df.c data reprezentation

[Daniel Berlin]

On Tuesday, September 25, 2001, at 10:25  AM, Jan Hubicka wrote:

> Hi,
> Just note about the data reprezentation.  Unlike our previous dataflow 
> analyzers
> (REG_DEAD/UNUSED notes+loglinks), we don't use RTL to reprezent the 
> dataflow here.
>
> Do you consider that as supperrior?
No.

> Main advantage of RTL based reprezentation is the
> fact that you can easilly attach the information to each insn and see 
> it reprezented
> in the dumps?
>
However, dataflow is completely seperate from the representation.

> It would actually mean to change REF structure to RTX form and use 
> expr_list for links.
> Insn info can use the existing loglink field with one new for the 
> oposite chain.
>
> What do you think?
>
This is a very bad idea.
I know I was, and others were, specifically planning on reusing the df 
module for dataflow on trees.
Right now, it only requires assigning each variable an id (trivial), and 
adding routines that know how to record defs/uses for trees.

If you want to transform the info at the end of dataflow into stuff on 
rtx, that's fine. But please don't make it do it in the actual routines, 
or in the dataflow structures.

> Honza