[Instruction] add moveAfter() convenience function; NFCI

As suggested in D37121, here's a wrapper for removeFromParent() + insertAfter(),
but implemented using moveBefore() for symmetry/efficiency.

Differential Revision: https://reviews.llvm.org/D37239

llvm-svn: 312001
diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index 365cb01..ceb521c 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -89,6 +89,10 @@
   moveBefore(*MovePos->getParent(), MovePos->getIterator());
 }
 
+void Instruction::moveAfter(Instruction *MovePos) {
+  moveBefore(*MovePos->getParent(), ++MovePos->getIterator());
+}
+
 void Instruction::moveBefore(BasicBlock &BB,
                              SymbolTableList<Instruction>::iterator I) {
   assert(I == BB.end() || I->getParent() == &BB);