feat(vcr-sel): ship cmp→select fusion default-on — v0.13.0 (VCR-SEL-004, #428, #242)

CHANGELOG.md

@@ -7,6 +7,29 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.13.0] - 2026-06-24
+
+**cmp→select fusion is now DEFAULT-ON (VCR-SEL-004, #428, epic #242).** The ARM
+backend's compare→select lowering no longer materializes a boolean and re-tests
+it (`cmp; SetCond; cmp #0; movne; moveq`); it predicates the moves directly on
+the compare's own flags (`cmp; mov{c}; mov{invert(c)}`), −2 instructions per
+select. This is a **byte-changing** release: `.text` shrinks on every function
+with a select (control_step 354→324 B, flight_seam 1016→902, flight_seam_flat
+1240→1122; −262 B across the frozen fixtures), and gale's `gust_mix` measured
+2.375×→2.125× vs LLVM with a 132→116 B function.
+
+Execution **results are preserved** — validated three ways before shipping: (1)
+the named-anchor differentials re-run with fusion on (control_step still
+`0x00210A55`, flat+inlined flight_algo still `0x07FDF307`); (2) a unicorn
+execution oracle that runs the two-move `mov{invert(c)}` arm (`cmp-select-oracle`
+CI job, 11/11 result-identical); (3) gale's `gale_decider_diff` sweep across all
+8 verified primitives (10,596 cases, native ≡ unfused ≡ fused). The byte gates
+were re-frozen to the fused `.text` on this commit.
+
+**Escape hatch:** `SYNTH_NO_CMP_SELECT_FUSE=1` reverts to the pre-fusion lowering.
+**Pending follow-up:** the on-silicon G474RE DWT cycle no-regression check is
+tracked post-ship (gale); the qemu `-icount` proxy showed a monotonic win.
+
 ## [0.12.0] - 2026-06-23
 
 **DWARF SOURCE-LINE DEBUGGING — `--debug-line` (VCR-DBG-001, #394, epic #242).**

Cargo.toml

@@ -27,7 +27,7 @@ resolver = "2"
 # semver to publish, so the convention now catches up: workspace
 # version follows the release tag, bumped pre-tag in the release
 # checklist. See docs/release-process.md.
-version = "0.12.0"
+version = "0.13.0"
 edition = "2024"
 rust-version = "1.88"
 authors = ["PulseEngine Team"]

MODULE.bazel

@@ -7,7 +7,7 @@ module(
     name = "synth",
     # Kept in lockstep with [workspace.package] version in Cargo.toml.
     # Both are bumped pre-tag — see docs/release-process.md.
-    version = "0.12.0",
+    version = "0.13.0",
 )
 
 # Bazel dependencies

artifacts/verified-codegen-roadmap.yaml

@@ -737,7 +737,16 @@ artifacts:
       exhaustive sweep); precond (2) (G474RE silicon no-regression) still OWED —
       gale's bench is thumbv7m/qemu today — flip stays held on it (user call
       2026-06-23: keep the silicon gate; close the exec gap first).
-    status: approved
+      FLIP SHIPPED v0.13.0 (2026-06-24, #428): default-on landed. User authorized
+      shipping on the qemu+sweep+oracle evidence and WAIVING precond (2) for the
+      release (gale takes the on-silicon G474RE DWT no-regression as a tracked
+      post-ship follow-up). Re-froze the fused .text on the same commit the
+      named-anchor differentials were re-run on (control_step preserved 0x00210A55,
+      flat+inlined flight_algo preserved 0x07FDF307; .text −262 B across the frozen
+      fixtures). Escape hatch SYNTH_NO_CMP_SELECT_FUSE=1 reverts the lowering.
+      SCOPE: the select half shipped; the br_if→predicated-branch half remains a
+      separate follow-up (branch consumers unmodeled by reg_effect).
+    status: implemented
     tags: [codegen, selector, peephole, compare-select, flag-fusion, gale-209, perf, track-b, vcr-oracle-001]
     links:
       - type: derives-from

