[JumpThread] No need to erase BB from LoopHeaders. NFC.

[junbuml]

Summary

No need to try to ease BB from LoopHeaders as we already know that BB is not in LoopHeaders.

[rengolin]

Obvious patch. LGTM. Thanks!

llvm/trunk/lib/Transforms/Scalar/JumpThreading.cpp

for (Function::iterator I = F.begin(), E = F.end(); I != E;) {
       // this dead.
       // We should not eliminate the loop header either, because eliminating
       // a loop header might later prevent LoopSimplify from transforming nested
       // loops into simplified form.
       if (BI && BI->isUnconditional() &&
           BB != &BB->getParent()->getEntryBlock() &&
           // If the terminator is the only non-phi instruction, try to nuke it.
           BB->getFirstNonPHIOrDbg()->isTerminator() && !LoopHeaders.count(BB)) {
-        // Since TryToSimplifyUncondBranchFromEmptyBlock may delete the
-        // block, we have to make sure it isn't in the LoopHeaders set.  We
-        // reinsert afterward if needed.
-        bool ErasedFromLoopHeaders = LoopHeaders.erase(BB);
-        BasicBlock *Succ = BI->getSuccessor(0);
-
         // FIXME: It is always conservatively correct to drop the info
         // for a block even if it doesn't get erased.  This isn't totally
         // awesome, but it allows us to use AssertingVH to prevent nasty
         // dangling pointer issues within LazyValueInfo.
         LVI->eraseBlock(BB);
-        if (TryToSimplifyUncondBranchFromEmptyBlock(BB)) {
+        if (TryToSimplifyUncondBranchFromEmptyBlock(BB))
           Changed = true;
-          // If we deleted BB and BB was the header of a loop, then the
-          // successor is now the header of the loop.
-          BB = Succ;
-        }
-
-        if (ErasedFromLoopHeaders)
-          LoopHeaders.insert(BB);
       }
     }
     EverChanged |= Changed;
   } while (Changed);
 
   LoopHeaders.clear();
   return EverChanged;
 }