Message ID | 20230429131223.2507236-3-bugaevc@gmail.com |
---|---|
State | New |
Headers | show |
Series | [1/3] cdefs.h: Define __COLD | expand |
It looks sensible to me indeed, any opinion from somebody else? Sergey Bugaev, le sam. 29 avril 2023 16:12:23 +0300, a ecrit: > GCC docs explicitly list perror () as a good candidate for using > __attribute__ ((cold)). So apply __COLD to perror () and similar > functions. > > Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> > --- > include/error.h | 4 ++-- > libio/stdio.h | 2 +- > misc/err.h | 12 ++++++------ > misc/error.h | 4 ++-- > 4 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/include/error.h b/include/error.h > index 9e96262f..4db67cba 100644 > --- a/include/error.h > +++ b/include/error.h > @@ -5,11 +5,11 @@ > > void > __error_internal (int status, int errnum, const char *message, > - va_list args, unsigned int mode_flags); > + va_list args, unsigned int mode_flags) __COLD; > > void > __error_at_line_internal (int status, int errnum, const char *file_name, > unsigned int line_number, const char *message, > - va_list args, unsigned int mode_flags); > + va_list args, unsigned int mode_flags) __COLD; > > #endif > diff --git a/libio/stdio.h b/libio/stdio.h > index 45ddafdf..2387590d 100644 > --- a/libio/stdio.h > +++ b/libio/stdio.h > @@ -859,7 +859,7 @@ extern int ferror_unlocked (FILE *__stream) __THROW __wur; > > This function is a possible cancellation point and therefore not > marked with __THROW. */ > -extern void perror (const char *__s); > +extern void perror (const char *__s) __COLD; > > > #ifdef __USE_POSIX > diff --git a/misc/err.h b/misc/err.h > index 0c752465..43df3a57 100644 > --- a/misc/err.h > +++ b/misc/err.h > @@ -32,9 +32,9 @@ __BEGIN_DECLS > /* Print "program: ", FORMAT, ": ", the standard error string for errno, > and a newline, on stderr. */ > extern void warn (const char *__format, ...) > - __attribute__ ((__format__ (__printf__, 1, 2))); > + __attribute__ ((__format__ (__printf__, 1, 2))) __COLD; > extern void vwarn (const char *__format, __gnuc_va_list) > - __attribute__ ((__format__ (__printf__, 1, 0))); > + __attribute__ ((__format__ (__printf__, 1, 0))) __COLD; > > /* Likewise, but without ": " and the standard error string. */ > extern void warnx (const char *__format, ...) > @@ -44,13 +44,13 @@ extern void vwarnx (const char *__format, __gnuc_va_list) > > /* Likewise, and then exit with STATUS. */ > extern void err (int __status, const char *__format, ...) > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; > extern void verr (int __status, const char *__format, __gnuc_va_list) > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; > extern void errx (int __status, const char *__format, ...) > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; > extern void verrx (int __status, const char *, __gnuc_va_list) > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; > > #include <bits/floatn.h> > #if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1 > diff --git a/misc/error.h b/misc/error.h > index 185b39c6..4fbd46c7 100644 > --- a/misc/error.h > +++ b/misc/error.h > @@ -29,11 +29,11 @@ __BEGIN_DECLS > If STATUS is nonzero, terminate the program with `exit (STATUS)'. */ > > extern void error (int __status, int __errnum, const char *__format, ...) > - __attribute__ ((__format__ (__printf__, 3, 4))); > + __attribute__ ((__format__ (__printf__, 3, 4))) __COLD; > > extern void error_at_line (int __status, int __errnum, const char *__fname, > unsigned int __lineno, const char *__format, ...) > - __attribute__ ((__format__ (__printf__, 5, 6))); > + __attribute__ ((__format__ (__printf__, 5, 6))) __COLD; > > /* If NULL, error will flush stdout, then print on stderr the program > name, a colon and a space. Otherwise, error will call this > -- > 2.40.1 >
On 2023-04-29 11:06, Samuel Thibault via Libc-alpha wrote: > It looks sensible to me indeed, any opinion from somebody else? > > > > > Sergey Bugaev, le sam. 29 avril 2023 16:12:23 +0300, a ecrit: >> GCC docs explicitly list perror () as a good candidate for using >> __attribute__ ((cold)). So apply __COLD to perror () and similar >> functions. >> >> Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> LGTM. It would be nice to do a build-many-glibcs run here since it touches public headers but the change itself looks fairly straightforward and should be fine for all compilers. Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org> >> --- >> include/error.h | 4 ++-- >> libio/stdio.h | 2 +- >> misc/err.h | 12 ++++++------ >> misc/error.h | 4 ++-- >> 4 files changed, 11 insertions(+), 11 deletions(-) >> >> diff --git a/include/error.h b/include/error.h >> index 9e96262f..4db67cba 100644 >> --- a/include/error.h >> +++ b/include/error.h >> @@ -5,11 +5,11 @@ >> >> void >> __error_internal (int status, int errnum, const char *message, >> - va_list args, unsigned int mode_flags); >> + va_list args, unsigned int mode_flags) __COLD; >> >> void >> __error_at_line_internal (int status, int errnum, const char *file_name, >> unsigned int line_number, const char *message, >> - va_list args, unsigned int mode_flags); >> + va_list args, unsigned int mode_flags) __COLD; >> >> #endif >> diff --git a/libio/stdio.h b/libio/stdio.h >> index 45ddafdf..2387590d 100644 >> --- a/libio/stdio.h >> +++ b/libio/stdio.h >> @@ -859,7 +859,7 @@ extern int ferror_unlocked (FILE *__stream) __THROW __wur; >> >> This function is a possible cancellation point and therefore not >> marked with __THROW. */ >> -extern void perror (const char *__s); >> +extern void perror (const char *__s) __COLD; >> >> >> #ifdef __USE_POSIX >> diff --git a/misc/err.h b/misc/err.h >> index 0c752465..43df3a57 100644 >> --- a/misc/err.h >> +++ b/misc/err.h >> @@ -32,9 +32,9 @@ __BEGIN_DECLS >> /* Print "program: ", FORMAT, ": ", the standard error string for errno, >> and a newline, on stderr. */ >> extern void warn (const char *__format, ...) >> - __attribute__ ((__format__ (__printf__, 1, 2))); >> + __attribute__ ((__format__ (__printf__, 1, 2))) __COLD; >> extern void vwarn (const char *__format, __gnuc_va_list) >> - __attribute__ ((__format__ (__printf__, 1, 0))); >> + __attribute__ ((__format__ (__printf__, 1, 0))) __COLD; >> >> /* Likewise, but without ": " and the standard error string. */ >> extern void warnx (const char *__format, ...) >> @@ -44,13 +44,13 @@ extern void vwarnx (const char *__format, __gnuc_va_list) >> >> /* Likewise, and then exit with STATUS. */ >> extern void err (int __status, const char *__format, ...) >> - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); >> + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; >> extern void verr (int __status, const char *__format, __gnuc_va_list) >> - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); >> + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; >> extern void errx (int __status, const char *__format, ...) >> - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); >> + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; >> extern void verrx (int __status, const char *, __gnuc_va_list) >> - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); >> + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; >> >> #include <bits/floatn.h> >> #if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1 >> diff --git a/misc/error.h b/misc/error.h >> index 185b39c6..4fbd46c7 100644 >> --- a/misc/error.h >> +++ b/misc/error.h >> @@ -29,11 +29,11 @@ __BEGIN_DECLS >> If STATUS is nonzero, terminate the program with `exit (STATUS)'. */ >> >> extern void error (int __status, int __errnum, const char *__format, ...) >> - __attribute__ ((__format__ (__printf__, 3, 4))); >> + __attribute__ ((__format__ (__printf__, 3, 4))) __COLD; >> >> extern void error_at_line (int __status, int __errnum, const char *__fname, >> unsigned int __lineno, const char *__format, ...) >> - __attribute__ ((__format__ (__printf__, 5, 6))); >> + __attribute__ ((__format__ (__printf__, 5, 6))) __COLD; >> >> /* If NULL, error will flush stdout, then print on stderr the program >> name, a colon and a space. Otherwise, error will call this >> -- >> 2.40.1 >> >
Siddhesh Poyarekar, le lun. 01 mai 2023 12:15:04 -0400, a ecrit: > > > On 2023-04-29 11:06, Samuel Thibault via Libc-alpha wrote: > > It looks sensible to me indeed, any opinion from somebody else? > > > > > > > > > > Sergey Bugaev, le sam. 29 avril 2023 16:12:23 +0300, a ecrit: > > > GCC docs explicitly list perror () as a good candidate for using > > > __attribute__ ((cold)). So apply __COLD to perror () and similar > > > functions. > > > > > > Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> > > LGTM. It would be nice to do a build-many-glibcs run here since it > touches public headers Yes, I ran i686-gnu, x86_64-gnu and x86_64-linux-gnu. > but the change itself looks fairly straightforward and should > be fine for all compilers. Applied, thanks! > Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org> > > > > --- > > > include/error.h | 4 ++-- > > > libio/stdio.h | 2 +- > > > misc/err.h | 12 ++++++------ > > > misc/error.h | 4 ++-- > > > 4 files changed, 11 insertions(+), 11 deletions(-) > > > > > > diff --git a/include/error.h b/include/error.h > > > index 9e96262f..4db67cba 