Implementation of Embarcadero array type traits

Patch authored by John Wiegley.

These are array type traits used for parsing code that employs certain
features of the Embarcadero C++ compiler: __array_rank(T) and
__array_extent(T, Dim).

llvm-svn: 130351

2 files changed, 129 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 7086176d89f..0617abd6805 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -2812,6 +2812,94 @@ ExprResult Sema::BuildBinaryTypeTrait(BinaryTypeTrait BTT,
                                                  ResultType));
 }
 
+ExprResult Sema::ActOnArrayTypeTrait(ArrayTypeTrait ATT,
+                                     SourceLocation KWLoc,
+                                     ParsedType Ty,
+                                     Expr* DimExpr,
+                                     SourceLocation RParen) {
+  TypeSourceInfo *TSInfo;
+  QualType T = GetTypeFromParser(Ty, &TSInfo);
+  if (!TSInfo)
+    TSInfo = Context.getTrivialTypeSourceInfo(T);
+
+  return BuildArrayTypeTrait(ATT, KWLoc, TSInfo, DimExpr, RParen);
+}
+
+static uint64_t EvaluateArrayTypeTrait(Sema &Self, ArrayTypeTrait ATT,
+                                           QualType T, Expr *DimExpr,
+                                           SourceLocation KeyLoc) {
+  assert((!T->isDependentType()) &&
+         "Cannot evaluate traits for dependent types.");
+
+  switch(ATT) {
+  case ATT_ArrayRank:
+    if (T->isArrayType()) {
+      unsigned Dim = 0;
+      while (const ArrayType *AT = Self.Context.getAsArrayType(T)) {
+        ++Dim;
+        T = AT->getElementType();
+      }
+      return Dim;
+    } else {
+      assert(! "Array type trait applied to non-array type");
+    }
+  case ATT_ArrayExtent: {
+    llvm::APSInt Value;
+    uint64_t Dim;
+    if (DimExpr->isIntegerConstantExpr(Value, Self.Context, 0, false))
+      Dim = Value.getLimitedValue();
+    else
+      assert(! "Dimension expression did not evaluate to a constant integer");
+
+    if (T->isArrayType()) {
+      unsigned D = 0;
+      bool Matched = false;
+      while (const ArrayType *AT = Self.Context.getAsArrayType(T)) {
+        if (Dim == D) {
+          Matched = true;
+          break;
+        }
+        ++D;
+        T = AT->getElementType();
+      }
+
+      assert(Matched && T->isArrayType() &&
+             "__array_extent does not refer to an array dimension");
+
+      llvm::APInt size = Self.Context.getAsConstantArrayType(T)->getSize();
+      return size.getLimitedValue();
+    } else {
+      assert(! "Array type trait applied to non-array type");
+    }
+  }
+  }
+  llvm_unreachable("Unknown type trait or not implemented");
+}
+
+ExprResult Sema::BuildArrayTypeTrait(ArrayTypeTrait ATT,
+                                     SourceLocation KWLoc,
+                                     TypeSourceInfo *TSInfo,
+                                     Expr* DimExpr,
+                                     SourceLocation RParen) {
+  QualType T = TSInfo->getType();
+
+  uint64_t Value;
+  if (!T->isDependentType())
+    Value = EvaluateArrayTypeTrait(*this, ATT, T, DimExpr, KWLoc);
+  else
+    return ExprError();
+
+  // Select trait result type.
+  QualType ResultType;
+  switch (ATT) {
+  case ATT_ArrayRank:    ResultType = Context.IntTy; break;
+  case ATT_ArrayExtent:  ResultType = Context.IntTy; break;
+  }
+
+  return Owned(new (Context) ArrayTypeTraitExpr(KWLoc, ATT, TSInfo, Value,
+                                                DimExpr, RParen, ResultType));
+}
+
 ExprResult Sema::ActOnExpressionTrait(ExpressionTrait ET,
                                      SourceLocation KWLoc,
                                      Expr* Queried,
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index b2aa85e7198..f5ec3a21701 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -1915,6 +1915,18 @@ public:
     return getSema().BuildBinaryTypeTrait(Trait, StartLoc, LhsT, RhsT, RParenLoc);
   }
 
+  /// \brief Build a new array type trait expression.
+  ///
+  /// By default, performs semantic analysis to build the new expression.
+  /// Subclasses may override this routine to provide different behavior.
+  ExprResult RebuildArrayTypeTrait(ArrayTypeTrait Trait,
+                                   SourceLocation StartLoc,
+                                   TypeSourceInfo *TSInfo,
+                                   Expr *DimExpr,
+                                   SourceLocation RParenLoc) {
+    return getSema().BuildArrayTypeTrait(Trait, StartLoc, TSInfo, DimExpr, RParenLoc);
+  }
+
   /// \brief Build a new expression trait expression.
   ///
   /// By default, performs semantic analysis to build the new expression.
@@ -6921,6 +6933,35 @@ TreeTransform<Derived>::TransformBinaryTypeTraitExpr(BinaryTypeTraitExpr *E) {
 
 template<typename Derived>
 ExprResult
+TreeTransform<Derived>::TransformArrayTypeTraitExpr(ArrayTypeTraitExpr *E) {
+  TypeSourceInfo *T = getDerived().TransformType(E->getQueriedTypeSourceInfo());
+  if (!T)
+    return ExprError();
+
+  if (!getDerived().AlwaysRebuild() &&
+      T == E->getQueriedTypeSourceInfo())
+    return SemaRef.Owned(E);
+
+  ExprResult SubExpr;
+  {
+    EnterExpressionEvaluationContext Unevaluated(SemaRef, Sema::Unevaluated);
+    SubExpr = getDerived().TransformExpr(E->getDimensionExpression());
+    if (SubExpr.isInvalid())
+      return ExprError();
+
+    if (!getDerived().AlwaysRebuild() && SubExpr.get() == E->getDimensionExpression())
+      return SemaRef.Owned(E);
+  }
+
+  return getDerived().RebuildArrayTypeTrait(E->getTrait(),
+                                            E->getLocStart(),
+                                            T,
+                                            SubExpr.get(),
+                                            E->getLocEnd());
+}
+
+template<typename Derived>
+ExprResult
 TreeTransform<Derived>::TransformExpressionTraitExpr(ExpressionTraitExpr *E) {
   ExprResult SubExpr;
   {