[CIR] Handle vtable pure and deleted virtual functions (#183862)

Finding reproducers for these that don't use the deferred vtable (which
    we haven't yet implemented) was a bit of a challenge, but I found
this setup to get these to be emitted. Fortunately it is a quite easy
implementation that doesn't do awfully much.

This patch implements both, plus the name through the itanium ABI.

clang/lib/CIR/CodeGen/CIRGenCXXABI.h

@@ -290,6 +290,9 @@ public:
       CIRGenFunction &cgf, const CXXRecordDecl *vtableClass, BaseSubobject base,
       const CXXRecordDecl *nearestVBase) = 0;
 
+  virtual llvm::StringRef getPureVirtualCallName() = 0;
+  virtual llvm::StringRef getDeletedVirtualCallName() = 0;
+
   /// Insert any ABI-specific implicit parameters into the parameter list for a
   /// function. This generally involves extra data for constructors and
   /// destructors.

clang/lib/CIR/CodeGen/CIRGenItaniumCXXABI.cpp

@@ -139,6 +139,12 @@ public:
 
   mlir::Attribute getAddrOfRTTIDescriptor(mlir::Location loc,
                                           QualType ty) override;
+
+  StringRef getPureVirtualCallName() override { return "__cxa_pure_virtual"; }
+  StringRef getDeletedVirtualCallName() override {
+    return "__cxa_deleted_virtual";
+  }
+
   CatchTypeInfo
   getAddrOfCXXCatchHandlerType(mlir::Location loc, QualType ty,
                                QualType catchHandlerType) override {

clang/lib/CIR/CodeGen/CIRGenVTables.cpp

@@ -176,13 +176,33 @@ mlir::Attribute CIRGenVTables::getVTableComponent(
 
     assert(!cir::MissingFeatures::cudaSupport());
 
+    auto getSpecialVirtFn = [&](StringRef name) -> cir::FuncOp {
+      assert(!cir::MissingFeatures::vtableRelativeLayout());
+
+      if (cgm.getLangOpts().OpenMP && cgm.getLangOpts().OpenMPIsTargetDevice &&
+          cgm.getTriple().isNVPTX())
+        cgm.errorNYI(gd.getDecl()->getSourceRange(),
+                     "getVTableComponent for OMP Device NVPTX");
+
+      cir::FuncType fnTy =
+          cgm.getBuilder().getFuncType({}, cgm.getBuilder().getVoidTy());
+      cir::FuncOp fnPtr = cgm.createRuntimeFunction(fnTy, name);
+
+      assert(!cir::MissingFeatures::opGlobalUnnamedAddr());
+      return fnPtr;
+    };
+
     cir::FuncOp fnPtr;
     if (cast<CXXMethodDecl>(gd.getDecl())->isPureVirtual()) {
-      cgm.errorNYI("getVTableComponent: CK_FunctionPointer: pure virtual");
-      return mlir::Attribute();
+      if (!pureVirtualFn)
+        pureVirtualFn =
+            getSpecialVirtFn(cgm.getCXXABI().getPureVirtualCallName());
+      fnPtr = pureVirtualFn;
     } else if (cast<CXXMethodDecl>(gd.getDecl())->isDeleted()) {
-      cgm.errorNYI("getVTableComponent: CK_FunctionPointer: deleted virtual");
-      return mlir::Attribute();
+      if (!deletedVirtualFn)
+        deletedVirtualFn =
+            getSpecialVirtFn(cgm.getCXXABI().getDeletedVirtualCallName());
+      fnPtr = deletedVirtualFn;
     } else if (nextVTableThunkIndex < layout.vtable_thunks().size() &&
                layout.vtable_thunks()[nextVTableThunkIndex].first ==
                    componentIndex) {

clang/lib/CIR/CodeGen/CIRGenVTables.h

@@ -46,6 +46,11 @@ class CIRGenVTables {
   /// indices.
   SecondaryVirtualPointerIndicesMapTy secondaryVirtualPointerIndices;
 
+  /// Cache for the pure virtual member call function.
+  cir::FuncOp pureVirtualFn = nullptr;
+  /// Cache for the deleted virtual member call function.
+  cir::FuncOp deletedVirtualFn = nullptr;
+
   mlir::Attribute
   getVTableComponent(const VTableLayout &layout, unsigned componentIndex,
                      mlir::Attribute rtti, unsigned &nextVTableThunkIndex,

clang/test/CIR/CodeGenCXX/vtable-pure-deleted-funcs.cpp

@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir -mmlir --mlir-print-ir-before=cir-lowering-prepare %s -o %t.cir 2> %t-before.cir
+// RUN: FileCheck %s --input-file=%t-before.cir --check-prefixes=CIR
+// RUN: FileCheck %s --input-file=%t.cir --check-prefixes=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o - | FileCheck %s --check-prefixes=LLVM,LLVM-CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm %s -o - | FileCheck %s --check-prefixes=LLVM,LLVM-OGCG
+
+struct Struct {
+  virtual void f1() = 0;
+  virtual void f2() = delete;
+  virtual void f3();
+};
+
+void Struct::f3(){}
+
+
+// CIR: cir.global "private" external @_ZTV6Struct = #cir.vtable<{#cir.const_array<[#cir.ptr<null> : !cir.ptr<!u8i>, #cir.global_view<@_ZTI6Struct> : !cir.ptr<!u8i>, #cir.global_view<@__cxa_pure_virtual> : !cir.ptr<!u8i>, #cir.global_view<@__cxa_deleted_virtual> : !cir.ptr<!u8i>, #cir.global_view<@_ZN6Struct2f3Ev> : !cir.ptr<!u8i>]> : !cir.array<!cir.ptr<!u8i> x 5>}>
+// LLVM: @_ZTV6Struct = {{.*}}{ [5 x ptr] } { [5 x ptr] [ptr null, ptr @_ZTI6Struct, ptr @__cxa_pure_virtual, ptr @__cxa_deleted_virtual, ptr @_ZN6Struct2f3Ev] }
+
+// CIR: cir.global constant external @_ZTI6Struct = #cir.typeinfo<{#cir.global_view<@_ZTVN10__cxxabiv117__class_type_infoE, [2 : i32]> : !cir.ptr<!u8i>, #cir.global_view<@_ZTS6Struct> : !cir.ptr<!u8i>}>
+// LLVM-CIR: @_ZTI6Struct = constant { ptr, ptr } { ptr getelementptr (i8, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 16), ptr @_ZTS6Struct }
+// LLVM-OGCG: @_ZTI6Struct = constant { ptr, ptr } { ptr getelementptr inbounds (ptr, ptr @_ZTVN10__cxxabiv117__class_type_infoE, i64 2), ptr @_ZTS6Struct }
+//
+// CIR: cir.func private dso_local @__cxa_pure_virtual()
+// LLVM: declare {{.*}}void @__cxa_pure_virtual()
+//
+// CIR: cir.func private dso_local @__cxa_deleted_virtual()
+// LLVM: declare {{.*}}void @__cxa_deleted_virtual()