This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: Designs for better debug info in GCC


On Dec 20, 2007, Ian Lance Taylor <iant@google.com> wrote:

> Alexandre Oliva <aoliva@redhat.com> writes:
>> > How do i know i need to change this DEBUG expression.
>> 
>> As reassoc looks for sets of variables it can freely mess with, it
>> should take note of variables that are used in debug annotations in
>> addition to the kind of single (?) non-debug uses it's interested in,
>> such that, when it modifies these variables, the annotations can be
>> compensated for.

> The question is how it finds them efficiently, without doing a scan of
> all instructions.

It must keep track of variables it can mess with, so it might as well
take notes about those it has to be more careful about.

*Or* it can just introduce new temporaries, rename the uses and leave
the original sets behind for "garbage collection" AKA dead code
elimination, like I said.

One is more implementation work, the other is potentially more
wasteful in terms of memory use.  None look particularly hard to me.

-- 
Alexandre Oliva         http://www.lsd.ic.unicamp.br/~oliva/
FSF Latin America Board Member         http://www.fsfla.org/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]