optimize LICM::hoist to use moveBefore. Correct its updating

of AST to remove the hoisted instruction from the AST, since it
is no longer in the loop.

llvm-svn: 112448

llvm/lib/Transforms/Scalar/LICM.cpp

@@ -574,12 +574,11 @@ void LICM::hoist(Instruction &I) {
   DEBUG(dbgs() << "LICM hoisting to " << Preheader->getName() << ": "
         << I << "\n");
 
-  // Remove the instruction from its current basic block... but don't delete the
-  // instruction.
-  I.removeFromParent();
-
-  // Insert the new node in Preheader, before the terminator.
-  Preheader->getInstList().insert(Preheader->getTerminator(), &I);
+  // The instruction is no longer in this loop.
+  CurAST->deleteValue(&I);
+  
+  // Move the new node to the Preheader, before its terminator.
+  I.moveBefore(Preheader->getTerminator());
 
   if (isa<LoadInst>(I)) ++NumMovedLoads;
   else if (isa<CallInst>(I)) ++NumMovedCalls;