[indvars] Missing variables at Og:

https://bugs.llvm.org/show_bug.cgi?id=51735
llvm#51077

Address @nikic comments about layering violation.
- Move code to 'LoopInfo.h'.

llvm/include/llvm/Analysis/LoopInfo.h

@@ -18,6 +18,8 @@
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/PassManager.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/ValueHandle.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/GenericLoopInfo.h"
 #include <algorithm>
@@ -392,13 +394,35 @@ class LLVM_EXTERNAL_VISIBILITY Loop : public LoopBase<BasicBlock, Loop> {
     return "<unnamed loop>";
   }
 
+  /// Preserve the induction variable exit value and its debug users by the
+  /// 'indvars' pass if the loop can deleted. Those debug users will be used
+  /// by the 'loop-delete' pass.
+  void preserveDebugInductionVariableInfo(
+      Value *FinalValue, SmallVector<DbgVariableIntrinsic *> DbgUsers) {
+    IndVarFinalValue = FinalValue;
+    for (DbgVariableIntrinsic *DebugUser : DbgUsers)
+      IndVarDebugUsers.push_back(DebugUser);
+  }
+
+  Value *getDebugInductionVariableFinalValue() { return IndVarFinalValue; }
+  SmallVector<WeakVH> &getDebugInductionVariableDebugUsers() {
+    return IndVarDebugUsers;
+  }
+
 private:
   Loop() = default;
 
   friend class LoopInfoBase<BasicBlock, Loop>;
   friend class LoopBase<BasicBlock, Loop>;
   explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
   ~Loop() = default;
+
+  // Induction variable exit value and its debug users, preserved by the
+  // 'indvars' pass, when it detects that the loop can be deleted and the
+  // there are no PHIs to be rewritten.
+  // For now, we only preserve single induction variables.
+  Value *IndVarFinalValue = nullptr;
+  SmallVector<WeakVH> IndVarDebugUsers;
 };
 
 // Implementation in Support/GenericLoopInfoImpl.h

llvm/include/llvm/Support/GenericLoopInfo.h

@@ -44,8 +44,6 @@
 #include "llvm/ADT/PostOrderIterator.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SetOperations.h"
-#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/IR/ValueHandle.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/GenericDomTree.h"
 
@@ -77,13 +75,6 @@ template <class BlockT, class LoopT> class LoopBase {
   const LoopBase<BlockT, LoopT> &
   operator=(const LoopBase<BlockT, LoopT> &) = delete;
 
-  // Induction variable exit value and its debug users, preserved by the
-  // 'indvars' pass, when it detects that the loop can be deleted and the
-  // there are no PHIs to be rewritten.
-  // For now, we only preserve single induction variables.
-  Value *IndVarFinalValue = nullptr;
-  SmallVector<WeakVH> IndVarDebugUsers;
-
 public:
   /// Return the nesting level of this loop.  An outer-most loop has depth 1,
   /// for consistency with loop depth values used for basic blocks, where depth
@@ -260,21 +251,6 @@ template <class BlockT, class LoopT> class LoopBase {
                           [&](BlockT *Pred) { return contains(Pred); });
   }
 
-  /// Preserve the induction variable exit value and its debug users by the
-  /// 'indvars' pass if the loop can deleted. Those debug users will be used
-  /// by the 'loop-delete' pass.
-  void preserveDebugInductionVariableInfo(
-      Value *FinalValue, SmallVector<DbgVariableIntrinsic *> DbgUsers) {
-    IndVarFinalValue = FinalValue;
-    for (DbgVariableIntrinsic *DebugUser : DbgUsers)
-      IndVarDebugUsers.push_back(DebugUser);
-  }
-
-  Value *getDebugInductionVariableFinalValue() { return IndVarFinalValue; }
-  SmallVector<WeakVH> &getDebugInductionVariableDebugUsers() {
-    return IndVarDebugUsers;
-  }
-
   //===--------------------------------------------------------------------===//
   // APIs for simple analysis of the loop.
   //