Do not pass an invalid domtree to SimplifyInstruction from
LoopUnswitch.  Fixes PR12887.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157140 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 930980f..58f7739 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -1214,8 +1214,8 @@
 
     // See if instruction simplification can hack this up.  This is common for
     // things like "select false, X, Y" after unswitching made the condition be
-    // 'false'.
-    if (Value *V = SimplifyInstruction(I, 0, 0, DT))
+    // 'false'.  TODO: update the domtree properly so we can pass it here.
+    if (Value *V = SimplifyInstruction(I))
       if (LI->replacementPreservesLCSSAForm(I, V)) {
         ReplaceUsesOfWith(I, V, Worklist, L, LPM);
         continue;