Unfortunately, adding those flags alone isn't enough to get Crypto++ to use
the AES-NI intrinsics when Clang is used as the compiler. Mainly, the macro
checking for (CRYPTOPP_GCC_VERSION >= 40400 || _MSC_FULL_VER >= 150030729
|| __INTEL_COMPILER >= 1110) fails, so
CRYPTOPP_BOOL_AESNI_INTRINSICS_AVAILABLE fails to get activated. Hacking
around that is easy enough, but compilation ends up dieing a terrible death
like what I'm including at the end of this email. Thus, I think I give up
on clang++ for this library.
Regards,
Gabe
clang++ -DNDEBUG -O2 -gdwarf-2 -maes -mpclmul -pipe -c camellia.cpp
In file included from camellia.cpp:16:
./cpu.h:33:64: warning: unknown attribute '__artificial__' ignored
[-Wunknown-attributes]
__inline int __attribute__((__gnu_inline__, __always_inline__,
__artificial__))
^
./cpu.h:40:68: warning: unknown attribute '__artificial__' ignored
[-Wunknown-attributes]
__inline __m128i __attribute__((__gnu_inline__, __always_inline__,
__artificial__))
^
./cpu.h:37:7: error: invalid operand for inline asm constraint 'i'
asm ("pextrd %2, %1, %0" : "=rm"(r) : "x"(a), "i"(i));
^
./cpu.h:43:7: error: invalid operand for inline asm constraint 'i'
asm ("pinsrd %2, %1, %0" : "+x"(a) : "rm"(b), "i"(i));
^
Stack dump:
0. Program arguments:
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang
-cc1 -triple x86_64-apple-macosx10.10.0 -emit-obj -disable-free
-disable-llvm-verifier -main-file-name camellia.cpp -mrelocation-model pic
-pic-level 2 -mdisable-fp-elim -masm-verbose -munwind-tables -target-cpu
core2 -target-feature +aes -target-feature +pclmul -target-linker-version
242 -gdwarf-2 -dwarf-column-info -coverage-file
/Users/ghackebeil/Courses/AppliedCrypto_CS519_W2015/DynamicSearchableEncryption/DSE_cpp/Thirdparty/cryptopp562/camellia.o
-resource-dir
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/clang/6.1.0
-D NDEBUG -stdlib=libc++ -O2 -fdeprecated-macro -fdebug-compilation-dir
/Users/ghackebeil/Courses/AppliedCrypto_CS519_W2015/DynamicSearchableEncryption/DSE_cpp/Thirdparty/cryptopp562
-ferror-limit 19 -fmessage-length 130 -stack-protector 1 -mstackrealign
-fblocks -fobjc-runtime=macosx-10.10.0 -fencode-extended-block-signature
-fcxx-exceptions -fexceptions -fmax-type-align=16 -fdiagnostics-show-option
-fcolor-diagnostics -vectorize-loops -vectorize-slp -o camellia.o -x c++
camellia.cpp
1. <eof> parser at end of file
2. Code generation
3. Running pass 'Function Pass Manager' on module 'camellia.cpp'.
4. Running pass 'Simple Register Coalescing' on function
'@_Z16_mm_insert_epi32Dv2_xii'
clang: error: unable to execute command: Segmentation fault: 11
clang: error: clang frontend command failed due to signal (use -v to see
invocation)
Apple LLVM version 6.1.0 (clang-602.0.49) (based on LLVM 3.6.0svn)
Target: x86_64-apple-darwin14.3.0
Thread model: posix
clang: note: diagnostic msg: PLEASE submit a bug report to
http://developer.apple.com/bugreporter/ and include the crash backtrace,
preprocessed source, and associated run script.
clang: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang: note: diagnostic msg:
/var/folders/p5/4dj9d59x27v7_5_ddgn8r8zm0000gn/T/camellia-031900.cpp
clang: note: diagnostic msg:
/var/folders/p5/4dj9d59x27v7_5_ddgn8r8zm0000gn/T/camellia-031900.sh
clang: note: diagnostic msg:
********************
make: *** [camellia.o] Error 254
On Friday, April 24, 2015 at 7:09:46 AM UTC-7, Mouse wrote:
>
> You need to explicitly specify "-maes -mpclmul" for clang to use AES-NI
> and PCLMUL instructions.
>
> Sent from my iPad
>
> On Apr 24, 2015, at 01:00, Gabriel Hackebeil <[email protected]
> <javascript:>> wrote:
>
> My apologies. I was incorrect in assuming only the Intel compiler was
> using the AES-NI intrinsics. I ran some code profiling on OS X and it
> showed that both the GNU and the Intel compilers were calling the AES-NI
> subroutines (Clang was the only compiler that failed to do so).
>
> So to slightly rephrase my question... What could be going on that's
> causing GNU to outperform Intel so dramatically (any optimization flags to
> consider)? Also, has anyone else encountered such an unbalanced performance
> outcome between two compilers on the same machine (both utilizing AES-NI)?
>
> Regards,
> Gabe
>
> On Thursday, April 23, 2015 at 7:14:01 PM UTC-7, Gabriel Hackebeil wrote:
>>
>> I've run the benchmark tests after compiling Crypto++ 5.6.2 with the
>> latest versions of the Intel compilers (icpc 15.0.2), GNU g++ (4.9 and
>> 5.1), and Clang (Apple LLVM version 6.1.0). I'm basically interested in
>> getting the best possible performance for AES in CTR mode, and the results
>> of the benchmarks were surprising. In my limited understanding, use of the
>> AES-NI instruction set (which I believe only the Intel compiler can
>> utilize) is supposed to provide a big performance boost for AES. The
>> results do not show this. For the AES mode of interest (CTR), the
>> throughput I achieve (as reported by the benchmark test suite) is roughly:
>>
>> Clang: ~1 GiB/second
>> Intel: ~1.7 GiB/second
>> GNU: ~4.1 GiB/second
>>
>> Can someone explain why GNU has such a huge boost in performance (~2.5x)
>> over Intel, when GNU can not use the AES-NI instructions (I don't care much
>> about Clang)? I get the same results comparing Intel and GNU on a Linux VM.
>> Let me know if you need any relevant machine specs (Intel core i7 cpu). The
>> relevant compiler flags appearing on Linux vs OS X are shown below (the
>> performance results are the same on either operation system and I've played
>> with various optimization flags for each without much change in
>> performance). Can anyone enlighten me about the lack of performance boost
>> from AES-NI?
>>
>> *On Linux VM:*
>> GNU:
>> $ make CXX=g++
>> $ g++ -DNDEBUG -g -O2 -march=native -pipe -c ...
>>
>> Intel:
>> $ make CXX=icpc
>> $ icpc -DNDEBUG -g -O2 -wd68 -wd186 -wd279 -wd327 -pipe ...
>>
>> *On OS X:*
>> GNU: (the "-Wa,-q" is to get around assembler errors)
>> $ make CXX="g++-5.1 -Wa,-q"
>> $ g++-5.1 -Wa,-q -DNDEBUG -g -O2 -arch x86_64 -DCRYPTOPP_DISABLE_ASM
>> -pipe ...
>>
>> Intel:
>> $ make CXX=icpc
>> $ icpc -DNDEBUG -g -O2 -wd68 -wd186 -wd279 -wd327 -DCRYPTOPP_DISABLE_ASM
>> -c ...
>>
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