Design model

import SpecArticleChrome from '@beskid/beskid-ui/platform-spec/SpecArticleChrome.astro';

<SpecArticleChrome />

Lowering boundary

Lowering is the last semantic gate before any backend runs. Inputs are a post-merge program snapshot (HIR + ModuleIndex + resolved types); output is an immutable CodegenArtifact containing Cranelift modules, data descriptors, extern imports, and debug metadata.

Backends must not re-run parse, mod host, or semantic rules on the artifact.

flowchart TB
  subgraph analysis [beskid_analysis]
    hir[HIR + ModuleIndex]
  end
  subgraph codegen [beskid_codegen]
    lower[lower_program / lower_source]
    art[CodegenArtifact]
  end
  subgraph backends [beskid_engine]
    jit[JitModule]
    aot[AOT object emit]
  end
  hir --> lower --> art
  art --> jit
  art --> aot

Artifact contents

Slice	Role
CLIF modules	Per-compilation-unit functions and globals
Builtin imports	declare_builtin_imports from BUILTIN_SPECS
ExternImport rows	User contract symbols for link step
Type descriptors	GC layout + array/string shapes for alloc

Invariants

• Lowering runs only when syntax_generation_id matches the merged tree used by semantic rules (stage ordering).
• Panic/abort paths use AbiReturnKind::Never imports so unreachable blocks are correct.
• JIT and AOT consume the same artifact type; divergence happens only after CodegenArtifact is sealed.

Code anchors

• beskid_codegen::lower_source in compiler/crates/beskid_codegen
• CodegenArtifact construction in compiler/crates/beskid_codegen
• JitModule in compiler/crates/beskid_engine/src/jit_module.rs
• Runtime smoke: compiler/crates/beskid_tests/src/runtime/jit.rs