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

[Jeff Garzik <jeff@garzik.org>]

Christopher Li wrote:
> 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?

Not true -- I can walk SYM_STRUCT of the function arguments' base_type 
passed to a SYM_FN.  Similarly so for struct-based variable declarations.

With that information, you can easily back-reference lvalue uses to the 
original struct.

	Jeff