SIR In-Memory Representation
SIR is represented as a (relatively obscured) graph in-memory. Representation for a given SIR function is divided between two different types:
DataFlowGraph: owns all the "things" in a function, and models data-flow between valuesLayout: orders the entities in a data-flow graph into lists of blocks, and lists of instructions in those blocks.
DataFlowGraph: The DFG
This is basically a massive overly-complicated lookup table. It stores lots of arenas that store everything in a function that matters, whether it be instructions, blocks, referenced function signatures, etc. Everything is stored inside of arenas, and 'references' to those entities is passed around by indices into those arenas.