Internal IRs

The current compiler architecture is built around explicit intermediate representations, not direct AST-to-codegen translation.

The important modern pipeline is:

Parse -> Resolve -> Check -> Elab -> CoreCanonicalize -> CoreCheck -> Mono -> Lower -> SSAVerify -> SSACleanup -> EmitSSA

Why This Matters

Concrete wants:

• explicit semantic boundaries
• a backend contract that can be checked
• better audit/report surfaces
• eventual proof work against a reduced, explicit core

That is why the compiler architecture is such a large part of the roadmap.

Core vs SSA

Two especially important IR boundaries are:

• Core: the main post-elaboration semantic representation
• SSA: the backend-facing representation consumed by code generation

Concrete’s long-term shape depends on keeping those boundaries clear and boring.

Control Flow In SSA

SSA represents control flow with:

• basic blocks
• terminators
• explicit values/registers

Recent compiler work has specifically hardened aggregate lowering so mutable aggregate state is kept in stable storage instead of being transported through fragile aggregate phi nodes.

Where To Read More

• docs/ARCHITECTURE.md for the full pass structure
• docs/PASSES.md for pass-by-pass contracts
• docs/ABI.md for type/layout rules