[AArch64] Add an AArch64 pass for loop idiom transformations

llvm/include/llvm/Analysis/TargetTransformInfo.h

@@ -1174,6 +1174,9 @@ class TargetTransformInfo {
   /// \return The associativity of the cache level, if available.
   std::optional<unsigned> getCacheAssociativity(CacheLevel Level) const;
 
+  /// \return The minimum architectural page size for the target.
+  std::optional<unsigned> getMinPageSize() const;
+
   /// \return How much before a load we should place the prefetch
   /// instruction.  This is currently measured in number of
   /// instructions.
@@ -1923,6 +1926,7 @@ class TargetTransformInfo::Concept {
   virtual std::optional<unsigned> getCacheSize(CacheLevel Level) const = 0;
   virtual std::optional<unsigned> getCacheAssociativity(CacheLevel Level)
       const = 0;
+  virtual std::optional<unsigned> getMinPageSize() const = 0;
 
   /// \return How much before a load we should place the prefetch
   /// instruction.  This is currently measured in number of
@@ -2520,6 +2524,10 @@ class TargetTransformInfo::Model final : public TargetTransformInfo::Concept {
     return Impl.getCacheAssociativity(Level);
   }
 
+  std::optional<unsigned> getMinPageSize() const override {
+    return Impl.getMinPageSize();
+  }
+
   /// Return the preferred prefetch distance in terms of instructions.
   ///
   unsigned getPrefetchDistance() const override {

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -501,6 +501,8 @@ class TargetTransformInfoImplBase {
     llvm_unreachable("Unknown TargetTransformInfo::CacheLevel");
   }
 
+  std::optional<unsigned> getMinPageSize() const { return {}; }
+
   unsigned getPrefetchDistance() const { return 0; }
   unsigned getMinPrefetchStride(unsigned NumMemAccesses,
                                 unsigned NumStridedMemAccesses,

llvm/lib/Analysis/TargetTransformInfo.cpp

@@ -37,6 +37,10 @@ static cl::opt<unsigned> CacheLineSize(
     cl::desc("Use this to override the target cache line size when "
              "specified by the user."));
 
+static cl::opt<unsigned> MinPageSize(
+    "min-page-size", cl::init(0), cl::Hidden,
+    cl::desc("Use this to override the target's minimum page size."));
+
 static cl::opt<unsigned> PredictableBranchThreshold(
     "predictable-branch-threshold", cl::init(99), cl::Hidden,
     cl::desc(
@@ -762,6 +766,11 @@ TargetTransformInfo::getCacheAssociativity(CacheLevel Level) const {
   return TTIImpl->getCacheAssociativity(Level);
 }
 
+std::optional<unsigned> TargetTransformInfo::getMinPageSize() const {
+  return MinPageSize.getNumOccurrences() > 0 ? MinPageSize
+                                             : TTIImpl->getMinPageSize();
+}
+
 unsigned TargetTransformInfo::getPrefetchDistance() const {
   return TTIImpl->getPrefetchDistance();
 }

llvm/lib/Target/AArch64/AArch64.h

@@ -88,6 +88,7 @@ void initializeAArch64DeadRegisterDefinitionsPass(PassRegistry&);
 void initializeAArch64ExpandPseudoPass(PassRegistry &);
 void initializeAArch64GlobalsTaggingPass(PassRegistry &);
 void initializeAArch64LoadStoreOptPass(PassRegistry&);
+void initializeAArch64LoopIdiomTransformLegacyPassPass(PassRegistry &);
 void initializeAArch64LowerHomogeneousPrologEpilogPass(PassRegistry &);
 void initializeAArch64MIPeepholeOptPass(PassRegistry &);
 void initializeAArch64O0PreLegalizerCombinerPass(PassRegistry &);