[analyzer] For now, don't inline [cd]tors of C++ containers.

This is a heuristic to make up for the fact that the analyzer doesn't
model C++ containers very well. One example is modeling that
'std::distance(I, E) == 0' implies 'I == E'. In the future, it would be
nice to model this explicitly, but for now it just results in a lot of
false positives.

The actual heuristic checks if the base type has a member named 'begin' or
'iterator'. If so, we treat the constructors and destructors of that type
as opaque, rather than inlining them.

This is intended to drastically reduce the number of false positives
reported with experimental destructor support turned on. We can tweak the
heuristic in the future, but we'd rather err on the side of false negatives
for now.

<rdar://problem/13497258>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@178516 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/StaticAnalyzer/Core/AnalyzerOptions.h

@@ -198,6 +198,9 @@ private:
   /// \sa mayInlineTemplateFunctions
   Optional<bool> InlineTemplateFunctions;
 
+  /// \sa mayInlineCXXContainerCtorsAndDtors
+  Optional<bool> InlineCXXContainerCtorsAndDtors;
+
   /// \sa mayInlineObjCMethod
   Optional<bool> ObjCInliningMode;
 
@@ -281,6 +284,13 @@ public:
   /// accepts the values "true" and "false".
   bool mayInlineTemplateFunctions();
 
+  /// Returns whether or not constructors and destructors of C++ container
+  /// objects may be considered for inlining.
+  ///
+  /// This is controlled by the 'c++-container-inlining' config option, which
+  /// accepts the values "true" and "false".
+  bool mayInlineCXXContainerCtorsAndDtors();
+
   /// Returns whether or not paths that go through null returns should be
   /// suppressed.
   ///

lib/StaticAnalyzer/Core/AnalyzerOptions.cpp

@@ -134,6 +134,13 @@ bool AnalyzerOptions::mayInlineTemplateFunctions() {
                           /*Default=*/true);
 }
 
+bool AnalyzerOptions::mayInlineCXXContainerCtorsAndDtors() {
+  return getBooleanOption(InlineCXXContainerCtorsAndDtors,
+                          "c++-container-inlining",
+                          /*Default=*/false);
+}
+
+
 bool AnalyzerOptions::mayInlineObjCMethod() {
   return getBooleanOption(ObjCInliningMode,
                           "objc-inlining",

lib/StaticAnalyzer/Core/ExprEngineCallAndReturn.cpp

@@ -674,6 +674,53 @@ static CallInlinePolicy mayInlineCallKind(const CallEvent &Call,
   return CIP_Allowed;
 }
 
+/// Returns true if the given C++ class is a container.
+///
+/// Our heuristic for this is whether it contains a method named 'begin()' or a
+/// nested type named 'iterator'.
+static bool isContainerClass(const ASTContext &Ctx, const CXXRecordDecl *RD) {
+  // Don't record any path information.
+  CXXBasePaths Paths(false, false, false);
+
+  const IdentifierInfo &BeginII = Ctx.Idents.get("begin");
+  DeclarationName BeginName = Ctx.DeclarationNames.getIdentifier(&BeginII);
+  DeclContext::lookup_const_result BeginDecls = RD->lookup(BeginName);
+  if (!BeginDecls.empty())
+    return true;
+  if (RD->lookupInBases(&CXXRecordDecl::FindOrdinaryMember,
+                        BeginName.getAsOpaquePtr(),
+                        Paths))
+    return true;
+  
+  const IdentifierInfo &IterII = Ctx.Idents.get("iterator");
+  DeclarationName IteratorName = Ctx.DeclarationNames.getIdentifier(&IterII);
+  DeclContext::lookup_const_result IterDecls = RD->lookup(IteratorName);
+  if (!IterDecls.empty())
+    return true;
+  if (RD->lookupInBases(&CXXRecordDecl::FindOrdinaryMember,
+                        IteratorName.getAsOpaquePtr(),
+                        Paths))
+    return true;
+
+  return false;
+}
+
+/// Returns true if the given function refers to a constructor or destructor of
+/// a C++ container.
+///
+/// We generally do a poor job modeling most containers right now, and would
+/// prefer not to inline their methods.
+static bool isContainerCtorOrDtor(const ASTContext &Ctx,
+                                  const FunctionDecl *FD) {
+  // Heuristic: a type is a container if it contains a "begin()" method
+  // or a type named "iterator".
+  if (!(isa<CXXConstructorDecl>(FD) || isa<CXXDestructorDecl>(FD)))
+    return false;
+
+  const CXXRecordDecl *RD = cast<CXXMethodDecl>(FD)->getParent();
+  return isContainerClass(Ctx, RD);
+}
+
 /// Returns true if the function in \p CalleeADC may be inlined in general.
 ///
 /// This checks static properties of the function, such as its signature and
@@ -681,16 +728,14 @@ static CallInlinePolicy mayInlineCallKind(const CallEvent &Call,
 /// in any context.
 static bool mayInlineDecl(const CallEvent &Call, AnalysisDeclContext *CalleeADC,
                           AnalyzerOptions &Opts) {
-  const Decl *D = CalleeADC->getDecl();
-
   // FIXME: Do not inline variadic calls.
   if (Call.isVariadic())
     return false;
 
