[2.3 BRANCH]: gstabs issue

[Andrew Hughes]

> > > ----- Original Message -----
> > >> On 08/06/2012 05:16 PM, Andrew Hughes wrote:
> > >>> ----- Original Message -----
> > >>>> On 08/06/2012 02:42 PM, Andrew Hughes wrote:
> > >>>>> There was a regression with DEBUG_BINARIES which resulted in
> > >>>>> some
> > >>>>> architectures
> > >>>>> (x86, SPARC, etc.) producing STABS debug information rather
> > >>>>> than
> > >>>>> DWARF.
> > >>>>>
> > >>>>> The fix for this is now in OpenJDK8 and IcedTea7 HEAD:
> > >>>>>
> > >>>>> http://hg.openjdk.java.net/icedtea/jdk7/hotspot/rev/c5430c659d54
> > >>>>>
> > >>>>> Ok to backport this to the 2.3 forest?
> > >>>>
> > >>>> It's very hard to understand what is supposed to be happening.
> > >>>>  I
> > >>>> think it means that ia64, amd64, arm, ppc get DWARF debug
> > >>>> info,
> > >>>> but
> > >>>> x86/32 and others get STABS.  But this makes no sense at all:
> > >>>> STABS
> > >>>> is not appropriate for x86/32 or any other Linux target
> > >>>> AFAIAA.
> > >>>
> > >>> No, that's what's happening now without this patch.  This patch
> > >>> corrects the behaviour so that DEBUG_BINARIES again takes
> > >>> precedence
> > >>> and applies "-g" in all cases (no "-gstabs") whatever the
> > >>> architecture or build type (fastdebug/debug/product).  It's
> > >>> hard
> > >>> to
> > >>> see because the patch is moving the previous lines inside an
> > >>> else
> > >>> block, which is only evaluated if DEBUG_BINARIES is not equal
> > >>> to
> > >>> true.
> > >>
> > >> OK, so it's still wrong if DEBUG_BINARIES is off, but it's only
> > >> wrong
> > >> on hosts other than ia64, amd64, arm and ppc.
> > > 
> > > "Wrong" for us yes.
> > 
> > Well, it results in a grossly degraded debug experience for
> > everyone.
> > I suspect that internally the HotSpot team do almost all of their
> > debugging in debug builds anyway.
> 
Maybe, but all of them use stabs on x86.  My reading of that thread
is that Coleen would like to see the back of them too, but Daniel won't
unless there's enough payoff vs. the size increase:

http://mail.openjdk.java.net/pipermail/hotspot-dev/2012-July/006253.html

There's at least now a bug:

http://mail.openjdk.java.net/pipermail/hotspot-dev/2012-July/006257.html

FYI, the original review of this particular patch is here:
 
http://mail.openjdk.java.net/pipermail/hotspot-runtime-dev/2012-August/004184.html

> 
> > 
> > > It's what Oracle intended and still do for the time being.
> > 
> > > But we need what is a regression for us fixed ASAP, hence this
> > > interim patch,
> > > rather than waiting for Oracle to make their minds up, especially
> > > if they
> > > decide to stick with STABS for whatever reason.
> > 
> > OK, true enough, but we need to make sure that this never affects
> > us
> > again.

I suggest checking builds for the presence of debuginfo in the correct format.
There are probably other useful checks that could be added too.

> > 
> > Andrew.
> > 
> > 
> > 
> 
> --
> Andrew :)
> 
> Free Java Software Engineer
> Red Hat, Inc. (http://www.redhat.com)
> 
> PGP Key: 248BDC07 (https://keys.indymedia.org/)
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> 
> 

-- 
Andrew :)

Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

PGP Key: 248BDC07 (https://keys.indymedia.org/)
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