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How to support AVX in _dl_runtime_profile on x86-64?
- From: "H.J. Lu" <hjl dot tools at gmail dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 30 Jun 2009 09:39:29 -0700
- Subject: How to support AVX in _dl_runtime_profile on x86-64?
Hi,
AVX has 256bit AVX registers. But _dl_runtime_profile on x86-64
only preserves the lower 128bit. How should we add AVX support
to _dl_runtime_profile?
I see a few options:
1. Build both
/lib64/ld-X-Y-avx.so
/lib64/ld-X-Y.so
and ldconfig will create a proper link depending on hardware.
2. Build the whole set of x86-64 glibc for AVX.
3. Create _dl_runtime_profile and _dl_runtime_profile_avx.
Pick the right one at run-time. Will STT_GNU_IFUNC help
us here?
Any comments?
Thanks.
--
H.J.