testland/embedded-coverage-strategy-reference

Pure-reference catalog of code-coverage strategy for embedded C/C++: the criteria hierarchy (statement / branch / decision / condition / MC/DC), the gcov toolchain (.gcno/.gcda, --coverage), the LLVM source-based toolchain (llvm-profdata / llvm-cov), host-build vs QEMU-build instrumentation, MISRA-C:2012 and DO-178C structural-coverage expectations by safety level (DAL A maps to MC/DC), and report-format choices. Use when choosing what structural-coverage level to require and wiring gcov / llvm-cov into the build; physical .gcda retrieval from hardware is in hardware-in-loop-reference, QEMU machine flags in qemu-system-test-runner, and to author the embedded tests themselves use googletest-embedded-arm or unity-test-framework-c.

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gcov flag reference for embedded coverage

Name: testland/embedded-coverage-strategy-reference
Rating: 74.4 (1 reviews)
Author: testland

Deep reference for the embedded-coverage-strategy-reference SKILL.md. Consult when reading a .gcov report or reaching past the --coverage / gcov -b -c basics shown in the SKILL.

gcov command-line flags

Key flags from the GCC gcov invocation page (gcc.gnu.org/onlinedocs/gcc/Invoking-Gcov.html):

Flag	Long form	Effect
`-a`	`--all-blocks`	Write per-basic-block counts
`-b`	`--branch-probabilities`	Write branch frequencies + summary to stdout
`-c`	`--branch-counts`	Branch frequencies as counts not percentages
`-f`	`--function-summaries`	Per-function coverage on top of file-level
`-n`	`--no-output`	Suppress the `.gcov` file
`-p`	`--preserve-paths`	Preserve full path in generated filenames
`-u`	`--unconditional-branches`	Include unconditional branches in `-b` output
`--json-format`	-	Emit `.gcov.json.gz` (gzip-compressed JSON, "does not require source code for generation")

Reading the `.gcov` text report

The text .gcov file annotates each source line with an execution count. Two sentinels matter:

- marks a non-executable line (declaration, blank, comment).
##### marks an executable line that was never run - the reads worth chasing.

-b -c together give branch coverage as raw counts, which is what an embedded branch-coverage gate reads. For per-operand visibility on short-circuit && / ||, gcov is not enough - use clang -fcoverage-mcdc (see the SKILL's LLVM section).