Canonicalize declaration pointers when forming APValues.

zygoloid · zygoloid · commit 913f6005669c · 2020-10-12T19:32:57.000-07:00
References to different declarations of the same entity aren't different values, so shouldn't have different representations. Recommit of e6393ee, most recently reverted in 9a33f02 due to a bug caused by ObjCInterfaceDecls not propagating availability attributes along their redeclaration chains; that bug was fixed in e2d4174.
diff --git a/clang/include/clang/AST/APValue.h b/clang/include/clang/AST/APValue.h
@@ -177,6 +177,7 @@ class APValue {
       return !(LHS == RHS);
     }
     friend llvm::hash_code hash_value(const LValueBase &Base);
+    friend struct llvm::DenseMapInfo<LValueBase>;
 
   private:
     PtrTy Ptr;
@@ -204,8 +205,7 @@ class APValue {
 
   public:
     LValuePathEntry() : Value() {}
-    LValuePathEntry(BaseOrMemberType BaseOrMember)
-        : Value{reinterpret_cast<uintptr_t>(BaseOrMember.getOpaqueValue())} {}
+    LValuePathEntry(BaseOrMemberType BaseOrMember);
     static LValuePathEntry ArrayIndex(uint64_t Index) {
       LValuePathEntry Result;
       Result.Value = Index;
diff --git a/clang/lib/AST/APValue.cpp b/clang/lib/AST/APValue.cpp
@@ -38,7 +38,7 @@ static_assert(
     "Type is insufficiently aligned");
 
 APValue::LValueBase::LValueBase(const ValueDecl *P, unsigned I, unsigned V)
-    : Ptr(P), Local{I, V} {}
+    : Ptr(P ? cast<ValueDecl>(P->getCanonicalDecl()) : nullptr), Local{I, V} {}
 APValue::LValueBase::LValueBase(const Expr *P, unsigned I, unsigned V)
     : Ptr(P), Local{I, V} {}
 
@@ -90,13 +90,19 @@ bool operator==(const APValue::LValueBase &LHS,
                 const APValue::LValueBase &RHS) {
   if (LHS.Ptr != RHS.Ptr)
     return false;
-  if (LHS.is<TypeInfoLValue>())
+  if (LHS.is<TypeInfoLValue>() || LHS.is<DynamicAllocLValue>())
     return true;
   return LHS.Local.CallIndex == RHS.Local.CallIndex &&
          LHS.Local.Version == RHS.Local.Version;
 }
 }
 
+APValue::LValuePathEntry::LValuePathEntry(BaseOrMemberType BaseOrMember) {
+  if (const Decl *D = BaseOrMember.getPointer())
+    BaseOrMember.setPointer(D->getCanonicalDecl());
+  Value = reinterpret_cast<uintptr_t>(BaseOrMember.getOpaqueValue());
+}
+
 void APValue::LValuePathEntry::profile(llvm::FoldingSetNodeID &ID) const {
   ID.AddInteger(Value);
 }
@@ -125,14 +131,16 @@ APValue::LValueBase::operator bool () const {
 
 clang::APValue::LValueBase
 llvm::DenseMapInfo<clang::APValue::LValueBase>::getEmptyKey() {
-  return clang::APValue::LValueBase(
-      DenseMapInfo<const ValueDecl*>::getEmptyKey());
+  clang::APValue::LValueBase B;
+  B.Ptr = DenseMapInfo<const ValueDecl*>::getEmptyKey();
+  return B;
 }
 
 clang::APValue::LValueBase
 llvm::DenseMapInfo<clang::APValue::LValueBase>::getTombstoneKey() {
-  return clang::APValue::LValueBase(
-      DenseMapInfo<const ValueDecl*>::getTombstoneKey());
+  clang::APValue::LValueBase B;
+  B.Ptr = DenseMapInfo<const ValueDecl*>::getTombstoneKey();
+  return B;
 }
 
 namespace clang {
@@ -926,8 +934,10 @@ void APValue::MakeMemberPointer(const ValueDecl *Member, bool IsDerivedMember,
   assert(isAbsent() && "Bad state change");
   MemberPointerData *MPD = new ((void*)(char*)Data.buffer) MemberPointerData;
   Kind = MemberPointer;
-  MPD->MemberAndIsDerivedMember.setPointer(Member);
+  MPD->MemberAndIsDerivedMember.setPointer(
+      Member ? cast<ValueDecl>(Member->getCanonicalDecl()) : nullptr);
   MPD->MemberAndIsDerivedMember.setInt(IsDerivedMember);
   MPD->resizePath(Path.size());
-  memcpy(MPD->getPath(), Path.data(), Path.size()*sizeof(const CXXRecordDecl*));
+  for (unsigned I = 0; I != Path.size(); ++I)
+    MPD->getPath()[I] = Path[I]->getCanonicalDecl();
 }
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
@@ -4686,11 +4686,9 @@ char *Buffer = new (getASTContext(), 1) char[Name.size() + 1];
 void ValueDecl::anchor() {}
 
 bool ValueDecl::isWeak() const {
-  for (const auto *I : attrs())
-    if (isa<WeakAttr>(I) || isa<WeakRefAttr>(I))
-      return true;
-
-  return isWeakImported();
+  auto *MostRecent = getMostRecentDecl();
+  return MostRecent->hasAttr<WeakAttr>() ||
+         MostRecent->hasAttr<WeakRefAttr>() || isWeakImported();
 }
 
 void ImplicitParamDecl::anchor() {}
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
@@ -720,7 +720,7 @@ bool Decl::isWeakImported() const {
   if (!canBeWeakImported(IsDefinition))
     return false;
 
