https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103984
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
What the C++ FE emits looks just weird to me. In the gimple dump:
[pr103984.C:35:1] D.31524.name = string_piece::str
([pr103984.C:35:1] &arg); [return slot optimization]
[pr103984.C:35:1] D.31544 = 1;
[pr103984.C:29:27] try
{
[pr103984.C:31:15] string_piece::string_piece
([pr103984.C:31:15] &D.31523, [pr103984.C:31:16] &arg);
try
{
[pr103984.C:31:15] _2 = to_stage ([pr103984.C:31:15]
&D.31523);
[pr103984.C:35:1] D.31524.stage = _2;
[pr103984.C:35:1] D.31544 = 0;
try
{
try
{
[pr103984.C:29:27]
std::vector<Z>::emplace_back<Z> ([pr103984.C:29:27] &input_files,
[pr103984.C:29:28] &D.31524);
}
finally
{
[pr103984.C:29:28] Z::~Z ([pr103984.C:29:28]
&D.31524);
}
}
finally
{
[pr103984.C:29:28] D.31524 = {CLOBBER(eol)};
}
}
finally
{
[pr103984.C:31:15] D.31523 = {CLOBBER(eol)};
}
}
catch
{
[pr103984.C:35:1] if (D.31544 != 0) goto <D.35853>; else
goto <D.35854>;
<D.35853>:
[pr103984.C:35:1]
std::__cxx11::basic_string<char>::~basic_string ([pr103984.C:35:1]
&D.31524.name);
goto <D.35855>;
<D.35854>:
<D.35855>:
}
Note the D.31524 CLOBBER being added only conditionally (if string_piece ctor
doesn't throw), while if it throws, there is a dtor on its element after that
and
no CLOBBER. The first spot that initializes part of the D.31524 temporary is
the above first line, so it would make more sense to me to wrap this whole
sequence above into try { ... } finally { [pr103984.C:29:28] D.31524 =
{CLOBBER(eol)}; } and remove the inner try finally that does that.
