Summary: For platforms which support slow unwinder only, we restrict the store context size to 1, basically only storing the current pc. We do this because the slow unwinder which is based on libunwind is not async signal safe and causes random freezes in forking applications as well as in signal handlers.
Reviewed by eugenis.
Differential: D23107
llvm-svn: 289027
Fixes 2 issues in origins arising from realloc() calls:
* In the in-place grow case origin for the new memory is not set at all.
* In the copy-realloc case __msan_memcpy is used, which unwinds stack from
inside the MSan runtime. This does not generally work (as we may be built
w/o frame pointers), and produces "bad" stack trace anyway, with several
uninteresting (internal) frames on top.
This change also makes realloc() honor "zeroise" and "poison_in_malloc" flags.
See https://code.google.com/p/memory-sanitizer/issues/detail?id=73.
llvm-svn: 226674
Sagar Thakur