Performance Comparison - gcc and llvm-gcc

Question

I compared gcc and llvm-gcc with the -O3 option on hmmer and mcf in the spec cpu2006 test. Surprisingly, I found gcc beat llvm-gcc for both cases. Is this because -O3 has different meanings? How do I set up experiments to get a fair comparison?

By the way, I did an experiment ONLY modifying cc in the makefile.

Thanks Bo

Answer 1

You seem surprised that gcc beat llvm is in your testing. Phoronix has many interesting tests in this area. For example, see:

• Benchmarking LLVM and Clang Against GCC 4.5 .
• Compiler Benchmarks GCC, LLVM-GCC, DragonEgg, Clang

(Lots of vibrant colors.)

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