[CIR] Add initial support for operator delete (#160574)

This adds basic operator delete handling in CIR. This does not yet
handle destroying delete or array delete, which will be added later. It
also does not insert non-null checks when not optimizing for size.

Author: andykaylor

clang/include/clang/CIR/MissingFeatures.h

@@ -208,6 +208,7 @@ struct MissingFeatures {
   static bool dataLayoutTypeAllocSize() { return false; }
   static bool dataLayoutTypeStoreSize() { return false; }
   static bool deferredCXXGlobalInit() { return false; }
+  static bool deleteArray() { return false; }
   static bool devirtualizeMemberFunction() { return false; }
   static bool ehCleanupFlags() { return false; }
   static bool ehCleanupScope() { return false; }
@@ -219,6 +220,7 @@ struct MissingFeatures {
   static bool emitCondLikelihoodViaExpectIntrinsic() { return false; }
   static bool emitLifetimeMarkers() { return false; }
   static bool emitLValueAlignmentAssumption() { return false; }
+  static bool emitNullCheckForDeleteCalls() { return false; }
   static bool emitNullabilityCheck() { return false; }
   static bool emitTypeCheck() { return false; }
   static bool emitTypeMetadataCodeForVCall() { return false; }

clang/lib/CIR/CodeGen/CIRGenExprCXX.cpp

@@ -210,6 +210,60 @@ RValue CIRGenFunction::emitCXXMemberOrOperatorCall(
   return emitCall(fnInfo, callee, returnValue, args, nullptr, loc);
 }
 
+namespace {
+/// The parameters to pass to a usual operator delete.
+struct UsualDeleteParams {
+  TypeAwareAllocationMode typeAwareDelete = TypeAwareAllocationMode::No;
+  bool destroyingDelete = false;
+  bool size = false;
+  AlignedAllocationMode alignment = AlignedAllocationMode::No;
+};
+} // namespace
+
+// FIXME(cir): this should be shared with LLVM codegen
+static UsualDeleteParams getUsualDeleteParams(const FunctionDecl *fd) {
+  UsualDeleteParams params;
+
+  const FunctionProtoType *fpt = fd->getType()->castAs<FunctionProtoType>();
+  auto ai = fpt->param_type_begin(), ae = fpt->param_type_end();
+
+  if (fd->isTypeAwareOperatorNewOrDelete()) {
+    params.typeAwareDelete = TypeAwareAllocationMode::Yes;
+    assert(ai != ae);
+    ++ai;
+  }
+
+  // The first argument after the type-identity parameter (if any) is
+  // always a void* (or C* for a destroying operator delete for class
+  // type C).
+  ++ai;
+
+  // The next parameter may be a std::destroying_delete_t.
+  if (fd->isDestroyingOperatorDelete()) {
+    params.destroyingDelete = true;
+    assert(ai != ae);
+    ++ai;
+  }
+
+  // Figure out what other parameters we should be implicitly passing.
+  if (ai != ae && (*ai)->isIntegerType()) {
+    params.size = true;
+    ++ai;
+  } else {
+    assert(!isTypeAwareAllocation(params.typeAwareDelete));
+  }
+
+  if (ai != ae && (*ai)->isAlignValT()) {
+    params.alignment = AlignedAllocationMode::Yes;
+    ++ai;
+  } else {
+    assert(!isTypeAwareAllocation(params.typeAwareDelete));
+  }
+
+  assert(ai == ae && "unexpected usual deallocation function parameter");
+  return params;
+}
+
 static mlir::Value emitCXXNewAllocSize(CIRGenFunction &cgf, const CXXNewExpr *e,
                                        unsigned minElements,
                                        mlir::Value &numElements,
@@ -332,6 +386,117 @@ static RValue emitNewDeleteCall(CIRGenFunction &cgf,
   return rv;
 }
 
