Harendra Kumar
I am confused by this flag. This flag allows us to allocate statically known arrays sizes of <= n to be allocated from the current nursery block. But looking at the code in allocateMightFail, as I interpret it, any size array up to LARGE_OBJECT_THRESHOLD is anyway allocated from the current nursery block. So why have this option? Why not fix this to LARGE_OBJECT_THRESHOLD? Maybe I am missing something.
In principle we could do so. The motivation for making this a flag isn't immediately clear from the commit implementing this optimisation (1eece45692fb5d1a5f4ec60c1537f8068237e9c1). One complication is that currently GHC has no way to know the value of LARGE_OBJECT_THRESHOLD (which is a runtime system macro). Typically to handle this sort of thing we use utils/deriveConstants to generate a Haskell binding mirroring the value of the C declaration. However, as GHC becomes runtime-retargetable we may need to revisit this design. Cheers, - Ben