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Re: [PATCH] Add pixel compare VIS intrinsics.
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: David Miller <davem at davemloft dot net>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Thu, 22 Sep 2011 19:31:07 +0000 (UTC)
- Subject: Re: [PATCH] Add pixel compare VIS intrinsics.
- References: <20110921.202857.949679174400106081.davem@davemloft.net>
On Wed, 21 Sep 2011, David Miller wrote:
> Unfortunately, we can't use these for comparisons on vectors as the
> compiler wants them. Instead of producing a vector of comparison
> results, these instructions produce a small bitmask of those results
> in a destination integer register. Therefore we have to provide
> them using unspecs and builtins.
Do you have any instructions to convert the bitmask into a vector of
results? (Cf. what I said in
<http://gcc.gnu.org/ml/gcc-patches/2010-08/msg01120.html> about vector
comparisons on C6X, where there are XPND2 and XPND4 instructions for that
conversion, but you'd still like operations written to use abstract
comparisons generating code that avoids the expansion instructions if
possible.)
--
Joseph S. Myers
joseph@codesourcery.com