Easiest way to collect dynamic Instruction execution counts?

Question

I'd like a simple and fast way to collect the number of times each Instruction in LLVM bitcode was executed in a given run of the application. As far as I can tell, there are a number of approaches I can take:

• Use PIN. This would require using DWARF debug info and Instruction debug info to attempt to map instructions in the binary to instructions in the bitcode; not 100% sure how accurate this will be.

• Use llvm-prof. Two questions here. First, I've seen on Stack Overflow an option to opt called --insert-edge-profiling. However, that option doesn't seem to be available in 3.6? Second, it appears that such profiling only records execution counts at the Function level, not at the individual Instruction level. Is that correct?

• Write a new tool similar to AddressSanitizer. This may work, but seems like overkill.

Is there an easier way to achieve my goal that I'm missing?

Answer 1

As part of my PhD research, I have written a tool to collect a trace of the basic blocks executed by a program. This tool also records the number of LLVM instructions in each basic block, so an analysis of the trace would give the dynamic Instruction execution count.

Another research tool is Harmony. It will provide the dynamic execution counts of each basic block in the program, which you could extend with the static instruction counts.

Otherwise, I would suggest writing your own tool. For each basic block, (atomically) increment a global counter by the number of instructions in that block.