A full summary of static measurements (code size, stack usage, etc) can now
be found with:
make summary
This is done through the combination of a new ./scripts/summary.py
script and the ability of existing scripts to merge into existing csv
files, allowing multiple results to be merged either in a pipeline, or
in parallel with a single ./script/summary.py call.
The ./scripts/summary.py script can also be used to quickly compare
different builds or configurations. This is a proper implementation
of a similar but hacky shell script that has already been very useful
for making optimization decisions:
$ ./scripts/structs.py new.csv -d old.csv --summary
name (2 added, 0 removed) code stack structs
TOTAL 28648 (-2.7%) 2448 1012
Also some other small tweaks to scripts:
- Removed state saving diff rules. This isn't the most useful way to
handle comparing changes.
- Added short flags for --summary (-Y) and --files (-F), since these
are quite often used.
- Added -L/--depth argument to show dependencies for scripts/stack.py,
this replaces calls.py
- Additional internal restructuring to avoid repeated code
- Removed incorrect diff percentage when there is no actual size
- Consistent percentage rendering in test.py
This required a patch to the --diff flag for the scripts to ignore
a missing file. This enables the useful one liner for making comparisons
with potentially missing previous versions:
./scripts/code.py lfs.o -d lfs.o.code.csv -o lfs.o.code.csv
function (0 added, 0 removed) old new diff
TOTAL 25476 25476 +0
One downside, these previous files are easy to delete as a part of make
clean, which limits their usefulness for comparing configuration
changes...
Note this detects loops (recursion), and renders this as infinity.
Currently littlefs does have a single recursive function and you can see
how this infects the full call graph. Eventually this should be removed.
Now with -s/--sort and -S/--reverse-sort for sorting the functions by
size.
You may wonder why add reverse-sort, since its utility doesn't seem
worth the cost to implement (these are just helper scripts after all),
the reason is that reverse-sort is quite useful on the command-line,
where scrollback may be truncated, and you only care about the larger
entries.
Outside of the command-line, normal sort is prefered.
Fortunately the difference is just the sign in the sort key.
Note this conflicts with the short --summary flag, so that has been
removed.
Now littlefs's Makefile can work with a custom build directory
for compilation output. Just set the BUILDDIR variable and the Makefile
will take care of the rest.
make BUILDDIR=build size
This makes it very easy to compare builds with different compile-time
configurations or different cross-compilers.
This meant most of code.py's build isolation is no longer needed,
so revisted the scripts and cleaned/tweaked a number of things.
Also bought code.py in line with coverage.py, fixing some of the
inconsistencies that were created while developing these scripts.
One change to note was removing the inline measuring logic, I realized
this feature is unnecessary thanks to GCC's -fkeep-static-functions and
-fno-inline flags.
Since we already have fairly complicated scriptts, I figured it wouldn't
be too hard to use the gcov tools and directly parse their output. Boy
was I wrong.
The gcov intermediary format is a bit of a mess. In version 5.4, a
text-based intermediary format is written to a single .gcov file per
executable. This changed sometime before version 7.5, when it started
writing separate .gcov files per .o files. And in version 9 this
intermediary format has been entirely replaced with an incompatible json
format!
Ironically, this means the internal-only .gcda/.gcno binary format has
actually been more stable than the intermediary format.
Also there's no way to avoid temporary .gcov files generated in the
project root, which risks messing with how test.py runs parallel tests.
Fortunately this looks like it will be fixed in gcov version 9.
---
Ended up switching to lcov, which was the right way to go. lcov handles
all of the gcov parsing, provides an easily parsable output, and even
provides a set of higher-level commands to manage coverage collection
from different runs.
Since this is all provided by lcov, was able to simplify coverage.py
quite a bit. Now it just parses the .info files output by lcov.
Now coverage information can be collected if you provide the --coverage
to test.py. Internally this uses GCC's gcov instrumentation along with a
new script, coverage.py, to parse *.gcov files.
The main use for this is finding coverage info during CI runs. There's a
risk that the instrumentation may make it more difficult to debug, so I
decided to not make coverage collection enabled by default.
