[PATCH] bcmp: note that this function is no longer legacy due to LLVM 9

[PATCH] bcmp: note that this function is no longer legacy due to LLVM 9

[Shawn Landden]

Signed-off-by: Shawn Landden <shawn@git.icu>
---
 man3/bcmp.3 | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/man3/bcmp.3 b/man3/bcmp.3
index ba9838019..18d238720 100644
--- a/man3/bcmp.3
+++ b/man3/bcmp.3
@@ -70,15 +70,21 @@ T{
 .BR bcmp ()
 T}	Thread safety	MT-Safe
 .TE
 .SH CONFORMING TO
 4.3BSD.
-This function is deprecated (marked as LEGACY in POSIX.1-2001): use
-.BR memcmp (3)
-in new programs.
+This function was deprecated (marked as LEGACY) by POSIX.1-2001).
 POSIX.1-2008 removes the specification of
 .BR bcmp ().
+LLVM 9, released in 2019, revived
+.BR bcmp ()
+and generates calls to it instead of
+.BR memcmp (3)
+as appropiate as an optimization (as
+.BR bcmp ()
+need not traverse memory in-order).
+.\" http://releases.llvm.org/9.0.0/docs/ReleaseNotes.html#noteworthy-optimizations
 .SH SEE ALSO
 .BR bstring (3),
 .BR memcmp (3),
 .BR strcasecmp (3),
 .BR strcmp (3),
-- 
2.20.1

Re: [PATCH] bcmp: note that this function is no longer legacy due to LLVM 9

[Dmitry V. Levin]

Hi,

On Sat, Jan 11, 2020 at 06:50:49PM +0400, Shawn Landden wrote:
> Signed-off-by: Shawn Landden <shawn@git.icu>
> ---
>  man3/bcmp.3 | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/man3/bcmp.3 b/man3/bcmp.3
> index ba9838019..18d238720 100644
> --- a/man3/bcmp.3
> +++ b/man3/bcmp.3
> @@ -70,15 +70,21 @@ T{
>  .BR bcmp ()
>  T}	Thread safety	MT-Safe
>  .TE
>  .SH CONFORMING TO
>  4.3BSD.
> -This function is deprecated (marked as LEGACY in POSIX.1-2001): use
> -.BR memcmp (3)
> -in new programs.
> +This function was deprecated (marked as LEGACY) by POSIX.1-2001).
>  POSIX.1-2008 removes the specification of
>  .BR bcmp ().
> +LLVM 9, released in 2019, revived
> +.BR bcmp ()
> +and generates calls to it instead of
> +.BR memcmp (3)
> +as appropiate as an optimization (as
> +.BR bcmp ()
> +need not traverse memory in-order).
> +.\" http://releases.llvm.org/9.0.0/docs/ReleaseNotes.html#noteworthy-optimizations

I believe the "CONFORMING TO" is about conformance and therefore
shall not be changed.

Any notes about llvm-specific implementation details should go
to a different section, e.g. "NOTES".


-- 
ldv

Re: [PATCH] bcmp: note that this function is no longer legacy due to LLVM 9

[Michael Kerrisk (man-pages)]

Shawn,

On 1/11/20 5:11 PM, Dmitry V. Levin wrote:
> Hi,
> 
> On Sat, Jan 11, 2020 at 06:50:49PM +0400, Shawn Landden wrote:
>> Signed-off-by: Shawn Landden <shawn@git.icu>
>> ---
>>  man3/bcmp.3 | 12 +++++++++---
>>  1 file changed, 9 insertions(+), 3 deletions(-)
>>
>> diff --git a/man3/bcmp.3 b/man3/bcmp.3
>> index ba9838019..18d238720 100644
>> --- a/man3/bcmp.3
>> +++ b/man3/bcmp.3
>> @@ -70,15 +70,21 @@ T{
>>  .BR bcmp ()
>>  T}	Thread safety	MT-Safe
>>  .TE
>>  .SH CONFORMING TO
>>  4.3BSD.
>> -This function is deprecated (marked as LEGACY in POSIX.1-2001): use
>> -.BR memcmp (3)
>> -in new programs.
>> +This function was deprecated (marked as LEGACY) by POSIX.1-2001).
>>  POSIX.1-2008 removes the specification of
>>  .BR bcmp ().
>> +LLVM 9, released in 2019, revived
>> +.BR bcmp ()
>> +and generates calls to it instead of
>> +.BR memcmp (3)
>> +as appropiate as an optimization (as
>> +.BR bcmp ()
>> +need not traverse memory in-order).
>> +.\" http://releases.llvm.org/9.0.0/docs/ReleaseNotes.html#noteworthy-optimizations
> 
> I believe the "CONFORMING TO" is about conformance and therefore
> shall not be changed.
> 
> Any notes about llvm-specific implementation details should go
> to a different section, e.g. "NOTES".

I'm not convinced that anything at all needs to be added to the
manual page. This is an implement-specific detail about a certain
compiler. Its behavior might change in the future. You do not
say anything about why t is relevant to document this detail.

Thanks,

Michael



-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

[PATCH] bcmp: note that this function is no longer legacy due to LLVM 9

[Shawn Landden]

Signed-off-by: Shawn Landden <shawn@git.icu>
---
 man3/bcmp.3 | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/man3/bcmp.3 b/man3/bcmp.3
index ba9838019..18d238720 100644
--- a/man3/bcmp.3
+++ b/man3/bcmp.3
@@ -70,15 +70,21 @@ T{
 .BR bcmp ()
 T}	Thread safety	MT-Safe
 .TE
 .SH CONFORMING TO
 4.3BSD.
-This function is deprecated (marked as LEGACY in POSIX.1-2001): use
-.BR memcmp (3)
-in new programs.
+This function was deprecated (marked as LEGACY) by POSIX.1-2001).
 POSIX.1-2008 removes the specification of
 .BR bcmp ().
+LLVM 9, released in 2019, revived
+.BR bcmp ()
+and generates calls to it instead of
+.BR memcmp (3)
+as appropiate as an optimization (as
+.BR bcmp ()
+need not traverse memory in-order).
+.\" http://releases.llvm.org/9.0.0/docs/ReleaseNotes.html#noteworthy-optimizations
 .SH SEE ALSO
 .BR bstring (3),
 .BR memcmp (3),
 .BR strcasecmp (3),
 .BR strcmp (3),
-- 
2.20.1

Re: [PATCH] bcmp: note that this function is no longer legacy due to LLVM 9

[Florian Weimer]

* Shawn Landden:

> +This function was deprecated (marked as LEGACY) by POSIX.1-2001).
>  POSIX.1-2008 removes the specification of
>  .BR bcmp ().
> +LLVM 9, released in 2019, revived
> +.BR bcmp ()
> +and generates calls to it instead of
> +.BR memcmp (3)
> +as appropiate as an optimization (as
> +.BR bcmp ()
> +need not traverse memory in-order).
> +.\" http://releases.llvm.org/9.0.0/docs/ReleaseNotes.html#noteworthy-optimizations

This is a pessimation on GNU/Linux if the program uses memcmp as well
because it introduces another relocation.

Thanks,
Florian