[Attributes] Add additional MemoryEffects APIs (NFC)

This adds the usual complement of APIs for creating and fetching
a non-trivial attribute.

Split out from D135780.

Author: nikic

llvm/include/llvm/IR/Attributes.h

@@ -146,6 +146,7 @@ class Attribute {
   static Attribute getWithPreallocatedType(LLVMContext &Context, Type *Ty);
   static Attribute getWithInAllocaType(LLVMContext &Context, Type *Ty);
   static Attribute getWithUWTableKind(LLVMContext &Context, UWTableKind Kind);
+  static Attribute getWithMemoryEffects(LLVMContext &Context, MemoryEffects ME);
 
   /// For a typed attribute, return the equivalent attribute with the type
   /// changed to \p ReplacementTy.
@@ -379,6 +380,7 @@ class AttributeSet {
   Optional<unsigned> getVScaleRangeMax() const;
   UWTableKind getUWTableKind() const;
   AllocFnKind getAllocKind() const;
+  MemoryEffects getMemoryEffects() const;
   std::string getAsString(bool InAttrGrp = false) const;
 
   /// Return true if this attribute set belongs to the LLVMContext.
@@ -878,6 +880,9 @@ class AttributeList {
 
   AllocFnKind getAllocKind() const;
 
+  /// Returns memory effects of the function.
+  MemoryEffects getMemoryEffects() const;
+
   /// Return the attributes at the index as a string.
   std::string getAsString(unsigned Index, bool InAttrGrp = false) const;
 

llvm/lib/IR/AttributeImpl.h

@@ -263,6 +263,7 @@ class AttributeSetNode final
   Optional<unsigned> getVScaleRangeMax() const;
   UWTableKind getUWTableKind() const;
   AllocFnKind getAllocKind() const;
+  MemoryEffects getMemoryEffects() const;
   std::string getAsString(bool InAttrGrp) const;
   Type *getAttributeType(Attribute::AttrKind Kind) const;
 

llvm/lib/IR/Attributes.cpp

@@ -211,6 +211,11 @@ Attribute Attribute::getWithUWTableKind(LLVMContext &Context,
   return get(Context, UWTable, uint64_t(Kind));
 }
 
+Attribute Attribute::getWithMemoryEffects(LLVMContext &Context,
+                                          MemoryEffects ME) {
+  return get(Context, Memory, ME.toIntValue());
+}
+
 Attribute
 Attribute::getWithAllocSizeArgs(LLVMContext &Context, unsigned ElemSizeArg,
                                 const Optional<unsigned> &NumElemsArg) {
@@ -831,6 +836,10 @@ AllocFnKind AttributeSet::getAllocKind() const {
   return SetNode ? SetNode->getAllocKind() : AllocFnKind::Unknown;
 }
 
+MemoryEffects AttributeSet::getMemoryEffects() const {
+  return SetNode ? SetNode->getMemoryEffects() : MemoryEffects::unknown();
+}
+
 std::string AttributeSet::getAsString(bool InAttrGrp) const {
   return SetNode ? SetNode->getAsString(InAttrGrp) : "";
 }
@@ -1009,6 +1018,12 @@ AllocFnKind AttributeSetNode::getAllocKind() const {
   return AllocFnKind::Unknown;
 }
 
+MemoryEffects AttributeSetNode::getMemoryEffects() const {
+  if (auto A = findEnumAttribute(Attribute::Memory))
+    return A->getMemoryEffects();
+  return MemoryEffects::unknown();
+}
+
 std::string AttributeSetNode::getAsString(bool InAttrGrp) const {
   std::string Str;
   for (iterator I = begin(), E = end(); I != E; ++I) {
@@ -1561,6 +1576,10 @@ AllocFnKind AttributeList::getAllocKind() const {
   return getFnAttrs().getAllocKind();
 }
 
+MemoryEffects AttributeList::getMemoryEffects() const {
+  return getFnAttrs().getMemoryEffects();
+}
+
 std::string AttributeList::getAsString(unsigned Index, bool InAttrGrp) const {
   return getAttributes(Index).getAsString(InAttrGrp);
 }