edg_decode and the prelinker do not decode IA-64 mangled names on Linux

[thinkoid]

Issue Summary

On Linux, edg_decode passes IA-64 mangled names through undecoded, and the prelinker warns "an error occurred during name decoding" on some of them. c++filt decodes the same names. The prelinker's messages then print mangled names. Building a library of about 100 objects with automatic instantiation, we saw the warning 22 times.

Observed Behavior

edg_decode leaves every name in this list unchanged, including names with no template or namespace:

$ printf '%s\n' _ZNSt15messages_bynameIcED1Ev _ZN4__rw1fEv _Z1fIiET_S0_ \
    _ZN4__rw12__rw_extractIcSt11char_traitsIcEtEERSt13basic_istreamIT_T0_ES7_RT1_ \
  | ./build/gcc-release/bin/edg_decode
_ZNSt15messages_bynameIcED1Ev
_ZN4__rw1fEv
_Z1fIiET_S0_
_ZN4__rw12__rw_extractIcSt11char_traitsIcEtEERSt13basic_istreamIT_T0_ES7_RT1_

c++filt gives:

std::messages_byname<char>::~messages_byname()
__rw::f()
int f<int>(int)
std::basic_istream<char, std::char_traits<char> >& __rw::__rw_extract<char, std::char_traits<char>, unsigned short>(std::basic_istream<char, std::char_traits<char> >&, unsigned short&)

The prelinker, with this source:

namespace __n { template <class T> T f (T t) { return t; } }
int main () { return __n::f (0); }

$ eccp -A -c t.cpp
$ eccp -A t.o -o t
C++ prelinker: warning: an error occurred during name decoding of "_ZN3__n1fIiEET_S1_"
C++ prelinker: _ZN3__n1fIiEET_S1_ assigned to file t.o
C++ prelinker: executing: <edgcpp>/util/eccp.sh -c -A t.cpp

The program links and runs. With the namespace named n there is no warning, but the assignment message still shows the mangled name, _ZN1n1fIiEET_S1_.

Seen at e24bb9a with linux-gcc-release, linux-gcc-debuggable-release and linux-gcc-debug. The two latter fail the final link on -lC in our builds, after the prelinker has run; the warning is the same.

Expected Behavior

edg_decode decodes these names as c++filt does. The prelinker decodes them without a warning and prints decoded names in its messages, as in the expected output quoted in #68.

Additional Details

The 22 names from the library build are all instances of one function template, __rw::__rw_extract<charT, Traits, T>, for char and wchar_t with eleven types T:

_ZN4__rw12__rw_extractIcSt11char_traitsIcEbEERSt13basic_istreamIT_T0_ES7_RT1_
_ZN4__rw12__rw_extractIcSt11char_traitsIcEPvEERSt13basic_istreamIT_T0_ES8_RT1_
_ZN4__rw12__rw_extractIwSt11char_traitsIwEtEERSt13basic_istreamIT_T0_ES7_RT1_
...

The test programs built against the library drew the same warning for 2,089 more distinct names.

I acknowledge that:

• I have checked open issues and existing discussions before filing this report.