From: "Joseph S. Myers" <jos...@codesourcery.com> Date: Thu, 22 Sep 2011 19:31:07 +0000 (UTC)
> 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.) Unfortunately, no. But it's interesting to know that another processor implements vector comparisons the same way Sparc VIS does.