Analyzing run-time behavior

Using fur to perform block profiling

fur is a tool that manipulates object files. It can:

rearrange functions,
rearrange the code within functions
insert code into functions.

fur can be used to do block and branch profiling. Programs can be broken into blocks, which are sets of statements that form a straight line (no ifs or loops). Block profiling records how many times each block is executed and how many times each block executed directly before it, allowing fur to surmise the flow of control through the program. This information is used in combination with flow profile information to tune programs for better cache utilization, better branch prediction, less jumping and less paging.

One can insert code of one's choosing into the code, but some useful code is provided. As was mentioned earlier, fur can insert code so that time profiling or flow profiling is done on the code. Here we discuss inserting code that performs block profiling.