APValues and Constants and MaterializedTemporaryExpr need to have stable maps

[majnemer]

Summary

We risk iterator invalidation issues if we use DenseMap structures for
MaterializedTemporaryExprs. Use a std::map to ensure that they don't
move around in memory.

This fixes PR24289.

[rsmith]

include/clang/AST/ASTContext.h

180

I would prefer a DenseMap<const MaterializedTemporaryExpr*, APValue*>, with APValues allocated by the ASTContext's BumpPtrAllocator.

[majnemer]

• Address Justin's review comments.
• Address Richard's review comments.

[rsmith]

lib/AST/ASTContext.cpp

8558

Maybe use a reference here rather than a pointer.

8560–8561

More succinctly expressed as:

MTVI = new (*this) APValue;

8561–8562

This is now just MaterializedTemporaryValues.lookup(E)

lib/CodeGen/CodeGenModule.h

377

Can you fix this instead by not holding onto Slot in CodeGenModule::GetAddrOfGlobalTemporary? (Do the map lookup again at the end of the function.) Twice as many DenseMap lookups seems likely to be cheaper than switching to a std::map.

[majnemer]

• Address Richard's latest review comments.

[rsmith]

LGTM

include/clang/AST/ASTContext.h

class ASTContext : public RefCountedBase<ASTContext> {
     
   /// \brief Mapping from class scope functions specialization to their
   /// template patterns.
   llvm::DenseMap<const FunctionDecl*, FunctionDecl*>
     ClassScopeSpecializationPattern;
 
   /// \brief Mapping from materialized temporaries with static storage duration
   /// that appear in constant initializers to their evaluated values.
-  llvm::DenseMap<const MaterializeTemporaryExpr*, APValue>
+  std::map<const MaterializeTemporaryExpr *, APValue>
     MaterializedTemporaryValues;
 
   /// \brief Representation of a "canonical" template template parameter that
   /// is used in canonical template names.
   class CanonicalTemplateTemplateParm : public llvm::FoldingSetNode {
     TemplateTemplateParmDecl *Parm;
     
   public:

lib/AST/ASTContext.cpp

 
 APValue *
 ASTContext::getMaterializedTemporaryValue(const MaterializeTemporaryExpr *E,
                                           bool MayCreate) {
   assert(E && E->getStorageDuration() == SD_Static &&
          "don't need to cache the computed value for this temporary");
   if (MayCreate)
     return &MaterializedTemporaryValues[E];
 
-  llvm::DenseMap<const MaterializeTemporaryExpr *, APValue>::iterator I =
+  std::map<const MaterializeTemporaryExpr *, APValue>::iterator I =
       MaterializedTemporaryValues.find(E);
   return I == MaterializedTemporaryValues.end() ? nullptr : &I->second;
 }
 
 bool ASTContext::AtomicUsesUnsupportedLibcall(const AtomicExpr *E) const {
   const llvm::Triple &T = getTargetInfo().getTriple();
   if (!T.isOSDarwin())
     return false;
 
   if (!(T.isiOS() && T.isOSVersionLT(7)) &&
       !(T.isMacOSX() && T.isOSVersionLT(10, 9)))

lib/CodeGen/CodeGenModule.h

private:
   /// Map used to get unique annotation strings.
   llvm::StringMap<llvm::Constant*> AnnotationStrings;
 
   llvm::StringMap<llvm::GlobalVariable *> CFConstantStringMap;
 
   llvm::DenseMap<llvm::Constant *, llvm::GlobalVariable *> ConstantStringMap;
   llvm::DenseMap<const Decl*, llvm::Constant *> StaticLocalDeclMap;
   llvm::DenseMap<const Decl*, llvm::GlobalVariable*> StaticLocalDeclGuardMap;
-  llvm::DenseMap<const Expr*, llvm::Constant *> MaterializedGlobalTemporaryMap;
+  std::map<const Expr*, llvm::Constant *> MaterializedGlobalTemporaryMap;
 
   llvm::DenseMap<QualType, llvm::Constant *> AtomicSetterHelperFnMap;
   llvm::DenseMap<QualType, llvm::Constant *> AtomicGetterHelperFnMap;
 
   /// Map used to get unique type descriptor constants for sanitizers.
   llvm::DenseMap<QualType, llvm::Constant *> TypeDescriptorMap;
 
