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t27c silicon: wire bitstream_reuse.t27 -- blocked by the no-growth rule for hand-written code #8295
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The 32-line glue, built and compiled locally against master 1ab051f. Apply with
git applyonce the way forward is chosen:diff --git a/bootstrap/src/main.rs b/bootstrap/src/main.rs index 1bf18d68d..0ba14acaf 100644 --- a/bootstrap/src/main.rs +++ b/bootstrap/src/main.rs @@ -117,6 +117,10 @@ mod silicon_queue; #[path = "../gen/rust/verified/bench_agent.rs"] #[allow(dead_code, unused_parens, unused_mut, unused_assignments, unused_variables, non_snake_case, non_upper_case_globals, clippy::all)] mod bench_agent; +// specs/verified/bitstream_reuse.t27 (#8095): when `t27c silicon` loads a bitstream it built before. +#[path = "../gen/rust/verified/bitstream_reuse.rs"] +#[allow(dead_code, unused_parens, unused_mut, unused_assignments, unused_variables, non_snake_case, non_upper_case_globals, clippy::all)] +mod bitstream_reuse; mod phi_f64_literals; mod weight_bram; mod bitnet_pipeline; diff --git a/bootstrap/src/service.rs b/bootstrap/src/service.rs index bc5887859..beada1e3f 100644 --- a/bootstrap/src/service.rs +++ b/bootstrap/src/service.rs @@ -4246,6 +4246,25 @@ pub fn run_silicon( let mut derived_chain: Option<u32> = None; let mut seen_sites: Vec<u32> = Vec::new(); + // #8095: load a bitstream built before from the same inputs by the same tools (specs/verified/bitstream_reuse.t27). + use crate::bitstream_reuse as br; + let bit_path = tmp.join(format!("{stem}.bit")); + let tools = [chipdb.clone(), pnr.clone(), xr.join("utils/fasm2frames.py"), PathBuf::from(run(Command::new("which").arg("xc7frames2bit")).1.trim())]; + let xdc_in = tops.last().map(|t| Path::new(t).with_extension("xdc")).filter(|p| p.exists()); + let mut key_in = format!("{}|{}|{pnr_seed:?}|{}|{}", run(Command::new("yosys").arg("-V")).1.trim(), run(Command::new("git").arg("-C").arg(&db).args(["rev-parse", "HEAD"])).1.trim(), br::BIT_RECIPE, env!("CARGO_PKG_VERSION")); + for f in sources.iter().map(PathBuf::from).chain(xdc_in).chain(tools) { key_in += &format!("|{}", crate::sha256_hex(&std::fs::read(&f).unwrap_or_default())); } + let cache = PathBuf::from(std::env::var_os("HOME").unwrap_or_default()).join(".cache/t27/bitstreams").join(crate::sha256_hex(key_in.as_bytes())); + let (cached_bit, cached_chain) = (std::fs::read(cache.join("design.bit")).ok(), std::fs::read_to_string(cache.join("chain")).ok()); + let intact = cached_bit.as_deref().map(crate::sha256_hex) == std::fs::read_to_string(cache.join("bit.sha256")).ok(); + let decision = br::bit_decision(std::env::var_os("T27_SILICON_REBUILD").is_some(), cached_bit.is_some(), cached_chain.is_some(), intact); + 'build: { + if decision == br::BIT_REUSE { + std::fs::write(&bit_path, cached_bit.as_deref().unwrap_or_default())?; + derived_chain = cached_chain.and_then(|c| c.trim().parse().ok()); + let note = format!("same inputs, same tools: {} (T27_SILICON_REBUILD=1 rebuilds)", cache.display()); + stages.push(Stage { name: "bitstream REUSED", secs: 0.0, code: Some(0), artefact: file_len(&bit_path), note }); + break 'build; + } for attempt in 0..6u32 { let t = Instant::now(); let chparam = match chain_override { @@ -4609,7 +4628,6 @@ pub fn run_silicon( }); // ---- bitstream, ONLY from non-empty frames ---- - let bit_path = tmp.join(format!("{stem}.bit")); let frames_ok = file_len(&frames_path).map(|(_, n)| n > 0).unwrap_or(false); let t = Instant::now(); let c = if frames_ok { @@ -4634,12 +4652,21 @@ pub fn run_silicon( "SKIPPED: empty frames would still yield a 9.7 MB .bit (T169)".into() }, }); + } let build_ok = print_table(&stages); if !build_ok { println!("FAIL -- the build did not complete. Nothing was loaded."); std::process::exit(1); } + if br::may_store(decision, build_ok, stages.iter().any(|s| s.name == "BSCAN chain == site" && s.ok())) { + let bit = std::fs::read(&bit_path)?; + std::fs::create_dir_all(&cache)?; + std::fs::write(cache.join("design.bit"), &bit)?; + std::fs::write(cache.join("chain"), derived_chain.map(|c| c.to_string()).unwrap_or_default())?; + std::fs::write(cache.join("bit.sha256"), crate::sha256_hex(&bit))?; // last: a torn entry reads CORRUPT + println!(" bitstream stored for reuse: {}", cache.display()); + } if skip_hardware { println!("PASS (build only) -- rerun without --skip-hardware to load and read.");
- added 4 commits that reference this issue
on Oct 9, 2026
Follow-up to #8290 / PR #8291, epic #8095.
specs/verified/bitstream_reuse.t27(PR #8291) decides whent27c siliconmay load a bitstream it built before. That skips about 27 s of yosys, nextpnr and fasm2frames per run on die A, and later lets an agent with no toolchain load a sealed bitstream.Wiring it needs I/O that t27 cannot express yet:
yosys -Vandgit rev-parse;~/.cache/t27/bitstreams/<key>/.The glue is 32 lines of Rust (service.rs +28, main.rs +4), written and built locally. Since the owner's rule of 2026-10-09, hand-written code in any language but t27 may not grow (own-language), and no label lifts that. So the glue is not landed.
Ways forward (the owner's call):
Acceptance criteria
t27c siliconrun of an unchanged spec prints abitstream REUSEDstage instead of yosys and nextpnrBoundary
specs/verified/bitstream_reuse.t27
User Scenarios
Given a verified spec that declares bitstream reuse via
specs/verified/bitstream_reuse.t27, Whent27c siliconruns a second time with unchanged inputs (gen-verilog output, --top files, chipdb, nextpnr binary, yosys version, git revision), Then the command prints abitstream REUSEDstage and skips yosys, nextpnr, and fasm2frames.Given the own-language rule (no net growth of hand-written Rust), When the wiring for bitstream reuse is submitted in a PR, Then the PR must either port at least 32 lines of existing bootstrap/src Rust to .t27 or depend on t27 gaining file/process/hash I/O (tracked in epic: self-host t27c -- rewrite the compiler from Rust into t27 #5980) so the glue is generated.
Requirements
FR-001: The second
t27c siliconrun of an unchanged spec MUST print abitstream REUSEDstage instead of invoking yosys and nextpnr.FR-002: The PR that wires
specs/verified/bitstream_reuse.t27MUST pass the own-language check (net change ≤ 0 lines of hand-written Rust).FR-003: Bitstream reuse key derivation MUST incorporate hashes of gen-verilog output, --top files, chipdb, nextpnr binary,
yosys -Voutput, andgit rev-parseoutput.FR-004: The implementation MUST read and write
~/.cache/t27/bitstreams/<key>/for cached bitstreams.