[CIR] Make PoisonAttr use AttrBuilderWithInferredContext (#1579)

Author: xlauko

clang/include/clang/CIR/Dialect/IR/CIRAttrs.td

@@ -268,13 +268,20 @@ def UndefAttr : CIR_Attr<"Undef", "undef", [TypedAttrInterface]> {
 //===----------------------------------------------------------------------===//
 
 def PoisonAttr : CIR_Attr<"Poison", "poison", [TypedAttrInterface]> {
-  let summary = "Represent an poison constant";
+  let summary = "Represent a typed poison constant";
   let description = [{
-    The PoisonAttr represents an poison constant, corresponding to LLVM's notion
-    of poison.
+    The PoisonAttr represents a typed poison constant, corresponding to LLVM's
+    notion of poison.
   }];
 
   let parameters = (ins AttributeSelfTypeParameter<"">:$type);
+
+  let builders = [
+    AttrBuilderWithInferredContext<(ins "mlir::Type":$type), [{
+      return $_get(type.getContext(), type);
+    }]>
+  ];
+
   let assemblyFormat = [{}];
 }
 

clang/lib/CIR/CodeGen/CIRGenBuiltinAArch64.cpp

@@ -2201,8 +2201,8 @@ static void vecExtendIntValue(CIRGenFunction &cgf, cir::VectorType argVTy,
   // it before inserting.
   arg = builder.createIntCast(arg, eltTy);
   mlir::Value zero = builder.getConstInt(loc, cgf.SizeTy, 0);
-  mlir::Value poison = builder.create<cir::ConstantOp>(
-      loc, builder.getAttr<cir::PoisonAttr>(eltTy));
+  mlir::Value poison =
+      builder.create<cir::ConstantOp>(loc, cir::PoisonAttr::get(eltTy));
   arg = builder.create<cir::VecInsertOp>(
       loc, builder.create<cir::VecSplatOp>(loc, argVTy, poison), arg, zero);
 }