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Re: Should we compile x86-64 ld.so with -mno-sse -mno-sse?
- From: Andreas Jaeger <aj at suse dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Richard Henderson <rth at twiddle dot net>,Carlos O'Donell <carlos at systemhalted dot org>, libc-alpha at sourceware dot org
- Date: Thu, 01 Nov 2012 06:18:10 +0100
- Subject: Re: Should we compile x86-64 ld.so with -mno-sse -mno-sse?
- References: <20121031132245.GA2117@gmail.com> <2353366.qlHrN9GaAk@byrd> <CAE2sS1gsk4rLVj9duAy7Ws_3a9ywnY7NdaYb8iGxGayXaju5Lw@mail.gmail.com> <5091AD68.4020806@twiddle.net> <CAMe9rOprLQuxXFMEgABYNRO=WKwb6MymPPVa5OpmdWm7wrMT8A@mail.gmail.com>
On 11/01/2012 12:18 AM, H.J. Lu wrote:
On Wed, Oct 31, 2012 at 3:59 PM, Richard Henderson <rth@twiddle.net> wrote:
On 2012-11-01 03:10, Carlos O'Donell wrote:
What use case is there for not wanting to touch SEE in ld.so?
I can only imagine HJL is worried about AVX performance if the
dynamic linker uses SSE insns.
That is not the main reason. We make sure that ld.so string/memory
functions never touch SSE/AVX registers. It is not for performance,
but for correctness. Otherwise callee will get random values in
vector registers,
And as you mention elsewhere, we test already for it - so is that test
failing now for you? Under which condition?
Andreas
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