CLion CMake Auto‑Reload Interaction with Profiling Runs for Bottleneck Measurement

Answer

Disabling auto‑reload and manually reloading CMake after a profiling run keeps the symbol index current without triggering a full rebuild, provided the CMake change does not alter compile flags, definitions or generated headers that affect targets.

Confirmed facts

1. Auto‑reload only re‑runs CMake configure/generation; it does not start a build.
2. When the option is off, a manual Reload CMake Project updates compile_commands.json and the IDE’s symbol index, but a rebuild occurs only if the regeneration changes inputs to compilation.
3. The profiler attaches to or launches the executable defined in the Run/Debug configuration; it profiles whatever binary exists at that path, independent of the symbol index.
4. If the Run configuration’s Before launch step includes Build, the binary is rebuilt immediately before profiling, guaranteeing that the measured binary matches the freshly indexed sources.

Steps for reliable bottleneck measurement

1. Open Settings | Build, Execution, Deployment | CMake and uncheck Reload CMake project on editing CMakeLists.txt.
2. Make required CMake edits, then run Build | Reload CMake Project manually.
3. Verify in the Build tool window that only the expected targets, or none, are recompiled.
4. Ensure the Run/Debug configuration used for profiling has Build as the first Before launch action.
5. Start the profiler from that configuration; the profiler will run against the binary that was just built.
6. After profiling, if CMakeLists.txt is edited again, repeat steps 2-5.

Missing diagnostic detail

Confirm whether your profiler configuration launches the binary automatically or attaches to an already running executable; this determines if a manual rebuild is required after a CMake reload to keep the profiler binary in sync with the refreshed index.