[LV] Rename CountRoundDown to VectorTripCount (NFC)

The name CountRoundDown is potentially misleading, as the number of
iterations can be rounded up when folding the tail.

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D119681

Author: rickyz

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -566,7 +566,7 @@ class InnerLoopVectorizer {
 
   /// Set up the values of the IVs correctly when exiting the vector loop.
   void fixupIVUsers(PHINode *OrigPhi, const InductionDescriptor &II,
-                    Value *CountRoundDown, Value *EndValue,
+                    Value *VectorTripCount, Value *EndValue,
                     BasicBlock *MiddleBlock, BasicBlock *VectorHeader);
 
   /// Handle all cross-iteration phis in the header.
@@ -3153,10 +3153,10 @@ void InnerLoopVectorizer::createInductionResumeValues(
       Type *StepType = II.getStep()->getType();
       Instruction::CastOps CastOp =
           CastInst::getCastOpcode(VectorTripCount, true, StepType, true);
-      Value *CRD = B.CreateCast(CastOp, VectorTripCount, StepType, "cast.crd");
+      Value *VTC = B.CreateCast(CastOp, VectorTripCount, StepType, "cast.vtc");
       Value *Step =
           CreateStepValue(II.getStep(), *PSE.getSE(), &*B.GetInsertPoint());
-      EndValue = emitTransformedIndex(B, CRD, II.getStartValue(), Step, II);
+      EndValue = emitTransformedIndex(B, VTC, II.getStartValue(), Step, II);
       EndValue->setName("ind.end");
 
       // Compute the end value for the additional bypass (if applicable).
@@ -3166,10 +3166,10 @@ void InnerLoopVectorizer::createInductionResumeValues(
                                          StepType, true);
         Value *Step =
             CreateStepValue(II.getStep(), *PSE.getSE(), &*B.GetInsertPoint());
-        CRD =
-            B.CreateCast(CastOp, AdditionalBypass.second, StepType, "cast.crd");
+        VTC =
+            B.CreateCast(CastOp, AdditionalBypass.second, StepType, "cast.vtc");
         EndValueFromAdditionalBypass =
-            emitTransformedIndex(B, CRD, II.getStartValue(), Step, II);
+            emitTransformedIndex(B, VTC, II.getStartValue(), Step, II);
         EndValueFromAdditionalBypass->setName("ind.end");
       }
     }
@@ -3304,7 +3304,7 @@ InnerLoopVectorizer::createVectorizedLoopSkeleton() {
 // value for the IV when arriving directly from the middle block.
 void InnerLoopVectorizer::fixupIVUsers(PHINode *OrigPhi,
                                        const InductionDescriptor &II,
-                                       Value *CountRoundDown, Value *EndValue,
+                                       Value *VectorTripCount, Value *EndValue,
                                        BasicBlock *MiddleBlock,
                                        BasicBlock *VectorHeader) {
   // There are two kinds of external IV usages - those that use the value
@@ -3342,7 +3342,7 @@ void InnerLoopVectorizer::fixupIVUsers(PHINode *OrigPhi,
         B.setFastMathFlags(II.getInductionBinOp()->getFastMathFlags());
 
       Value *CountMinusOne = B.CreateSub(
-          CountRoundDown, ConstantInt::get(CountRoundDown->getType(), 1));
+          VectorTripCount, ConstantInt::get(VectorTripCount->getType(), 1));
       Value *CMO =
           !II.getStep()->getType()->isIntegerTy()
               ? B.CreateCast(Instruction::SIToFP, CountMinusOne,
@@ -7759,8 +7759,7 @@ EpilogueVectorizerMainLoop::createEpilogueVectorizedLoopSkeleton() {
       emitMinimumIterationCountCheck(LoopScalarPreHeader, false);
 
   // Generate the induction variable.
-  Value *CountRoundDown = getOrCreateVectorTripCount(LoopVectorPreHeader);
-  EPI.VectorTripCount = CountRoundDown;
+  EPI.VectorTripCount = getOrCreateVectorTripCount(LoopVectorPreHeader);
 
   // Skip induction resume value creation here because they will be created in
   // the second pass. If we created them here, they wouldn't be used anyway,