[CIR] Add support for destructing class members

[andykaylor]

This adds the necessary cleanup handling to get class destructors to call the destructor for fields that require it.

[llvmbot]

@llvm/pr-subscribers-clangir

@llvm/pr-subscribers-clang

Author: Andy Kaylor (andykaylor)

Changes

This adds the necessary cleanup handling to get class destructors to call the destructor for fields that require it.

---

Full diff: https://github.com/llvm/llvm-project/pull/162196.diff

4 Files Affected:

• (modified) clang/lib/CIR/CodeGen/CIRGenClass.cpp (+103)
• (modified) clang/lib/CIR/CodeGen/CIRGenFunction.cpp (+10-4)
• (modified) clang/lib/CIR/CodeGen/CIRGenFunction.h (+27)
• (modified) clang/test/CIR/CodeGen/dtors.cpp (+37)

diff --git a/clang/lib/CIR/CodeGen/CIRGenClass.cpp b/clang/lib/CIR/CodeGen/CIRGenClass.cpp
index 8f4377b435775..d9ebf19534dc4 100644
--- a/clang/lib/CIR/CodeGen/CIRGenClass.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenClass.cpp
@@ -870,6 +870,109 @@ void CIRGenFunction::destroyCXXObject(CIRGenFunction &cgf, Address addr,
                             /*delegating=*/false, addr, type);
 }
 
+namespace {
+class DestroyField final : public EHScopeStack::Cleanup {
+  const FieldDecl *field;
+  CIRGenFunction::Destroyer *destroyer;
+
+public:
+  DestroyField(const FieldDecl *field, CIRGenFunction::Destroyer *destroyer)
+      : field(field), destroyer(destroyer) {}
+
+  void emit(CIRGenFunction &cgf) override {
+    // Find the address of the field.
+    Address thisValue = cgf.loadCXXThisAddress();
+    CanQualType recordTy =
+        cgf.getContext().getCanonicalTagType(field->getParent());
+    LValue thisLV = cgf.makeAddrLValue(thisValue, recordTy);
+    LValue lv = cgf.emitLValueForField(thisLV, field);
+    assert(lv.isSimple());
+
+    assert(!cir::MissingFeatures::ehCleanupFlags());
+    cgf.emitDestroy(lv.getAddress(), field->getType(), destroyer);
+  }
+
+  // This is a placeholder until EHCleanupScope is implemented.
+  size_t getSize() const override {
+    assert(!cir::MissingFeatures::ehCleanupScope());
+    return sizeof(DestroyField);
+  }
+};
+} // namespace
+
+/// Emit all code that comes at the end of class's destructor. This is to call
+/// destructors on members and base classes in reverse order of their
+/// construction.
+///
+/// For a deleting destructor, this also handles the case where a destroying
+/// operator delete completely overrides the definition.
+void CIRGenFunction::enterDtorCleanups(const CXXDestructorDecl *dd,
+                                       CXXDtorType dtorType) {
+  assert((!dd->isTrivial() || dd->hasAttr<DLLExportAttr>()) &&
+         "Should not emit dtor epilogue for non-exported trivial dtor!");
+
+  // The deleting-destructor phase just needs to call the appropriate
+  // operator delete that Sema picked up.
+  if (dtorType == Dtor_Deleting) {
+    cgm.errorNYI(dd->getSourceRange(), "deleting destructor cleanups");
+    return;
+  }
+
+  const CXXRecordDecl *classDecl = dd->getParent();
+
+  // Unions have no bases and do not call field destructors.
+  if (classDecl->isUnion())
+    return;
+
+  // The complete-destructor phase just destructs all the virtual bases.
+  if (dtorType == Dtor_Complete) {
+    assert(!cir::MissingFeatures::sanitizers());
+
+    if (classDecl->getNumVBases())
+      cgm.errorNYI(dd->getSourceRange(), "virtual base destructor cleanups");
+
+    return;
+  }
+
+  assert(dtorType == Dtor_Base);
+  assert(!cir::MissingFeatures::sanitizers());
+
+  // Destroy non-virtual bases.
+  for (const CXXBaseSpecifier &base : classDecl->bases()) {
+    // Ignore virtual bases.
+    if (base.isVirtual())
+      continue;
+
+    CXXRecordDecl *baseClassDecl = base.getType()->getAsCXXRecordDecl();
+
+    if (baseClassDecl->hasTrivialDestructor())
+      assert(!cir::MissingFeatures::sanitizers());
+    else
+      cgm.errorNYI(dd->getSourceRange(),
+                   "non-trivial base destructor cleanups");
+  }
+
+  assert(!cir::MissingFeatures::sanitizers());
+
+  // Destroy direct fields.
+  for (const FieldDecl *field : classDecl->fields()) {
+    QualType type = field->getType();
+    QualType::DestructionKind dtorKind = type.isDestructedType();
+    if (!dtorKind)
+      continue;
+
+    // Anonymous union members do not have their destructors called.
+    const RecordType *rt = type->getAsUnionType();
+    if (rt && rt->getOriginalDecl()->isAnonymousStructOrUnion())
+      continue;
+
+    CleanupKind cleanupKind = getCleanupKind(dtorKind);
+    assert(!cir::MissingFeatures::ehCleanupFlags());
+    ehStack.pushCleanup<DestroyField>(cleanupKind, field,
+                                      getDestroyer(dtorKind));
+  }
+}
+
 void CIRGenFunction::emitDelegatingCXXConstructorCall(
     const CXXConstructorDecl *ctor, const FunctionArgList &args) {
   assert(ctor->isDelegatingConstructor());
diff --git a/clang/lib/CIR/CodeGen/CIRGenFunction.cpp b/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
index 52fb0d758dff8..7a774e0441bbb 100644
--- a/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
+++ b/clang/lib/CIR/CodeGen/CIRGenFunction.cpp
@@ -689,7 +689,9 @@ void CIRGenFunction::emitDestructorBody(FunctionArgList &args) {
     cgm.errorNYI(dtor->getSourceRange(), "function-try-block destructor");
 
