| Message ID | orsjyrqzry.fsf@livre.localdomain |
|---|---|
| State | New |
| Headers | show |
On Wed, Nov 24, 2010 at 2:24 AM, Alexandre Oliva <aoliva@redhat.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? Ok. Thanks, Richard. > > > -- > 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 > >
for gcc/ChangeLog from Alexandre Oliva <aoliva@redhat.com> PR debug/46258 * tree-cfg.c (replace_uses_by): Don't mark BBs as altered on debug stmts. Index: gcc/tree-cfg.c =================================================================== --- gcc/tree-cfg.c.orig 2010-11-18 10:37:23.716685868 -0200 +++ gcc/tree-cfg.c 2010-11-18 10:37:31.701412567 -0200 @@ -1570,7 +1570,7 @@ replace_uses_by (tree name, tree val) size_t i; fold_stmt_inplace (stmt); - if (cfgcleanup_altered_bbs) + if (cfgcleanup_altered_bbs && !is_gimple_debug (stmt)) bitmap_set_bit (cfgcleanup_altered_bbs, gimple_bb (stmt)->index); /* FIXME. This should go in update_stmt. */