There were no objections, and I have now removed user annotations from
`cg_annotate`.
Nick
On Wed, 29 Mar 2023 at 09:03, Nicholas Nethercote <n.netherc...@gmail.com>
wrote:
> Hi,
>
> I recently rewrote `cg_annotate`, `cg_diff`, and `cg_merge` in Python. The
> old versions were written in Perl, Perl, and C, respectively. The new
> versions are much nicer and easier to modify, and I have various ideas for
> improving `cg_annotate`. This email is about one of those ideas.
>
> A typical way to invoke `cg_annotate` is like this:
>
> > cg_annotate cachegrind.out.12345
>
> This implies `--auto=yes`, which requests line-by-line "auto-annotation"
> of source files. I.e. `cg_annotate` will automatically annotate all files
> in the profile that meet the significance threshold.
>
> It's also possible to do something like this:
>
> > cg_annotate --auto=no cachegrind.out.12345 a.c b.c
>
> Which instead requests "user annotation" of the files `a.c` and `b.c`.
>
> My thesis is that auto-annotation suffices in practice for all reasonable
> use cases, and that user annotation is unnecessary and can be removed.
>
> When I first wrote `cg_annotate` in 2002, only user annotation was
> implemented. Shortly after, I added the `--auto={yes,no}` option. Since
> then I've never used user annotation, and I suspect nobody else has either.
> User annotation is ok when dealing with tiny programs, but as soon as you
> are profiling a program with more than a handful of source files it becomes
> impractical.
>
> The only possible use cases I can think of for user annotation are as
> follows.
>
> - If you want to see a particular file(s) annotated but you don't want
> to see any others, then you can use user annotation in combination with
> `--auto=no`. But it's trivial to search through the output for the
> particular file, so this doesn't seem important.
> - If the path to a file is somehow really messed up in the debug info,
> it might be possible that auto-annotation would fail to find it, but user
> annotation could find it, possibly in combination with `-I`. But this seems
> unlikely. Some basic testing shows that gcc, clang and rustc all default to
> using full paths in debug info. gcc supports `-fdebug-prefix-map` but that
> seems to mostly be used for changing full paths to relative paths, which
> will still work fine.
>
> Removing user annotation would (a) simplify the code and docs, and (b)
> enable the possibility of moving the merge functionality from `cg_merge`
> into `cg_annotate`, by allowing the user to specify multiple cachegrind.out
> files as input.
>
> So: is anybody using user annotation? Does anybody see any problems with
> this proposal?
>
> Thanks.
>
> Nick
>
_______________________________________________
Valgrind-users mailing list
Valgrind-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/valgrind-users
