[SLPVectorizer] Prefer pre-increments. NFCI.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@359989 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -4350,7 +4350,7 @@ bool BoUpSLP::BlockScheduling::extendSchedulingRegion(Value *V,
                           << "\n");
         return true;
       }
-      UpIter++;
+      ++UpIter;
     }
     if (DownIter != LowerEnd) {
       if (&*DownIter == I) {
@@ -4364,7 +4364,7 @@ bool BoUpSLP::BlockScheduling::extendSchedulingRegion(Value *V,
                           << "\n");
         return true;
       }
-      DownIter++;
+      ++DownIter;
     }
     assert((UpIter != UpperEnd || DownIter != LowerEnd) &&
            "instruction not found in block");
@@ -6650,7 +6650,7 @@ bool SLPVectorizerPass::vectorizeChainsInBlock(BasicBlock *BB, BoUpSLP &R) {
 
   SmallVector<WeakVH, 8> PostProcessInstructions;
   SmallDenseSet<Instruction *, 4> KeyNodes;
-  for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; it++) {
+  for (BasicBlock::iterator it = BB->begin(), e = BB->end(); it != e; ++it) {
     // We may go through BB multiple times so skip the one we have checked.
     if (!VisitedInstrs.insert(&*it).second) {
       if (it->use_empty() && KeyNodes.count(&*it) > 0 &&