[llvm] [LiveIntervals] repairIntervalsInRange: recompute width changes (PR #78564)

[Carl Ritson via llvm-commits]

perlfu wrote:

> ```
> $vgpr0 = V_MOV_B32_e32 $sgpr0, implicit $exec, implicit-def $vgpr0_vgpr1, implicit $sgpr0_sgpr1
> ```
> 
> How should these be handled? Your patch will call removeInterval on them.

That's an interesting point.
This change will not break those, as they will be recomputed in the code below.
It creates some inefficiency as we perform unnecessary recomputations; however, is it worth the cost to detect them?
I guess we could simply disable this logic for implicit defs?


https://github.com/llvm/llvm-project/pull/78564