I've been using perf probe with malloc, but can't seem to find a suitable perf event for when variable assignment happens. Is there such an event?
Ideally when something like int var = 17; occurs there is some corresponding event I'm missing? Outside of the instantiation of the variable, but the actual assignment of the value and on each successive change.
Yes this is possible with hardware breakpoint events. perf record supports this if you know the address:
a hardware breakpoint event in the form of \mem:addr[/len][:access] where addr is the address in memory you want to break in. Access is the memory access type (read, write, execute) it can be passed as follows: \mem:addr[:[r][w][x]]. len is the range, number of bytes from specified addr, which the breakpoint will cover. If you want to profile read-write accesses in 0x1000, just set mem:0x1000:rw. If you want to profile write accesses in [0x1000~1008), just set mem:0x1000/8:w.
It may be difficult to get the memory address before hand. You can also use perf_event_open inside your program, but then you need to parse the perf sample records in your program.