Re: [cocci] Iterator macros

[Andrzej Hajda <andrzej.hajda@intel.com>]

On 13.08.2024 08:34, Julia Lawall wrote:
>
> On Tue, 13 Aug 2024, Peter Senna Tschudin wrote:
>
>> Hi Julia,
>>
>>
>>
>> On Tue, Aug 13, 2024 at 8:19 AM Julia Lawall <julia.lawall@inria.fr> wrote:
>>
>>
>>        On Tue, 13 Aug 2024, Peter Senna Tschudin wrote:
>>
>>        > Dear List,
>>        >
>>        > I am trying to make changes to a macro iterator from
>>        igt-gpu-tools*, and I am failing to use Coccinelle. My current
>>        attempt only captures about 1/2 of call sites, and I am not
>>        really sure how to ask Coccinelle to make the changes I want.
>>        Here is the pattern I am trying to change:
>>        >
>>        >
>>        > From:
>>        >
>>        > const struct intel_execution_engine2 *e2;
>>        > ...
>>        > for_each_ctx_engine(i915, ctx, e2) {
>>        >     execbuf.flags = e2->flags;
>>        >     gem_execbuf(i915, &execbuf);
>>        > }
>>        >
>>        >
>>        > To:
>>        >
>>        > struct intel_engine_data ied;
>>        > ...
>>        > for_each_ctx_engine(i915, ctx, ied) {
>>        >     execbuf.flags = ied.current_engine->flags;
>>        >     gem_execbuf(i915, &execbuf);
>>        > }
>>        >
>>        > Changes I want:
>>        > 1. From `const struct intel_execution_engine2 *e2` to `struct
>>        intel_engine_data ied`.
>>        > 2. Replace the last argument of for_each_ctx_engine()
>>        following the change on previous step.
>>        > 3. Change references from `e2` to `ied.current_engine` inside
>>        the iterator statement.
>>        >
>>        > Here is my starting point that finds about half of the call
>>        sites:
>>        >
>>        > @r1@
>>        > iterator I =~ "for_each_ctx_engine";
>>        > statement S;
>>        > @@
>>        > * I(...)
>>        > S
>>        >
>>        > I assume that I should create other rules and import I from r1
>>        as the
>>        > core of the changes I want. Can you point me to an example to
>>        help me
>>        > here?
>>
>>        Are you just looking for
>>
>>        iterator r.I;
>>
>>        If you have only one iterator name, you don't need the regexp.
>>        Just put
>>
>>        iterator name for_each_ctx_engine;
>>
>> Thank you! This is much faster but captures one instance less.
> You can use multiple names like
>
> (name1@I|name2@I|name3@I)(...) S
>
> The you can use r.I in your other rules.  name1 etc would be iterator name
> and I would be iterator.

I guess the issue here could be a problem with parsing igt code (it is 
also an issue with kernel drivers using iterators).
Cocci quite often does not recognize automatically iterators or other 
constructs, and does not scan them at all.
Try run for example:
$ spatch --parse-c tests/intel/gem_ctx_exec.c
...
NB total files = 1; perfect = 0; pbs = 1; timeout = 0; =========> 0%
nb good = 385,  nb passed = 19 =========> 3.12% passed
nb good = 385,  nb bad = 204 =========> 66.45% good or passed

As I understand, lines marked as "bad" are skipped during cocci pass, am 
I right?
Some workaround is to define iterators by hand in the script or include 
files.

Regards
Andrzej

>
> julia
>
>>   
>>
>>        julia
>>
>>        >
>>        > Thank you,
>>        >
>>        > Peter
>>        >
>>        > * - https://gitlab.freedesktop.org/drm/igt-gpu-tools
>>        >
>>
>>
>>
>> --
>>                           Peter
>>
> >