While investigating recent failures in bootstrap on ppc64le buildbot, I found that the current stack coloring pass does not regard TBAA information when merging two allocas of different types (Actually there is a FIXME comment on handling of TBAA information in StackColoring.cpp)
Although the current failures are observed only on ppc64le, the cause of failures seems to be a platform-neutral issue and other platforms can suffer from similar problems.
I submitted a work-in-progress patch in Phabricator to resolve this issue. https://reviews.llvm.org/D35907
Any suggestions or comments would be truly appreciated.