From df90841690c4c1c30aa9ea8cfd37c429bb1e9d0b Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Thu, 27 Nov 2008 01:16:00 +0000
Subject: Avoid inserting noop's in the middle of a loop.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60141 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/LoopAligner.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

(limited to 'lib/CodeGen/LoopAligner.cpp')

diff --git a/lib/CodeGen/LoopAligner.cpp b/lib/CodeGen/LoopAligner.cpp
index b8d00595d8..b67f5c3bf9 100644
--- a/lib/CodeGen/LoopAligner.cpp
+++ b/lib/CodeGen/LoopAligner.cpp
@@ -64,8 +64,14 @@ bool LoopAligner::runOnMachineFunction(MachineFunction &MF) {
 
   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
     MachineBasicBlock *MBB = I;
-    if (MLI->isLoopHeader(MBB))
+    if (MLI->isLoopHeader(MBB)) {
+      MachineBasicBlock *PredBB = prior(I);
+      if (MLI->getLoopFor(MBB) == MLI->getLoopFor(PredBB))
+        // If previously BB is in the same loop, don't align this BB. We want
+        // to prevent adding noop's inside a loop.
+        continue;
       MBB->setAlignment(Align);
+    }
   }
 
   return true;
-- 
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