Sysdig is open source, system-level exploration: capture system state and activity from a running Linux instance, then save, filter and analyze. Think of it as strace + tcpdump + lsof + awesome sauce.
With a little Lua cherry on top.

In this document we will take a look at how to map various classic high-level programming language constructs to LLVM IR. The purpose of the document is to make the learning curve less steep for aspiring LLVM users.

Each C++ expression (an operator with its arguments, a literal, a variable name, etc) is characterized by two independent properties: a type and a value category. Each expression has some non-reference type, and each expression belongs to exactly one of the three primary value categories.