[CIR] [Codegen] Implement LValue emission for global variable declaration of reference type (#1899)

Fixes #1803

Author: badumbatish

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -935,7 +935,8 @@ static LValue emitGlobalVarDeclLValue(CIRGenFunction &CGF, const Expr *E,
   }
   LValue LV;
   if (VD->getType()->isReferenceType())
-    assert(0 && "NYI");
+    LV = CGF.emitLoadOfReferenceLValue(Addr, CGF.getLoc(E->getExprLoc()),
+                                       VD->getType(), AlignmentSource::Decl);
   else
     LV = CGF.makeAddrLValue(Addr, T, AlignmentSource::Decl);
   assert(!cir::MissingFeatures::setObjCGCLValueClass() && "NYI");

clang/test/CIR/CodeGen/static_class_ref.cpp

@@ -0,0 +1,31 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -fclangir -emit-cir -o - %s | FileCheck %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -fclangir -emit-llvm -o - %s | FileCheck %s -check-prefix=LLVM
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -O2 -emit-llvm -o - %s | FileCheck %s -check-prefix=OGCG
+
+// CIR: !rec_A = !cir.record<class "A" {!s32i} #cir.record.decl.ast>
+// CIR: cir.global "private" constant external @_ZN1B1AE : !cir.ptr<!rec_A> {alignment = 8 : i64}
+
+// LLVM: @_ZN1B1AE = external local_unnamed_addr constant ptr, align 8
+// OGCG: @_ZN1B1AE = external local_unnamed_addr constant ptr, align 8
+class A { int p = 1;};
+class B {
+public:
+  static A &A;
+};
+A& ref() {
+  // CIR-LABEL: _Z3refv
+  // CIR: [[GLOBAL:%.*]] = cir.get_global @_ZN1B1AE : !cir.ptr<!cir.ptr<!rec_A>>
+  // CIR: [[LD1:%.*]] = cir.load [[GLOBAL]] : !cir.ptr<!cir.ptr<!rec_A>>, !cir.ptr<!rec_A>
+  // CIR: cir.store align(8) [[LD1]], [[ALLOCA:%.*]] : !cir.ptr<!rec_A>, !cir.ptr<!cir.ptr<!rec_A>>
+  // CIR: [[LD2:%.*]] = cir.load [[ALLOCA:%.*]]: !cir.ptr<!cir.ptr<!rec_A>>, !cir.ptr<!rec_A>
+  // CIR: cir.return [[LD2]] : !cir.ptr<!rec_A>
+
+  // LLVM-LABEL: _Z3refv
+  // LLVM: [[LD:%.*]] = load ptr, ptr @_ZN1B1AE
+  // LLVM-NEXT: ret ptr [[LD]]
+
+  // OGCG-LABEL: _Z3refv
+  // OGCG: [[LD:%.*]] = load ptr, ptr @_ZN1B1AE
+  // OGCG-NEXT: ret ptr [[LD]]
+  return B::A;
+}