testland/embedded-coverage-strategy-reference
Use when deciding what code coverage level embedded C/C++ needs (statement, branch, MC/DC) and wiring gcov or llvm-cov into the build: host vs QEMU instrumentation, MISRA-C and DO-178C expectations by safety level, and report formats.
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gcov-flag-reference.mdreferences/
gcov flag reference for embedded coverage
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).