Fixes case where two printf statements might have the same format
string but still require their outputs to be displayed differently.
This can happen with the new func builtin, which is printed as a
string, but passes through an address to be symbolicated.
e.g.
kprobe:sys_open { printf("hi %s\n", func); printf("hi %s\n", comm) }

Improves accuracy and efficiency

Issue #5

e.g.: kprobe:sys_read,sys_write { @[func] = count() }

Issue #2

Issue #1

Behave like regular variables from other languages
- scoped within each probe block
- can only be used after being assigned
- not saved to BPF maps

Codegen: Use unsigned versions of division/modulo operations (LLVM BPF backend doesn't support signed)

Called when '==' or '!=' are used on string values

Allows statements such as '@x = (1 == 2)' to work