[llvm-dev] DFAPacketizer assert failure

[Krzysztof Parzyszek via llvm-dev]

On 11/16/2015 3:49 PM, Rail Shafigulin wrote:
>
>     Does the instruction that is being added have an itinerary
>     associated with it?
>
> So I checked again, and it turns out that it does have an itinerary
> associated with it. However it is a pseudo instruction. Does the
> packetizer do something special with the pseudo instructions? I didn't
> see any special code, but I could have missed it.

The packetizer should not do anything with these---they should not be 
inserted into a bundle.  I'm not sure if the code in DFAPacketizer.cpp 
does that or not.  In the Hexagon backend we originally treated CFI 
instructions as "solo", i.e. they could not be packetized with any other 
instruction.  Now we simply delay the generation of these instructions 
until after packetization.  The reason for this is that two instructions 
that could be packetized together were not packetized together if there 
was an CFI instruction in between.  This was causing different code to 
be generated with the CFI instructions present.

In general, most pseudo instructions should have been expanded into real 
instructions by the time the packetizer runs. For exeptional cases, you 
can treat them as not being packetizable with any other instructions.

-Krzysztof

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