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.
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