> Hi,
>
> with -fno-toplevel-reorder (and -fwhole-program), there apparently can
> be local functions without any callers. This is something that IPA-CP
If there is possibility to trigger a local function without callers, I
think one can also make two local functions calling each other but with
no other callers.
So I think you need to wait until dataflow solution stabilizes and then
then find such isolated cases and do something sensible (as of not
crashing since the code is dead anyway).
-fno-toplevel-reorder was kind of meant to get close to what -fno-unit-at-a-time
did to make legacy code (kernel) happy. Without unit-at-a-time we did
not remove local functions unless we decided to inline them since they
were output before we had chance to realize that they were unused.
Since we document that only about static variables, perhaps we could
simply start removing functions to avoid these side cases?
Honza
> does not like because its propagation verifier checks that local
> functions do not end up with TOP in their lattices. Therefore there
> is an assert checking that all call-less unreachable functions have
> been removed, which triggers in PR 106260 with these two options.
>
> This patch detects the situation and marks the lattices as variable,
> thus avoiding both the assert trigger and the verification failure.
>
> Bootstrapped and tested on x86_64-linux. OK for master and then all
> active release branches?
>
> Thanks,
>
> Martin
>
>
> gcc/ChangeLog:
>
> 2022-07-13 Martin Jambor <mjam...@suse.cz>
>
> PR ipa/106260
> * ipa-cp.cc (initialize_node_lattices): Replace assert that there are
> callers with handling that situation when -fno-toplevel_reorder.
>
> gcc/testsuite/ChangeLog:
>
> 2022-07-13 Martin Jambor <mjam...@suse.cz>
>
> PR ipa/106260
> * g++.dg/ipa/pr106260.C: New test.
> ---
> gcc/ipa-cp.cc | 6 ++-
> gcc/testsuite/g++.dg/ipa/pr106260.C | 64 +++++++++++++++++++++++++++++
> 2 files changed, 69 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/g++.dg/ipa/pr106260.C
>
> diff --git a/gcc/ipa-cp.cc b/gcc/ipa-cp.cc
> index 543a9334e2c..f699a8dadc0 100644
> --- a/gcc/ipa-cp.cc
> +++ b/gcc/ipa-cp.cc
> @@ -1286,10 +1286,14 @@ initialize_node_lattices (struct cgraph_node *node)
> int caller_count = 0;
> node->call_for_symbol_thunks_and_aliases (count_callers, &caller_count,
> true);
> - gcc_checking_assert (caller_count > 0);
> if (caller_count == 1)
> node->call_for_symbol_thunks_and_aliases (set_single_call_flag,
> NULL, true);
> + else if (caller_count == 0)
> + {
> + gcc_checking_assert (!opt_for_fn (node->decl, flag_toplevel_reorder));
> + variable = true;
> + }
> }
> else
> {
> diff --git a/gcc/testsuite/g++.dg/ipa/pr106260.C
> b/gcc/testsuite/g++.dg/ipa/pr106260.C
> new file mode 100644
> index 00000000000..bd3b6e0af79
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/ipa/pr106260.C
> @@ -0,0 +1,64 @@
> +// { dg-do compile }
> +// { dg-options "-O2 -std=gnu++14 -fwhole-program -fno-unit-at-a-time" }
> +
> +struct A;
> +template <class T>
> +struct Q { Q (T); };
> +template<typename T, class D>
> +struct U {
> + ~U () { m1 (nullptr); }
> + D m2 ();
> + T *u;
> + void m1 (T *) { m2 () (u); }
> +};
> +struct F { F (int *); };
> +template <class, class T = F>
> +using W = Q<T>;
> +int a, b;
> +void fn1 (void *);
> +template <class T>
> +void
> +fn2 (T *x)
> +{
> + if (x)
> + x->~T();
> + fn1 (x);
> +}
> +template <typename T>
> +struct C {
> + void operator() (T *x) { fn2 (x); }
> +};
> +struct D;
> +template <typename T, typename D = C<T> >
> +using V = U<T, D>;
> +struct A {
> + A (int *);
> +};
> +struct S;
> +struct G {
> + V<S> m3 ();
> +};
> +struct S {
> + int e;
> + virtual ~S () {}
> +};
> +template<typename T>
> +struct H {
> + H (int, T x, int) : h(x) {}
> + G g;
> + void m4 () { g.m3 (); }
> + T h;
> +};
> +struct I {
> + I(A, W<D>);
> +};
> +void
> +test ()
> +{
> + A c (&b);
> + W<D> d (&b);
> + I e (c, d);
> + H<I> f (0, e, a);
> + f.m4 ();
> +}
> +
> --
> 2.36.1
>
