Use -no-struct-path-tbaa to turn it off.
This is the same as r191695, which was reverted because it depends on a
commit that has issues.
llvm-svn: 192497
An updated version of r191586 with bug fix.
Struct-path aware TBAA generates tags to specify the access path,
while scalar TBAA only generates tags to scalar types.
We should not generate a TBAA tag with null being the first field. When
a TBAA type node is null, the tag should be null too. Make sure we
don't decorate an instruction with a null TBAA tag.
Added a testing case for the bug reported by Richard with -relaxed-aliasing
and -fsanitizer=thread.
llvm-svn: 192145
Duncan P. N. Exon Smith