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Re: Thoughts on LLVM and LTO


Daniel Berlin wrote:
2. It natively supports Alpha, Sparc, IA64, X86, and PowerPC.  An
LLVM->RTL converter is not that hard, which simply removes the entire
argument anyway.

I see the phrase "doing X is not that hard" in response to many questions about this proposal. Now, I'm arguing the difficulty of the given tasks, but even a simple task requires someone to do it. And maintain it.


Which begs the question: Are these proposals practical within the existing GCC developer community, particularly over the long term (years, decades)?

How did moving to tree-ssa affect the developer community? Did more people come on board, are fewer people working on GCC now, or did it have no net influence on the developer base?

I honestly don't know, hence my queries.

The bottom line I just don't see any sane argument for redo'ing what
others have done very well, unless using that will require more
resources than doing it from scratch.

I can't honestly believe that the work required to make LLVM usable for
us is anywhere near the work we are going to need to tree-ssa to do the
same things LLVM does.

Reverse the question: What does tree-ssa do that LLVM does not? I know that's been covered to some extent in these threads, but maybe someone knowledgable could lay out a very simple bullet point list comparing what needs to be done with both plans.


I'm not saying which way GCC should go -- I merely think that all the consequences need to be considered carefully.

--
Scott Robert Ladd <scott.ladd@coyotegulch.com>
Coyote Gulch Productions
http://www.coyotegulch.com


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