LLVM optimisation passes / tables next to code

Simon Marlow marlowsd at gmail.com
Thu Mar 1 09:42:18 CET 2012


On 29/02/2012 12:06, Sergiu Ivanov wrote:
> On Wed, Feb 29, 2012 at 12:37 PM, Simon Marlow<marlowsd at gmail.com>  wrote:
>>
>> It's hard to say.  All of the proposed solutions are a compromise of one
>> kind or another, and they would all impose some kind of penalty - code size
>> or speed - on the NCG too, since we have to use the same ABI.  If the
>> penalty can be shown to be negligible then it would be OK, but of course
>> then we argue about what negligible means.  It seems particularly hard to
>> accept any penalty at all since we already have a solution (albeit an ugly
>> one) but which imposes no penalty or ABI changes.
>
> It should be possible to implement the trick with the jump instruction
> first; it feels like it should be basically doable within a rather
> small time-frame.  Then we may actually try to implement TNTC our way,
> do the comparisons, and try to convince the LLVM people to accept this
> other implementation (especially if this implementation is going to be
> simpler and clearer).  In case they keep disagreeing, we will still
> have something working.
>
> Does this make any sense?

Seems reasonable, yes.

Cheers,
	Simon




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