[PATCH] PR19958 wrong code at -O1 and above on x86_64-linux-gnu (InstCombine)

[Sanjay Patel]

I'm not sure what LLVM test case policy is, but I think it would be good to have contra-test cases too. Eg, a test case that doesn't specify 'exact', a test case that isn't eq/ne - these would ensure that your code is not firing when it wasn't intended. Also, can you include a 'ne' test?

http://reviews.llvm.org/D4068