If the preheader of the loop was the entry block of the function, make sure

that the exit block of the loop becomes the new entry block of the function.

This was causing a verifier assertion on 252.eon.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13039 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopUnroll.cpp b/lib/Transforms/Scalar/LoopUnroll.cpp
index 266afbbe9b349ade600d8972cfd0fdd33a9d8901..90de9e946daa38bc13a24ef1ec6f48f8c753017a 100644 (file)
--- a/lib/Transforms/Scalar/LoopUnroll.cpp
+++ b/lib/Transforms/Scalar/LoopUnroll.cpp
@@ -300,10 +300,15 @@ bool LoopUnroll::visitLoop(Loop *L) {
     ChangeExitBlocksFromTo(LI->begin(), LI->end(),
                            Preheader, LoopExit);
 
+  // If the preheader was the entry block of this function, move the exit block
+  // to be the new entry of the loop.
+  Function *F = LoopExit->getParent();
+  if (Preheader == &F->front())
+    F->getBasicBlockList().splice(F->begin(), F->getBasicBlockList(), LoopExit);
 
   // Actually delete the blocks now.
-  LoopExit->getParent()->getBasicBlockList().erase(Preheader);
-  LoopExit->getParent()->getBasicBlockList().erase(BB);
+  F->getBasicBlockList().erase(Preheader);
+  F->getBasicBlockList().erase(BB);
 
   ++NumUnrolled;
   return true;