From 5987038dc3f455a5c307f5748b650d43193541ff Mon Sep 17 00:00:00 2001
From: Max Kazantsev <max.kazantsev@azul.com>
Date: Sun, 17 Feb 2019 18:21:51 +0000
Subject: [PATCH] [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.

llvm-svn: 354227
---
 lib/Transforms/Scalar/LoopSimplifyCFG.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index 4f1213d92a3..eb8de34c3af 100644
--- a/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -94,15 +94,19 @@ static void removeBlockFromLoops(BasicBlock *BB, Loop *FirstLoop,
 /// 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 {