[PATCH] [BasicAA] Make better use of zext and sign information.

[hfinkel at anl.gov]

> You're right - that call doesn't actually affect anything so I've removed it. It seems the actual cause of Rich's bug was using AllPositive to break out of the loop; if the loop break condition i != e is changed to i != e && AllPositive then the test_modulo_analysis_with_global test I've added will fail as the Modulo will be calculated incorrectly (as the last loop iteration is skipped, so Modulo isn't updated with its Scale). I've also added a few more tests and comments for the modulo functionality too, as I spent a bit of time exploring how it works. Thanks -

Okay, thanks! I'll retest with this version.

http://reviews.llvm.org/D5866