On Mon, 3 Mar 2025, Filip Kastl wrote:
> Hi Richard,
>
> I almost forgot that the issue is also present on GCC 14. Can I backport to
> releases/gcc-14 branch?
Sure.
> Thanks,
> Filip Kastl
>
> On Fri 2025-02-28 17:46:42, Richard Biener wrote:
> >
> >
> > > Am 28.02.2025 um 17:02 schrieb Filip Kastl <fka...@suse.cz>:
> > >
> > > Hi,
> > >
> > > bootstrapped and regtested on x86_64 linux. Ok to be pushed?
> >
> > Ok
> >
> > Richard
> >
> > > Thanks,
> > > Filip Kastl
> > >
> > >
> > > -- 8< --
> > >
> > >
> > > While writing the sccopy pass I didn't realize that 'replace_uses_by ()'
> > > can
> > > remove portions of the CFG. This happens when replacing arguments of some
> > > statement results in the removal of an EH edge. Because of this sccopy
> > > can
> > > then work with GIMPLE statements that aren't part of the IR anymore. In
> > > PR117919 this triggered an assertion within the pass which assumes that
> > > statements the pass works with are reachable.
> > >
> > > This patch tells the pass to notice when a statement isn't in the IR
> > > anymore
> > > and remove it from it's worklist.
> > >
> > > PR tree-optimization/117919
> > >
> > > gcc/ChangeLog:
> > >
> > > * gimple-ssa-sccopy.cc (scc_copy_prop::propagate): Prune
> > > statements that 'replace_uses_by ()' removed.
> > >
> > > gcc/testsuite/ChangeLog:
> > >
> > > * g++.dg/pr117919.C: New test.
> > >
> > > Signed-off-by: Filip Kastl <fka...@suse.cz>
> > > ---
> > > gcc/gimple-ssa-sccopy.cc | 13 +++++++++
> > > gcc/testsuite/g++.dg/pr117919.C | 52 +++++++++++++++++++++++++++++++++
> > > 2 files changed, 65 insertions(+)
> > > create mode 100644 gcc/testsuite/g++.dg/pr117919.C
> > >
> > > diff --git a/gcc/gimple-ssa-sccopy.cc b/gcc/gimple-ssa-sccopy.cc
> > > index 9f25fbaff36..7ffb5718ab6 100644
> > > --- a/gcc/gimple-ssa-sccopy.cc
> > > +++ b/gcc/gimple-ssa-sccopy.cc
> > > @@ -568,6 +568,19 @@ scc_copy_prop::propagate ()
> > > {
> > > vec<gimple *> scc = worklist.pop ();
> > >
> > > + /* When we do 'replace_scc_by_value' it may happen that some EH
> > > edges
> > > + get removed. That means parts of CFG get removed. Those may
> > > + contain copy statements. For that reason we prune SCCs here. */
> > > + unsigned i;
> > > + for (i = 0; i < scc.length (); i++)
> > > + if (gimple_bb (scc[i]) == NULL)
> > > + scc.unordered_remove (i);
> > > + if (scc.is_empty ())
> > > + {
> > > + scc.release ();
> > > + continue;
> > > + }
> > > +
> > > auto_vec<gimple *> inner;
> > > hash_set<tree> outer_ops;
> > > tree last_outer_op = NULL_TREE;
> > > diff --git a/gcc/testsuite/g++.dg/pr117919.C
> > > b/gcc/testsuite/g++.dg/pr117919.C
> > > new file mode 100644
> > > index 00000000000..fa2d9c9cd1e
> > > --- /dev/null
> > > +++ b/gcc/testsuite/g++.dg/pr117919.C
> > > @@ -0,0 +1,52 @@
> > > +/* PR tree-optimization/117919 */
> > > +/* { dg-do compile } */
> > > +/* { dg-options "-O1 -fno-tree-forwprop -fnon-call-exceptions
> > > --param=early-inlining-insns=192 -std=c++20" } */
> > > +
> > > +char _M_p, _M_construct___beg;
> > > +struct _Alloc_hider {
> > > + _Alloc_hider(char);
> > > +};
> > > +long _M_string_length;
> > > +void _M_destroy();
> > > +void _S_copy_chars(char *, char *, char *) noexcept;
> > > +char _M_local_data();
> > > +struct Trans_NS___cxx11_basic_string {
> > > + _Alloc_hider _M_dataplus;
> > > + bool _M_is_local() {
> > > + if (_M_local_data())
> > > + if (_M_string_length)
> > > + return true;
> > > + return false;
> > > + }
> > > + void _M_dispose() {
> > > + if (!_M_is_local())
> > > + _M_destroy();
> > > + }
> > > + char *_M_construct___end;
> > > + Trans_NS___cxx11_basic_string(Trans_NS___cxx11_basic_string &)
> > > + : _M_dataplus(0) {
> > > + struct _Guard {
> > > + ~_Guard() { _M_guarded->_M_dispose(); }
> > > + Trans_NS___cxx11_basic_string *_M_guarded;
> > > + } __guard0;
> > > + _S_copy_chars(&_M_p, &_M_construct___beg, _M_construct___end);
> > > + }
> > > +};
> > > +namespace filesystem {
> > > +struct path {
> > > + path();
> > > + Trans_NS___cxx11_basic_string _M_pathname;
> > > +};
> > > +} // namespace filesystem
> > > +struct FileWriter {
> > > + filesystem::path path;
> > > + FileWriter() : path(path) {}
> > > +};
> > > +struct LanguageFileWriter : FileWriter {
> > > + LanguageFileWriter(filesystem::path) {}
> > > +};
> > > +int
> > > +main() {
> > > + filesystem::path output_file;
> > > + LanguageFileWriter writer(output_file);
> > > +}
> > > --
> > > 2.47.1
> > >
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
