Add r134057 back, but splice the predecessor after the successors phi

nodes.

Original message:
Let simplify cfg simplify bb with only debug and lifetime intrinsics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134182 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/BasicBlock.h

@@ -138,6 +138,12 @@ public:
     return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbg();
   }
 
+  // Same as above, but also skip lifetime intrinsics.
+  Instruction* getFirstNonPHIOrDbgOrLifetime();
+  const Instruction* getFirstNonPHIOrDbgOrLifetime() const {
+    return const_cast<BasicBlock*>(this)->getFirstNonPHIOrDbgOrLifetime();
+  }
+
   /// removeFromParent - This method unlinks 'this' from the containing
   /// function, but does not delete it.
   ///