crates/synth-backend-awsm/Cargo.toml

@@ -11,6 +11,6 @@ categories.workspace = true
 description = "aWsm backend integration for the Synth compiler"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.12.0" }
+synth-core = { path = "../synth-core", version = "0.13.0" }
 anyhow.workspace = true
 thiserror.workspace = true

crates/synth-backend-riscv/Cargo.toml

@@ -11,8 +11,8 @@ categories.workspace = true
 description = "RISC-V encoder, ELF builder, PMP allocator, and bare-metal startup for synth"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.12.0" }
-synth-synthesis = { path = "../synth-synthesis", version = "0.12.0" }
+synth-core = { path = "../synth-core", version = "0.13.0" }
+synth-synthesis = { path = "../synth-synthesis", version = "0.13.0" }
 anyhow.workspace = true
 thiserror.workspace = true
 tracing.workspace = true

crates/synth-backend-wasker/Cargo.toml

@@ -11,6 +11,6 @@ categories.workspace = true
 description = "Wasker backend integration for the Synth compiler"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.12.0" }
+synth-core = { path = "../synth-core", version = "0.13.0" }
 anyhow.workspace = true
 thiserror.workspace = true

crates/synth-backend/Cargo.toml

@@ -15,7 +15,7 @@ default = ["arm-cortex-m"]
 arm-cortex-m = ["synth-synthesis"]
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.12.0" }
-synth-synthesis = { path = "../synth-synthesis", version = "0.12.0", optional = true }
+synth-core = { path = "../synth-core", version = "0.13.0" }
+synth-synthesis = { path = "../synth-synthesis", version = "0.13.0", optional = true }
 anyhow.workspace = true
 thiserror.workspace = true

crates/synth-backend/src/arm_backend.rs

@@ -433,15 +433,20 @@ fn compile_wasm_to_arm(
     // sound (flags reused only when nothing clobbers them in the window; the
     // boolean deleted only when provably dead) — see `fuse_cmp_select`.
     //
-    // BEHIND `SYNTH_CMP_SELECT_FUSE=1` while it is validated against the
-    // differential oracle + gale's on-target gust_codegen_bench (G474RE). Off by
-    // default ⇒ a literal no-op ⇒ every fixture stays bit-identical
-    // (control_step 0x00210A55 / flat+inlined flight_algo 0x07FDF307 / divseam).
-    // The default-on flip is the held byte-changing step, gated on silicon.
-    let arm_instrs = if std::env::var("SYNTH_CMP_SELECT_FUSE").is_ok() {
+    // DEFAULT-ON as of v0.13.0 (#428): cmp→select fusion ships by default. The
+    // byte-changing flip is validated by (a) the unicorn execution oracle that runs
+    // the two-move `mov{invert(c)}` arm (cmp_select_two_move_differential.py), (b)
+    // gale's gale_decider_diff 10,596-case sweep across all 8 verified primitives
+    // (native ≡ flag-off ≡ flag-on = 0x88e73178d232bcf5), and (c) the named-anchor
+    // differentials re-run with fusion ON — control_step still 0x00210A55, flat+
+    // inlined flight_algo still 0x07FDF307 (results preserved; bytes deliberately
+    // changed, re-frozen on this commit). Escape hatch: `SYNTH_NO_CMP_SELECT_FUSE=1`
+    // reverts to the pre-fusion lowering. The on-silicon G474RE DWT no-regression
+    // check is a tracked post-ship follow-up (gale owns it).
+    let arm_instrs = if std::env::var("SYNTH_NO_CMP_SELECT_FUSE").is_err() {
         // The rewritten stream is identical to `fuse_cmp_select`'s 2-tuple form;
         // the extra `two_move` count is diagnostic only (the fusion census /
-        // blast-radius datum for the flip decision — #7 made that arm reachable).
+        // blast-radius datum — #7 made that arm reachable).
         let (out, fused, two_move) =
             synth_synthesis::liveness::fuse_cmp_select_with_stats(&arm_instrs);
         if std::env::var("SYNTH_FUSE_STATS").is_ok() {

