[LLVMdev] AddressSanitizer+CMake unittest question

[Chandler Carruth]

Context: I'm trying to implement support for ASan's unittest suite in
CMake. This is ... quite challenging.

I think I can get it to work with one significant caveat: it will require
manual dependency management. None of the automatic header tracking. I
think this is fine in some cases, and not so fine in other cases. Let me
explain.

It feels like these tests are really comprised of two distinct collections
of tests:

1) Those that rather directly test the ASan runtime. These do not rely upon
the compiler instrumenting the code, and simply exercise the runtime
library directly.
2) Those that expect to be instrumented by the compiler, and exercise the
runtime through GoogleTest's death tests on seemingly innocuous code.

For the first bucket, there is no problem. We should be able to handle
these easily.

For the second bucket, this can be a bit tricky. It requires compiling the
tests with a custom compiler and flags. Let's talk about the options for
supporting this case.

A) We could require the host compiler to have support for
-faddress-sanitizer, but ensure that the just-built runtime library is used
rather than the host compiler's runtime library.
B) We can depend upon the Clang built in the same LLVM/Clang/CompilerRT
checkout, and provide a custom compilation strategy to use it to instrument
the unittest code.


Option A has fairly obvious problems: it introduces version skew into the
equation, and would require a full bootstrap to test new instrumentation.
However, it plays very nicely with the build system, requiring no special
magic. It also would "Just Work" in the cross-compilation scenario, as much
as any unittest would.

Option B avoids any version skew issues, but at the cost of requiring us to
implement a "complete" custom compilation strategy for these source files.
At the very least, this will not be portable and thus will only be enabled
on a few platforms, and it will not get automatic header dependency
tracking.


I can pursue either of these options, but I'd like to know which the ASan
folks would be most interested in working with.

Second, it would be extremely helpful to have a very firm separation
between bucket #1 and bucket #2. Currently, there is one collection of
tests clearly in bucket #1 (asan_noinst_test.cc), and plenty of tests
clearly in bucket #2, but there seems to be quite a bit of overlap as well.
For example, I would naively expect asan_interface_test.cc to not require
instrumentation -- it almost exclusively directly calls the runtime. But it
is currently being compiled with instrumentation by the Makefile.old, so
I'm at a loss. Separating these two scenarios into at least separate files,
and ideally linking them into two separate binaries would make everything
much simpler. For example, bucket #2 shouldn't need to include any of
ASan's header files, making it easier to manage manual dependencies if
necessary.
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