   // Check certain C++-related inlining policies.
-  ASTContext &Ctx = D->getASTContext();
+  ASTContext &Ctx = CalleeADC->getASTContext();
   if (Ctx.getLangOpts().CPlusPlus) {
-    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(CalleeADC->getDecl())) {
       // Conditionally control the inlining of template functions.
       if (!Opts.mayInlineTemplateFunctions())
         if (FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate)
@@ -701,6 +746,13 @@ static bool mayInlineDecl(const CallEvent &Call, AnalysisDeclContext *CalleeADC,
         if (Ctx.getSourceManager().isInSystemHeader(FD->getLocation()))
           if (IsInStdNamespace(FD))
             return false;
+
+      // Conditionally control the inlining of methods on objects that look
+      // like C++ containers.
+      if (!Opts.mayInlineCXXContainerCtorsAndDtors())
+        if (!Ctx.getSourceManager().isFromMainFile(FD->getLocation()))
+          if (isContainerCtorOrDtor(Ctx, FD))
+            return false;
     }
   }
 

test/Analysis/analyzer-config.cpp

@@ -11,6 +11,7 @@ public:
 };
 
 // CHECK: [config]
+// CHECK-NEXT: c++-container-inlining = false
 // CHECK-NEXT: c++-inlining = constructors
 // CHECK-NEXT: c++-stdlib-inlining = true
 // CHECK-NEXT: c++-template-inlining = true
@@ -25,4 +26,4 @@ public:
 // CHECK-NEXT: max-times-inline-large = 32
 // CHECK-NEXT: mode = deep
 // CHECK-NEXT: [stats]
-// CHECK-NEXT: num-entries = 13
+// CHECK-NEXT: num-entries = 14

test/Analysis/diagnostics/explicit-suppression.cpp

@@ -13,7 +13,7 @@ void testCopyNull(int *I, int *E) {
   std::copy(I, E, (int *)0);
 #ifndef SUPPRESSED
   // This line number comes from system-header-simulator-cxx.h.
-  // expected-warning@65 {{Dereference of null pointer}}
+  // expected-warning@79 {{Dereference of null pointer}}
 #endif
 }
 
@@ -56,6 +56,15 @@ void testCopyNull(int *I, int *E) {
 
 
 
+
+
+
+
+
+
+
+
+
 
 
 

