[LLVMdev] Need advice on writing scheduling pass

[ether zhhb]

hi Jonas,

On Wed, May 25, 2011 at 12:59 AM, Jakob Stoklund Olesen <stoklund at 2pi.dk> wrote:
>
> On May 24, 2011, at 8:22 AM, Jonas Paulsson wrote:
>
>> Hi (Jakob),
>>
>> in reference to the prior message below, I have the following follow-up questions, as I also need a scheduling pass
>> prior to regalloc. I need to do this in order to set VLIW-flags, so that the RA is aware of several MI's
>> per cycle with a redefined LiveRange::overlap-function. On a multiple-issue cycle, a register that gets killed
>> can be reused by another MI - these live ranges do not then overlap.
>
> Redefining overlap() won't work for that. There is other code assuming that overlap means overlap, for example the LiveIntervalUnion used by the new register allocators.
>
> For VLIW, you probably want to number your packets instead of individual instructions. We don't have any VLIW support, so nobody has thought about how best to do it.

People had discussed VLIW support before, you may have a look at this:
http://old.nabble.com/VLIW-Scheduling-td857833.html

I implemented the VLIW scheduling/register allocate in llvm backend
like the way described in the above thread, and it work without any
problem.

best regards
ether