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Re: [PR debug/41343] introduce debug expr temps
- From: Alexandre Oliva <aoliva at redhat dot com>
- To: Richard Guenther <richard dot guenther at gmail dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 02 Oct 2009 03:06:23 -0300
- Subject: Re: [PR debug/41343] introduce debug expr temps
- References: <orws3q22sk.fsf@huru.localdomain> <84fc9c000909230117k43fbc016of09049d18b8f4df0@mail.gmail.com> <84fc9c000909230437n6f811db7q26598e241378619c@mail.gmail.com> <84fc9c000909230459gcb04994qc4e4bf1da57e4706@mail.gmail.com> <orhbukj3n7.fsf@huru.localdomain> <84fc9c000909300240x4baad127nda0c463a756c22ad@mail.gmail.com>
On Sep 30, 2009, Richard Guenther <richard.guenther@gmail.com> wrote:
> On Wed, Sep 30, 2009 at 9:25 AM, Alexandre Oliva <aoliva@redhat.com> wrote:
>> What's preventing it is the same code that prevents us from breaking
>> executable code. ÂSay, if we had:
>>
>> Â<bb 2>
>> Â Âfoo = a;
>> Â Âa = 0
>>
>> we wouldn't be allowed to move a = 0 before foo = a. ÂOptimizers
>> shouldn't ignore uses along the way, and although they might have to
>> disregard debug stmts when making decision, they ought to adjust them
>> just like they would should they make transformations that would affect
>> executable code.
> But they don't see the DEBUG_STMT uses because DEBUG_STMTs
> do not have virtual operands.
Uhh... Maybe debug stmts should have VOPs, then... I don't remember
having thought much about whether or not they should. I ended up doing
without them, but from what you say I conclude it was a mistake. Ugh.
--
Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
You must be the change you wish to see in the world. -- Gandhi
Be Free! -- http://FSFLA.org/ FSF Latin America board member
Free Software Evangelist Red Hat Brazil Compiler Engineer