+namespace {
+/// Calls the given 'operator delete' on a single object.
+struct CallObjectDelete final : EHScopeStack::Cleanup {
+  mlir::Value ptr;
+  const FunctionDecl *operatorDelete;
+  QualType elementType;
+
+  CallObjectDelete(mlir::Value ptr, const FunctionDecl *operatorDelete,
+                   QualType elementType)
+      : ptr(ptr), operatorDelete(operatorDelete), elementType(elementType) {}
+
+  void emit(CIRGenFunction &cgf) override {
+    cgf.emitDeleteCall(operatorDelete, ptr, elementType);
+  }
+
+  // This is a placeholder until EHCleanupScope is implemented.
+  size_t getSize() const override {
+    assert(!cir::MissingFeatures::ehCleanupScope());
+    return sizeof(CallObjectDelete);
+  }
+};
+} // namespace
+
+/// Emit the code for deleting a single object.
+static void emitObjectDelete(CIRGenFunction &cgf, const CXXDeleteExpr *de,
+                             Address ptr, QualType elementType) {
+  // C++11 [expr.delete]p3:
+  //   If the static type of the object to be deleted is different from its
+  //   dynamic type, the static type shall be a base class of the dynamic type
+  //   of the object to be deleted and the static type shall have a virtual
+  //   destructor or the behavior is undefined.
+  assert(!cir::MissingFeatures::emitTypeCheck());
+
+  const FunctionDecl *operatorDelete = de->getOperatorDelete();
+  assert(!operatorDelete->isDestroyingOperatorDelete());
+
+  // Find the destructor for the type, if applicable.  If the
+  // destructor is virtual, we'll just emit the vcall and return.
+  const CXXDestructorDecl *dtor = nullptr;
+  if (const auto *rd = elementType->getAsCXXRecordDecl()) {
+    if (rd->hasDefinition() && !rd->hasTrivialDestructor()) {
+      dtor = rd->getDestructor();
+
+      if (dtor->isVirtual()) {
+        cgf.cgm.errorNYI(de->getSourceRange(),
+                         "emitObjectDelete: virtual destructor");
+      }
+    }
+  }
+
+  // Make sure that we call delete even if the dtor throws.
+  // This doesn't have to a conditional cleanup because we're going
+  // to pop it off in a second.
+  cgf.ehStack.pushCleanup<CallObjectDelete>(
+      NormalAndEHCleanup, ptr.getPointer(), operatorDelete, elementType);
+
+  if (dtor) {
+    cgf.emitCXXDestructorCall(dtor, Dtor_Complete,
+                              /*ForVirtualBase=*/false,
+                              /*Delegating=*/false, ptr, elementType);
+  } else if (elementType.getObjCLifetime()) {
+    assert(!cir::MissingFeatures::objCLifetime());
+    cgf.cgm.errorNYI(de->getSourceRange(), "emitObjectDelete: ObjCLifetime");
+  }
+
+  // In traditional LLVM codegen null checks are emitted to save a delete call.
+  // In CIR we optimize for size by default, the null check should be added into
+  // this function callers.
+  assert(!cir::MissingFeatures::emitNullCheckForDeleteCalls());
+
+  cgf.popCleanupBlock();
+}
+
+void CIRGenFunction::emitCXXDeleteExpr(const CXXDeleteExpr *e) {
+  const Expr *arg = e->getArgument();
+  Address ptr = emitPointerWithAlignment(arg);
+
+  // Null check the pointer.
+  //
+  // We could avoid this null check if we can determine that the object
+  // destruction is trivial and doesn't require an array cookie; we can
+  // unconditionally perform the operator delete call in that case. For now, we
+  // assume that deleted pointers are null rarely enough that it's better to
