On 24/06/06 11:31AM, Patrick Steinhardt wrote: > We have recently noticed that our CI does not always notice variables > that may be used uninitialized. While it is expected that compiler > warnings aren't perfect, this one was a but puzzling because it was s/but/bit/ > rather obvious that the variable can be uninitialized. > > Many compiler warnings unfortunately depend on the optimization level > used by the compiler. While `-O0` for example will disable a lot of > warnings altogether because optimization passes go away, `-O2`, which is > our default optimization level used in CI, may optimize specific code > away or even double down on undefined behaviour. Interestingly, this > specific instance that triggered the investigation does get noted by GCC > when using `-Og`. > > While we could adapt all jobs to compile with `-Og` now, that would > potentially mask other warnings that only get diagnosed with `-O2`. > Instead, adapt the "linux-gcc-default" job to compile with `-Og`. This > job is chosen because it uses the "ubuntu:latest" image and should thus > have a comparatively recent compiler toolchain, and because we have > other jobs that use "ubuntu:latest" so that we do not loose coverage for s/loose/lose/ > warnings diagnosed only on `-O2` level. > > To make it easier to set up the optimization level in our CI, add > support in our Makefile to specify the level via an environment > variable. > > Signed-off-by: Patrick Steinhardt <ps@xxxxxx> > --- > > I was a little torn whether we really want to name the variable `O` > here because it feels so easy to set it by accident. We could rename > this to `OPTIMIZATION` or `OPTIMIZATION_LEVEL`, but that's quite a > mouthful. > > Alternatively, if we don't want to have this variable in the first > place, then I'm also happy to adapt the script itself to pass the > optimization level via an argument. I think the variable itself is fine, but for a name I think that either `OPTIMIZATION` or `OPTIMIZATION_LEVEL` would be a better pick. We have some other lengthy environment varible names so I don't think its too bad. Otherwise, this looks good to me :) -Justin
