Hello! >> There is already a higher priority for registers not requiring REX. >> My patch affects cases when compiler has to use xmm8-15 and it just >> tries to say LRA to assign them for non SSE4 instructions. I doubt it >> would have some use for other targets than Silvermont. > > When it is just a hint, shouldn't there be something like Ya,???x > or Ya,!x or similar in the SSE4 constraints? I mean, xmm{8-15} can be used, > just is costly.
Maybe we can use "Ya*x", similar to *pushdf pattern, where it is costly - but tolerable - to push DFmode value through integer registers. Oh, and I didn't notice that Ya name is already taken... Uros.