add codegen support for casting an element to a union.
There are some more complex cases (_Complex and structs)
that I'm still working on.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67218 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index b3cf921..93b2382 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -186,12 +186,7 @@
case Expr::CXXDynamicCastExprClass:
case Expr::CXXReinterpretCastExprClass:
case Expr::CXXConstCastExprClass:
- // Casts are only lvalues when the source and destination types are the
- // same.
- assert(getContext().hasSameUnqualifiedType(E->getType(),
- cast<CastExpr>(E)->getSubExpr()->getType()) &&
- "Type changing cast is not an lvalue");
- return EmitLValue(cast<CastExpr>(E)->getSubExpr());
+ return EmitCastLValue(cast<CastExpr>(E));
}
}
@@ -994,8 +989,7 @@
return LV;
}
-LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E)
-{
+LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr* E){
const llvm::Type *LTy = ConvertType(E->getType());
llvm::Value *DeclPtr = CreateTempAlloca(LTy, ".compoundliteral");
@@ -1013,6 +1007,29 @@
return Result;
}
+/// EmitCastLValue - Casts are never lvalues. If a cast is needed by the code
+/// generator in an lvalue context, then it must mean that we need the address
+/// of an aggregate in order to access one of its fields. This can happen for
+/// all the reasons that casts are permitted with aggregate result, including
+/// noop aggregate casts, and cast from scalar to union.
+LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
+ // If this is an aggregate-to-aggregate cast, just use the input's address as
+ // the lvalue.
+ if (getContext().hasSameUnqualifiedType(E->getType(),
+ E->getSubExpr()->getType()))
+ return EmitLValue(E->getSubExpr());
+
+ // Otherwise, we must have a cast from scalar to union.
+ assert(E->getType()->isUnionType() && "Expected scalar-to-union cast");
+
+ // Casts are only lvalues when the source and destination types are the same.
+ llvm::Value *Temp = CreateTempAlloca(ConvertType(E->getType()));
+ EmitAnyExpr(E, Temp, false);
+
+ return LValue::MakeAddr(Temp, E->getType().getCVRQualifiers(),
+ getContext().getObjCGCAttrKind(E->getType()));
+}
+
//===--------------------------------------------------------------------===//
// Expression Emission
//===--------------------------------------------------------------------===//