[llvm] r354227 - [NFC] Teach getInnermostLoopFor walk up the loop trees

[Max Kazantsev via llvm-commits]

Author: mkazantsev
Date: Sun Feb 17 10:21:51 2019
New Revision: 354227

URL: http://llvm.org/viewvc/llvm-project?rev=354227&view=rev
Log:
[NFC] Teach getInnermostLoopFor walk up the loop trees

This should be NFC in current use case of this method, but it will
help to use it for solving more compex tasks in follow-up patches.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp?rev=354227&r1=354226&r2=354227&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopSimplifyCFG.cpp Sun Feb 17 10:21:51 2019
@@ -94,15 +94,19 @@ static void removeBlockFromLoops(BasicBl
 /// contains the header of loop \p L.
 static Loop *getInnermostLoopFor(SmallPtrSetImpl<BasicBlock *> &BBs,
                                  Loop &L, LoopInfo &LI) {
-  Loop *StillReachable = nullptr;
+  Loop *Innermost = nullptr;
   for (BasicBlock *BB : BBs) {
     Loop *BBL = LI.getLoopFor(BB);
-    if (BBL && BBL->contains(L.getHeader()))
-      if (!StillReachable ||
-          BBL->getLoopDepth() > StillReachable->getLoopDepth())
-        StillReachable = BBL;
+    while (BBL && !BBL->contains(L.getHeader()))
+      BBL = BBL->getParentLoop();
+    if (BBL == &L)
+      BBL = BBL->getParentLoop();
+    if (!BBL)
+      continue;
+    if (!Innermost || BBL->getLoopDepth() > Innermost->getLoopDepth())
+      Innermost = BBL;
   }
-  return StillReachable;
+  return Innermost;
 }
 
 namespace {