LoopPass: Simplify the API for adding a new loop. NFC

The insertLoop() API is only used to add new loops, and has confusing
ownership semantics. Simplify it by replacing it with addLoop().

llvm-svn: 251064

llvm/include/llvm/Analysis/LoopPass.h

@@ -130,12 +130,9 @@ public:
   // Delete loop from the loop queue and loop nest (LoopInfo).
   void deleteLoopFromQueue(Loop *L);
 
-  // Insert loop into the loop queue and add it as a child of the
-  // given parent.
-  void insertLoop(Loop *L, Loop *ParentLoop);
-
-  // Insert a loop into the loop queue.
-  void insertLoopIntoQueue(Loop *L);
+  // Add a new loop into the loop queue as a child of the given parent, or at
+  // the top level if \c ParentLoop is null.
+  Loop &addLoop(Loop *ParentLoop);
 
   // Reoptimize this loop. LPPassManager will re-insert this loop into the
   // queue. This allows LoopPass to change loop nest for the loop. This

llvm/lib/Analysis/LoopPass.cpp

@@ -101,38 +101,29 @@ void LPPassManager::deleteLoopFromQueue(Loop *L) {
 }
 
 // Inset loop into loop nest (LoopInfo) and loop queue (LQ).
-void LPPassManager::insertLoop(Loop *L, Loop *ParentLoop) {
+Loop &LPPassManager::addLoop(Loop *ParentLoop) {
+  // Create a new loop. LI will take ownership.
+  Loop *L = new Loop();
 
-  assert (CurrentLoop != L && "Cannot insert CurrentLoop");
-
-  // Insert into loop nest
-  if (ParentLoop)
-    ParentLoop->addChildLoop(L);
-  else
+  // Insert into the loop nest and the loop queue.
+  if (!ParentLoop) {
+    // This is the top level loop.
     LI->addTopLevelLoop(L);
-
-  insertLoopIntoQueue(L);
-}
-
-void LPPassManager::insertLoopIntoQueue(Loop *L) {
-  // Insert L into loop queue
-  if (L == CurrentLoop)
-    redoLoop(L);
-  else if (!L->getParentLoop())
-    // This is top level loop.
     LQ.push_front(L);
-  else {
-    // Insert L after the parent loop.
-    for (std::deque<Loop *>::iterator I = LQ.begin(),
-           E = LQ.end(); I != E; ++I) {
-      if (*I == L->getParentLoop()) {
-        // deque does not support insert after.
-        ++I;
-        LQ.insert(I, 1, L);
-        break;
-      }
+    return *L;
+  }
+
+  ParentLoop->addChildLoop(L);
+  // Insert L into the loop queue after the parent loop.
+  for (auto I = LQ.begin(), E = LQ.end(); I != E; ++I) {
+    if (*I == L->getParentLoop()) {
+      // deque does not support insert after.
+      ++I;
+      LQ.insert(I, 1, L);
+      break;
     }
   }
+  return *L;
 }
 
 // Reoptimize this loop. LPPassManager will re-insert this loop into the

llvm/lib/Transforms/Scalar/LoopUnswitch.cpp

@@ -670,20 +670,19 @@ bool LoopUnswitch::UnswitchIfProfitable(Value *LoopCond, Constant *Val,
 /// mapping the blocks with the specified map.
 static Loop *CloneLoop(Loop *L, Loop *PL, ValueToValueMapTy &VM,
                        LoopInfo *LI, LPPassManager *LPM) {
-  Loop *New = new Loop();
-  LPM->insertLoop(New, PL);
+  Loop &New = LPM->addLoop(PL);
 
   // Add all of the blocks in L to the new loop.
   for (Loop::block_iterator I = L->block_begin(), E = L->block_end();
        I != E; ++I)
     if (LI->getLoopFor(*I) == L)
-      New->addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), *LI);
+      New.addBasicBlockToLoop(cast<BasicBlock>(VM[*I]), *LI);
 
   // Add all of the subloops to the new loop.
   for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
-    CloneLoop(*I, New, VM, LI, LPM);
+    CloneLoop(*I, &New, VM, LI, LPM);
 
-  return New;
+  return &New;
 }
 
 static void copyMetadata(Instruction *DstInst, const Instruction *SrcInst,