new one? They seem identical save for an extra expansion with 
__REDIRECT_LDBL.

> 
>   /* Alias name defined automatically, with leading underscores.  */
>   #  define __LDBL_REDIR2_DECL(name) \
> @@ -605,6 +608,8 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf
>     extern __typeof (name) name __asm (__ASMNAME (#alias));
>   #  define __LDBL_REDIR_DECL(name) \
>     extern __typeof (name) name __asm (__ASMNAME ("__nldbl_" #name));
> +#  define __LDBL_REDIRECT(name, proto, alias) \
> +  extern void name proto __asm (__ASMNAME ("__nldbl_" #alias));
>   #  define __REDIRECT_LDBL(name, proto, alias) \
>     __LDBL_REDIR1 (name, proto, __nldbl_##alias)
>   #  define __REDIRECT_NTH_LDBL(name, proto, alias) \
> @@ -619,6 +624,7 @@ _Static_assert (0, "IEEE 128-bits long double requires redirection on this platf
>   # define __LDBL_REDIR_NTH(name, proto) name proto __THROW
>   # define __LDBL_REDIR2_DECL(name)
>   # define __LDBL_REDIR_DECL(name)
> +# define __LDBL_REDIRECT(name, proto, alias)
>   # ifdef __REDIRECT
>   #  define __REDIRECT_LDBL(name, proto, alias) __REDIRECT (name, proto, alias)
>   #  define __REDIRECT_NTH_LDBL(name, proto, alias) \