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Re: [PATCH] Make strcmp optimized for SSE2 with unaligned load/store as default
- From: Roland McGrath <roland at hack dot frob dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: OndÅej BÃlka <neleai at seznam dot cz>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 25 Aug 2015 12:21:03 -0700 (PDT)
- Subject: Re: [PATCH] Make strcmp optimized for SSE2 with unaligned load/store as default
- Authentication-results: sourceware.org; auth=none
- References: <CAMe9rOqgek-2_GfDeFYdHpHvvt0RodUCOBrb-0nKMiCEd62ycg at mail dot gmail dot com> <20150825185920 dot 2DF5A2C3A73 at topped-with-meat dot com> <CAMe9rOr0_GpATYS8cYYZups3ti8eke9HCoiCpY3H6wXz5Y8WBw at mail dot gmail dot com>
> ld.so and libc use the same code in sysdeps/x86_64/strcmp.S. When we
> move sysdeps/x86_64/multiarch/strcmp-sse2-unaligned.S to
> sysdeps/x86_64/strcmp.S to make it the default in libc, it is used by ld.so.
> To make ld.so not to use it requires extra work, which doesn't make any
> senses. If it is OK for libc, it should be OK for ld.so.
The first change is to eliminate any explicit difference between libc and
ld.so. There is no controversy about that. The second change is which
strcmp implementation is used by everybody, which needs the same kind of
rationale made explicit as does every other performance-motivated change.