[System Model] [TTI] Move default cache/prefetch implementations

[greened]

Summary

Move the default implementations of cache and prefetch queries to TargetTransformInfoImplBase and delete them from NoTIIImpl. This brings these interfaces in line with how other TTI interfaces work.

[hfinkel]

LGTM

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

public:
 
   bool
   shouldConsiderAddressTypePromotion(const Instruction &I,
                                      bool &AllowPromotionWithoutCommonHeader) {
     AllowPromotionWithoutCommonHeader = false;
     return false;
   }
 
+  unsigned getCacheLineSize() const { return 0; }
+
+  llvm::Optional<unsigned> getCacheSize(TargetTransformInfo::CacheLevel Level) const {
+    switch (Level) {
+    case TargetTransformInfo::CacheLevel::L1D:
+      LLVM_FALLTHROUGH;
+    case TargetTransformInfo::CacheLevel::L2D:
+      return llvm::Optional<unsigned>();
+    }
+    llvm_unreachable("Unknown TargetTransformInfo::CacheLevel");
+  }
+
+  llvm::Optional<unsigned> getCacheAssociativity(
+    TargetTransformInfo::CacheLevel Level) const {
+    switch (Level) {
+    case TargetTransformInfo::CacheLevel::L1D:
+      LLVM_FALLTHROUGH;
+    case TargetTransformInfo::CacheLevel::L2D:
+      return llvm::Optional<unsigned>();
+    }
+
+    llvm_unreachable("Unknown TargetTransformInfo::CacheLevel");
+  }
+
+  unsigned getPrefetchDistance() const { return 0; }
+  unsigned getMinPrefetchStride() const { return 1; }
+  unsigned getMaxPrefetchIterationsAhead() const { return UINT_MAX; }
+
   unsigned getMaxInterleaveFactor(unsigned VF) { return 1; }
 
   unsigned getArithmeticInstrCost(unsigned Opcode, Type *Ty,
                                   TTI::OperandValueKind Opd1Info,
                                   TTI::OperandValueKind Opd2Info,
                                   TTI::OperandValueProperties Opd1PropInfo,
                                   TTI::OperandValueProperties Opd2PropInfo,
                                   ArrayRef<const Value *> Args) {

llvm/include/llvm/CodeGen/BasicTTIImpl.h

public:
   virtual Optional<unsigned>
   getCacheSize(TargetTransformInfo::CacheLevel Level) const {
     return Optional<unsigned>(
       getST()->getCacheSize(static_cast<unsigned>(Level)));
   }
 
   virtual Optional<unsigned>
   getCacheAssociativity(TargetTransformInfo::CacheLevel Level) const {
-    return Optional<unsigned>(
-      getST()->getCacheAssociativity(static_cast<unsigned>(Level)));
+    Optional<unsigned> TargetResult =
+        getST()->getCacheAssociativity(static_cast<unsigned>(Level));
+
+    if (TargetResult)
+      return TargetResult;
+
+    return BaseT::getCacheAssociativity(Level);
   }
 
   virtual unsigned getCacheLineSize() const {
     return getST()->getCacheLineSize();
   }
 
   virtual unsigned getPrefetchDistance() const {
     return getST()->getPrefetchDistance();

llvm/lib/Analysis/TargetTransformInfo.cpp

 namespace {
 /// No-op implementation of the TTI interface using the utility base
 /// classes.
 ///
 /// This is used when no target specific information is available.
 struct NoTTIImpl : TargetTransformInfoImplCRTPBase<NoTTIImpl> {
   explicit NoTTIImpl(const DataLayout &DL)
       : TargetTransformInfoImplCRTPBase<NoTTIImpl>(DL) {}
-
-  unsigned getCacheLineSize() const { return 0; }
-
-  llvm::Optional<unsigned> getCacheSize(TargetTransformInfo::CacheLevel Level) const {
-    switch (Level) {
-    case TargetTransformInfo::CacheLevel::L1D:
-      LLVM_FALLTHROUGH;
-    case TargetTransformInfo::CacheLevel::L2D:
-      return llvm::Optional<unsigned>();
-    }
-    llvm_unreachable("Unknown TargetTransformInfo::CacheLevel");
-  }
-
-  llvm::Optional<unsigned> getCacheAssociativity(
-    TargetTransformInfo::CacheLevel Level) const {
-    switch (Level) {
-    case TargetTransformInfo::CacheLevel::L1D:
-      LLVM_FALLTHROUGH;
-    case TargetTransformInfo::CacheLevel::L2D:
-      return llvm::Optional<unsigned>();
-    }
-
-    llvm_unreachable("Unknown TargetTransformInfo::CacheLevel");
-  }
-
-  unsigned getPrefetchDistance() const { return 0; }
-  unsigned getMinPrefetchStride() const { return 1; }
-  unsigned getMaxPrefetchIterationsAhead() const { return UINT_MAX; }
 };
 }
 
 bool HardwareLoopInfo::canAnalyze(LoopInfo &LI) {
   // If the loop has irreducible control flow, it can not be converted to
   // Hardware loop.
   LoopBlocksRPO RPOT(L);  
   RPOT.perform(&LI);