Move the implementation of LoopInfo into LoopInfoImpl.h.

The implementation only needs inclusion from LoopInfo.cpp and
MachineLoopInfo.cpp. Clients of the interface should only include the
interface. This makes the interface readable and speeds up rebuilds
after modifying the implementation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158787 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/LoopInfo.cpp

@@ -18,6 +18,7 @@
 #include "llvm/Constants.h"
 #include "llvm/Instructions.h"
 #include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/LoopInfoImpl.h"
 #include "llvm/Analysis/LoopIterator.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Assembly/Writer.h"
@@ -29,6 +30,10 @@
 #include <algorithm>
 using namespace llvm;
 
+// Explicitly instantiate methods in LoopInfoImpl.h for IR-level Loops.
+template class llvm::LoopBase<BasicBlock, Loop>;
+template class llvm::LoopInfoBase<BasicBlock, Loop>;
+
 // Always verify loopinfo if expensive checking is enabled.
 #ifdef XDEBUG
 static bool VerifyLoopInfo = true;