591914 - Remove large size branch from GC::Alloc

Status: RESOLVED WONTFIX

(Tamarin Graveyard :: Garbage Collection (mmGC), defect)

Description

[Tommy Reilly]

If we made GCLargeAlloc a GCAlloc and placed it at the end of the GCAlloc's array and had a branch-free way to clamp the size class index to the end of the size class array we could remove a branch from GC::Alloc

I think this can be made to work:

http://bob.allegronetwork.com/prog/tricks.html#clamp

Comment 1

[Lars T Hansen]

This is probably not important because in almost all cases that test is or can be constant-folded (needs to be substantiated, but it is credible).