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

[Jan Voung via llvm-commits]

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@@ -2032,6 +2033,30 @@ void Verifier::verifyParameterAttrs(AttributeSet Attrs, Type *Ty,
     }
   }
 
+  if (Attrs.hasAttribute(Attribute::Initializes)) {
+    auto Inits = Attrs.getAttribute(Attribute::Initializes)
+                     .getValueAsConstantRangeList();
+    Check(!Inits.isEmptySet(),
+          "Attribute 'initializes' does not support empty list", V);
+    Check(!Inits.isFullSet(),
+          "Attribute 'initializes' does not support full list", V);
+
+    Check(Inits.getRange(0).getLower().slt(Inits.getRange(0).getUpper()),
+          "Attribute 'initializes' requires interval lower less than upper", V);
+    for (size_t i = 1; i < Inits.size(); i++) {
+      auto Previous = Inits.getRange(i - 1);
+      auto Current = Inits.getRange(i);
+      Check(Current.getLower().slt(Current.getUpper()),
+            "Attribute 'initializes' requires interval lower less than upper",
+            V);
+      Check(Current.getLower().sge(Previous.getLower()),
+            "Attribute 'initializes' requires intervals in ascending order!",
+            V);
+      Check(Current.getLower().sge(Previous.getUpper()),
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jvoung wrote:

should this be sgt ?

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