LTO support

[raybellis]

The code crashes on start up with LTO enabled (-flto in CXXFLAGS) as the list of parsers is being constructed. The reason is unknown:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7ccd4ae in std::local_Rb_tree_decrement (__x=0x55555557f708 <StringsetParser::parsers[abi:cxx11]+8>)
    at ../../../../../libstdc++-v3/src/c++98/tree.cc:98
Downloading source file /usr/src/debug/gcc-13.2.1-4.fc38.x86_64/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/src/c++98/../../../../../libstdc++-v3/src/c++98/tree.cc
98              && __x->_M_parent->_M_parent == __x)                                                                  
(gdb) bt
#0  0x00007ffff7ccd4ae in std::local_Rb_tree_decrement (__x=0x55555557f708 <StringsetParser::parsers[abi:cxx11]+8>)
    at ../../../../../libstdc++-v3/src/c++98/tree.cc:98
#1  std::_Rb_tree_decrement (__x=__x@entry=0x55555557f708 <StringsetParser::parsers[abi:cxx11]+8>)
    at ../../../../../libstdc++-v3/src/c++98/tree.cc:123
#2  0x000055555555fcb0 in std::_Rb_tree_iterator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> >::operator-- (this=<synthetic pointer>)
    at /usr/include/c++/13/bits/stl_tree.h:302
#3  std::_Rb_tree<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*>, std::_Select1st<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> > >::_M_get_insert_unique_pos(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) [clone .constprop.0] (__k="fsl_dpaa2_eth", this=<optimized out>) at /usr/include/c++/13/bits/stl_tree.h:2127
#4  0x000055555555ef96 in std::_Rb_tree<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*>, std::_Select1st<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> > >::_M_get_insert_hint_unique_pos (this=0x55555557f700 <StringsetParser::parsers[abi:cxx11]>, 
    __k="fsl_dpaa2_eth", __position=...) at /usr/include/c++/13/bits/stl_tree.h:2256
#5  std::_Rb_tree<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*>, std::_Select1st<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> >, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> > >::_M_emplace_hint_unique<std::piecewise_construct_t const&, std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&>, std::tuple<> >(std::_Rb_tree_const_iterator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> >, std::piecewise_construct_t const&, std::tuple<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&>&&, std::tuple<>&&) (
    this=0x55555557f700 <StringsetParser::parsers[abi:cxx11]>, __pos=...) at /usr/include/c++/13/bits/stl_tree.h:2463
#6  std::map<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, StringsetParser*, std::less<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::pair<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, StringsetParser*> > >::operator[] (
    this=0x55555557f700 <StringsetParser::parsers[abi:cxx11]>, __k=...) at /usr/include/c++/13/bits/stl_map.h:513
#7  StringsetParser::save (name=..., this=<optimized out>) at /home/pemensik/upstream/ethq/ethq-0_6_3/parser.cc:29
#8  StringsetParser::save (this=this@entry=0x55555557f800 <nxp_daap2>, drivers=...)
    at /home/pemensik/upstream/ethq/ethq-0_6_3/parser.cc:24
#9  0x000055555555f1ce in StringsetParser::StringsetParser (drivers=..., this=<optimized out>)
    at /home/pemensik/upstream/ethq/ethq-0_6_3/parser.cc:19
#10 RegexParser::RegexParser (this=<optimized out>, drivers=..., total=..., queue=..., this=<optimized out>, 
    drivers=..., total=..., queue=...) at /home/pemensik/upstream/ethq/ethq-0_6_3/parser.cc:54
#11 0x000055555555ff12 in _sub_I_65535_0.0 ()
#12 0x00007ffff7a49cc4 in call_init (env=<optimized out>, argv=0x7fffffffddc8, argc=1) at ../csu/libc-start.c:145
#13 __libc_start_main_impl (main=0x55555555c4f0 <main(int, char**)>, argc=1, argv=0x7fffffffddc8, 
    init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffddb8)
    at ../csu/libc-start.c:347
#14 0x0000555555560de5 in _start ()

https://bugzilla.redhat.com/show_bug.cgi?id=2263560#c2

[pemensik]

It could be caused by multiple static constructors happening in undefined order. Something described on: https://isocpp.org/wiki/faq/ctors#static-init-order-on-first-use

That should be created by a function, which would first ensure static storage (parsermap_t) is initialized, before anyone else tries to insert items into it. I have tries few experiments, but that leads to non-functional ethq.

[pemensik]

Pushed my attempts to PR #31 draft. My attempt does not crash, but does not work anyway. I failed to spot why.

[raybellis]

potentially fixed by 313a343

[pemensik]

It does not seem to be changed, when I include also -flto=auto parameter. It is still broken even after this change.

[raybellis]

I can't replicate that here. Has the stack trace changed?

[pemensik]

no, it does not crash anymore, but does not parse the driver also. It fails to match_total for my driver. As soon as I remove -flto flag, the parsing works.

It ends now with:
error: couldn't parse NIC stats for e1000e:enp0s31f6

[pemensik]

It seems it fails on if (total.first.mark_count() == 0) return false; in RegexParser::match_total. Depending RegexParser static members does not yet seem to be constructed.

[pemensik]

Updated PR #31 with small change, after which it finally works even with LTO enabled.