profile guided optimizations


I have one question on LLVM 3.3 profile guided optimizations.

I see in the utils/ there are supports for “-insert-block-profiling”, “-insert-edge-profiling” and “-insert-function-profiling”, but it seems only -insert-edge-profiling is working and the other 2 gets suggested to “-insert-gcov-profiling”. and llvm_start_basic_block_tracing does not seem to be called anywhere in the LLVM src code.

Thank you,