[llvm] Add the 'initializes' attribute langref and support (PR #84803)

[Arthur Eubanks via llvm-commits]

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@@ -191,6 +192,36 @@ Attribute Attribute::get(LLVMContext &Context, Attribute::AttrKind Kind,
   return Attribute(PA);
 }
 
+Attribute Attribute::get(LLVMContext &Context, Attribute::AttrKind Kind,
+                         ArrayRef<ConstantRange> Val) {
+  assert(Attribute::isConstantRangeListAttrKind(Kind) &&
+         "Not a ConstantRangeList attribute");
+  LLVMContextImpl *pImpl = Context.pImpl;
+  FoldingSetNodeID ID;
+  ID.AddInteger(Kind);
+  ID.AddInteger(Val.size());
+  for (auto &CR : Val) {
+    CR.getLower().Profile(ID);
+    CR.getUpper().Profile(ID);
+  }
+
+  void *InsertPoint;
+  AttributeImpl *PA = pImpl->AttrsSet.FindNodeOrInsertPos(ID, InsertPoint);
+
+  if (!PA) {
+    // If we didn't find any existing attributes of the same shape then create a
+    // new one and insert it.
+    void *Mem = pImpl->Alloc.Allocate(
+        ConstantRangeListAttributeImpl::totalSizeToAlloc(Val),
+        alignof(ConstantRangeListAttributeImpl));
+    PA = new (Mem) ConstantRangeListAttributeImpl(Kind, Val);
+    pImpl->AttrsSet.InsertNode(PA, InsertPoint);
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aeubanks wrote:

hmm I'm not seeing where the existing ConstantRangeAttributeImpl's destructor gets called

https://github.com/llvm/llvm-project/pull/84803