Re: git: 5fc3cc2713ef - main - amd64: make bcmp in libc just call memcmp

On 3/12/22, Kyle Evans <kevans@freebsd.org> wrote:
> On Sat, Mar 12, 2022 at 8:59 AM Mateusz Guzik <mjg@freebsd.org> wrote:
>>
>> The branch main has been updated by mjg:
>>
>> URL:
>> https://cgit.FreeBSD.org/src/commit/?id=5fc3cc2713eff8cdabbf6e5d03bf8a799adf808c
>>
>> commit 5fc3cc2713eff8cdabbf6e5d03bf8a799adf808c
>> Author:     Mateusz Guzik <mjg@FreeBSD.org>
>> AuthorDate: 2022-03-12 12:27:25 +0000
>> Commit:     Mateusz Guzik <mjg@FreeBSD.org>
>> CommitDate: 2022-03-12 14:59:14 +0000
>>
>>     amd64: make bcmp in libc just call memcmp
>>
>>     Preferably bcmp would just alias memcmp but there is build magic
>> which
>>     makes this problematic.
>>
>>     Reviewed by:    jhb
>>     Differential Revision:          https://reviews.freebsd.org/D28846
>> ---
>>  lib/libc/amd64/string/Makefile.inc |  1 -
>>  lib/libc/amd64/string/bcmp.c       | 16 ++++++++++++++++
>>  2 files changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/libc/amd64/string/Makefile.inc
>> b/lib/libc/amd64/string/Makefile.inc
>> index cb370bc6be1c..b77079afc933 100644
>> --- a/lib/libc/amd64/string/Makefile.inc
>> +++ b/lib/libc/amd64/string/Makefile.inc
>> @@ -1,7 +1,6 @@
>>  # $FreeBSD$
>>
>>  MDSRCS+= \
>> -       bcmp.S \
>>         memcmp.S \
>>         memcpy.S \
>>         memmove.S \
>
> We should probably add a tools/build/depend-cleanup.sh entry for this,
> so that non-clean builds pick up the new object, but
>
>> diff --git a/lib/libc/amd64/string/bcmp.c b/lib/libc/amd64/string/bcmp.c
>> new file mode 100644
>> index 000000000000..b45176dc2d56
>> --- /dev/null
>> +++ b/lib/libc/amd64/string/bcmp.c
>> @@ -0,0 +1,16 @@
>> +/*-
>> + * Written by Mateusz Guzik <mjg@freebsd.org>
>> + * Public domain.
>> + */
>> +
>> +#include <sys/cdefs.h>
>> +__FBSDID("$FreeBSD$");
>> +
>> +#include <string.h>
>> +
>> +int
>> +bcmp(const void *b1, const void *b2, size_t len)
>> +{
>> +
>> +       return (memcmp(b1, b2, len));
>> +}
>
> Why do this instead of replacing the previous contents of bcmp.S with
> either:
>
> #define memcmp bcmp
> #include "memcmp.S"
>
> or, restructure memcmp like you did with memcpy/memmove?
>

I wanted to get rid of another instance where a routine is copied.

The real fix would turn bcmp into a straight up alias to memcmp, but I
gave up on the libc build process.

-- 
Mateusz Guzik <mjguzik gmail.com>