Hojun-Cho
cb57cd795d
Phase 10 step 8 (delete the C trees) is deferred to v1.0 — until the compiler stops churning we keep Cstage as the fresh-checkout entry point. Split the Makefile so the two stages are named, and add BOOTSTRAP.md describing the cstage → ww1 → ww2 → ww3 fixed-point flow. PLAN.md gets a status note pointing at it.
71 lines
2.6 KiB
Markdown
71 lines
2.6 KiB
Markdown
# BOOTSTRAP
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How `ww` builds itself.
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`ww` is self-hosted: the ww-side compiler/assembler/linker/driver live
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under `selfhost/cmd/` and reach a byte-identical fixed point under
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`make bootstrap`. But the *first* ww binary on a fresh checkout has to
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come from somewhere. Today, that "somewhere" is a small C bootstrap
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toolchain — the **Cstage**:
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cmd/wwc/ frontend library (lex, parse, check) → libwwc.a
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cmd/6c/ amd64 compiler .ww → .s
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cmd/6a/ amd64 assembler .s → .o
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cmd/6l/ amd64 linker .o → static ELF
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cmd/ww/ user-facing driver (orchestrates 6c → 6a → 6l)
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Cstage is built with `cc`. Once it exists, it compiles the
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ww-rewritten tools (the **wwstage**) under `selfhost/cmd/`, which then
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self-compile to a byte-identical fixed point. After that, no C is
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involved.
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## Build flow
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cstage (cc → C tools, one-time)
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│
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├──→ ww1 wwstage tools, built by Cstage
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│ │
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│ └──→ ww2 wwstage self-compiles
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│ │
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│ └──→ ww3 ww2 self-compiles
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│ │
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│ ↓
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│ cmp ww2 ww3 → fixed point ✓
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↑
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└ from here on, no C is invoked
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## Make targets
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make builds cstage + wwstage + libs
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make cstage Cstage only (cc → ww, 6c, 6a, 6l, wwdump, libs)
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make wwstage wwstage only (assumes cstage)
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make bootstrap three-stage build; gates on cmp ww2 == ww3
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make test runs all tests, including the 990–993 diffs
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(ww-side tools vs C-side tools, byte-for-byte)
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## Status
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Phase 10 of `PLAN.md` is at its first exit criterion: the bootstrap is
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green and `selfhost/cmd/{wwc,6a,6l,ww}` are byte-identical to their
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Cstage counterparts. The second exit criterion — deleting the C trees
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— is **deferred to v1.0**: until the compiler stops churning, the
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Cstage stays as the fresh-checkout entry point. A `git clone` today
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still requires `cc`.
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## What "no C" looks like
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When the compiler stabilises:
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1. Cross-compile or natively build a known-good wwstage on each
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supported arch.
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2. Ship those binaries under `bootstrap/<arch>/{ww,6c,6a,6l}` in the
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tree. They are the new stage 0.
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3. Delete `cmd/wwc/`, `cmd/6c/`, `cmd/6a/`, `cmd/6l/`, `cmd/ww/`.
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4. Move `selfhost/cmd/*` to `cmd/*`.
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5. Build path: stage-0 binary → ww1 → ww2 → fixed point, same as
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today, just without `cc`.
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This is the standard self-hosting story (Go, Rust, OCaml all do
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variants of it). The bootstrap binaries become the new "trusting
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trust" surface.
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