[Cocci] Performance issue with quite simple patch?

[Maxime Ripard <maxime@cerno.tech>]

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Hi!

I've been trying to get a patch to rename any variable called "state" in
a given set of callbacks.

This is the patch that I've come up with:

@ plane_atomic_func @
identifier helpers;
identifier func;
@@

(
 static const struct drm_plane_helper_funcs helpers = {
 	...,
 	.atomic_check = func,
	...,
 };
|
 static const struct drm_plane_helper_funcs helpers = {
 	...,
 	.atomic_disable = func,
	...,
 };
|
 static const struct drm_plane_helper_funcs helpers = {
 	...,
 	.atomic_update = func,
	...,
 };
)

@@
identifier plane_atomic_func.func;
symbol state;
expression e;
type T;
@@

 func(...)
 {
 	...
-	T state = e;
+	T plane_state = e;
 	<+...
-	state
+	plane_state
 	...+>
 }

However, it seems like at least on a file (in Linux,
drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c), it takes quite big
performance hit with one CPU running at 100% until the timeout is hit.

Replacing <+... by ... makes it work instantly, but doesn't really do
what I'm expecting, so I guess it's a matter of the patch being
subobtimal?

Is there a more optimal way of doing it?

Thanks!
Maxime

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