search for: vni32

...t;  Can you walk me through how that > > works with Altivec? > > The basic idea is quite simple - lower everything to vNi8 and write > all the patterns using only these types. Yeah, I figured that out after thinking a bit more. However, I think in this case we only want to lower to vNi32 since there are no immediate-mask shuffles in X86 that operate on smaller element types. Doing it at the byte level would just be more confusing, I think. PSHUFB is really a completely different instruction than PSHUFD, for example. -Dave

Hello, David > Can you expand on this with an example?  There seems to be an awful lot of > shuffle patterns and predicates in PPCInstrAltivec.td.  What do you mean by, > "Canonicalize to byte ops?"  Can you walk me through how that works with > Altivec? The basic idea is quite simple - lower everything to vNi8 and write all the patterns using only these types. -- With

...that >>> works with Altivec? >> >> The basic idea is quite simple - lower everything to vNi8 and write >> all the patterns using only these types. > > Yeah, I figured that out after thinking a bit more. However, I think in this > case we only want to lower to vNi32 since there are no immediate-mask shuffles > in X86 that operate on smaller element types. Doing it at the byte level > would just be more confusing, I think. > > PSHUFB is really a completely different instruction than PSHUFD, for example. Aside from consuming one of its inputs, wh...

On Thursday 17 December 2009 17:16, Nate Begeman wrote: > David, this is probably the wrong approach, based on the accreted awfulness > of the X86 shuffle lowering code, Ha! I have no issue believing this statement. :) > The correct approach is probably a rewrite based around what > AltiVec does: Canonicalize to byte ops, and write all the patterns once > rather than having to