The waterfall was restarted so it's not clear exactly at which point it started failing:

https://build.chromium.org/p/chromium.fyi/builders/ClangToTLinux/builds/8102 was good
https://build.chromium.org/p/chromium.fyi/builders/ClangToTLinux/builds/8103 compiled for 2 hours, so probably good (clang 302462)
https://build.chromium.org/p/chromium.fyi/builders/ClangToTLinux/builds/8104 was bad (clang 302483)


My guess:

------------------------------------------------------------------------
r302469 | adrian | 2017-05-08 14:17:08 -0700 (Mon, 08 May 2017) | 13 lines

Make it illegal for two Functions to point to the same DISubprogram

As recently discussed on llvm-dev [1], this patch makes it illegal for
two Functions to point to the same DISubprogram and updates
FunctionCloner to also clone the debug info of a function to conform
to the new requirement. To simplify the implementation it also factors
out the creation of inlineAt locations from the Inliner into a
general-purpose utility in DILocation.

[1] http://lists.llvm.org/pipermail/llvm-dev/2017-May/112661.html
<rdar://problem/31926379>

Differential Revision: https://reviews.llvm.org/D32975
------------------------------------------------------------------------

Reverted in r302533

https://bugs.llvm.org/show_bug.cgi?id=32977