[Cocci] __asm statements confuse spatch

[julia.lawall@lip6.fr (Julia Lawall)]

On Wed, 17 Oct 2018, Timur Tabi wrote:

> On 10/17/18 12:25 AM, Julia Lawall wrote:
> > Linux uses __asm__ ( ... ), which is what Coccinelle recognizes.  I can
> > probably add _asm and __asm with the braces.  On the other hand, the
> > second case, with no delimiter seems awkward.  Does that occur a lot?
> > Basically it's not clear how to parse it.  I could have __asm eat up
> > everything until the end of the line, but then the third case won't work.
>
> Well, it doesn't occur *a lot*, since it's only one set of files that has this
> problem for me.  I believe this code isn't compiled with gcc, which is why the
> syntax is non-standard.
>
> I don't know if it's worth updating spatch for it.  For now, I just manually
> comment-out the offending code in the C file and then run spatch.
>
> > > Another problem I've having with the source file is that it has
> > > inconsistent usage of braces, and sometimes spatch wants to add
> > > unnecessary braces that look off.  For example, this:
> > >
> > >          if (...)
> > >              DBG_PRINTF((...));
> > >          else
> > >              DBG_PRINTF((...));
> > >          }
> > >
> > > (the } belongs to some if-statement much earlier in code somewhere)
> > > becomes:
> > >
> > >          if (...) {
> > >              NV_PRINTF(...);
> > >          }
> > >          else {
> > >              NV_PRINTF(...);
> > >          }
> > >          }
> > >
> > > I really don't want spatch to add the braces.
>
> > I don't think this has anything to do with the trailing }.
>
> Sorry, I didn't mean to imply that it does.  My point was that the trailing }
> is in an awkward position already, and when spatch adds its own brace, the
> result looks weird.
>
> > Coccinelle
> > knows which brace goes with what, independent of the indentation.
> > Something about your rule is making it unsure whether the changed code is
> > in a branch by itself, or whether you have added multiple statements.
> >
> > For example, if your rule is
> >
> > - A;
> > + B;
> > + C;
>
> Hmmm....  I run some tests with my script to see if anything stands out, but
> the whole purpose of my script is to replace DBG_PRINTF with NV_PRINTF.  I
> never add a second line.
>
> > and the code is if (x) A;, then the braces are needed.  Spatch is a bit
> > conservative about this, ie it adds brace unless it is clear that there is
> > a replacement of a single statement by another one.
> >
> > You could try to track down the problem by making a minimal semantic
> > patch and C code that show the problem, or just add some rules to clean
> > up afterwards.
>
> What would a clean-up rule look like? Something like this?
>
> -{
> NV_PRINTF2(...)
> -}

That is missing a ; but with that it should be OK.  In the Linux kernel,
if one branch has {} the other should too, so if you want to respect that
rule, then you would need various cases for various configurations of if.

julia