Generate straightline code for inline array allocation
GHC has an optimization for allocating arrays when the size is
statically known -- it'll generate the code allocating and initializing
the array inline (instead of a call to a procedure from
However, the generated code uses a loop to do the initialization. Since
we already check that the requested size is small (we check against
maxInlineAllocSize), we can generate faster straightline code instead.
This brings about 15% improvement for newSmallArray# in my testing and
slightly simplifies the code in GHC.
Signed-off-by: Michal Terepeta <firstname.lastname@example.org>