On Tue, 18 Jan 2022, Jan Hubicka wrote:
> > The following change avoids doing IPA inlining of small functions
> > into functions compiled with -Og - those functions will see almost no
> > followup scalar cleanups so that the benefit anticipated by the
> > inliner will not be realized and instead the late diagnostic code
> > will be confused by dead code that is left around.
> >
> > Bootstrap & regtest pending on x86_64-unknown-linux-gnu.
> >
> > OK?
> OK. Do we also want to disable inlining when callee is -Og and caller
> is not?
I thought about that but decided to not do that - the issue here
is really that -Og doesn't run post-IPA optimizations so if we
inline a -Og early optimized function into a -O2 optimized function
at IPA time that issue doesn't apply.
So if then we should do that separately and with another motivating
testcase.
Thanks,
Richard.
>
> Honza
> >
> > Thanks,
> > Richard.
> >
> > 2022-01-18 Richard Biener <rguent...@suse.de>
> >
> > PR ipa/103989
> > * ipa-inline.cc (inline_small_functions): Do not enqueue call
> > edges originating in functions compiled with -Og.
> >
> > * g++.dg/opt/pr103989.C: New testcase.
> > ---
> > gcc/ipa-inline.cc | 7 ++++++-
> > gcc/testsuite/g++.dg/opt/pr103989.C | 30 +++++++++++++++++++++++++++++
> > 2 files changed, 36 insertions(+), 1 deletion(-)
> > create mode 100644 gcc/testsuite/g++.dg/opt/pr103989.C
> >
> > diff --git a/gcc/ipa-inline.cc b/gcc/ipa-inline.cc
> > index 38522771118..f8bb072c422 100644
> > --- a/gcc/ipa-inline.cc
> > +++ b/gcc/ipa-inline.cc
> > @@ -2029,7 +2029,12 @@ inline_small_functions (void)
> > struct cgraph_edge *next = NULL;
> > bool has_speculative = false;
> >
> > - if (!opt_for_fn (node->decl, optimize))
> > + if (!opt_for_fn (node->decl, optimize)
> > + /* With -Og we do not want to perform IPA inlining of small
> > + functions since there are no scalar cleanups after it
> > + that would realize the anticipated win. All abstraction
> > + is removed during early inlining. */
> > + || opt_for_fn (node->decl, optimize_debug))
> > continue;
> >
> > if (dump_file)
> > diff --git a/gcc/testsuite/g++.dg/opt/pr103989.C
> > b/gcc/testsuite/g++.dg/opt/pr103989.C
> > new file mode 100644
> > index 00000000000..4604811b42a
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/opt/pr103989.C
> > @@ -0,0 +1,30 @@
> > +// { dg-require-effective-target c++17 }
> > +// { dg-options "-Og -Wall" }
> > +
> > +#include <optional>
> > +#include <memory>
> > +
> > +struct A {
> > + A (int a) : a {a}
> > + {}
> > +
> > + const std::shared_ptr <int> x;
> > + int a;
> > +};
> > +
> > +class B
> > +{
> > +public:
> > + B (const std::optional <A>& a)
> > + : a {a}
> > + {
> > + }
> > +public:
> > + const std::optional <A> a;
> > +};
> > +
> > +int
> > +main ()
> > +{
> > + B b {std::nullopt};
> > +}
> > --
> > 2.31.1
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Ivo Totev; HRB 36809 (AG Nuernberg)