-  for (const auto *A : attrs()) {
+  for (const auto *A : getMostRecentDecl()->attrs()) {
     if (isa<WeakImportAttr>(A))
       return true;
 
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
@@ -1982,18 +1982,11 @@ static bool HasSameBase(const LValue &A, const LValue &B) {
     return false;
 
   if (A.getLValueBase().getOpaqueValue() !=
-      B.getLValueBase().getOpaqueValue()) {
-    const Decl *ADecl = GetLValueBaseDecl(A);
-    if (!ADecl)
-      return false;
-    const Decl *BDecl = GetLValueBaseDecl(B);
-    if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl())
-      return false;
-  }
+      B.getLValueBase().getOpaqueValue())
+    return false;
 
-  return IsGlobalLValue(A.getLValueBase()) ||
-         (A.getLValueCallIndex() == B.getLValueCallIndex() &&
-          A.getLValueVersion() == B.getLValueVersion());
+  return A.getLValueCallIndex() == B.getLValueCallIndex() &&
+         A.getLValueVersion() == B.getLValueVersion();
 }
 
 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
@@ -3163,7 +3156,8 @@ static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
 
   // If we're currently evaluating the initializer of this declaration, use that
   // in-flight value.
-  if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) {
+  if (declaresSameEntity(Info.EvaluatingDecl.dyn_cast<const ValueDecl *>(),
+                         VD)) {
     Result = Info.EvaluatingDeclValue;
     return true;
   }
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -1877,6 +1877,10 @@ ConstantLValue
 ConstantLValueEmitter::tryEmitBase(const APValue::LValueBase &base) {
   // Handle values.
   if (const ValueDecl *D = base.dyn_cast<const ValueDecl*>()) {
+    // The constant always points to the canonical declaration. We want to look
+    // at properties of the most recent declaration at the point of emission.
+    D = cast<ValueDecl>(D->getMostRecentDecl());
+
     if (D->hasAttr<WeakRefAttr>())
       return CGM.GetWeakRefReference(D).getPointer();
 
diff --git a/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp b/clang/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p9.cpp
@@ -24,11 +24,10 @@ constexpr double &ni3; // expected-error {{declaration of reference variable 'ni
 
 constexpr int nc1 = i; // expected-error {{constexpr variable 'nc1' must be initialized by a constant expression}} expected-note {{read of non-const variable 'i' is not allowed in a constant expression}}
 constexpr C nc2 = C(); // expected-error {{cannot have non-literal type 'const C'}}
-int &f(); // expected-note {{declared here}}
+int &f(); // expected-note 2{{declared here}}
 constexpr int &nc3 = f(); // expected-error {{constexpr variable 'nc3' must be initialized by a constant expression}} expected-note {{non-constexpr function 'f' cannot be used in a constant expression}}
 constexpr int nc4(i); // expected-error {{constexpr variable 'nc4' must be initialized by a constant expression}} expected-note {{read of non-const variable 'i' is not allowed in a constant expression}}
 constexpr C nc5((C())); // expected-error {{cannot have non-literal type 'const C'}}
-int &f(); // expected-note {{here}}
 constexpr int &nc6(f()); // expected-error {{constexpr variable 'nc6' must be initialized by a constant expression}} expected-note {{non-constexpr function 'f'}}
 
 struct pixel {
diff --git a/clang/test/CodeGenCXX/weak-external.cpp b/clang/test/CodeGenCXX/weak-external.cpp
@@ -64,3 +64,15 @@ class _LIBCPP_EXCEPTION_ABI runtime_error
 void dummysymbol() {
   throw(std::runtime_error("string"));
 }
+
+namespace not_weak_on_first {
+  int func();
+  // CHECK: {{.*}} extern_weak {{.*}} @_ZN17not_weak_on_first4funcEv(
+  int func() __attribute__ ((weak));
+
+  typedef int (*FuncT)();
+
+  extern const FuncT table[] = {
+      func,
+  };
+}
diff --git a/clang/test/OpenMP/ordered_messages.cpp b/clang/test/OpenMP/ordered_messages.cpp
@@ -16,6 +16,9 @@ void xxx(int argc) {
 }
 
 int foo();
+#if __cplusplus >= 201103L
+// expected-note@-2 {{declared here}}
+#endif
 
 template <class T>
 T foo() {
@@ -176,7 +179,7 @@ T foo() {
 
 int foo() {
 #if __cplusplus >= 201103L
-// expected-note@-2 2 {{declared here}}
+// expected-note@-2 {{declared here}}
 #endif
 int k;
   #pragma omp for ordered
