Code Size Comparison

Compare TinyUSB code size between a base ref (default master) and the current branch using tools/metrics_compare_base.py. Three granularities — pick the narrowest one that exercises your change:

Granularity	When to use	Command
single example, one board	Focused change touching one feature	-b BOARD -e device/cdc_msc
all examples, one board	Per-board regression sweep	-b BOARD
all examples, all CI families (combined)	Pre-merge full check	--ci

The script does the whole base-vs-branch dance itself: a temporary git worktree of the base ref under cmake-metrics/_worktree/ (removed on exit), base + branch builds under cmake-metrics/<board>/{base,build}/, then tools/metrics.py compare (report paths under Outputs).

Choosing arguments

Infer from the user's request:

• Board(s): named board → -b BOARD (repeatable). "All boards" / "CI" / "full sweep" → --ci (first board of each arm-gcc family). Default to a fast board (raspberry_pi_pico) if unspecified for an iterative check.
• Example: named example → -e <group>/<name> (e.g. -e device/cdc_msc). "All examples" → omit -e.
• Bloaty: only with -e. Use when the user wants a section/symbol-level breakdown for a single binary.
• Base ref: default master. Override with --base-branch <ref> (tag or commit also works).
• Filter: default is the absolute path of each side's <checkout>/src/ directory, which uniquely identifies TinyUSB stack code without matching vendored deps that also have a src/ (e.g. pico-sdk/src/). Override with one or more -f SUBSTRING flags to use repo-relative substrings instead. Change only if asked.

Common invocations

# Single example, one board (linkermap, fastest; add --bloaty for section/symbol breakdown):
python3 tools/metrics_compare_base.py -b raspberry_pi_pico -e device/cdc_msc

# All examples for one board (repeat -b for several boards):
python3 tools/metrics_compare_base.py -b raspberry_pi_pico

# Full CI sweep (first board per arm-gcc family, combined):
python3 tools/metrics_compare_base.py --ci

Outputs

• Per-board: cmake-metrics/<board>/metrics_compare.md (and _<example>.md when -e is set)
• Combined (--combined, auto-set by --ci): cmake-metrics/_combined/metrics_compare.md, aggregating all boards
• Bloaty: printed to stdout as section + symbol diffs

Timing

• Single example, single board: ~30 s
• All examples, single board: ~60-90 s
• --ci (all arm-gcc families, first board each): 4-8 minutes — sequential sweep across boards (Ninja parallelizes within each board, not across)

Use timeouts ≥ 10 minutes (600000 ms) for --ci.

Reporting results

After running:

• Show the markdown report's summary table to the user.
• Highlight any rows with non-zero % diff — under the default filter every row is a TinyUSB stack source file (e.g. usbd.c, cdc_device.c, dcd_<port>.c), so any non-zero delta is a real stack-size impact.
• If the diff is unexpected, follow up with a single-example --bloaty run to localize.