On Mon, 15 Feb 2021, Denis Efremov wrote:
>
>
> On 2/15/21 2:47 PM, Julia Lawall wrote:
> >
> >
> > On Mon, 15 Feb 2021, Denis Efremov wrote:
> >
> >> Hi,
> >>
> >> I wrote a simple rule (swap.cocci):
> >>
> >> virtual patch
> >>
> >> @depends on patch@
> >> identifier tmp;
> >> expression a, b;
> >> type T;
> >> @@
> >>
> >> (
> >> - T tmp;
> >> |
> >> - T tmp = 0;
> >> |
> >> - T *tmp = NULL;
> >> )
> >> ... when != tmp
> >> - tmp = a;
> >> - a = b;
> >> - b = tmp;
> >> + swap(a, b);
> >> ... when != tmp
> >>
> >> I would expect it to remove a local variable only if there is a match
> >> with swap template.
> >>
> >> However, it generates "partial" patch on 5.11 linux code:
> >> $ spatch --version
> >> spatch version 1.0.8-00201-g267f9cf8cc82 compiled with OCaml version 4.11.1
> >> $ spatch -D patch --sp-file swap.cocci mm/filemap.c
> >> --- mm/filemap.c
> >> +++ /tmp/cocci-output-445786-88aa66-filemap.c
> >> @@ -2348,7 +2348,7 @@ static int generic_file_buffered_read_ge
> >> struct file_ra_state *ra = &filp->f_ra;
> >> pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
> >> pgoff_t last_index = (iocb->ki_pos + iter->count + PAGE_SIZE-1) >>
> >> PAGE_SHIFT;
> >> - int i, j, nr_got, err = 0;
> >> + int i, nr_got, err = 0;
> >>
> >> nr = min_t(unsigned long, last_index - index, nr);
> >> find_page:
> >>
> >> How can I improve the rule?
> >
> > I don't get a match with the latest version of Coccinelle.
> >
> > If the latest version of Coccinelle were to become a release, would that
> > be good enough for you? Or do you need 1.0.8 to work as well?
>
> I planned to submit the swap rule to scripts/coccinelle. However, I can
> create more strict pattern for the patch mode. Maybe adding "when strict"
> is suitable here?
If there is a release, then the submitted rule can just have a constraint
about the release.
You can try when strict. Normally, that is to ensure that error paths
aren't excused from having the pattern. I don't see why it would help
here, but perhaps it's worth a try.
julia
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