[Bug tree-optimization/109945] Escape analysis hates copy elision: different result with -O1 vs -O2

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109945

--- Comment #19 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #13)
> (In reply to Richard Biener from comment #12)
> > For the fun of it I'm testing
> > 
> > diff --git a/gcc/tree-ssa-structalias.cc b/gcc/tree-ssa-structalias.cc
> > index 56021c59cb9..1e7f0383371 100644
> > --- a/gcc/tree-ssa-structalias.cc
> > +++ b/gcc/tree-ssa-structalias.cc
> > @@ -4366,7 +4366,7 @@ handle_rhs_call (gcall *stmt, vec<ce_s> *results,
> >    /* And if we applied NRV the address of the return slot escapes as well. 
> > */
> >    if (gimple_call_return_slot_opt_p (stmt)
> >        && gimple_call_lhs (stmt) != NULL_TREE
> > -      && TREE_ADDRESSABLE (TREE_TYPE (gimple_call_lhs (stmt))))
> > +      && aggregate_value_p (gimple_call_lhs (stmt), gimple_call_fntype
> > (stmt)))
> >      {
> >        int flags = gimple_call_retslot_flags (stmt);
> >        const int relevant_flags = EAF_NO_DIRECT_ESCAPE
> 
> FAIL: g++.dg/opt/pr91838.C  -std=c++14  scan-assembler
> pxor\\\\s+%xmm0,\\\\s+%xmm0

The above is present even without the patch so it's only the tailcall
testcase that's fallout.

> FAIL: gcc.dg/tree-ssa/tailcall-7.c scan-tree-dump-times tailc "Found tail
> call" 5
> 
> with the former for -m64 and the latter for -m32 only seems to be the
> only fallout here.