-fprofile-arcs changes the structure of basic blocks

[Liu Haibin]

Hi,

I want to use profiling information. I know there're two relevent
fields in each basic block, count and frequency. I want to use
frequency because the compiled program is for another architecture so
it cannot run on the host.

I use -fprofile-arcs. And I can see the frequency value when I debug
cc1. But I happen to realize that when I add -fprofile-arcs, it change
the the whole structure of basic block. I compared the vcg output
files with and without the -fprofile-arcs. I found they're totally
different.

My question is why it is so? I want to know the profiling info, but if
profiling info I get is for another different structure of basic
block, it's useless to me.

Where do I go wrong here? Which option is the suitable in this case?
The gcc version is 3.3.3. Thanks.


Regards,
Timothy