100644 > > > --- a/include/error.h > > > +++ b/include/error.h > > > @@ -5,11 +5,11 @@ > > > void > > > __error_internal (int status, int errnum, const char *message, > > > - va_list args, unsigned int mode_flags); > > > + va_list args, unsigned int mode_flags) __COLD; > > > void > > > __error_at_line_internal (int status, int errnum, const char *file_name, > > > unsigned int line_number, const char *message, > > > - va_list args, unsigned int mode_flags); > > > + va_list args, unsigned int mode_flags) __COLD; > > > #endif > > > diff --git a/libio/stdio.h b/libio/stdio.h > > > index 45ddafdf..2387590d 100644 > > > --- a/libio/stdio.h > > > +++ b/libio/stdio.h > > > @@ -859,7 +859,7 @@ extern int ferror_unlocked (FILE *__stream) __THROW __wur; > > > This function is a possible cancellation point and therefore not > > > marked with __THROW. */ > > > -extern void perror (const char *__s); > > > +extern void perror (const char *__s) __COLD; > > > #ifdef __USE_POSIX > > > diff --git a/misc/err.h b/misc/err.h > > > index 0c752465..43df3a57 100644 > > > --- a/misc/err.h > > > +++ b/misc/err.h > > > @@ -32,9 +32,9 @@ __BEGIN_DECLS > > > /* Print "program: ", FORMAT, ": ", the standard error string for errno, > > > and a newline, on stderr. */ > > > extern void warn (const char *__format, ...) > > > - __attribute__ ((__format__ (__printf__, 1, 2))); > > > + __attribute__ ((__format__ (__printf__, 1, 2))) __COLD; > > > extern void vwarn (const char *__format, __gnuc_va_list) > > > - __attribute__ ((__format__ (__printf__, 1, 0))); > > > + __attribute__ ((__format__ (__printf__, 1, 0))) __COLD; > > > /* Likewise, but without ": " and the standard error string. */ > > > extern void warnx (const char *__format, ...) > > > @@ -44,13 +44,13 @@ extern void vwarnx (const char *__format, __gnuc_va_list) > > > /* Likewise, and then exit with STATUS. */ > > > extern void err (int __status, const char *__format, ...) > > > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); > > > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; > > > extern void verr (int __status, const char *__format, __gnuc_va_list) > > > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); > > > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; > > > extern void errx (int __status, const char *__format, ...) > > > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); > > > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; > > > extern void verrx (int __status, const char *, __gnuc_va_list) > > > - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); > > > + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; > > > #include <bits/floatn.h> > > > #if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1 > > > diff --git a/misc/error.h b/misc/error.h > > > index 185b39c6..4fbd46c7 100644 > > > --- a/misc/error.h > > > +++ b/misc/error.h > > > @@ -29,11 +29,11 @@ __BEGIN_DECLS > > > If STATUS is nonzero, terminate the program with `exit (STATUS)'. */ > > > extern void error (int __status, int __errnum, const char *__format, ...) > > > - __attribute__ ((__format__ (__printf__, 3, 4))); > > > + __attribute__ ((__format__ (__printf__, 3, 4))) __COLD; > > > extern void error_at_line (int __status, int __errnum, const char *__fname, > > > unsigned int __lineno, const char *__format, ...) > > > - __attribute__ ((__format__ (__printf__, 5, 6))); > > > + __attribute__ ((__format__ (__printf__, 5, 6))) __COLD; > > > /* If NULL, error will flush stdout, then print on stderr the program > > > name, a colon and a space. Otherwise, error will call this > > > -- > > > 2.40.1 > > > > > >
a On Sat, Apr 29, 2023 at 9:12 AM Sergey Bugaev via Libc-alpha < libc-alpha@sourceware.org> wrote: > GCC docs explicitly list perror () as a good candidate for using > __attribute__ ((cold)). So apply __COLD to perror () and similar > functions. > abort() and all the function wrappers called by assert on failure are also cold. Cheers! >
Cristian Rodríguez, le lun. 01 mai 2023 17:52:17 -0400, a ecrit: > On Sat, Apr 29, 2023 at 9:12 AM Sergey Bugaev via Libc-alpha <[1] > libc-alpha@sourceware.org> wrote: > > GCC docs explicitly list perror () as a good candidate for using > __attribute__ ((cold)). So apply __COLD to perror () and similar > functions. > > > abort() and all the function wrappers called by assert on failure are also > cold. Indeed, most __noreturn__ functions a probably worth having a look at. Samuel