+  // keep the branch. This might be worth revisiting for a -O0 code size win.
+  //
+  // CIR note: emit the code size friendly by default for now, such as mentioned
+  // in `emitObjectDelete`.
+  assert(!cir::MissingFeatures::emitNullCheckForDeleteCalls());
+  QualType deleteTy = e->getDestroyedType();
+
+  // A destroying operator delete overrides the entire operation of the
+  // delete expression.
+  if (e->getOperatorDelete()->isDestroyingOperatorDelete()) {
+    cgm.errorNYI(e->getSourceRange(),
+                 "emitCXXDeleteExpr: destroying operator delete");
+    return;
+  }
+
+  // We might be deleting a pointer to array.
+  deleteTy = getContext().getBaseElementType(deleteTy);
+  ptr = ptr.withElementType(builder, convertTypeForMem(deleteTy));
+
+  if (e->isArrayForm()) {
+    assert(!cir::MissingFeatures::deleteArray());
+    cgm.errorNYI(e->getSourceRange(), "emitCXXDeleteExpr: array delete");
+    return;
+  } else {
+    emitObjectDelete(*this, e, ptr, deleteTy);
+  }
+}
+
 mlir::Value CIRGenFunction::emitCXXNewExpr(const CXXNewExpr *e) {
   // The element type being allocated.
   QualType allocType = getContext().getBaseElementType(e->getAllocatedType());
@@ -443,3 +608,53 @@ mlir::Value CIRGenFunction::emitCXXNewExpr(const CXXNewExpr *e) {
                      allocSizeWithoutCookie);
   return result.getPointer();
 }
+
+void CIRGenFunction::emitDeleteCall(const FunctionDecl *deleteFD,
+                                    mlir::Value ptr, QualType deleteTy) {
+  assert(!cir::MissingFeatures::deleteArray());
+
+  const auto *deleteFTy = deleteFD->getType()->castAs<FunctionProtoType>();
+  CallArgList deleteArgs;
+
+  UsualDeleteParams params = getUsualDeleteParams(deleteFD);
+  auto paramTypeIt = deleteFTy->param_type_begin();
+
+  // Pass std::type_identity tag if present
+  if (isTypeAwareAllocation(params.typeAwareDelete))
+    cgm.errorNYI(deleteFD->getSourceRange(),
+                 "emitDeleteCall: type aware delete");
+
+  // Pass the pointer itself.
+  QualType argTy = *paramTypeIt++;
+  mlir::Value deletePtr =
+      builder.createBitcast(ptr.getLoc(), ptr, convertType(argTy));
+  deleteArgs.add(RValue::get(deletePtr), argTy);
+
+  // Pass the std::destroying_delete tag if present.
+  if (params.destroyingDelete)
+    cgm.errorNYI(deleteFD->getSourceRange(),
+                 "emitDeleteCall: destroying delete");
+
+  // Pass the size if the delete function has a size_t parameter.
+  if (params.size) {
+    QualType sizeType = *paramTypeIt++;
+    CharUnits deleteTypeSize = getContext().getTypeSizeInChars(deleteTy);
+    assert(mlir::isa<cir::IntType>(convertType(sizeType)) &&
+           "expected cir::IntType");
+    cir::ConstantOp size = builder.getConstInt(
+        *currSrcLoc, convertType(sizeType), deleteTypeSize.getQuantity());
+
+    deleteArgs.add(RValue::get(size), sizeType);
+  }
+
+  // Pass the alignment if the delete function has an align_val_t parameter.
+  if (isAlignedAllocation(params.alignment))
+    cgm.errorNYI(deleteFD->getSourceRange(),
+                 "emitDeleteCall: aligned allocation");
+
+  assert(paramTypeIt == deleteFTy->param_type_end() &&
+         "unknown parameter to usual delete function");
+
+  // Emit the call to delete.
+  emitNewDeleteCall(*this, deleteFD, deleteFTy, deleteArgs);
+}

