"Ilpo Järvinen" <ilpo.jarvinen@xxxxxxxxxxx> wrote:
> On Thu, 18 Jun 2009, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Jun 18, 2009 at 01:28:20PM -0700, Zack Weinberg escreveu:
> > > - You do not have to process C declaration syntax to find the
> > > name of each field.
>
> Good point, this is one of the most complex tasks in scripts to get
> general case right. Besides typedefs, especially those function
> pointers which appear in return value and arguments make it a task
> too hairy for any sane people, not that I'd say it is
> impossible... :-)
I used to hack gcc. I know *exactly* how hard it is to parse C
declarations. :-)
I had been doing okay, for the limited thing I am trying to do, with
sed scripts to munge the pahole output into something that could be
relatively easily parsed by a Python script, but then I ran into this
construct:
struct S {
...
struct T {
int a;
} tee[2];
};
No hint that there are two copies of T embedded in S, here, until it's
far too late to do anything about it (if you're a sed script).
> > > - There is never missing data; in many cases pahole currently
> > > will omit the offset in its annotation of a full nested structure,
> > > for instance, which is fine for humans but really bad for
> > > machine processing.
> >
> > Annoying "simplification", I'll put the offset there explicitely,
> > just worried that Ilpo may be using it in his sed scripts... Ilpo?
>
> No, I'm not. I usually try to avoid trusting such things anyway,
> unless I really have to. You just don't parse anything c-like with
> newlines / spaces as significant :-).
I actually have a patch for this one now :-) I looked harder at my
data set and realized it only happens with unions. There's also a
small typo fix in here, I was getting "classnsThing *" a lot...
diff --git a/dwarves_fprintf.c b/dwarves_fprintf.c
index e3e621f..bbc5dd6 100644
--- a/dwarves_fprintf.c
+++ b/dwarves_fprintf.c
@@ -319,7 +319,7 @@ static const char *tag__prefix(const struct cu *cu, const uint32_t tag)
case DW_TAG_structure_type:
return cu->language == DW_LANG_C_plus_plus ? "class " :
"struct ";
- case DW_TAG_class_type: return "class";
+ case DW_TAG_class_type: return "class ";
case DW_TAG_union_type: return "union ";
case DW_TAG_pointer_type: return " *";
case DW_TAG_reference_type: return " &";
@@ -679,6 +679,7 @@ static size_t union_member__fprintf(struct class_member *self,
const struct conf_fprintf *conf, FILE *fp)
{
const size_t size = self->byte_size;
+ const size_t offset = conf->base_offset;
size_t printed = type__fprintf(type, cu, s(cu, self->name), conf, fp);
if ((tag__is_union(type) || tag__is_struct(type) ||
@@ -693,17 +694,17 @@ static size_t union_member__fprintf(struct class_member *self,
* '} member_name;' last line of the type printed in the
* above call to type__fprintf.
*/
- printed += fprintf(fp, ";%*s/* %11zd */",
+ printed += fprintf(fp, ";%*s/* %5zd %5zd */",
(conf->type_spacing +
- conf->name_spacing - slen - 3), " ", size);
+ conf->name_spacing - slen - 3), " ", offset, size);
}
} else {
printed += fprintf(fp, ";");
if (!conf->suppress_offset_comment) {
const int spacing = conf->type_spacing + conf->name_spacing - printed;
- printed += fprintf(fp, "%*s/* %11zd */",
- spacing > 0 ? spacing : 0, " ", size);
+ printed += fprintf(fp, "%*s/* %5zd %5zd */",
+ spacing > 0 ? spacing : 0, " ", offset, size);
}
}
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