Hello, On Tue, May 2, 2023 at 12:54 AM Samuel Thibault <samuel.thibault@gnu.org> wrote: > Cristian Rodríguez, le lun. 01 mai 2023 17:52:17 -0400, a ecrit: > > abort() and all the function wrappers called by assert on failure are also > > cold. > > Indeed, most __noreturn__ functions a probably worth having a look at. I was under the impression that noreturn functions automatically get treated similarly to ones with an explicit attribute((cold)). (But I still marked some, but not all -- fairly arbitrarily -- noreturn functions __COLD in this patch...) From taking a closer look now, I see that while the generated assembly instructions may be similar/identical, it's not strictly the same thing: with attribute((cold)) the cold path code goes into .text.unlikely, and without it's still in the regular .text. So applying __COLD should be beneficial indeed. I will send a follow-up patch; thank you for pointing this out and making me double-check :) Is there some sort of a benchmark where we could see whether this makes any difference? (Not calling the cold function in a loop, of course -- that is likely to regress, in fact -- but rather calling a hot function in a loop and benefitting from the cold path not getting in the way, improved code locality etc.) Sergey
diff --git a/include/error.h b/include/error.h index 9e96262f..4db67cba 100644 --- a/include/error.h +++ b/include/error.h @@ -5,11 +5,11 @@ void __error_internal (int status, int errnum, const char *message, - va_list args, unsigned int mode_flags); + va_list args, unsigned int mode_flags) __COLD; void __error_at_line_internal (int status, int errnum, const char *file_name, unsigned int line_number, const char *message, - va_list args, unsigned int mode_flags); + va_list args, unsigned int mode_flags) __COLD; #endif diff --git a/libio/stdio.h b/libio/stdio.h index 45ddafdf..2387590d 100644 --- a/libio/stdio.h +++ b/libio/stdio.h @@ -859,7 +859,7 @@ extern int ferror_unlocked (FILE *__stream) __THROW __wur; This function is a possible cancellation point and therefore not marked with __THROW. */ -extern void perror (const char *__s); +extern void perror (const char *__s) __COLD; #ifdef __USE_POSIX diff --git a/misc/err.h b/misc/err.h index 0c752465..43df3a57 100644 --- a/misc/err.h +++ b/misc/err.h @@ -32,9 +32,9 @@ __BEGIN_DECLS /* Print "program: ", FORMAT, ": ", the standard error string for errno, and a newline, on stderr. */ extern void warn (const char *__format, ...) - __attribute__ ((__format__ (__printf__, 1, 2))); + __attribute__ ((__format__ (__printf__, 1, 2))) __COLD; extern void vwarn (const char *__format, __gnuc_va_list) - __attribute__ ((__format__ (__printf__, 1, 0))); + __attribute__ ((__format__ (__printf__, 1, 0))) __COLD; /* Likewise, but without ": " and the standard error string. */ extern void warnx (const char *__format, ...) @@ -44,13 +44,13 @@ extern void vwarnx (const char *__format, __gnuc_va_list) /* Likewise, and then exit with STATUS. */ extern void err (int __status, const char *__format, ...) - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; extern void verr (int __status, const char *__format, __gnuc_va_list) - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; extern void errx (int __status, const char *__format, ...) - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))); + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 3))) __COLD; extern void verrx (int __status, const char *, __gnuc_va_list) - __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))); + __attribute__ ((__noreturn__, __format__ (__printf__, 2, 0))) __COLD; #include <bits/floatn.h> #if defined __LDBL_COMPAT || __LDOUBLE_REDIRECTS_TO_FLOAT128_ABI == 1 diff --git a/misc/error.h b/misc/error.h index 185b39c6..4fbd46c7 100644 --- a/misc/error.h +++ b/misc/error.h @@ -29,11 +29,11 @@ __BEGIN_DECLS If STATUS is nonzero, terminate the program with `exit (STATUS)'. */ extern void error (int __status, int __errnum, const char *__format, ...) - __attribute__ ((__format__ (__printf__, 3, 4))); + __attribute__ ((__format__ (__printf__, 3, 4))) __COLD; extern void error_at_line (int __status, int __errnum, const char *__fname, unsigned int __lineno, const char *__format, ...) - __attribute__ ((__format__ (__printf__, 5, 6))); + __attribute__ ((__format__ (__printf__, 5, 6))) __COLD; /* If NULL, error will flush stdout, then print on stderr the program name, a colon and a space. Otherwise, error will call this
GCC docs explicitly list perror () as a good candidate for using __attribute__ ((cold)). So apply __COLD to perror () and similar functions. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> --- include/error.h | 4 ++-- libio/stdio.h | 2 +- misc/err.h | 12 ++++++------ misc/error.h | 4 ++-- 4 files changed, 11 insertions(+), 11 deletions(-)