This flag, if set, is a regexp for function names. If there are heap
allocations in the matching function names, these heap allocations will
be printed with an explanation why the heap allocation exists (and why
the object can't be stack allocated).
The LLVM CoroFrame pass appears to be tripping over this zero-sized
alloca. Therefore, do what the runtime would do: return a pointer to
runtime.zeroSizedAlloc. Or just don't deal with this case. But don't
emit a zero sized alloca to avoid this LLVM bug.
More information: https://bugs.llvm.org/show_bug.cgi?id=49916
Also add unit tests.
This is the first of several transformation (optimization/lowering)
passes that I'd like to move to the new transform package. This
separates the compiler from the optimizer.
Also, it finally adds unit tests for the compiler, not just end-to-end
compilation tests. This should improve robustness and should make it
easier to change these transformation passes in the future.
While the heap-to-stack transform is relatively simple, other passes are
much more complex. Adding unit tests not only helps robustness over
time, but also doubles as documentation as to what these transformation
passes do exactly.
