xcode-compilation-analyzer

1# Xcode Compilation Analyzer
2 
3Use this skill when compile time, not just general project configuration, looks like the bottleneck.
4 
5## Core Rules
6 
7- Start from evidence, ideally a recent `.build-benchmark/` artifact or raw timing-summary output.
8- Prefer analysis-only compiler flags over persistent project edits during investigation.
9- Rank findings by expected **wall-clock** impact, not cumulative compile-time impact. When compile tasks are heavily parallelized (sum of compile categories >> wall-clock median), note that fixing individual hotspots may improve parallel efficiency without reducing build wait time.
10- When the evidence points to parallelized work rather than serial bottlenecks, label recommendations as "Reduces compiler workload (parallel)" rather than "Reduces build time."
11- Do not edit source or build settings without explicit developer approval.
12 
13## What To Inspect
14 
15- `Build Timing Summary` output from clean and incremental builds
16- long-running `CompileSwiftSources` or per-file compilation tasks
17- `SwiftEmitModule` time -- can reach 60s+ after a single-line change in large modules; if it dominates incremental builds, the module is likely too large or macro-heavy
18- `Planning Swift module` time -- if this category is disproportionately large in incremental builds (up to 30s per module), it signals unexpected input invalidation or macro-related rebuild cascading
19- ad hoc runs with:
20  - `-Xfrontend -warn-long-expression-type-checking=<ms>`
21…