PR14772: Support constant expression evaluation for _Atomic types.

 * Treat _Atomic(T) as a literal type if T is a literal type.
 * Evaluate expressions of this type properly.
 * Fix a lurking bug where we built completely bogus ASTs for converting to
   _Atomic types in C++ in some cases, caught by the tests for this change.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@182541 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index fbef525ce4f094d7c90d2e05735186b3436ec75f..ade258b96d4db673d62836392c8c5f755ab6d02d 100644 (file)
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -915,6 +915,7 @@ static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
                                     EvalInfo &Info);
 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
+static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info);
 
 //===----------------------------------------------------------------------===//
 // Misc utilities
@@ -3702,8 +3703,13 @@ public:
     default:
       break;
 
-    case CK_AtomicToNonAtomic:
-    case CK_NonAtomicToAtomic:
+    case CK_AtomicToNonAtomic: {
+      APValue AtomicVal;
+      if (!EvaluateAtomic(E->getSubExpr(), AtomicVal, Info))
+        return false;
+      return DerivedSuccess(AtomicVal, E);
+    }
+
     case CK_NoOp:
     case CK_UserDefinedConversion:
       return StmtVisitorTy::Visit(E->getSubExpr());
@@ -6469,6 +6475,7 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
   case CK_IntegralComplexToFloatingComplex:
   case CK_BuiltinFnToFnPtr:
   case CK_ZeroToOCLEvent:
+  case CK_NonAtomicToAtomic:
     llvm_unreachable("invalid cast kind for integral value");
 
   case CK_BitCast:
@@ -6484,7 +6491,6 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
   case CK_UserDefinedConversion:
   case CK_LValueToRValue:
   case CK_AtomicToNonAtomic:
-  case CK_NonAtomicToAtomic:
   case CK_NoOp:
     return ExprEvaluatorBaseTy::VisitCastExpr(E);
 
@@ -6937,11 +6943,11 @@ bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
   case CK_CopyAndAutoreleaseBlockObject:
   case CK_BuiltinFnToFnPtr:
   case CK_ZeroToOCLEvent:
+  case CK_NonAtomicToAtomic:
     llvm_unreachable("invalid cast kind for complex value");
 
   case CK_LValueToRValue:
   case CK_AtomicToNonAtomic:
-  case CK_NonAtomicToAtomic:
   case CK_NoOp:
     return ExprEvaluatorBaseTy::VisitCastExpr(E);
 
@@ -7197,6 +7203,46 @@ bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
   return ExprEvaluatorBaseTy::VisitInitListExpr(E);
 }
 
+//===----------------------------------------------------------------------===//
+// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
+// implicit conversion.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class AtomicExprEvaluator :
+    public ExprEvaluatorBase<AtomicExprEvaluator, bool> {
+  APValue &Result;
+public:
+  AtomicExprEvaluator(EvalInfo &Info, APValue &Result)
+      : ExprEvaluatorBaseTy(Info), Result(Result) {}
+
+  bool Success(const APValue &V, const Expr *E) {
+    Result = V;
+    return true;
+  }
+
+  bool ZeroInitialization(const Expr *E) {
+    ImplicitValueInitExpr VIE(
+        E->getType()->castAs<AtomicType>()->getValueType());
+    return Evaluate(Result, Info, &VIE);
+  }
+
+  bool VisitCastExpr(const CastExpr *E) {
+    switch (E->getCastKind()) {
+    default:
+      return ExprEvaluatorBaseTy::VisitCastExpr(E);
+    case CK_NonAtomicToAtomic:
+      return Evaluate(Result, Info, E->getSubExpr());
+    }
+  }
+};
+} // end anonymous namespace
+
+static bool EvaluateAtomic(const Expr *E, APValue &Result, EvalInfo &Info) {
+  assert(E->isRValue() && E->getType()->isAtomicType());
+  return AtomicExprEvaluator(Info, Result).Visit(E);
+}
+
 //===----------------------------------------------------------------------===//
 // Void expression evaluation, primarily for a cast to void on the LHS of a
 // comma operator
@@ -7234,56 +7280,60 @@ static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
   // In C, function designators are not lvalues, but we evaluate them as if they
   // are.
-  if (E->isGLValue() || E->getType()->isFunctionType()) {
+  QualType T = E->getType();
+  if (E->isGLValue() || T->isFunctionType()) {
     LValue LV;
     if (!EvaluateLValue(E, LV, Info))
       return false;
     LV.moveInto(Result);
-  } else if (E->getType()->isVectorType()) {
+  } else if (T->isVectorType()) {
     if (!EvaluateVector(E, Result, Info))
       return false;
-  } else if (E->getType()->isIntegralOrEnumerationType()) {
+  } else if (T->isIntegralOrEnumerationType()) {
     if (!IntExprEvaluator(Info, Result).Visit(E))
       return false;
-  } else if (E->getType()->hasPointerRepresentation()) {
+  } else if (T->hasPointerRepresentation()) {
     LValue LV;
     if (!EvaluatePointer(E, LV, Info))
       return false;
     LV.moveInto(Result);
-  } else if (E->getType()->isRealFloatingType()) {
+  } else if (T->isRealFloatingType()) {
     llvm::APFloat F(0.0);
     if (!EvaluateFloat(E, F, Info))
       return false;
     Result = APValue(F);
-  } else if (E->getType()->isAnyComplexType()) {
+  } else if (T->isAnyComplexType()) {
     ComplexValue C;
     if (!EvaluateComplex(E, C, Info))
       return false;
     C.moveInto(Result);
-  } else if (E->getType()->isMemberPointerType()) {
+  } else if (T->isMemberPointerType()) {
     MemberPtr P;
     if (!EvaluateMemberPointer(E, P, Info))
       return false;
     P.moveInto(Result);
     return true;
-  } else if (E->getType()->isArrayType()) {
+  } else if (T->isArrayType()) {
     LValue LV;
     LV.set(E, Info.CurrentCall->Index);
     if (!EvaluateArray(E, LV, Info.CurrentCall->Temporaries[E], Info))
       return false;
     Result = Info.CurrentCall->Temporaries[E];
-  } else if (E->getType()->isRecordType()) {
+  } else if (T->isRecordType()) {
     LValue LV;
     LV.set(E, Info.CurrentCall->Index);
     if (!EvaluateRecord(E, LV, Info.CurrentCall->Temporaries[E], Info))
       return false;
     Result = Info.CurrentCall->Temporaries[E];
-  } else if (E->getType()->isVoidType()) {
+  } else if (T->isVoidType()) {
     if (!Info.getLangOpts().CPlusPlus11)
       Info.CCEDiag(E, diag::note_constexpr_nonliteral)
         << E->getType();
     if (!EvaluateVoid(E, Info))
       return false;
+  } else if (T->isAtomicType()) {
+    if (!EvaluateAtomic(E, Result, Info))
+      return false;
   } else if (Info.getLangOpts().CPlusPlus11) {
     Info.Diag(E, diag::note_constexpr_nonliteral) << E->getType();
     return false;

diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 004e31af178d307b4496da953123f3ab4a8e794d..639ae186c142f6f27b347cfdd25ccd7af4bfb433 100644 (file)
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -1196,6 +1196,10 @@ bool Type::isLiteralType(ASTContext &Ctx) const {
     return true;
   }
 
+  // We treat _Atomic T as a literal type if T is a literal type.
+  if (const AtomicType *AT = BaseTy->getAs<AtomicType>())
+    return AT->getValueType()->isLiteralType(Ctx);
+
   // If this type hasn't been deduced yet, then conservatively assume that
   // it'll work out to be a literal type.
   if (isa<AutoType>(BaseTy->getCanonicalTypeInternal()))

diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 1d2a554ea2cc0bf0fee861a8af21331174a60277..21f00b22fc24090482f252d80848ef80b1bd17f2 100644 (file)
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -2555,6 +2555,14 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
     FromType = From->getType();
   }
 
+  // If we're converting to an atomic type, first convert to the corresponding
+  // non-atomic type.
+  QualType ToAtomicType;
+  if (const AtomicType *ToAtomic = ToType->getAs<AtomicType>()) {
+    ToAtomicType = ToType;
+    ToType = ToAtomic->getValueType();
+  }
+
   // Perform the first implicit conversion.
   switch (SCS.First) {
   case ICK_Identity:
@@ -2864,7 +2872,7 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
         << ToType.getNonReferenceType();
 
     break;
-    }
+  }
 
   default:
     llvm_unreachable("Improper third standard conversion");
@@ -2872,11 +2880,13 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
 
   // If this conversion sequence involved a scalar -> atomic conversion, perform
   // that conversion now.
-  if (const AtomicType *ToAtomic = ToType->getAs<AtomicType>())
-    if (Context.hasSameType(ToAtomic->getValueType(), From->getType()))
-      From = ImpCastExprToType(From, ToType, CK_NonAtomicToAtomic, VK_RValue, 0,
-                               CCK).take();
-      
+  if (!ToAtomicType.isNull()) {
+    assert(Context.hasSameType(
+        ToAtomicType->castAs<AtomicType>()->getValueType(), From->getType()));
+    From = ImpCastExprToType(From, ToAtomicType, CK_NonAtomicToAtomic,
+                             VK_RValue, 0, CCK).take();
+  }
+
   return Owned(From);
 }
 

diff --git a/test/SemaCXX/constant-expression-cxx11.cpp b/test/SemaCXX/constant-expression-cxx11.cpp
index 97b0b91b99f338310c8613a578dd85a4bea5f9b0..9beacf887e1556396caa024db9030fcede84ee18 100644 (file)
--- a/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1138,6 +1138,31 @@ namespace ComplexConstexpr {
   static_assert(&__imag test6 == &__real test6 + 1, "");
 }
 
+// _Atomic(T) is exactly like T for the purposes of constant expression
+// evaluation..
+namespace Atomic {
+  constexpr _Atomic int n = 3;
+
+  struct S { _Atomic(double) d; };
+  constexpr S s = { 0.5 };
+  constexpr double d1 = s.d;
+  constexpr double d2 = n;
+  constexpr _Atomic double d3 = n;
+
+  constexpr _Atomic(int) n2 = d3;
+  static_assert(d1 == 0.5, "");
+  static_assert(d3 == 3.0, "");
+
+  namespace PR16056 {
+    struct TestVar {
+      _Atomic(int) value;
+      constexpr TestVar(int value) : value(value) {}
+    };
+    constexpr TestVar testVar{-1};
+    static_assert(testVar.value == -1, "");
+  }
+}
+
 namespace InstantiateCaseStmt {
   template<int x> constexpr int f() { return x; }
   template<int x> int g(int c) { switch(c) { case f<x>(): return 1; } return 0; }