Crate cmtir

Source

Expand description

cmtir is the central intermediate representation (IR) for Cement (cmt2) languages and compiler tools.

Key features:

Rule-based syntax and semantics
Natural parse-print support
Def-use support for operations
Compatibility with FIRRTL

§Design

cmtir is implemented based on kir, which provides a consistent pattern of parse-print support for all IR components.

src/ir defines different components of cmtir:

ir::op: operations.
ir::instance: instance declaration and usage.
ir::literal: literals.
ir::rule: rules.
ir::structure: module and circuit.
ir::error: span and error messages.

All structs in cmtir have the consistent pattern of SExpr derive, which is a macro that provides parse-print support (see kir::SExpr).

For operations, cmtir derives OpIO trait (also defined in kir), which provides def-use support: taking/updating def/use values of operations. For most operations, the OpIO trait is derived automatically when #[opio(xxx)] is specified on the struct fields.

§External Module

cmtir accepts FIRRTL code as external modules. This is useful for reusing existing modules from the FIRRTL (or Chisel, Chipyard) ecosystem. Also, since FIRRTL supports blackbox SV modules, cmtir is also compatible with SV legacy code indirectly.

The question is, how cmtir treat RTL external modules in the rule-based semantics? cmtir provides syntax to declare external rules for external modules, each of which specifies the real hardware behavior of the corresponding rule, like setting up some signals. cmtir also provides syntax to bind cmtir module ports and RTL ports in external modules.

Re-exports§

pub use anyhow;
pub use json;
pub use common::*;
pub use utils::*;
pub use ir::*;
pub use to_fir::*;

Modules§

common
fir: FIRRTL.
flatindex
fsmgen: cmtir’s operation creation support for FSMGEN (generating FSMs from procedural descriptions)primitives, including seq, par, branch, for, …
ir: cmtir’s IR components.
to_fir
utils