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -687,6 +687,10 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
   mlir::Value VisitCXXNewExpr(const CXXNewExpr *e) {
     return cgf.emitCXXNewExpr(e);
   }
+  mlir::Value VisitCXXDeleteExpr(const CXXDeleteExpr *e) {
+    cgf.emitCXXDeleteExpr(e);
+    return {};
+  }
 
   mlir::Value VisitCXXThrowExpr(const CXXThrowExpr *e) {
     cgf.emitCXXThrowExpr(e);

clang/lib/CIR/CodeGen/CIRGenFunction.h

@@ -1197,6 +1197,8 @@ class CIRGenFunction : public CIRGenTypeCache {
                               bool delegating, Address thisAddr,
                               CallArgList &args, clang::SourceLocation loc);
 
+  void emitCXXDeleteExpr(const CXXDeleteExpr *e);
+
   void emitCXXDestructorCall(const CXXDestructorDecl *dd, CXXDtorType type,
                              bool forVirtualBase, bool delegating,
                              Address thisAddr, QualType thisTy);
@@ -1244,6 +1246,9 @@ class CIRGenFunction : public CIRGenTypeCache {
   void emitDelegatingCXXConstructorCall(const CXXConstructorDecl *ctor,
                                         const FunctionArgList &args);
 
+  void emitDeleteCall(const FunctionDecl *deleteFD, mlir::Value ptr,
+                      QualType deleteTy);
+
   mlir::LogicalResult emitDoStmt(const clang::DoStmt &s);
 
   /// Emit an expression as an initializer for an object (variable, field, etc.)

