[LLVMdev] GenericValue changes from 1.8 to 2.0

[Sarah Thompson]

Chris Lattner wrote:
> On Tue, 17 Jul 2007, Sarah Thompson wrote:
>
>   
>> Do I understand correctly that there is nothing that the current gcc
>> front end generates that wouldn't fit an old-style GenericValue? I'm
>> wondering if this might be an interim approach that would avoid me
>> needing to rewrite huge amounts of code, and since we're not likely to
>> be supporting anything other than C and C++ in the forseeable future, it
>> makes some sense. Model checking VHDL and Verilog can come later. :-)
>>     
>
> Right now, the only interesting thing is 128-bit integers.  You can get 
> these on 64-bit targets if you use some funky GCC extensions.  Normal code 
> only produces "usual" sized integers.
>   
OK, in that case I have a 2 phase plan:

1: Refactor my code to use a 'OldGenericValue' class that resembles the 
pre-2.0 version of GenericValue, and implement conversions as necessary. 
This will require relatively few changes to my code, so shouldn't be too 
much of a problem as a first step. This should leave me with a working 
model checker relatively quickly (and fewer sharp things waved at me by 
other NASA people who are waiting for it).

2: Refactor the code again to move to the for-real GenericValue class. 
This is a harder/longer job, but I should at least have a working 
version of the model checker while I'm working on it.

In an ideal world, I'd go straight for 2, but I'm under too much time 
pressure to go that route unfortunately. None of this should require 
unusual versions of LLVM or changes to the LLVM codebase. My intention 
is initially to do this against the 2.0 release, but once that's working 
(probably concurrently with 2 above) I intend to move to coding against 
the head branch of LLVM so that my code evolves along with the rest of 
LLVM. I might be able to give more useful feedback to you lot that way 
too, of course.

Sarah