crates/synth-cli/Cargo.toml

@@ -27,18 +27,18 @@ verify = ["synth-verify"]
 # Path deps carry `version` so `cargo publish` rewrites them to the
 # crates.io coordinate. Bumping the workspace version requires
 # updating these in lockstep — see docs/release-process.md.
-synth-core = { path = "../synth-core", version = "0.12.0" }
-synth-frontend = { path = "../synth-frontend", version = "0.12.0" }
-synth-synthesis = { path = "../synth-synthesis", version = "0.12.0" }
-synth-backend = { path = "../synth-backend", version = "0.12.0" }
+synth-core = { path = "../synth-core", version = "0.13.0" }
+synth-frontend = { path = "../synth-frontend", version = "0.13.0" }
+synth-synthesis = { path = "../synth-synthesis", version = "0.13.0" }
+synth-backend = { path = "../synth-backend", version = "0.13.0" }
 
 # Optional external backends
-synth-backend-awsm = { path = "../synth-backend-awsm", version = "0.12.0", optional = true }
-synth-backend-wasker = { path = "../synth-backend-wasker", version = "0.12.0", optional = true }
-synth-backend-riscv = { path = "../synth-backend-riscv", version = "0.12.0", optional = true }
+synth-backend-awsm = { path = "../synth-backend-awsm", version = "0.13.0", optional = true }
+synth-backend-wasker = { path = "../synth-backend-wasker", version = "0.13.0", optional = true }
+synth-backend-riscv = { path = "../synth-backend-riscv", version = "0.13.0", optional = true }
 
 # Optional verification (requires z3)
-synth-verify = { path = "../synth-verify", version = "0.12.0", optional = true, features = ["z3-solver", "arm"] }
+synth-verify = { path = "../synth-verify", version = "0.13.0", optional = true, features = ["z3-solver", "arm"] }
 
