[PATCH] D19550: [InstCombine] Determine the result of a select based on a dominating condition.

[Gerolf Hoflehner via llvm-commits]

Gerolf added inline comments.

================
Comment at: test/Transforms/InstCombine/pr21210.ll:44
@@ -44,1 +43,3 @@
+; This seems perfectly fine to me?
+; CHECK: phi i32 [ %len, %bb ], [ undef, %b0 ], [ %0, %entry ]
   %1 = phi i32 [ %cond, %bb ], [ undef, %b0 ], [ %0, %entry ]
----------------
cond can be different from len, so you cannot replace it.
bb-> bb1 vs entry -> b1.

I think this test covers self-build issues I had ran into when I missed some cases in the  icmp->select->icmp optimization which removes the select in some narrow cases. 


http://reviews.llvm.org/D19550