[PATCH] Teach InstCombine about pointer address spaces

[Matt Arsenault]

  Those are required. When the sizes are inconsistent between those places, you hit assertions everywhere. There's also another ValueTracking piece I thought might be independent, but it's not. I think I can split those pieces out before this one and not break anything, but they can't be tested with different address spaces until this one.

http://llvm-reviews.chandlerc.com/D1250