Crash in DL_GroupParameters_IntegerBased::GetEncodedElementSize for Cygwin i386 at -O3

[noloader]

Here are the symptoms:

$ make
g++ -DNDEBUG -g2 -O3 -march=native -DCRYPTOPP_NO_UNALIGNED_DATA_ACCESS -pipe -c cryptlib.cpp
g++ -DNDEBUG -g2 -O3 -march=native -DCRYPTOPP_NO_UNALIGNED_DATA_ACCESS -pipe -c shacal2.cpp
...

$ ./cryptest.exe v
...

MQV validation suite running...

passed    authenticated key agreement domain parameters validation
...

$ gdb ./cryptest.exe
...
Program received signal SIGSEGV, Segmentation fault.
CryptoPP::DL_GroupParameters_IntegerBased::GetEncodedElementSize (this=0x11,
    reversible=0x1) at gfpcrypt.h:65
65        {CRYPTOPP_UNUSED(reversible); return GetModulus().ByteCount();}
(gdb)

Here is the platform and compiler version:

$ g++ --version
g++ (GCC) 4.9.3
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ uname -a
CYGWIN_NT-6.1-WOW windows-7-x64 2.2.1(0.289/5/3) 2015-08-20 11:40 i686 Cygwin

The issue is present with -DCRYPTOPP_DISABLE_ASM.

Despite best efforts, its still unclear why this pointer is 0x11.

[noloader]

The work around was to move the definition for DL_GroupParameters_IntegerBased::GetEncodedElementSize out-of-line. That is, move the implementation to the CPP file.

Its unclear why this worked...