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Re: [PATCH] [BZ #19679] [x86_64] Set DL_RUNIME_UNALIGNED_VEC_SIZE to 8
- From: Florian Weimer <fweimer at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: "Carlos O'Donell" <carlos at redhat dot com>, GNU C Library <libc-alpha at sourceware dot org>
- Date: Sat, 20 Feb 2016 09:38:46 +0100
- Subject: Re: [PATCH] [BZ #19679] [x86_64] Set DL_RUNIME_UNALIGNED_VEC_SIZE to 8
- Authentication-results: sourceware.org; auth=none
- References: <20160219220955 dot GA25540 at intel dot com> <56C79D14 dot 1050900 at redhat dot com> <CAMe9rOr9ewbZEj_AY_pLv8GUWju=ZxVNbOgQ1FxO_6Z5vL8EXQ at mail dot gmail dot com>
On 02/20/2016 12:49 AM, H.J. Lu wrote:
> +#ifndef DL_RUNTIME_UNALIGNED_VEC_SIZE
> +/* The maximum size in bytes of unaligned vector load and store in the
> + dynamic linker. Since SSE optimized memory/string functions with
> + aligned SSE register load and store are used in the dynamic linker,
> + we must set this to 8 so that _dl_runtime_resolve_sse will align the
> + stack before calling _dl_fixup. */
> +# define DL_RUNTIME_UNALIGNED_VEC_SIZE 8
The comment doesn't really explain the situation. If all programs
actually fallowed the psABI, we wouldn't need this.
I think it's easier at this point to change the psABI to say that
__tls_getaddr can be called with an 8-byte-aligned stack.
And DL_RUNTIME_UNALIGNED_VEC_SIZE etc. can be removed.