google/souper — pull request #39 by regehr (2014-08-20 03:45:15+00:00)
Title: minor changes to make it easier to debug miscompilations

this is code that I've been using to narrow down a miscompilation, that I believe will be useful in the future

it has three parts
- build compiler-rt so that we can use UBSan from our LLVM version
- detailed srcloc printing for replaced instructions
- two command line options supporting binary search for a bogus
transformation