[PATCH] lib/decompress_unxz.c: removing all memory helper functions

On Thu, 2012-05-24 at 10:29 -0700, H. Peter Anvin wrote:

On 05/24/2012 10:26 AM, Joe Perches wrote:

quoted

On Thu, 2012-05-24 at 10:03 -0600, T Makphaibulchoke wrote:

quoted

The patch cleans up the file lib/decompress_unxz.c by removing all memory
helper functions, e.g., memmove.  By doing so, any architecture's preboot
environment supporting the XZ decompression needs to define its own copy of
any of the missing memory helper functions.

Perhaps a silly question, but why not use
the __builtin variants?

For a lot of cases the __builtin variants just generate a call to the
expected out-of-line function, so you need it anyway.

While I'm not completely knowledgeable about gcc,
aren't all the __builtin_mem<foo> functions always
available in gcc 3+

http://gcc.gnu.org/onlinedocs/gcc-3.0.4/gcc_5.html#SEC114

It does say:

Many of these functions are only optimized in certain cases; if not
optimized in a particular case, a call to the library function will be
emitted.