PR12086, PR15117
Introduce CXXStdInitializerListExpr node, representing the implicit
construction of a std::initializer_list<T> object from its underlying array.
The AST representation of such an expression goes from an InitListExpr with a
flag set, to a CXXStdInitializerListExpr containing a MaterializeTemporaryExpr
containing an InitListExpr (possibly wrapped in a CXXBindTemporaryExpr).
This more detailed representation has several advantages, the most important of
which is that the new MaterializeTemporaryExpr allows us to directly model
lifetime extension of the underlying temporary array. Using that, this patch
*drastically* simplifies the IR generation of this construct, provides IR
generation support for nested global initializer_list objects, fixes several
bugs where the destructors for the underlying array would accidentally not get
invoked, and provides constant expression evaluation support for
std::initializer_list objects.
llvm-svn: 183872
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index d94efc1..21fb459 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -4576,6 +4576,7 @@
bool VisitCastExpr(const CastExpr *E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E);
+ bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
};
}
@@ -4691,10 +4692,6 @@
}
bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
- // Cannot constant-evaluate std::initializer_list inits.
- if (E->initializesStdInitializerList())
- return false;
-
const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
@@ -4810,6 +4807,58 @@
Result);
}
+bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
+ const CXXStdInitializerListExpr *E) {
+ const ConstantArrayType *ArrayType =
+ Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
+
+ LValue Array;
+ if (!EvaluateLValue(E->getSubExpr(), Array, Info))
+ return false;
+
+ // Get a pointer to the first element of the array.
+ Array.addArray(Info, E, ArrayType);
+
+ // FIXME: Perform the checks on the field types in SemaInit.
+ RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
+ RecordDecl::field_iterator Field = Record->field_begin();
+ if (Field == Record->field_end())
+ return Error(E);
+
+ // Start pointer.
+ if (!Field->getType()->isPointerType() ||
+ !Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
+ ArrayType->getElementType()))
+ return Error(E);
+
+ // FIXME: What if the initializer_list type has base classes, etc?
+ Result = APValue(APValue::UninitStruct(), 0, 2);
+ Array.moveInto(Result.getStructField(0));
+
+ if (++Field == Record->field_end())
+ return Error(E);
+
+ if (Field->getType()->isPointerType() &&
+ Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
+ ArrayType->getElementType())) {
+ // End pointer.
+ if (!HandleLValueArrayAdjustment(Info, E, Array,
+ ArrayType->getElementType(),
+ ArrayType->getSize().getZExtValue()))
+ return false;
+ Array.moveInto(Result.getStructField(1));
+ } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
+ // Length.
+ Result.getStructField(1) = APValue(APSInt(ArrayType->getSize()));
+ else
+ return Error(E);
+
+ if (++Field != Record->field_end())
+ return Error(E);
+
+ return true;
+}
+
static bool EvaluateRecord(const Expr *E, const LValue &This,
APValue &Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isRecordType() &&
@@ -7762,6 +7811,7 @@
case Expr::UnresolvedLookupExprClass:
case Expr::DependentScopeDeclRefExprClass:
case Expr::CXXConstructExprClass:
+ case Expr::CXXStdInitializerListExprClass:
case Expr::CXXBindTemporaryExprClass:
case Expr::ExprWithCleanupsClass:
case Expr::CXXTemporaryObjectExprClass: