[PM/LoopUnswitch] Remove another over-aggressive assert.

This code path can very clearly be called in a context where we have
baselined all the cloned blocks to a particular loop and are trying to
handle nested subloops. There is no harm in this, so just relax the
assert. I've added a test case that will make sure we actually exercise
this code path.

llvm-svn: 330680

1 files changed, 1 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
index c7b071b36b5..c28311fe4b0 100644
--- a/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
+++ b/llvm/lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
@@ -913,11 +913,8 @@ static Loop *cloneLoopNest(Loop &OrigRootL, Loop *RootParentL,
     for (auto *BB : OrigL.blocks()) {
       auto *ClonedBB = cast<BasicBlock>(VMap.lookup(BB));
       ClonedL.addBlockEntry(ClonedBB);
-      if (LI.getLoopFor(BB) == &OrigL) {
-        assert(!LI.getLoopFor(ClonedBB) &&
-               "Should not have an existing loop for this block!");
+      if (LI.getLoopFor(BB) == &OrigL)
         LI.changeLoopFor(ClonedBB, &ClonedL);
-      }
     }
   };