[LLVMdev] going from gcc 4.0.1 to gcc 4.2

[Chris Lattner]

On Wed, 8 Nov 2006, Reid Spencer wrote:
>> The current llvm-gcc4 frontend is based on GCC 4.0.1, as far as I can
>> tell from the docs. I also understand that GCC 4.1.x will probably be
>> skipped, to go to the upcoming GCC 4.2 release directly (which is
>> only a few weeks away I think).
>
> I can't answer that, its up to Apple. Chris might know. I do know that
> the 4.1.x release will be skipped entirely. I suppose whether Apple uses
> 4.2 is a matter of how good 4.2 is. Currently it looks pretty disastrous
> on scalability.

We plan to eventually support it with LLVM, but don't have a timeframe 
right now.  Of course, you don't have to wait for Apple to do something, 
if you want it done, you can make it happen :)

>> Will this happen before the 2.0 release of LLVM, or are other things
>> more needed for the next (i.e. after 1.9) release?
>
> The two aren't really coupled that much. The change to a new llvm-gcc
> baseline could happen either before 2.0 or after. Again, its somewhat up
> to Apple and Chris.

I see 2.0 as being a normal release, perhaps with a longer development 
cycle (6mo instead of 3).  Since it is a major version number, I think we 
should take the opportunity to drop support for:

1. backwards compatibility with some really old .bc file formats.
2. llvmgcc3.

Other than that, I think it will be a normal release, which means that 
whatever is ready in time will go in, something that isn't ready in time 
will be just fine in 2.1.

>> Related to that, are there any plans to create a llvm-gfortran
>> frontend from the gfortran compiler included in the GCC 4.x releases?
>
> I don't know.

When we do 4.2, I'd like to have fortran.  However, it's not personally a 
big priority, so it depends on whether others contribute.  Work on 
llvm-gcc 4.2 won't be a big secret, so I hope the community will be 
involved.

-Chris

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