| # Compiler Architecture |
| |
| ## Intro |
| |
| Consider reading [fir-basics.md](../docs/fir/fir-basics.md). |
| |
| ## Two Frontends |
| |
| 1. **K1/FE 1.0 (Legacy)**: Located in `compiler/frontend/` - uses PSI and BindingContext |
| 2. **K2/FIR (Current)**: Located in `compiler/fir/` - Frontend IR, the new compiler frontend |
| |
| ## FIR Compilation Phases |
| |
| FIR processes code through sequential phases (see `FirResolvePhase.kt`). |
| |
| Key invariant: In phase B following phase A, all FIR elements visible in B are resolved to phase A. |
| |
| ## IR (Intermediate Representation) |
| |
| Located in `compiler/ir/`. Backend IR is used by all targets for: |
| - Lowering (transforming code to target-friendly form) |
| - Optimization |
| - Serialization to klibs |
| |
| Backend implementations: |
| - `compiler/ir/backend.jvm/` - JVM backend |
| - `compiler/ir/backend.js/` - JavaScript backend |
| - `compiler/ir/backend.wasm/` - WebAssembly backend |
| - `kotlin-native/backend.native/`, `native/` - Native backend |
| |
| ## Inference |
| |
| For type inference implementation details, read [inference.md](../docs/fir/inference.md). |
| |
| ## Commit Guidelines |
| |
| - **FIR prefix**: When changes are mostly related to FIR (`compiler/fir/`), use `FIR: ` prefix in the commit subject line. |
| - **Test-before-fix**: When fixing an issue and adding a test, commit the test data as a separate commit **before** the fix. This helps reviewers see how the fix actually changes semantics (the test will show diagnostic differences in the fix commit). |
| |
| ## Testing |
| |
| For FIR analysis test data format (directives, diagnostic markers, file structure), see [analysis-tests/AGENTS.md](fir/analysis-tests/AGENTS.md). |
