Re: pass manager question

[Sandra Loosemore <sandra at codesourcery dot com>]

On 10/03/2017 05:36 AM, Martin Jambor wrote:
> Hi,
>
> On Mon, Oct 02, 2017 at 01:27:05PM -0600, Sandra Loosemore wrote:
> > Is there an idiom for target-specific back end code to ask the pass manager
> > if a particular pass (e.g., "split1") has already run?
>
> (I might be wrong but) I don't think there is.  But it might be a
> useful thing to have generally, it would allow us for example to merge
> early SRA and "late" SRA which differ in behavior only because the
> first one must not touch aggregates that pass_stdarg will operate on.
>
> And I guess the infrastructure to do that could be as simple as adding
> a flag (or a counter) to class opt_pass that the pass manager would
> set (or increment) when running the pass.

When I was looking at this, I saw that there is already the 
static_pass_number field already in the pass object, but it's documented 
as being used only for dump file names, so I don't know if that's a 
suitable counter or not.  Also there's a variable that holds the current 
pass object, and a function for looking up a pass by name.

A lot of my confusion has to do with when the numbers are assigned and 
what the extent of the information is (since functions can be compiled 
with different optimization settings).  So, even if this would all "just 
work" using the existing code, I think we'd need to document an external 
interface for this purpose, even if only in the form of comments in the 
code.

-Sandra