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Re: [PR debug/46258] tree cfgcleanup BB marking vs debug stmts
- From: Richard Guenther <richard dot guenther at gmail dot com>
- To: Alexandre Oliva <aoliva at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Wed, 24 Nov 2010 12:50:36 +0100
- Subject: Re: [PR debug/46258] tree cfgcleanup BB marking vs debug stmts
- References: <firstname.lastname@example.org>
On Wed, Nov 24, 2010 at 2:24 AM, Alexandre Oliva <email@example.com> wrote:
> When cleaning up the tree^Wtuples CFG, we will sometimes replace uses of
> SSA names with other values.
> Problem is, if the only tuples modified in a dominated block are debug
> stmts, there may be divergence between -g and -g0 compilations, as there
> was with the given testcase in the PR (from the GCC testsuite, so not
> included in the patch): a block visited containing a modified debug stmt
> was successfully simplified in the cfgcleanup loop that visits only
> blocks marked before.
> I suppose this may be exposing a weakness in our block marking strategy,
> for the block could have been cleaned up in both cases, and after this
> change, it isn't before a subsequence full cfgcleanup run. ?However, in
> this patch, I'm only addressing the -g/-g0 divergence.
> Regstrapped on x86_64-linux-gnu and i686-pc-linux-gnu. ?Ok to install?
> 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