From 60c7d5bc2cbeff9eff16716295ffd6a5374dc6bc Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Wed, 20 Jun 2012 20:17:20 +0000
Subject: [PATCH] Add "extern template" declarations now that we use explicit
 instantiation.

This is supported by gcc and clang, but guarded by a macro for MSVC 2008.

The extern template declaration is not necessary but generally good
form. It can avoid extra instantiations of the template methods
defined inline.

The EXTERN_TEMPLATE_INSTANTIATION macro could probably be generalized to
handle multiple template parameters if someone thinks it's worthwhile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@158840 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Analysis/LoopInfo.h       | 10 ++++++++++
 include/llvm/CodeGen/MachineLoopInfo.h | 14 +++++++++++++-
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h
index 453633b3050..14d87e0034b 100644
--- a/include/llvm/Analysis/LoopInfo.h
+++ b/include/llvm/Analysis/LoopInfo.h
@@ -316,6 +316,11 @@ raw_ostream& operator<<(raw_ostream &OS, const LoopBase<BlockT, LoopT> &Loop) {
   return OS;
 }
 
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+__extension__ extern template class LoopBase<BasicBlock, Loop>;
+#endif
+
 class Loop : public LoopBase<BasicBlock, Loop> {
 public:
   Loop() {}
@@ -541,6 +546,11 @@ public:
   void print(raw_ostream &OS) const;
 };
 
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+__extension__ extern template class LoopInfoBase<BasicBlock, Loop>;
+#endif
+
 class LoopInfo : public FunctionPass {
   LoopInfoBase<BasicBlock, Loop> LI;
   friend class LoopBase<BasicBlock, Loop>;
diff --git a/include/llvm/CodeGen/MachineLoopInfo.h b/include/llvm/CodeGen/MachineLoopInfo.h
index 6dd9440500b..3e204bed15a 100644
--- a/include/llvm/CodeGen/MachineLoopInfo.h
+++ b/include/llvm/CodeGen/MachineLoopInfo.h
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file defines the MachineLoopInfo class that is used to identify natural 
+// This file defines the MachineLoopInfo class that is used to identify natural
 // loops and determine the loop depth of various nodes of the CFG.  Note that
 // natural loops may actually be several loops that share the same header node.
 //
@@ -35,6 +35,12 @@
 
 namespace llvm {
 
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+class MachineLoop;
+__extension__ extern template class LoopBase<MachineBasicBlock, MachineLoop>;
+#endif
+
 class MachineLoop : public LoopBase<MachineBasicBlock, MachineLoop> {
 public:
   MachineLoop();
@@ -57,6 +63,12 @@ private:
     : LoopBase<MachineBasicBlock, MachineLoop>(MBB) {}
 };
 
+// Implementation in LoopInfoImpl.h
+#ifdef __GNUC__
+__extension__ extern template
+class LoopInfoBase<MachineBasicBlock, MachineLoop>;
+#endif
+
 class MachineLoopInfo : public MachineFunctionPass {
   LoopInfoBase<MachineBasicBlock, MachineLoop> LI;
   friend class LoopBase<MachineBasicBlock, MachineLoop>;
-- 
2.34.1