Init df for split pass since some target use REG_NOTE in split pattern

Jeff Law
Mon Aug 8 19:45:00 GMT 2016

On 07/25/2016 08:31 PM, Kito Cheng wrote:
> Hi Jeff:
> Oop, patch in attachment, and I hit this bug in gcc.dg/torture/vshuf-v2di.c
> with our nds32 internal branch.
> Hi Richard:
> I think we really need reg dead note for some optimization, and btw,
> here is our split pattern:
So I see a real need to be able to look at those notes -- I think the 
big question in my mind is whether or not we want to pay the price for 
all the splitter passes or if we can/should restrict it to a subset of 
the passes.  Note that I think we have 4 distinct passes that call 

For the H8, we could restrict it to cases where epilogue_completed is 
true.  I haven't looked closely at the other targets.

I'm pretty sure we do _not_ want it for split_all_insns_noflow since 
that's used when the CFG is not necessarily correct and thus I don't see 
how we can reliably have death/unused notes.


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