llvm dev - Jun 2014 - [LLVMdev] Looking for a fix to memory leak in DWARF support

David, (and everyone else)

  I am forced to do some maintenance work on a fairly old LLVM branch
(likely based on release 3.1) that among other issues has a major problem
with memory leak somewhere around DWARF debug support.
In fact customer is unable to build with -g at all - simply running out of
memory on their project... 

  I seem to remember that there has been a major fix related to it, but
finding it hard to pinpoint. So the appeal to the communal memory - do you
remember if  there was a single fix (since the middle of 2012 or so) that
would have addressed such issue?

  I know the code was drastically change since - I have seen this for
instance
llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/ELFObjectWriter.cpp?view=log&
pathrev=205990

...but not sure this is what I am looking for, and whether there is
something less drastic than I can do to plug that leak.

Any clue would be very much appreciated.

Thanks.

Sergei

---
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by
The Linux Foundation

Are you sure it's a leak, not just a large memory footprint?

A lot of things have changed. Heck, even the bugs that we've fixed
might not have existed two years ago (I've certainly created (and
fixed) my share of bugs in debug info).

Best you start with a leak tracking tool and at least be able to point
to the major leak culprit (eg: "90% of the leaked memory was allocated
at <stack trace>")

On Fri, Jun 13, 2014 at 9:16 AM, Sergei Larin <slarin at codeaurora.org>
wrote:
>
> David, (and everyone else)
>
>   I am forced to do some maintenance work on a fairly old LLVM branch
> (likely based on release 3.1) that among other issues has a major problem
> with memory leak somewhere around DWARF debug support.
> In fact customer is unable to build with -g at all - simply running out of
> memory on their project...
>
>   I seem to remember that there has been a major fix related to it, but
> finding it hard to pinpoint. So the appeal to the communal memory - do you
> remember if  there was a single fix (since the middle of 2012 or so) that
> would have addressed such issue?
>
>   I know the code was drastically change since - I have seen this for
> instance
>
llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/ELFObjectWriter.cpp?view=log&
> pathrev=205990
>
> ...but not sure this is what I am looking for, and whether there is
> something less drastic than I can do to plug that leak.
>
> Any clue would be very much appreciated.
>
> Thanks.
>
> Sergei
>
> ---
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
by
> The Linux Foundation
>

David,

Thanks for the quick response... 


No, at this point I am just getting into the issue... I assume it is a leak, but
no clear proof yet. I was hoping it was an obvious thing since I recall a
discussion about it a while ago... but maybe I am just confused.

Was your work for compressing DWARF data  motivated by a certain inefficiency in
debug info representation? Did it result in significant savings?

Thanks.

Sergei

---
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The
Linux Foundation

> -----Original Message-----
> From: David Blaikie [mailto:dblaikie at gmail.com]
> Sent: Friday, June 13, 2014 12:41 PM
> To: Sergei Larin
> Cc: LLVM Developers Mailing List
> Subject: Re: Looking for a fix to memory leak in DWARF support
> 
> Are you sure it's a leak, not just a large memory footprint?
> 
> A lot of things have changed. Heck, even the bugs that we've fixed
might not
> have existed two years ago (I've certainly created (and
> fixed) my share of bugs in debug info).
> 
> Best you start with a leak tracking tool and at least be able to point to
the
> major leak culprit (eg: "90% of the leaked memory was allocated at
<stack
> trace>")
> 
> On Fri, Jun 13, 2014 at 9:16 AM, Sergei Larin <slarin at
codeaurora.org> wrote:
> >
> > David, (and everyone else)
> >
> >   I am forced to do some maintenance work on a fairly old LLVM branch
> > (likely based on release 3.1) that among other issues has a major
> > problem with memory leak somewhere around DWARF debug support.
> > In fact customer is unable to build with -g at all - simply running
> > out of memory on their project...
> >
> >   I seem to remember that there has been a major fix related to it,
> > but finding it hard to pinpoint. So the appeal to the communal memory
> > - do you remember if  there was a single fix (since the middle of 2012
> > or so) that would have addressed such issue?
> >
> >   I know the code was drastically change since - I have seen this for
> > instance
> > llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/ELFObjectWriter.cpp?vie
> > w=log&
> > pathrev=205990
> >
> > ...but not sure this is what I am looking for, and whether there is
> > something less drastic than I can do to plug that leak.
> >
> > Any clue would be very much appreciated.
> >
> > Thanks.
> >
> > Sergei
> >
> > ---
> > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> > hosted by The Linux Foundation
> >