On Tue, 16 Aug 2016, Jakub Jelinek wrote:
> Hi!
>
> The FRE devirtualization unlike gimple-fold or other places would transform
> some method call with TREE_ADDRESSABLE lhs into __builtin_unreachable call
> with the same lhs, which is invalid (__builtin_unreachable returns void).
> Also, gimple_call_fntype has not been adjusted in these cases.
>
> Fixed thusly, bootstrapped/regtested on x86_64-linux and i686-linux, ok for
> trunk? What about 6.x? Do you prefer it in 6.2, or 6.3?
I think the patch can be simplified to just set fntype - PRE/FRE already
arrange to fixup stmts, including calling fixup_noreturn_call which
removes the lhs if required.
Richard.
> 2016-08-16 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/77259
> * tree-ssa-pre.c (eliminate_dom_walker::before_dom_children): If
> turning a call into __builtin_unreachable-like noreturn call, adjust
> gimple_call_set_fntype and remove lhs if needed.
>
> * g++.dg/ipa/devirt-52.C: New test.
>
> --- gcc/tree-ssa-pre.c.jj 2016-08-12 17:33:46.000000000 +0200
> +++ gcc/tree-ssa-pre.c 2016-08-16 11:24:53.605976981 +0200
> @@ -4543,6 +4543,32 @@ eliminate_dom_walker::before_dom_childre
> lang_hooks.decl_printable_name (fn, 2));
> }
> gimple_call_set_fndecl (call_stmt, fn);
> + /* If changing the call to __builtin_unreachable
> + or similar noreturn function, adjust gimple_call_fntype
> + too. */
> + if ((gimple_call_flags (call_stmt) & ECF_NORETURN)
> + && VOID_TYPE_P (TREE_TYPE (TREE_TYPE (fn)))
> + && TYPE_ARG_TYPES (TREE_TYPE (fn))
> + && (TREE_VALUE (TYPE_ARG_TYPES (TREE_TYPE (fn)))
> + == void_type_node))
> + gimple_call_set_fntype (call_stmt, TREE_TYPE (fn));
> + tree lhs = gimple_call_lhs (call_stmt);
> + /* If the call becomes noreturn, remove the lhs. */
> + if (lhs
> + && gimple_call_noreturn_p (call_stmt)
> + && (VOID_TYPE_P (TREE_TYPE (gimple_call_fntype
> + (call_stmt)))
> + || should_remove_lhs_p (lhs)))
> + {
> + if (TREE_CODE (lhs) == SSA_NAME)
> + {
> + tree var = create_tmp_var (TREE_TYPE (lhs));
> + tree def = get_or_create_ssa_default_def (cfun, var);
> + gimple *new_stmt = gimple_build_assign (lhs, def);
> + gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
> + }
> + gimple_call_set_lhs (call_stmt, NULL_TREE);
> + }
> maybe_remove_unused_call_args (cfun, call_stmt);
> gimple_set_modified (stmt, true);
> }
> --- gcc/testsuite/g++.dg/ipa/devirt-52.C.jj 2016-08-16 11:08:49.943108247
> +0200
> +++ gcc/testsuite/g++.dg/ipa/devirt-52.C 2016-08-16 11:32:25.295300721
> +0200
> @@ -0,0 +1,56 @@
> +// PR middle-end/77259
> +// { dg-do compile { target c++11 } }
> +// { dg-options "-O2" }
> +
> +template <typename, typename = int> class A;
> +template <typename, typename> struct A
> +{
> + A (A &&);
> +};
> +template <typename S, typename T, typename U>
> +A<S> operator+(S *, const A<T, U> &);
> +template <typename S, typename T, typename U>
> +void operator+(const A<T, U> &, S *);
> +struct B
> +{
> + template <typename V> B (V);
> +};
> +template <typename V> V foo (B) {}
> +class C;
> +template <typename> struct D
> +{
> + C *operator->() { return d; }
> + C *d;
> +};
> +struct C
> +{
> + virtual A<int> bar ();
> +};
> +struct E
> +{
> + ~E ();
> + virtual A<char> bar (const B &) const;
> +};
> +template <typename> struct F : E
> +{
> +};
> +template <typename W> struct F<D<W>> : E
> +{
> + A<char> bar (const B &) const try
> + {
> + D<W> a = baz ();
> + }
> + catch (int)
> + {
> + }
> + D<W> baz () const
> + {
> + D<C> b = foo<D<C>>(0);
> + "" + b->bar () + "";
> + }
> +};
> +struct G : F<D<int>>
> +{
> + G (int);
> +};
> +void test () { G (0); }
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
