Gcc profile questions

[Qing Zhao]

Hi,

Suppose we have a program called foo which is built with gcc -fprofile-generate,  Now when foo is executed a bunch of .gcda files are created.  

What happens when foo is executed more than once.  Are the .gcda files updated with each execution?  Or are the .gcda files overwritten with new .gcda files (and thus contain profile info only for the last execution)?

Thanks for the info.

Qing