[LLVMdev] MMX vs SSE

[Dale Johannesen]

On Sep 8, 2010, at 3:08 PMPDT, Dale Johannesen wrote:

> I'm working on changing the MMX implementation to use intrinsics in  
> all cases, which should stop various optimization passes from  
> creating MMX instructions that screw up the x87 stack.   Right now  
> the MMX instructions are split between X86InstrMMX.td and  
> X86InstrSSE.td, presumably on the historical grounds that some of  
> them weren't introduced until SSE or SSSE3, and require support for  
> that feature to work.  I'm thinking it would be cleaner to keep them  
> all in X86InstrMMX.  Does anyone have an opinion about this?

To clarify, by "MMX instruction" I mean anything that puts the chip  
into MMX mode, so that x87 instructions no longer work.  This includes  
some instructions that also use SSE registers.