[PATCH] D12210: [InstCombine] Transform A & (L - 1) u< L --> L != 0

[Philip Reames via llvm-commits]

reames added inline comments.

================
Comment at: test/Transforms/InstCombine/ult-and-bitwise-and.ll:5
@@ +4,3 @@
+; CHECK: @f(
+  %lim.sub = add i32 %lim, -1
+  %val.and = and i32 %val, %lim.sub
----------------
Add a version of this test case with sub 1.

I think you need the fact that %lim is >= 0 for this to hold.  Consider %lim with 0x101 and %val of 0x110.  The original check fails, yours succeeds.  

Also, I think that if the add is nsw, we can infer lim is > 0 and thus directly fold to true.  


http://reviews.llvm.org/D12210