http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60418
--- Comment #28 from rguenther at suse dot de <rguenther at suse dot de> --- On Tue, 11 Mar 2014, hjl.tools at gmail dot com wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60418 > > --- Comment #26 from H.J. Lu <hjl.tools at gmail dot com> --- > This patch avoids removing preheader when optimizing since > preheader will be added back later even if it is removed: > > diff --git a/gcc/tree-cfgcleanup.c b/gcc/tree-cfgcleanup.c > index 926d300..af5b24b 100644 > --- a/gcc/tree-cfgcleanup.c > +++ b/gcc/tree-cfgcleanup.c > @@ -328,7 +328,10 @@ tree_forwarder_block_p (basic_block bb, bool phi_wanted) > (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)); > } > else if (bb->loop_father == loop_outer (dest->loop_father)) > - return !loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS); > + /* Preserve preheader when optimizing since it will be added > + back later. */ > + return !(optimize > + || loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)); > /* Always preserve other edges into loop headers that are > not simple latches or preheaders. */ > return false; HJ, these patches don't make sense - this patch will regress the testcase the code above was introduced for.