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emit_metal

A single moderately complex shader. Compiled to multiple targets by the harness (same source, varying -target) to isolate generateOutput cost. ``n`` scales the amount of straight-line math the backend must emit. Scaling null: n scales op count and the emitted output is O(n); ideal codegen cost is O(n).

bucket: codegen_source  ·  mode: target  ·  flags: -target metal

Phase composition vs N (stacked sub-counters)

compileInner split into phase buckets (named leaves + (self) residuals) stacked across the sweep sizes — the top edge is compileInner, so you can see which phase drives the scaling.

emit_metal — phase composition vs N (v2026.13, median ms) emit_metal 49.0× over N 100→800 0.0 2357 4714 100 200 400 800 N emit_metal — parseTranslationUnit emit_metal — SemanticChecking emit_metal — generateIR emit_metal — frontEndExecute (self) emit_metal — specializeModule emit_metal — simplifyIR emit_metal — linkIR emit_metal — unrollLoopsInModule emit_metal — legalizeResourceTypes emit_metal — legalizeExistentialTypeLayout emit_metal — performMandatoryEarlyInlining emit_metal — performForceInlining emit_metal — emitEntryPointsSourceFromIR emit_metal — compileInner (self) phase buckets parseTranslationUnit SemanticChecking generateIR frontEndExecute (self) specializeModule simplifyIR linkIR unrollLoopsInModule legalizeResourceTypes legalizeExistentialTypeLayout performMandatoryEarlyInlining performForceInlining linkAndOptimizeIR (self) emitEntryPointsSourceFromIR generateOutput (self) compileInner (self)

Scaling analysis

floor-subtracted power-law fit (t − floor) = a·Nk; floor = the minimal workload (fixed per-compile cost), k the global exponent, top-2× the local high-end doubling ratio.

N rangefloor (ms)k (work)fit R²t(Nmin)t(Nmax)top-2×
100–800101.930.9988943654.35×

Growth attribution (N=100 → N=800)

compileInner grows by 4276 ms across the sweep; the mutually-exclusive phase buckets below partition that growth exactly (no nested-timer double counting). × lin is the same metric as the top-level panels, per bucket: the end point vs a linear expectation anchored to the bucket's share of the minimal floor and fitted on the low-N half — 1.0 = grew exactly linearly, >1 bends up. The super-linearity lives where × lin (and k) are red.

buckett@N=100t@N=800Δ msshare× lin∝Nk
emitEntryPointsSourceFromIR352151+211650%4.88×1.99
legalizeExistentialTypeLayout10811+80219%5.56×2.12
legalizeResourceTypes10799+78918%5.65×2.12
simplifyIR8382+3749%4.28×1.87
specializeModule5106+1012%2.56×1.50

Near-constant (≤2% of growth each): SemanticChecking (15→62 ms), generateIR (5→47 ms), linkIR (1→2 ms), parseTranslationUnit (0→2 ms), performMandatoryEarlyInlining (0→1 ms), performForceInlining (0→1 ms), compileInner (self) (0→0 ms), unrollLoopsInModule (0→0 ms), frontEndExecute (self) (0→0 ms).

Sweep numbers (median ms)

NcompileInneremitEntryPointsSourceFromIRgenerateOutput
100896868
200267236237
4001004952953
800436542534253