clang/test/CIR/CodeGen/delete.cpp

@@ -0,0 +1,88 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -fclangir -mconstructor-aliases -emit-cir %s -o %t.cir
+// RUN: FileCheck --check-prefix=CIR --input-file=%t.cir %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -fclangir -mconstructor-aliases -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --check-prefix=LLVM --input-file=%t-cir.ll %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -std=c++20 -mconstructor-aliases -emit-llvm %s -o %t.ll
+// RUN: FileCheck --check-prefix=OGCG --input-file=%t.ll %s
+
+typedef __typeof(sizeof(int)) size_t;
+
+struct SizedDelete {
+  void operator delete(void*, size_t);
+  int member;
+};
+void test_sized_delete(SizedDelete *x) {
+  delete x;
+}
+
+// SizedDelete::operator delete(void*, unsigned long)
+// CIR:  cir.func private @_ZN11SizedDeletedlEPvm(!cir.ptr<!void>, !u64i)
+// LLVM: declare void @_ZN11SizedDeletedlEPvm(ptr, i64)
+
+// CIR: cir.func dso_local @_Z17test_sized_deleteP11SizedDelete
+// CIR:   %[[X:.*]] = cir.load{{.*}} %{{.*}}
+// CIR:   %[[X_CAST:.*]] = cir.cast(bitcast, %[[X]] : !cir.ptr<!rec_SizedDelete>), !cir.ptr<!void>
+// CIR:   %[[OBJ_SIZE:.*]] = cir.const #cir.int<4> : !u64i
+// CIR:   cir.call @_ZN11SizedDeletedlEPvm(%[[X_CAST]], %[[OBJ_SIZE]]) nothrow : (!cir.ptr<!void>, !u64i) -> ()
+
+// LLVM: define dso_local void @_Z17test_sized_deleteP11SizedDelete
+// LLVM:   %[[X:.*]] = load ptr, ptr %{{.*}}
+// LLVM:   call void @_ZN11SizedDeletedlEPvm(ptr %[[X]], i64 4)
+
+// OGCG: define dso_local void @_Z17test_sized_deleteP11SizedDelete
+// OGCG:   %[[X:.*]] = load ptr, ptr %{{.*}}
+// OGCG:   %[[ISNULL:.*]] = icmp eq ptr %[[X]], null
+// OGCG:   br i1 %[[ISNULL]], label %{{.*}}, label %[[DELETE_NOTNULL:.*]]
+// OGCG: [[DELETE_NOTNULL]]:
+// OGCG:   call void @_ZN11SizedDeletedlEPvm(ptr noundef %[[X]], i64 noundef 4)
+
+// This function is declared below the call in OGCG.
+// OGCG: declare void @_ZN11SizedDeletedlEPvm(ptr noundef, i64 noundef)
+
+struct Contents {
+  ~Contents() {}
+};
+struct Container {
+  Contents *contents;
+  ~Container();
+};
+Container::~Container() { delete contents; }
+
+// Contents::~Contents()
+// CIR: cir.func comdat linkonce_odr @_ZN8ContentsD2Ev
+// LLVM: define linkonce_odr void @_ZN8ContentsD2Ev
+
+// operator delete(void*, unsigned long)
+// CIR: cir.func private @_ZdlPvm(!cir.ptr<!void>, !u64i)
+// LLVM: declare void @_ZdlPvm(ptr, i64)
+
+// Container::~Container()
+// CIR: cir.func dso_local @_ZN9ContainerD2Ev
+// CIR:   %[[THIS:.*]] = cir.load %{{.*}}
+// CIR:   %[[CONTENTS_PTR_ADDR:.*]] = cir.get_member %[[THIS]][0] {name = "contents"} : !cir.ptr<!rec_Container> -> !cir.ptr<!cir.ptr<!rec_Contents>>
+// CIR:   %[[CONTENTS_PTR:.*]] = cir.load{{.*}} %[[CONTENTS_PTR_ADDR]]
+// CIR:   cir.call @_ZN8ContentsD2Ev(%[[CONTENTS_PTR]]) nothrow : (!cir.ptr<!rec_Contents>) -> ()
+// CIR:   %[[CONTENTS_CAST:.*]] = cir.cast(bitcast, %[[CONTENTS_PTR]] : !cir.ptr<!rec_Contents>), !cir.ptr<!void>
+// CIR:   %[[OBJ_SIZE:.*]] = cir.const #cir.int<1> : !u64i
+// CIR:   cir.call @_ZdlPvm(%[[CONTENTS_CAST]], %[[OBJ_SIZE]]) nothrow : (!cir.ptr<!void>, !u64i) -> ()
+
+// LLVM: define dso_local void @_ZN9ContainerD2Ev
+// LLVM:   %[[THIS:.*]] = load ptr, ptr %{{.*}}
+// LLVM:   %[[CONTENTS_PTR_ADDR:.*]] = getelementptr %struct.Container, ptr %[[THIS]], i32 0, i32 0
+// LLVM:   %[[CONTENTS_PTR:.*]] = load ptr, ptr %[[CONTENTS_PTR_ADDR]]
+// LLVM:   call void @_ZN8ContentsD2Ev(ptr %[[CONTENTS_PTR]])
+// LLVM:   call void @_ZdlPvm(ptr %[[CONTENTS_PTR]], i64 1)
+
+// OGCG: define dso_local void @_ZN9ContainerD2Ev
+// OGCG:   %[[THIS:.*]] = load ptr, ptr %{{.*}}
+// OGCG:   %[[CONTENTS:.*]] = getelementptr inbounds nuw %struct.Container, ptr %[[THIS]], i32 0, i32 0
+// OGCG:   %[[CONTENTS_PTR:.*]] = load ptr, ptr %[[CONTENTS]]
+// OGCG:   %[[ISNULL:.*]] = icmp eq ptr %[[CONTENTS_PTR]], null
+// OGCG:   br i1 %[[ISNULL]], label %{{.*}}, label %[[DELETE_NOTNULL:.*]]
+// OGCG: [[DELETE_NOTNULL]]:
+// OGCG:   call void @_ZN8ContentsD2Ev(ptr noundef nonnull align 1 dereferenceable(1) %[[CONTENTS_PTR]])
+// OGCG:   call void @_ZdlPvm(ptr noundef %[[CONTENTS_PTR]], i64 noundef 1)
+
+// These functions are declared/defined below the calls in OGCG.
+// OGCG: define linkonce_odr void @_ZN8ContentsD2Ev
+// OGCG: declare void @_ZdlPvm(ptr noundef, i64 noundef)