https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65076
--- Comment #11 from Jan Hubicka <hubicka at gcc dot gnu.org> ---
Sorry, the number of clobbers drops at DSE1, not during ehcleanup2, I just
messed up my grep.
I tried the following patch:
Index: passes.def
===================================================================
--- passes.def (revision 221541)
+++ passes.def (working copy)
@@ -87,6 +87,7 @@ along with GCC; see the file COPYING3.
NEXT_PASS (pass_build_ealias);
NEXT_PASS (pass_fre);
NEXT_PASS (pass_merge_phi);
+ NEXT_PASS (pass_dse);
NEXT_PASS (pass_cd_dce);
NEXT_PASS (pass_early_ipa_sra);
NEXT_PASS (pass_tail_recursion);
This brings number of CLOBBER statements at release_ssa time down to 7392 (50%
reduction). A nice effect of this patch is that it tends to simplify
destructors often to empty to make them more inlinable:
ObserverEvent::~ObserverEvent() (struct ObserverEvent * const this)
{
<bb 2>:
- this_2(D)->_vptr.ObserverEvent = &MEM[(void *)&_ZTV13ObserverEvent + 16B];
MEM[(struct &)this_2(D)] ={v} {CLOBBER};
return;
saves a lot of the clobbers:
Engine<3, double, ExpressionTag<UnaryNode<FnNorm, BinaryNode<OpSubtract,
Reference<Field<NoMesh<3>, Vector<3, double, Full>, ViewEngine<3,
IndexFunction<GenericURM<MeshTraits<3, double, UniformRectilinearTag,
CartesianTag, 3> >::PositionsFunctor> > > >, Scalar<Vector<3, double, Full> > >
> > >::~Engine() (struct Engine * const this)
{
<bb 2>:
- MEM[(struct &)this_2(D) + 32] ={v} {CLOBBER};
- MEM[(struct &)this_2(D) + 32] ={v} {CLOBBER};
- MEM[(struct &)this_2(D) + 8] ={v} {CLOBBER};
- MEM[(struct &)this_2(D) + 8] ={v} {CLOBBER};
- MEM[(struct &)this_2(D) + 8] ={v} {CLOBBER};
- MEM[(struct &)this_2(D)] ={v} {CLOBBER};
- MEM[(struct &)this_2(D)] ={v} {CLOBBER};
- MEM[(struct &)this_2(D)] ={v} {CLOBBER};
+ MEM[(struct &)this_1(D)] ={v} {CLOBBER};
return;
which is especially nice for LTO streaming.
and saves about 7% of code apparently after inlining:
$ wc -l *copyprop2
200189 tramp3d-v4.ii.085t.copyprop2
$ wc -l ../5/*copyprop2
215060 ../5/tramp3d-v4.ii.084t.copyprop2
Even though the inline decisions does not seem to be changed considerably (at
least on tramp3d).
On unrelated note I noticed PR65502
Still I guess this does not really explain the origin of regression in
statement count relative to 4.9...
