>>> I can't really match spec and code. For the lmul = 2 case sure, >>> but W84 e.g. allows v4 and not v6? What actually is "highest-numbered >>>part"? > Yes. > > For vwcvt, LMUL 4 -> LMUL 8. > We allow overlap vwcvt v0 (occupy v0 - v7), v4 (occupy v4 - v7) > This patch support the overlap above.
Ok thanks, that way it makes sense. The allowed overlap size is the size of the source group which is determined by the "extension factor". But don't we allow e.g. v2 and v4 with W82? Shouldn't it be % 8 == 6 and % 8 == 7 for W82 and W81? Or for W41, % 4 == 3? At least when looking at the given spec example that would correspond to W82? > This is kito's code. Could you suggest another name ? I can modify it. overlap or group_overlap. Then change "no" to "none" and rename "vconstraint_enabled" to "group_overlap_valid" (or without the group). Add a comment to group_overlap_valid: ; Widening instructions have group-overlap constraints. Those are only ; valid for certain register-group sizes. This attribute marks the ; alternatives not matching the required register-group size as disabled. > I experiment with many tests, turns out adding ? generate better codegen. > You can try it (remove ?) and testing it on case (I added in this patch). It looks like we spill without it but I don't get why. Well, as long as it works, I guess we can defer that question. Regards Robin
