[CIR} Add support for static member variable instantiation (#153200)

This patch handles both implicit and explicit template instantiations of
template class static member variables.

Author: mmha

clang/lib/CIR/CodeGen/CIRGenModule.cpp

@@ -438,6 +438,20 @@ void CIRGenModule::emitGlobalFunctionDefinition(clang::GlobalDecl gd,
     errorNYI(funcDecl->getSourceRange(), "deferredAnnotations");
 }
 
+void CIRGenModule::handleCXXStaticMemberVarInstantiation(VarDecl *vd) {
+  VarDecl::DefinitionKind dk = vd->isThisDeclarationADefinition();
+  if (dk == VarDecl::Definition && vd->hasAttr<DLLImportAttr>())
+    return;
+
+  TemplateSpecializationKind tsk = vd->getTemplateSpecializationKind();
+  // If we have a definition, this might be a deferred decl. If the
+  // instantiation is explicit, make sure we emit it at the end.
+  if (vd->getDefinition() && tsk == TSK_ExplicitInstantiationDefinition)
+    getAddrOfGlobalVar(vd);
+
+  emitTopLevelDecl(vd);
+}
+
 mlir::Operation *CIRGenModule::getGlobalValue(StringRef name) {
   return mlir::SymbolTable::lookupSymbolIn(theModule, name);
 }

clang/lib/CIR/CodeGen/CIRGenModule.h

@@ -120,6 +120,9 @@ class CIRGenModule : public CIRGenTypeCache {
 
   mlir::Operation *lastGlobalOp = nullptr;
 
+  /// Tell the consumer that this variable has been instantiated.
+  void handleCXXStaticMemberVarInstantiation(VarDecl *vd);
+
   llvm::DenseMap<const Decl *, cir::GlobalOp> staticLocalDeclMap;
 
   mlir::Operation *getGlobalValue(llvm::StringRef ref);

clang/lib/CIR/CodeGen/CIRGenerator.cpp

@@ -163,7 +163,7 @@ void CIRGenerator::HandleCXXStaticMemberVarInstantiation(VarDecl *D) {
   if (diags.hasErrorOccurred())
     return;
 
-  cgm->errorNYI(D->getSourceRange(), "HandleCXXStaticMemberVarInstantiation");
+  cgm->handleCXXStaticMemberVarInstantiation(D);
 }
 
 void CIRGenerator::CompleteTentativeDefinition(VarDecl *d) {

clang/test/CIR/CodeGen/static-vars.cpp

@@ -2,6 +2,37 @@
 // RUN: FileCheck --input-file=%t.cir %s
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t1.ll
 // RUN: FileCheck --check-prefix=LLVM --input-file=%t1.ll %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o %t1.ll
+// RUN: FileCheck --check-prefix=OGCG --input-file=%t1.ll %s
+
+template<typename T>
+struct implicitly_instantiated {
+  static T member;
+};
+
+template<typename T>
+T implicitly_instantiated<T>::member = 12345;
+
+int use_implicitly_instantiated() {
+  return implicitly_instantiated<int>::member;
+}
+
+// CHECK-DAG: cir.global linkonce_odr comdat @_ZN23implicitly_instantiatedIiE6memberE = #cir.int<12345> : !s32i
+// LLVM-DAG: @_ZN23implicitly_instantiatedIiE6memberE = linkonce_odr global i32 12345, comdat
+// OGCG-DAG: @_ZN23implicitly_instantiatedIiE6memberE = linkonce_odr global i32 12345, comdat
+
+template<typename T>
+struct explicitly_instantiated {
+    static T member;
+};
+
+template<typename T>
+T explicitly_instantiated<T>::member = 54321;
+
+template int explicitly_instantiated<int>::member;
+// CHECK-DAG: cir.global weak_odr comdat @_ZN23explicitly_instantiatedIiE6memberE = #cir.int<54321> : !s32i
+// LLVM-DAG: @_ZN23explicitly_instantiatedIiE6memberE = weak_odr global i32 54321, comdat
+// OGCG-DAG: @_ZN23explicitly_instantiatedIiE6memberE = weak_odr global i32 54321, comdat
 
 void func1(void) {
   // Should lower default-initialized static vars.
@@ -42,6 +73,8 @@ void func2(void) {
 
 // LLVM-DAG: $_ZZ4testvE1c = comdat any
 // LLVM-DAG: @_ZZ4testvE1c = linkonce_odr global i32 0, comdat, align 4
+// OGCG-DAG: $_ZZ4testvE1c = comdat any
+// OGCG-DAG: @_ZZ4testvE1c = linkonce_odr global i32 0, comdat, align 4
 
 inline void test() { static int c; }
 // CHECK-LABEL: @_Z4testv