[PM] Split DominatorTree into a concrete analysis result object which

can be used by both the new pass manager and the old.

This removes it from any of the virtual mess of the pass interfaces and
lets it derive cleanly from the DominatorTreeBase<> template. In turn,
tons of boilerplate interface can be nuked and it turns into a very
straightforward extension of the base DominatorTree interface.

The old analysis pass is now a simple wrapper. The names and style of
this split should match the split between CallGraph and
CallGraphWrapperPass. All of the users of DominatorTree have been
updated to match using many of the same tricks as with CallGraph. The
goal is that the common type remains the resulting DominatorTree rather
than the pass. This will make subsequent work toward the new pass
manager significantly easier.

Also in numerous places things became cleaner because I switched from
re-running the pass (!!! mid way through some other passes run!!!) to
directly recomputing the domtree.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199104 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 21 insertions, 16 deletions

diff --git a/lib/Transforms/Scalar/LoopRotation.cpp b/lib/Transforms/Scalar/LoopRotation.cpp
index bc12e6a379..004ca14260 100644
--- a/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/lib/Transforms/Scalar/LoopRotation.cpp
@@ -45,7 +45,7 @@ namespace {
 
     // LCSSA form makes instruction renaming easier.
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.addPreserved<DominatorTree>();
+      AU.addPreserved<DominatorTreeWrapperPass>();
       AU.addRequired<LoopInfo>();
       AU.addPreserved<LoopInfo>();
       AU.addRequiredID(LoopSimplifyID);
@@ -252,8 +252,9 @@ bool LoopRotate::simplifyLoopLatch(Loop *L) {
   // Nuke the Latch block.
   assert(Latch->empty() && "unable to evacuate Latch");
   LI->removeBlock(Latch);
-  if (DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>())
-    DT->eraseNode(Latch);
+  if (DominatorTreeWrapperPass *DTWP =
+          getAnalysisIfAvailable<DominatorTreeWrapperPass>())
+    DTWP->getDomTree().eraseNode(Latch);
   Latch->eraseFromParent();
   return true;
 }
@@ -434,23 +435,25 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
     // The conditional branch can't be folded, handle the general case.
     // Update DominatorTree to reflect the CFG change we just made.  Then split
     // edges as necessary to preserve LoopSimplify form.
-    if (DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>()) {
+    if (DominatorTreeWrapperPass *DTWP =
+            getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
+      DominatorTree &DT = DTWP->getDomTree();
       // Everything that was dominated by the old loop header is now dominated
       // by the original loop preheader. Conceptually the header was merged
       // into the preheader, even though we reuse the actual block as a new
       // loop latch.
-      DomTreeNode *OrigHeaderNode = DT->getNode(OrigHeader);
+      DomTreeNode *OrigHeaderNode = DT.getNode(OrigHeader);
       SmallVector<DomTreeNode *, 8> HeaderChildren(OrigHeaderNode->begin(),
                                                    OrigHeaderNode->end());
-      DomTreeNode *OrigPreheaderNode = DT->getNode(OrigPreheader);
+      DomTreeNode *OrigPreheaderNode = DT.getNode(OrigPreheader);
       for (unsigned I = 0, E = HeaderChildren.size(); I != E; ++I)
-        DT->changeImmediateDominator(HeaderChildren[I], OrigPreheaderNode);
+        DT.changeImmediateDominator(HeaderChildren[I], OrigPreheaderNode);
 
-      assert(DT->getNode(Exit)->getIDom() == OrigPreheaderNode);
-      assert(DT->getNode(NewHeader)->getIDom() == OrigPreheaderNode);
+      assert(DT.getNode(Exit)->getIDom() == OrigPreheaderNode);
+      assert(DT.getNode(NewHeader)->getIDom() == OrigPreheaderNode);
 
       // Update OrigHeader to be dominated by the new header block.
-      DT->changeImmediateDominator(OrigHeader, OrigLatch);
+      DT.changeImmediateDominator(OrigHeader, OrigLatch);
     }
 
     // Right now OrigPreHeader has two successors, NewHeader and ExitBlock, and
@@ -472,15 +475,17 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
     PHBI->eraseFromParent();
 
     // With our CFG finalized, update DomTree if it is available.
-    if (DominatorTree *DT = getAnalysisIfAvailable<DominatorTree>()) {
+    if (DominatorTreeWrapperPass *DTWP =
+            getAnalysisIfAvailable<DominatorTreeWrapperPass>()) {
+      DominatorTree &DT = DTWP->getDomTree();
       // Update OrigHeader to be dominated by the new header block.
-      DT->changeImmediateDominator(NewHeader, OrigPreheader);
-      DT->changeImmediateDominator(OrigHeader, OrigLatch);
+      DT.changeImmediateDominator(NewHeader, OrigPreheader);
+      DT.changeImmediateDominator(OrigHeader, OrigLatch);
 
       // Brute force incremental dominator tree update. Call
       // findNearestCommonDominator on all CFG predecessors of each child of the
       // original header.
-      DomTreeNode *OrigHeaderNode = DT->getNode(OrigHeader);
+      DomTreeNode *OrigHeaderNode = DT.getNode(OrigHeader);
       SmallVector<DomTreeNode *, 8> HeaderChildren(OrigHeaderNode->begin(),
                                                    OrigHeaderNode->end());
       bool Changed;
@@ -493,11 +498,11 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
           pred_iterator PI = pred_begin(BB);
           BasicBlock *NearestDom = *PI;
           for (pred_iterator PE = pred_end(BB); PI != PE; ++PI)
-            NearestDom = DT->findNearestCommonDominator(NearestDom, *PI);
+            NearestDom = DT.findNearestCommonDominator(NearestDom, *PI);
 
           // Remember if this changes the DomTree.
           if (Node->getIDom()->getBlock() != NearestDom) {
-            DT->changeImmediateDominator(BB, NearestDom);
+            DT.changeImmediateDominator(BB, NearestDom);
             Changed = true;
           }
         }