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Re: Removing ARCNET stuffs



David Holland skrev den 2015-06-03 07:56:

  > PCC, to the best of my knowledge is still in the [very early] planning
  > stages.  One of its design choices would be to go pure SSA.  Another
  > option, closer to GCC (RTL), would be to retain existing code-gen
  > passes.  Tough choices.

I'm not sure why it's such a big deal, except that everything in gcc
is a big deal because gcc is such a mess inside.

Moving an existing representation to SSA just requires adding phi
nodes to the representation, writing a check pass to enforce the
single assignment property, and updating existing passes to maintain
the property -- in a language without proper algebraic data types this
is a bigger deal than otherwise but it does not seem like a
particularly major undertaking. Unless the representation is totally
wrong in other ways that need to be rectified first.
SSA representation was added to pcc in 2008.
  > > backend is an orthogonal issue.
  >
  > I'm being fast and loose.  My reading of the code was that debug info
  > was being generated by the back of the front end (very roughly
  > "gimplify" in this diagram of GCC
  > https://gcc.gnu.org/projects/tree-ssa/#ssa).   It was pretty much hard
  > wired printfs, and explained to me why "-g -O" wasn't supported.

printfing from the back of the front end is definitely "totally wrong
in other ways that need to be rectified first" :(
Hm, I may be missing something, but what is wrong?
Where should you print it out otherwise?

-- Ragge


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