Revert "[LoopVectorizer] NFCI: Calculate register usage based on TLI.getTypeLegalizationCost."

This reverts commits:
* [LoopVectorizer] NFCI: Calculate register usage based on TLI.getTypeLegalizationCost.
  b873aba.
* [LoopVectorizer] Silence warning in GetRegUsage.
  9ff7011.

Author: sdesmalen-arm

llvm/include/llvm/Analysis/TargetTransformInfo.h

@@ -708,9 +708,6 @@ class TargetTransformInfo {
   /// Return true if this type is legal.
   bool isTypeLegal(Type *Ty) const;
 
-  /// Returns the estimated number of registers required to represent \p Ty.
-  unsigned getRegUsageForType(Type *Ty) const;
-
   /// Return true if switches should be turned into lookup tables for the
   /// target.
   bool shouldBuildLookupTables() const;
@@ -1450,7 +1447,6 @@ class TargetTransformInfo::Concept {
   virtual bool isProfitableToHoist(Instruction *I) = 0;
   virtual bool useAA() = 0;
   virtual bool isTypeLegal(Type *Ty) = 0;
-  virtual unsigned getRegUsageForType(Type *Ty) = 0;
   virtual bool shouldBuildLookupTables() = 0;
   virtual bool shouldBuildLookupTablesForConstant(Constant *C) = 0;
   virtual bool useColdCCForColdCall(Function &F) = 0;
@@ -1811,9 +1807,6 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
   }
   bool useAA() override { return Impl.useAA(); }
   bool isTypeLegal(Type *Ty) override { return Impl.isTypeLegal(Ty); }
-  unsigned getRegUsageForType(Type *Ty) override {
-    return Impl.getRegUsageForType(Ty);
-  }
   bool shouldBuildLookupTables() override {
     return Impl.shouldBuildLookupTables();
   }

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -259,8 +259,6 @@ class TargetTransformInfoImplBase {
 
   bool isTypeLegal(Type *Ty) { return false; }
 
-  unsigned getRegUsageForType(Type *Ty) { return 1; }
-
   bool shouldBuildLookupTables() { return true; }
   bool shouldBuildLookupTablesForConstant(Constant *C) { return true; }
 

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -297,10 +297,6 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     return getTLI()->isTypeLegal(VT);
   }
 
-  unsigned getRegUsageForType(Type *Ty) {
-    return getTLI()->getTypeLegalizationCost(DL, Ty).first;
-  }
-
   int getGEPCost(Type *PointeeType, const Value *Ptr,
                  ArrayRef<const Value *> Operands) {
     return BaseT::getGEPCost(PointeeType, Ptr, Operands);

llvm/lib/Analysis/TargetTransformInfo.cpp

@@ -482,10 +482,6 @@ bool TargetTransformInfo::isTypeLegal(Type *Ty) const {
   return TTIImpl->isTypeLegal(Ty);
 }
 
-unsigned TargetTransformInfo::getRegUsageForType(Type *Ty) const {
-  return TTIImpl->getRegUsageForType(Ty);
-}
-
 bool TargetTransformInfo::shouldBuildLookupTables() const {
   return TTIImpl->shouldBuildLookupTables();
 }

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -5793,17 +5793,23 @@ LoopVectorizationCostModel::calculateRegisterUsage(ArrayRef<ElementCount> VFs) {
   unsigned MaxSafeDepDist = -1U;
   if (Legal->getMaxSafeDepDistBytes() != -1U)
     MaxSafeDepDist = Legal->getMaxSafeDepDistBytes() * 8;
+  unsigned WidestRegister =
+      std::min(TTI.getRegisterBitWidth(true), MaxSafeDepDist);
+  const DataLayout &DL = TheFunction->getParent()->getDataLayout();
 
   SmallVector<RegisterUsage, 8> RUs(VFs.size());
   SmallVector<SmallMapVector<unsigned, unsigned, 4>, 8> MaxUsages(VFs.size());
 
   LLVM_DEBUG(dbgs() << "LV(REG): Calculating max register usage:\n");
 
   // A lambda that gets the register usage for the given type and VF.
-  auto GetRegUsage = [&TTI=TTI](Type *Ty, ElementCount VF) {
+  auto GetRegUsage = [&DL, WidestRegister](Type *Ty, ElementCount VF) {
     if (Ty->isTokenTy())
       return 0U;
-    return TTI.getRegUsageForType(VectorType::get(Ty, VF));
+    unsigned TypeSize = DL.getTypeSizeInBits(Ty->getScalarType());
+    assert(!VF.isScalable() && "scalable vectors not yet supported.");
+    return std::max<unsigned>(1, VF.getKnownMinValue() * TypeSize /
+                                     WidestRegister);
   };
 
   for (unsigned int i = 0, s = IdxToInstr.size(); i < s; ++i) {