test/Analysis/inlining/containers.cpp

@@ -0,0 +1,234 @@
+// RUN: %clang_cc1 -analyze -std=c++11 -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-inlining=destructors -analyzer-config c++-container-inlining=false -verify %s
+// RUN: %clang_cc1 -analyze -std=c++11 -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-inlining=destructors -analyzer-config c++-container-inlining=true -DINLINE=1 -verify %s
+
+#ifndef HEADER
+
+void clang_analyzer_eval(bool);
+void clang_analyzer_checkInlined(bool);
+
+#define HEADER
+#include "containers.cpp"
+#undef HEADER
+
+void test() {
+  MySet set(0);
+
+  clang_analyzer_eval(set.isEmpty());
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+
+  clang_analyzer_eval(set.raw_begin() == set.raw_end());
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+
+  clang_analyzer_eval(set.begin().impl == set.end().impl);
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+}
+
+void testSubclass(MySetSubclass &sub) {
+  sub.useIterator(sub.begin());
+
+  MySetSubclass local;
+}
+
+void testWrappers(BeginOnlySet &w1, IteratorStructOnlySet &w2,
+                  IteratorTypedefOnlySet &w3, IteratorUsingOnlySet &w4) {
+  BeginOnlySet local1;
+  IteratorStructOnlySet local2;
+  IteratorTypedefOnlySet local3;
+  IteratorUsingOnlySet local4;
+
+  clang_analyzer_eval(w1.begin().impl.impl == w1.begin().impl.impl);
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+
+  clang_analyzer_eval(w2.start().impl == w2.start().impl);
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+
+  clang_analyzer_eval(w3.start().impl == w3.start().impl);
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+
+  clang_analyzer_eval(w4.start().impl == w4.start().impl);
+#if INLINE
+  // expected-warning@-2 {{TRUE}}
+#else
+  // expected-warning@-4 {{UNKNOWN}}
+#endif
+}
+
+
+#else
+
+class MySet {
+  int *storage;
+  unsigned size;
+public:
+  MySet() : storage(0), size(0) {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  MySet(unsigned n) : storage(new int[n]), size(n) {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  ~MySet() { delete[] storage; }
+
+  bool isEmpty() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return size == 0;
+  }
+
+  struct iterator {
+    int *impl;
+
+    iterator(int *p) : impl(p) {}
+  };
+
+  iterator begin() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return iterator(storage);
+  }
+
+  iterator end() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return iterator(storage+size);
+  }
+
+  typedef int *raw_iterator;
+
+  raw_iterator raw_begin() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return storage;
+  }
+  raw_iterator raw_end() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return storage + size;
+  }
+};
+
+class MySetSubclass : public MySet {
+public:
+  MySetSubclass() {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  void useIterator(iterator i) {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+  }
+};
+
+class BeginOnlySet {
+  MySet impl;
+public:
+  struct IterImpl {
+    MySet::iterator impl;
+    IterImpl(MySet::iterator i) : impl(i) {
+      clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    }
+  };
+
+  BeginOnlySet() {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  typedef IterImpl wrapped_iterator;
+
+  wrapped_iterator begin() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return IterImpl(impl.begin());
+  }
+};
+
+class IteratorTypedefOnlySet {
+  MySet impl;
+public:
+
+  IteratorTypedefOnlySet() {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  typedef MySet::iterator iterator;
+
+  iterator start() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return impl.begin();
+  }
+};
+
+class IteratorUsingOnlySet {
+  MySet impl;
+public:
+
+  IteratorUsingOnlySet() {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  using iterator = MySet::iterator;
+
+  iterator start() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return impl.begin();
+  }
+};
+
+class IteratorStructOnlySet {
+  MySet impl;
+public:
+
+  IteratorStructOnlySet() {
+    clang_analyzer_checkInlined(true);
+#if INLINE
+    // expected-warning@-2 {{TRUE}}
+#endif
+  }
+
+  struct iterator {
+    int *impl;
+  };
+
+  iterator start() {
+    clang_analyzer_checkInlined(true); // expected-warning {{TRUE}}
+    return iterator{impl.begin().impl};
+  }
+};
+
+#endif

test/Analysis/inlining/stl.cpp

@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-stdlib-inlining=false -verify %s
-// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-stdlib-inlining=true -DINLINE=1 -verify %s
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-container-inlining=true -analyzer-config c++-stdlib-inlining=false -verify %s
+// RUN: %clang_cc1 -analyze -analyzer-checker=core,unix.Malloc,debug.ExprInspection -analyzer-config c++-container-inlining=true -analyzer-config c++-stdlib-inlining=true -DINLINE=1 -verify %s
 
 #include "../Inputs/system-header-simulator-cxx.h"