   assert(!cir::MissingFeatures::sanitizers());
-  assert(!cir::MissingFeatures::dtorCleanups());
+
+  // Enter the epilogue cleanups.
+  RunCleanupsScope dtorEpilogue(*this);
 
   // If this is the complete variant, just invoke the base variant;
   // the epilogue will destruct the virtual bases.  But we can't do
@@ -708,7 +710,8 @@ void CIRGenFunction::emitDestructorBody(FunctionArgList &args) {
     assert((body || getTarget().getCXXABI().isMicrosoft()) &&
            "can't emit a dtor without a body for non-Microsoft ABIs");
 
-    assert(!cir::MissingFeatures::dtorCleanups());
+    // Enter the cleanup scopes for virtual bases.
+    enterDtorCleanups(dtor, Dtor_Complete);
 
     if (!isTryBody) {
       QualType thisTy = dtor->getFunctionObjectParameterType();
@@ -723,7 +726,9 @@ void CIRGenFunction::emitDestructorBody(FunctionArgList &args) {
   case Dtor_Base:
     assert(body);
 
-    assert(!cir::MissingFeatures::dtorCleanups());
+    // Enter the cleanup scopes for fields and non-virtual bases.
+    enterDtorCleanups(dtor, Dtor_Base);
+
     assert(!cir::MissingFeatures::vtableInitialization());
 
     if (isTryBody) {
@@ -741,7 +746,8 @@ void CIRGenFunction::emitDestructorBody(FunctionArgList &args) {
     break;
   }
 
-  assert(!cir::MissingFeatures::dtorCleanups());
+  // Jump out through the epilogue cleanups.
+  dtorEpilogue.forceCleanup();
 
