By x86-64 specification, 32-bit destination registers are zero-extended
to 64 bits. There is no need to use 64-bit registers when only the lower
32 bits are non-zero. Also 2 instructions in:
mov %rdi, %rcx
and $15, %rcx
jz L(length_less16_offset0)
mov %rdi, %rcx <<< redundant
and $15, %rcx <<< redundant
are redundant.
* sysdeps/x86_64/memrchr.S (__memrchr): Use 32-bit registers for
the lower 32 bits. Remove redundant instructions.
On x86_64, memrchr (not a standard function) is defined as a strong
symbol, instead of a weak alias of __memrchr as on other
architectures. This results in linknamespace test failures from the
use of __memrchr from dirname. (Not a conformance issue because of
the mem* reservation, but contrary to glibc conventions.) This patch
makes x86_64 follow other architectures by defining memrchr as a weak
alias.
Tested for x86_64 (testsuite, and that disassembly of installed shared
libraries is unchanged by the patch).
[BZ #17719]
* sysdeps/x86_64/memrchr.S (memrchr): Rename to __memrchr and
define as weak alias of __memrchr.
(__memrchr): Do not define as strong alias of memrchr.
* conform/Makefile (test-xfail-XPG4/libgen.h/linknamespace):
Remove variable.
(test-xfail-UNIX98/libgen.h/linknamespace): Likewise.
(test-xfail-XOPEN2K/libgen.h/linknamespace): Likewise.
(test-xfail-XOPEN2K8/libgen.h/linknamespace): Likewise.
