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 cuda
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.
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 range | floor (ms) | k (work) | fit R² | t(Nmin) | t(Nmax) | top-2× |
|---|---|---|---|---|---|---|
| 100–800 | 14 | 1.84 | 0.991 | 78 | 3028 | 4.80× |
compileInner grows by 2950 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.
| bucket | t@N=100 | t@N=800 | Δ ms | share | × lin | ∝Nk |
|---|---|---|---|---|---|---|
| emitEntryPointsSourceFromIR | 27 | 1475 | +1448 | 49% | 4.77× | 1.92 |
| linkAndOptimizeIR (self) | 8 | 863 | +855 | 29% | 6.93× | 2.29 |
| simplifyIR | 10 | 450 | +441 | 15% | 4.22× | 1.85 |
| specializeModule | 6 | 104 | +98 | 3% | 2.42× | 1.46 |
Near-constant (≤2% of growth each): SemanticChecking (19→66 ms), generateIR (6→54 ms), compileInner (self) (0→7 ms), linkIR (1→4 ms), parseTranslationUnit (0→2 ms), frontEndExecute (self) (0→1 ms), performMandatoryEarlyInlining (0→1 ms), performForceInlining (0→1 ms), unrollLoopsInModule (0→0 ms).
| N | compileInner | emitEntryPointsSourceFromIR | generateOutput |
|---|---|---|---|
| 100 | 78 | 52 | 52 |
| 200 | 195 | 161 | 162 |
| 400 | 631 | 578 | 579 |
| 800 | 3028 | 2897 | 2898 |