Re: [PATCH v2] sparse: add LLVM code generation backend

[Christopher Li <sparse@chrisli.org>]

On Mon, Apr 27, 2009 at 3:39 PM, Jeff Garzik <jeff@garzik.org> wrote:
> You can see the above code was taken verbatim from show-parse.c, and is
> probably nothing more than a check the original author (Linus?) felt
> appropriate at the time, for show-parse.c.  I wouldn't read too much into
> its presence in s2l-gen.c -- maybe those checks can simply be deleted.

I did not explain it clear it enough. It is not about the code is not
used. My point is:

1) linearize instruction does not lose the information you care about
   generating better LLVM code. The evaluation does.

2) By writing your own AST recursive code, it does not gain more
   information than what you can already do with current linearize
   instruction. The EXPR_DEREF is processed in evaluation stage.
   The structure laid you care about is already gone by the time your
   s2l-gen about to emit LLVM byte codes. You did not generate any
   GET_ELEMENT_PTR in your LLVM byte code, right?

I still think you should write your LLVM back end base on linearized
instructions. Avoiding it right now does not gain your new features, but
duplicate a lot of complexity. I am not convinced those complexity is
justifiable yet.

Chris
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