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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 (v2026.12, median ms) emit_metal 51.2× over N 100→800 0.0 2567 5135 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×
100–800141.970.9969347544.69×

Growth attribution (N=100 → N=800)

compileInner grows by 4661 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
emitEntryPointsSourceFromIR362343+230749%5.29×2.01
legalizeResourceTypes10910+90019%6.41×2.16
legalizeExistentialTypeLayout10888+87819%6.13×2.16
simplifyIR8394+3868%4.42×1.89

Near-constant (≤2% of growth each): specializeModule (5→94 ms), SemanticChecking (15→65 ms), generateIR (5→50 ms), frontEndExecute (self) (0→3 ms), linkIR (1→3 ms), parseTranslationUnit (0→2 ms), performForceInlining (0→1 ms), performMandatoryEarlyInlining (0→1 ms), unrollLoopsInModule (0→0 ms), compileInner (self) (0→0 ms).

Sweep numbers (median ms)

NcompileInneremitEntryPointsSourceFromIRgenerateOutput
100937171
200267236236
4001014961962
800475446384639