Hi Richard,
I almost forgot that the issue is also present on GCC 14. Can I backport to
releases/gcc-14 branch?
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
> >