 # Optional PulseEngine WASM optimizer
 # Uncomment when loom crate is available:

crates/synth-cli/tests/frozen_codegen_bytes.rs

@@ -55,15 +55,16 @@ fn fixture(name: &str) -> std::path::PathBuf {
 
 /// Compile a frozen fixture for `(backend, target)` with the exact `--all-exports
 /// --relocatable` config the `.py` differentials use, and return the SHA-256 hex
-/// of its `.text` and the section length. `SYNTH_CMP_SELECT_FUSE` / `SYNTH_CONST_CSE`
-/// are explicitly removed so an enabled-in-the-environment flag can never silently
-/// re-freeze the gate — it locks the SHIPPED, flag-off lowering. The `object`
-/// crate reads `.text` arch-agnostically (ARM Thumb-2 and RV32 alike).
+/// of its `.text` and the section length. `SYNTH_NO_CMP_SELECT_FUSE` (the v0.13.0
+/// cmp→select opt-out) / `SYNTH_CONST_CSE` are explicitly removed so a flag set in
+/// the environment can never silently re-freeze the gate — it locks the SHIPPED
+/// lowering, which since v0.13.0 INCLUDES cmp→select fusion (default-on). The
+/// `object` crate reads `.text` arch-agnostically (ARM Thumb-2 and RV32 alike).
 fn text_sha256(wasm: &str, backend: &str, target: &str) -> (String, usize) {
     let path = fixture(wasm);
     let elf = format!("/tmp/frozenbytes_{backend}_{wasm}.elf");
     let out = Command::new(synth())
-        .env_remove("SYNTH_CMP_SELECT_FUSE")
+        .env_remove("SYNTH_NO_CMP_SELECT_FUSE")
         .env_remove("SYNTH_CONST_CSE")
         .args([
             "compile",
@@ -125,24 +126,30 @@ fn assert_frozen(cases: &[(&str, &str, usize)], backend: &str, target: &str) {
 /// the `.py` differentials cover): control_step ↔ 0x00210A55, flight_seam_flat ↔
 /// flat+inlined flight_algo 0x07FDF307, plus flight_seam and the div seam.
 ///
-/// Goldens derived on main @ ef97f86 (post-#444 cmp→select, flag-off), 2026-06-23.
+/// Goldens RE-FROZEN for v0.13.0 (#428): cmp→select fusion is now default-on, so
+/// these lock the FUSED .text. The execution RESULTS are preserved — re-verified on
+/// this commit with fusion on: control_step still 0x00210A55 (control_step_differential
+/// .py 13/13), flat+inlined flight_algo still 0x07FDF307 (flight_seam_differential.py
+/// MATCH). .text shrank: control_step 354→324, flight_seam 1016→902, flight_seam_flat
+/// 1240→1122 (−262 B total); signed_div_const (0 fusion sites) unchanged. Prior
+/// flag-off goldens were on main @ ef97f86 (post-#444), 2026-06-23.
 #[test]
 fn frozen_fixtures_text_is_bit_identical_oracle_001() {
     let cases = [
         (
             "control_step.wasm",
-            "5efa58ca2667fb2f910b5ebf0ef8020a7fc1b9224f3ec070e9e0028de9d83a57",
-            354usize,
+            "b4c4c290be2c8a83055d4c9696ae4ebb16486a8fd3fc268531607eeef35325e5",
+            324usize,
         ),
         (
             "flight_seam.wasm",
-            "1f39b77b65f0695693deda9ee56e3a7fb3af4127858a8ac6c3ce0fd3398de516",
-            1016,
+            "300fdf3b92a0941da63b3215441a799d9b32ef942fd404b4803a83a6efb1bb60",
+            902,
         ),
         (
             "flight_seam_flat.wasm",
-            "f6244f35f932aac7661b9ed1cbf70dc1b5353a9f5c03178ebad3a38a891d7b8f",
-            1240,
+            "23d0b6829414a855f365d84c7c3301c256f1843fe46b2cc9b369fec30610913d",
+            1122,
         ),
         (
             "signed_div_const.wasm",

crates/synth-frontend/Cargo.toml

@@ -14,7 +14,7 @@ description = "WASM/WAT parser and module decoder frontend for the Synth compile
 # Internal path deps carry an explicit version so `cargo publish`
 # can rewrite to the crates.io coordinate. `path` is used for
 # in-workspace builds; `version` is what crates.io sees.
-synth-core = { path = "../synth-core", version = "0.12.0" }
+synth-core = { path = "../synth-core", version = "0.13.0" }
 
 wasmparser.workspace = true
 wasm-encoder.workspace = true

crates/synth-opt/Cargo.toml

@@ -11,7 +11,7 @@ categories.workspace = true
 description = "Peephole optimization passes for the Synth compiler"
 
 [dependencies]
-synth-cfg = { path = "../synth-cfg", version = "0.12.0" }
+synth-cfg = { path = "../synth-cfg", version = "0.13.0" }
 
 [dev-dependencies]
 criterion = { version = "0.8", features = ["html_reports"] }

crates/synth-synthesis/Cargo.toml

@@ -11,9 +11,9 @@ categories.workspace = true
 description = "WASM-to-ARM instruction selection and peephole optimizer"
 
 [dependencies]
-synth-core = { path = "../synth-core", version = "0.12.0" }
-synth-cfg = { path = "../synth-cfg", version = "0.12.0" }
-synth-opt = { path = "../synth-opt", version = "0.12.0" }
+synth-core = { path = "../synth-core", version = "0.13.0" }
+synth-cfg = { path = "../synth-cfg", version = "0.13.0" }
+synth-opt = { path = "../synth-opt", version = "0.13.0" }
 serde.workspace = true
 anyhow.workspace = true
 thiserror.workspace = true