Eliminate the IS_PHI_DEF flag and VNInfo::setIsPHIDef().

A value number is a PHI def if and only if it begins at a block
boundary. This can be derived from the def slot, a separate flag is not
necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160893 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 9a751c1..98ed2cf 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -1047,8 +1047,7 @@
     if (ParentVNI->isUnused())
       continue;
     unsigned RegIdx = RegAssign.lookup(ParentVNI->def);
-    VNInfo *VNI = defValue(RegIdx, ParentVNI, ParentVNI->def);
-    VNI->setIsPHIDef(ParentVNI->isPHIDef());
+    defValue(RegIdx, ParentVNI, ParentVNI->def);
 
     // Force rematted values to be recomputed everywhere.
     // The new live ranges may be truncated.