We only need to base it on the compiler in config.h. config.h activates the code path guarded by HasNEON(). The source file that actially provides the NEON implementation will be compiled with -fpu=neon or -march=armv8-a.
Since we are providing the specialized implementation in a sequestered source file (and not a header file), we can probably avoid the defines like CRYPTOPP_ARM_NEON_AVAILABLE altogether.
Make builds reproducible
See https://reproducible-builds.org/ for why this is good.
Without this patch g++ would order functions in libcryptopp.so.5.6.5
depending on random order of files in the build system's filesystem.
We have not been able to determine a reliable way to detect cpu's and platforms with Cmake. We are side stepping the Cmake problem by building rdrand.cpp all the time. If its not avilable for a cpu or platform, then RDRAND or RDSEED throw an exception.
They are giving ARIA and BLAKE2 trouble. It looks like SSE4 support appeared in the GCC compiler around 4.1 or 4.2. It looks like SHA support appeared in the GNU assembler around 2.18
regtest.cpp is where ciphers register by name. The library has added a number of ciphers over the last couple of years and the source file has experienced bloat. Most of the ARM and MIPS test borads were suffering Out of Memory (OOM) kills as the compiler processed the source fille and the included header files.
This won't stop the OOM kills, but it will help the situation. An early BeagleBoard with 512 MB of RAM is still going to have trouble, but it can be worked around by building with 1 make job as opposed to 2 or 4.
This check-in also enables the 64-bit RDRAND routines for X32. The changes were with held until they could be tested. The testing occurred with Issue 395
Wrap DetectArmFeatures and DetectX86Features in InitializeCpu class
Use init_priority for InitializeCpu
Remove HAVE_GCC_CONSTRUCTOR1 and HAVE_GCC_CONSTRUCTOR0
Use init_seg(<name>) on Windows and explicitly insert at XCU segment
Simplify logic for HAVE_GAS
Remove special recipies for MACPORTS_GCC_COMPILER
Move C++ static initializers into anonymous namespace when possible
Add default NullNameValuePairs ctor for Clang
Port rdrand.S to Cygwin and OS X
Add DISABLE_NATIVE_ARCH to CmakefileList and GNUmakefile. It supresses the addition of -march=native. DISABLE_NATIVE_ARCH replaces DISABLE_CXXFLAGS_OPTIMIZATIONS in CmakefileList (the latter is now deprecated).
Jeffrey Walton
Bernhard M. Wiedemann