[cfe-dev] Using Clang -O4 with CMake

[Clark Gaebel]

I'm running...

clark at clark-laptop ~/dev/cpp/GoGo/build $ clang++ --version
clang version 1.5 (trunk 101682)
Target: x86_64-unknown-linux-gnu
Thread model: posix

On 06/18/10 23:07, Eric Christopher wrote:
> On Jun 18, 2010, at 8:01 PM, Clark Gaebel wrote:
>
>   
>> When trying out -O4 instead of my usual -O3 on my C++ code using CMake,
>> I got this error...
>>
>> Linking CXX executable test_memory
>> cd /home/clark/dev/cpp/GoGo/build/util/test && /usr/bin/cmake -E
>> cmake_link_script CMakeFiles/test_memory.dir/link.txt --verbose=1
>> /usr/local/bin/clang++     
>> CMakeFiles/test_memory.dir/test_memory.cpp.o  -o test_memory -rdynamic
>> -lboost_filesystem-mt-1_42 -lboost_iostreams-mt-1_42
>> -lboost_program_options-mt-1_42 -lboost_regex-mt-1_42
>> -lboost_serialization-mt-1_42 -lboost_signals-mt-1_42
>> -lboost_thread-mt-1_42 -lboost_wave-mt-1_42
>> CMakeFiles/test_memory.dir/test_memory.cpp.o: file not recognized: File
>> format not recognized
>> collect2: ld returned 1 exit status
>>
>> What am I doing wrong? This works fine on every other optimization
>> setting. Literally, the only thing I did differently was -O4 instead of -O3.
>>     
> O4 means use lto.  What platform are you on? Does it support llvm lto? :)
>
> And I have no idea if the cmake files are set up for that either.
>
> -eric

-- 
Regards,
-Clark