[MLton] approaches to parallelism in ML
sweeks at sweeks.com
Tue Oct 10 15:45:53 PDT 2006
> if someone wants to invest the time in a low-level target, their
> best bet is to write a MLRISC or C-- or LLVM codegen, and gain
> multiple targets at one go.
It's hard to argue with the logic here. But I will point out that one
possibly serious drawback of using one of those projects is having to
deal with a moving target and bugs that are beyond our control. I
believe it would have been a mistake had we chosen to use MLRISC or
C-- at the time we added MLton's x86 codegen. Also, witness the
difficulties that Matthew encountered with his C-- MLton backend.
> How much of a performance gain do generated executables get from the
The link that Matthew sent
showed an average 35% hit for using the C codegen. My rule of thumb
is no worse than a 2X slowdown, and usually less than 50%. This on
x86 of course. It's quite possible that the hit on other, less
forgiving, platforms is worse.
> LLVM appears to be the most actively developed of the three. Is this
> correct? Would porting to one of these be the same amount of work as
> to a specific architecture?
As a rough guess, yes. Although my above point about instability does
apply. LLVM is a less stable target than SPARC assembly.
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