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Re: [PATCH] Add a new macro to mask a float
- From: Joseph Myers <joseph at codesourcery dot com>
- To: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>
- Cc: <libc-alpha at sourceware dot org>
- Date: Wed, 29 Jun 2016 20:20:04 +0000
- Subject: Re: [PATCH] Add a new macro to mask a float
- Authentication-results: sourceware.org; auth=none
- References: <1467142073-13886-1-git-send-email-tuliom at linux dot vnet dot ibm dot com> <alpine dot DEB dot 2 dot 20 dot 1606282056460 dot 12650 at digraph dot polyomino dot org dot uk> <577402AC dot 5080208 at linaro dot org> <alpine dot DEB dot 2 dot 20 dot 1606291725470 dot 22371 at digraph dot polyomino dot org dot uk> <577419D9 dot 8070903 at linaro dot org>
On Wed, 29 Jun 2016, Adhemerval Zanella wrote:
> Now that you raised these questioning I do not think this change is safe
> for float values in POWER. Current patch does:
In that case we get back to the question of whether you can show that each
individual instance is in fact safe because the code cannot get subnormals
or because the resulting masking is in fact safe when it does get
subnormals. In which case changes in glibc would make sense instead of
compiler changes (as the compiler probably wouldn't be able to tell the
code sequence is safe in a particular case), given performance evidence,
appropriate comments explaining the rules for when the macro can be used,
coding standards fixes, etc.
--
Joseph S. Myers
joseph@codesourcery.com