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control_flow_ssa

A single entry point with n stacked control-flow blocks — nested if/else, a bounded inner loop with break/continue, and a switch — all mutating a small set of carried locals (a, b, c, d). Re-assigning the same locals across many branches and loop back-edges is what forces SSA construction to insert phi nodes and what the CFG simplifier (constructSSA, inside simplifyIR) must chew through. Isolates the SSA/CFG axis that complexity_ladder only touches as one of several mixed dimensions; nothing else stresses it alone. Scales by breadth = number of control-flow blocks, so basic-block and phi counts grow with n. Scaling null: n scales control-flow blocks; ideal SSA construction is near-linear in block count.

bucket: control_flow  ·  mode: target  ·  flags: -target spirv -emit-spirv-directly

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.

control_flow_ssa — phase composition vs N (v2026.12, median ms) control_flow_ssa 16.7× over N 60→480 0.0 955 1910 60 120 240 480 N control_flow_ssa — parseTranslationUnit control_flow_ssa — SemanticChecking control_flow_ssa — generateIR control_flow_ssa — frontEndExecute (self) control_flow_ssa — specializeModule control_flow_ssa — simplifyIR control_flow_ssa — linkIR control_flow_ssa — unrollLoopsInModule control_flow_ssa — legalizeResourceTypes control_flow_ssa — legalizeExistentialTypeLayout control_flow_ssa — performMandatoryEarlyInlining control_flow_ssa — performForceInlining control_flow_ssa — linkAndOptimizeIR (self) control_flow_ssa — generateOutput (self) control_flow_ssa — 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×
60–480141.420.99610617692.99×

Growth attribution (N=60 → N=480)

compileInner grows by 1663 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=60t@N=480Δ msshare× lin∝Nk
generateOutput (self)32633+60136%2.19×1.47
linkAndOptimizeIR (self)14542+52832%3.37×1.79
simplifyIR17164+1489%1.21×1.11
generateIR12158+1469%1.83×1.28
performMandatoryEarlyInlining180+795%6.09×2.02

Also growing (below top-5): SemanticChecking (+66 ms, 4%).

Near-constant (≤2% of growth each): specializeModule (5→37 ms), compileInner (self) (0→29 ms), legalizeExistentialTypeLayout (2→13 ms), legalizeResourceTypes (2→13 ms), linkIR (1→6 ms), parseTranslationUnit (1→5 ms), performForceInlining (0→2 ms), unrollLoopsInModule (0→1 ms), frontEndExecute (self) (0→0 ms).

Sweep numbers (median ms)

NcompileInnersimplifyIRfrontEndExecute
601061731
1202293450
2405927399
4801769164248