   // Exit the try if applicable.
   if (isTryBody)
diff --git a/clang/lib/CIR/CodeGen/CIRGenFunction.h b/clang/lib/CIR/CodeGen/CIRGenFunction.h
index cbc0f4a068d7b..9162c36aaaa9f 100644
--- a/clang/lib/CIR/CodeGen/CIRGenFunction.h
+++ b/clang/lib/CIR/CodeGen/CIRGenFunction.h
@@ -556,6 +556,33 @@ class CIRGenFunction : public CIRGenTypeCache {
                                               cir::GlobalOp gv,
                                               cir::GetGlobalOp gvAddr);
 
+  /// Enter the cleanups necessary to complete the given phase of destruction
+  /// for a destructor. The end result should call destructors on members and
+  /// base classes in reverse order of their construction.
+  void enterDtorCleanups(const CXXDestructorDecl *dtor, CXXDtorType type);
+
+  /// Determines whether an EH cleanup is required to destroy a type
+  /// with the given destruction kind.
+  /// TODO(cir): could be shared with Clang LLVM codegen
+  bool needsEHCleanup(QualType::DestructionKind kind) {
+    switch (kind) {
+    case QualType::DK_none:
+      return false;
+    case QualType::DK_cxx_destructor:
+    case QualType::DK_objc_weak_lifetime:
+    case QualType::DK_nontrivial_c_struct:
+      return getLangOpts().Exceptions;
+    case QualType::DK_objc_strong_lifetime:
+      return getLangOpts().Exceptions &&
+             cgm.getCodeGenOpts().ObjCAutoRefCountExceptions;
+    }
+    llvm_unreachable("bad destruction kind");
+  }
+
+  CleanupKind getCleanupKind(QualType::DestructionKind kind) {
+    return (needsEHCleanup(kind) ? NormalAndEHCleanup : NormalCleanup);
+  }
+
   /// Set the address of a local variable.
   void setAddrOfLocalVar(const clang::VarDecl *vd, Address addr) {
     assert(!localDeclMap.count(vd) && "Decl already exists in LocalDeclMap!");
diff --git a/clang/test/CIR/CodeGen/dtors.cpp b/clang/test/CIR/CodeGen/dtors.cpp
index 66554b70e1700..49952a79c2cec 100644
--- a/clang/test/CIR/CodeGen/dtors.cpp
+++ b/clang/test/CIR/CodeGen/dtors.cpp
@@ -171,3 +171,40 @@ bool test_temp_and() { return make_temp(1) && make_temp(2); }
 // OGCG:   br label %[[CLEANUP_DONE]]
 // OGCG: [[CLEANUP_DONE]]:
 // OGCG:   call void @_ZN1BD2Ev(ptr {{.*}} %[[REF_TMP0]])
+
+struct C {
+  ~C();
+};
+
+struct D {
+  int n;
+  C c;
+  ~D() {}
+};
+
+// CIR: cir.func {{.*}} @_ZN1DD2Ev
+// CIR:   %[[C:.*]] = cir.get_member %{{.*}}[1] {name = "c"}
+// CIR:   cir.call @_ZN1CD1Ev(%[[C]])
+
+// LLVM: define {{.*}} void @_ZN1DD2Ev
+// LLVM:   %[[C:.*]] = getelementptr %struct.D, ptr %{{.*}}, i32 0, i32 1
+// LLVM:   call void @_ZN1CD1Ev(ptr %[[C]])
+
+// This destructor is defined after the calling function in OGCG.
+
+void test_nested_dtor() {
+  D d;
+}
+
+// CIR: cir.func{{.*}} @_Z16test_nested_dtorv()
+// CIR:   cir.call @_ZN1DD2Ev(%{{.*}})
+
+// LLVM: define {{.*}} void @_Z16test_nested_dtorv()
+// LLVM:   call void @_ZN1DD2Ev(ptr %{{.*}})
+
+// OGCG: define {{.*}} void @_Z16test_nested_dtorv()
+// OGCG:   call void @_ZN1DD2Ev(ptr {{.*}} %{{.*}})
+
+// OGCG: define {{.*}} void @_ZN1DD2Ev
+// OGCG:   %[[C:.*]] = getelementptr inbounds i8, ptr %{{.*}}, i64 4
+// OGCG:   call void @_ZN1CD1Ev(ptr {{.*}} %[[C]])