debug strings output order is arbitrary

debug strings output order is arbitrary

[Martin Uecker]

Hi list,

the strings in the ".debug_str" section are output
in an arbitrary order. Could this be changed?

The function 'output_indirect_strings' in 'gcc/dwarf2out.c'
uses htab_traverse which then outputs the string in the
order they appear in the hash table. Instead, it would
be nicer to output them based on their labels (which are
assigned based on the order of creation).

This would minimize differences between builds with
slightly different build environments, e.g. directory.

Martin

Re: debug strings output order is arbitrary

[Richard Biener]

On Sun, Mar 16, 2014 at 3:58 AM, Martin Uecker <uecker@eecs.berkeley.edu> wrote:
>
> Hi list,
>
> the strings in the ".debug_str" section are output
> in an arbitrary order. Could this be changed?
>
> The function 'output_indirect_strings' in 'gcc/dwarf2out.c'
> uses htab_traverse which then outputs the string in the
> order they appear in the hash table. Instead, it would
> be nicer to output them based on their labels (which are
> assigned based on the order of creation).
>
> This would minimize differences between builds with
> slightly different build environments, e.g. directory.

Can you propose a patch?  Note that at creation time only
the string itself is known, so sorting after the string may
be another possibility.

Richard.

Re: debug strings output order is arbitrary

[Martin Uecker]

Am Mon, 17 Mar 2014 09:44:53 +0100
schrieb Richard Biener <richard.guenther@gmail.com>:

> On Sun, Mar 16, 2014 at 3:58 AM, Martin Uecker <uecker@eecs.berkeley.edu> wrote:
> >
> > Hi list,
> >
> > the strings in the ".debug_str" section are output
> > in an arbitrary order. Could this be changed?
> >
> > The function 'output_indirect_strings' in 'gcc/dwarf2out.c'
> > uses htab_traverse which then outputs the string in the
> > order they appear in the hash table. Instead, it would
> > be nicer to output them based on their labels (which are
> > assigned based on the order of creation).
> >
> > This would minimize differences between builds with
> > slightly different build environments, e.g. directory.
> 
> Can you propose a patch?  Note that at creation time only
> the string itself is known, so sorting after the string may
> be another possibility.

I will propose a patch.

Sorting at the end would be easiest, but one could also keep
track of the order. Is this performance critical?

Also it seems there is other stuff which is output/indexed
in hash table order, maybe this should be changed to.

Martin

Re: debug strings output order is arbitrary

[Richard Biener]

On Mon, Mar 17, 2014 at 10:01 PM, Martin Uecker
<uecker@eecs.berkeley.edu> wrote:
> Am Mon, 17 Mar 2014 09:44:53 +0100
> schrieb Richard Biener <richard.guenther@gmail.com>:
>
>> On Sun, Mar 16, 2014 at 3:58 AM, Martin Uecker <uecker@eecs.berkeley.edu> wrote:
>> >
>> > Hi list,
>> >
>> > the strings in the ".debug_str" section are output
>> > in an arbitrary order. Could this be changed?
>> >
>> > The function 'output_indirect_strings' in 'gcc/dwarf2out.c'
>> > uses htab_traverse which then outputs the string in the
>> > order they appear in the hash table. Instead, it would
>> > be nicer to output them based on their labels (which are
>> > assigned based on the order of creation).
>> >
>> > This would minimize differences between builds with
>> > slightly different build environments, e.g. directory.
>>
>> Can you propose a patch?  Note that at creation time only
>> the string itself is known, so sorting after the string may
>> be another possibility.
>
> I will propose a patch.
>
> Sorting at the end would be easiest, but one could also keep
> track of the order. Is this performance critical?

Sure it is.

> Also it seems there is other stuff which is output/indexed
> in hash table order, maybe this should be changed to.

Maybe.

Richard.

> Martin
>