By attaching an extra integer tag to heap origins, we are able
to distinguish between uninits
- created by heap allocation,
- created by heap deallocation (i.e. use-after-free),
- created by __msan_allocated_memory call,
- etc.
See https://code.google.com/p/memory-sanitizer/issues/detail?id=35.
llvm-svn: 226821
MSan does not assign origin for instrumentation temps (i.e. the ones that do
not come from the application code), but "select" instrumentation erroneously
tried to use one of those.
https://code.google.com/p/memory-sanitizer/issues/detail?id=78
llvm-svn: 222918