[analysis] Introduce an AnyCall helper class, for abstraction over different callables

A lot of code, particularly in the analyzer, has to perform a lot of
duplication to handle functions/ObjCMessages/destructors/constructors in
a generic setting.
The analyzer already has a CallEvent helper class abstracting over such
calls, but it's not always suitable, since it's tightly coupled to other
analyzer classes (ExplodedNode, ProgramState, etc.) and it's not always
possible to construct.

This change introduces a very simple, very lightweight helper class to
do simple generic operations over callables.

In future, parts of CallEvent could be changed to use this class to
avoid some duplication.

Differential Revision: https://reviews.llvm.org/D57126

llvm-svn: 352148

clang/include/clang/Analysis/AnyCall.h

@@ -0,0 +1,174 @@
+//=== AnyCall.h - Abstraction over different callables --------*- C++ -*--//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// A utility class for performing generic operations over different callables.
+//
+//===----------------------------------------------------------------------===//
+//
+#ifndef LLVM_CLANG_ANALYSIS_ANY_CALL_H
+#define LLVM_CLANG_ANALYSIS_ANY_CALL_H
+
+#include "clang/AST/Decl.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/ExprObjC.h"
+
+namespace clang {
+
+/// An instance of this class corresponds to a 'callable' call.
+class AnyCall {
+public:
+  enum Kind {
+    /// A function, function pointer, or a C++ method call
+    Function,
+
+    /// A call to an Objective-C method
+    ObjCMethod,
+
+    /// A call to an Objective-C block
+    Block,
+
+    /// An implicit C++ destructor call (called implicitly
+    /// or by operator 'delete')
+    Destructor,
+
+    /// An implicit or explicit C++ constructor call
+    Constructor,
+
+    /// A C++ allocation function call (operator `new`), via C++ new-expression
+    Allocator,
+
+    /// A C++ deallocation function call (operator `delete`), via C++
+    /// delete-expression
+    Deallocator
+  };
+
+private:
+  /// Call expression, remains null iff the call is an implicit destructor call.
+  const Expr *E = nullptr;
+
+  /// Corresponds to a statically known declaration of the called function,
+  /// or null if it is not known (e.g. for a function pointer).
+  const Decl *D = nullptr;
+  Kind K;
+
+  AnyCall(const Expr *E, const Decl *D, Kind K) : E(E), D(D), K(K) {}
+
+public:
+  AnyCall(const CallExpr *CE) : E(CE) {
+    D = CE->getCalleeDecl();
+    K = (CE->getCallee()->getType()->getAs<BlockPointerType>()) ? Block
+                                                                : Function;
+    if (D && ((K == Function && !isa<FunctionDecl>(D)) ||
+              (K == Block && !isa<BlockDecl>(D))))
+      D = nullptr;
+  }
+
+  AnyCall(const ObjCMessageExpr *ME)
+      : E(ME), D(ME->getMethodDecl()), K(ObjCMethod) {}
+
+  AnyCall(const CXXNewExpr *NE)
+      : E(NE), D(NE->getOperatorNew()), K(Allocator) {}
+
+  AnyCall(const CXXDeleteExpr *NE)
+      : E(NE), D(NE->getOperatorDelete()), K(Deallocator) {}
+
+  AnyCall(const CXXConstructExpr *NE)
+      : E(NE), D(NE->getConstructor()), K(Constructor) {}
+
+  /// If {@code E} is a generic call (to ObjC method /function/block/etc),
+  /// return a constructed {@code AnyCall} object. Return None otherwise.
+  static Optional<AnyCall> forExpr(const Expr *E) {
+    if (const auto *ME = dyn_cast<ObjCMessageExpr>(E)) {
+      return AnyCall(ME);
+    } else if (const auto *CE = dyn_cast<CallExpr>(E)) {
+      return AnyCall(CE);
+    } else if (const auto *CXNE = dyn_cast<CXXNewExpr>(E)) {
+      return AnyCall(CXNE);
+    } else if (const auto *CXDE = dyn_cast<CXXDeleteExpr>(E)) {
+      return AnyCall(CXDE);
+    } else if (const auto *CXCE = dyn_cast<CXXConstructExpr>(E)) {
+      return AnyCall(CXCE);
+    } else {
+      return None;
+    }
+  }
+
+  static AnyCall forDestructorCall(const CXXDestructorDecl *D) {
+    return AnyCall(/*E=*/nullptr, D, Destructor);
+  }
+
+  /// \returns formal parameters for direct calls (including virtual calls)
+  ArrayRef<ParmVarDecl *> parameters() const {
+    if (!D)
+      return None;
+
+    if (const auto *FD = dyn_cast<FunctionDecl>(D)) {
+      return FD->parameters();
+    } else if (const auto *MD = dyn_cast<ObjCMethodDecl>(D)) {
+      return MD->parameters();
+    } else if (const auto *CD = dyn_cast<CXXConstructorDecl>(D)) {
+      return CD->parameters();
+    } else if (const auto *BD = dyn_cast<BlockDecl>(D)) {
+      return BD->parameters();
+    } else {
+      return None;
+    }
+  }
+
+  using param_const_iterator = ArrayRef<ParmVarDecl *>::const_iterator;
+  param_const_iterator param_begin() const { return parameters().begin(); }
+  param_const_iterator param_end() const { return parameters().end(); }
+  size_t param_size() const { return parameters().size(); }
+  bool param_empty() const { return parameters().empty(); }
+
+  QualType getReturnType(ASTContext &Ctx) const {
+    switch (K) {
+    case Function:
+    case Block:
+      return cast<CallExpr>(E)->getCallReturnType(Ctx);
+    case ObjCMethod:
+      return cast<ObjCMessageExpr>(E)->getCallReturnType(Ctx);
+    case Destructor:
+    case Constructor:
+    case Allocator:
+    case Deallocator:
+      return cast<FunctionDecl>(D)->getReturnType();
+    }
+  }
+
+  /// \returns Function identifier if it is a named declaration,
+  /// {@code nullptr} otherwise.
+  const IdentifierInfo *getIdentifier() const {
+    if (const auto *ND = dyn_cast_or_null<NamedDecl>(D))
+      return ND->getIdentifier();
+    return nullptr;
+  }
+
+  const Decl *getDecl() const {
+    return D;
+  }
+
+  const Expr *getExpr() const {
+    return E;
+  }
+
+  Kind getKind() const {
+    return K;
+  }
+
+  void dump() const {
+    if (E)
+      E->dump();
+    if (D)
+      D->dump();
+  }
+};
+
+}
+
+#endif // LLVM_CLANG_ANALYSIS_ANY_CALL_H