   /// Map used to track internal linkage functions declared within

test/CodeGenCXX/PR24289.cpp

+// RUN: %clang_cc1 -emit-llvm %s -o - -triple=x86_64-pc-linux-gnu -std=c++11 | FileCheck %s
+
+namespace std {
+template <class T>
+struct initializer_list {
+  const T *Begin;
+  __SIZE_TYPE__ Size;
+
+  constexpr initializer_list(const T *B, __SIZE_TYPE__ S)
+      : Begin(B), Size(S) {}
+};
+}
+
+void f() {
+  static std::initializer_list<std::initializer_list<int>> a{
+      {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}};
+  static std::initializer_list<std::initializer_list<int>> b{
+      {0}, {0}, {0}, {0}};
+  static std::initializer_list<std::initializer_list<int>> c{
+      {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}};
+  static std::initializer_list<std::initializer_list<int>> d{
+      {0}, {0}, {0}, {0}, {0}};
+  static std::initializer_list<std::initializer_list<int>> e{
+      {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}, {0}};
+}
+
+// CHECK-DAG: @_ZZ1fvE1a = internal global %{{.*}} { %{{.*}}* getelementptr inbounds ([14 x %{{.*}}], [14 x %{{.*}}]
+// CHECK-DAG: * @_ZGRZ1fvE1a_, i32 0, i32 0), i64 14 }
+// CHECK-DAG: @_ZGRZ1fvE1a0_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a1_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a2_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a3_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a4_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a5_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a6_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a7_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a8_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a9_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1aA_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1aB_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1aC_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1aD_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1a_ = internal constant [14 x %{{.*}}] [%{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a0_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a1_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a2_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a3_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a4_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a5_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a6_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a7_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a8_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1a9_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1aA_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1aB_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1aC_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1aD_, i32 0, i32 0), i64 1 }]
+// CHECK-DAG: @_ZZ1fvE1b = internal global %{{.*}} { %{{.*}}* getelementptr inbounds ([4 x %{{.*}}], [4 x %{{.*}}]*
+// CHECK-DAG: @_ZGRZ1fvE1b_, i32 0, i32 0), i64 4 }
+// CHECK-DAG: @_ZGRZ1fvE1b0_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1b1_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1b2_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1b3_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1b_ = internal constant [4 x %{{.*}}] [%{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1b0_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1b1_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1b2_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1b3_, i32 0, i32 0), i64 1 }]
+// CHECK-DAG: @_ZZ1fvE1c = internal global %{{.*}} { %{{.*}}* getelementptr inbounds ([9 x %{{.*}}], [9 x %{{.*}}]*
+// CHECK-DAG: @_ZGRZ1fvE1c_, i32 0, i32 0), i64 9 }
+// CHECK-DAG: @_ZGRZ1fvE1c0_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c1_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c2_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c3_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c4_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c5_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c6_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c7_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c8_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1c_ = internal constant [9 x %{{.*}}] [%{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c0_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c1_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c2_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c3_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c4_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c5_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c6_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c7_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1c8_, i32 0, i32 0), i64 1 }]
+// CHECK-DAG: @_ZZ1fvE1d = internal global %{{.*}} { %{{.*}}* getelementptr inbounds ([5 x %{{.*}}], [5 x %{{.*}}]* @_ZGRZ1fvE1d_, i32 0, i32 0), i64 5 }
+// CHECK-DAG: @_ZGRZ1fvE1d0_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1d1_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1d2_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1d3_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1d4_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1d_ = internal constant [5 x %{{.*}}] [%{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1d0_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1d1_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1d2_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1d3_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1d4_, i32 0, i32 0), i64 1 }]
+// CHECK-DAG: @_ZZ1fvE1e = internal global %{{.*}} { %{{.*}}* getelementptr inbounds ([11 x %{{.*}}], [11 x %{{.*}}]* @_ZGRZ1fvE1e_, i32 0, i32 0), i64 11 }
+// CHECK-DAG: @_ZGRZ1fvE1e0_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e1_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e2_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e3_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e4_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e5_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e6_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e7_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e8_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e9_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1eA_ = internal constant [1 x i32] zeroinitializer
+// CHECK-DAG: @_ZGRZ1fvE1e_ = internal constant [11 x %{{.*}}] [%{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e0_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e1_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e2_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e3_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e4_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e5_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e6_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e7_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e8_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1e9_, i32 0, i32 0), i64 1 }, %{{.*}} { i32* getelementptr inbounds ([1 x i32], [1 x i32]* @_ZGRZ1fvE1eA_, i32 0, i32 0), i64 1 }]