Instead of doing https://bugs.webkit.org/show_bug.cgi?id=148717 all at once, I will tackle the GetById caches first.
Created attachment 260488 [details]
a small start
Created attachment 260502 [details]
Oh man, this is painful.
It seems like I should probably do this at the same time as https://bugs.webkit.org/show_bug.cgi?id=148717, because my approach involves moving logic out of StructureStubInfo/Repatch and into PolymorphicGetByIdList. But a lot of that logic is shared by the put_by_id paths, so probably PolymorphicPutByIdList should be folded into PolymorphicGetByIdList.
Created attachment 260550 [details]
I think that it's better to handle all of the inline caches in one go, rather than trying to just fix get_by_id.
*** This bug has been marked as a duplicate of bug 148717 ***