Recognize when the named return value optimization applies in a
"return" statement and mark the corresponding CXXConstructExpr as
elidable. Teach CodeGen that eliding a temporary is different from
eliding an object construction.
This is just a baby step toward NRVO.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@103849 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaInit.h b/lib/Sema/SemaInit.h
index 5f2592f..35adf9e 100644
--- a/lib/Sema/SemaInit.h
+++ b/lib/Sema/SemaInit.h
@@ -85,11 +85,16 @@
/// the VarDecl, ParmVarDecl, or FieldDecl, respectively.
DeclaratorDecl *VariableOrMember;
- /// \brief When Kind == EK_Result, EK_Exception, or EK_New, the
- /// location of the 'return', 'throw', or 'new' keyword,
- /// respectively. When Kind == EK_Temporary, the location where
- /// the temporary is being created.
- unsigned Location;
+ struct {
+ /// \brief When Kind == EK_Result, EK_Exception, or EK_New, the
+ /// location of the 'return', 'throw', or 'new' keyword,
+ /// respectively. When Kind == EK_Temporary, the location where
+ /// the temporary is being created.
+ unsigned Location;
+
+ /// \brief Whether the
+ bool NRVO;
+ } LocAndNRVO;
/// \brief When Kind == EK_Base, the base specifier that provides the
/// base class. The lower bit specifies whether the base is an inherited
@@ -116,8 +121,13 @@
/// \brief Create the initialization entity for the result of a
/// function, throwing an object, performing an explicit cast, or
/// initializing a parameter for which there is no declaration.
- InitializedEntity(EntityKind Kind, SourceLocation Loc, QualType Type)
- : Kind(Kind), Parent(0), Type(Type), Location(Loc.getRawEncoding()) { }
+ InitializedEntity(EntityKind Kind, SourceLocation Loc, QualType Type,
+ bool NRVO = false)
+ : Kind(Kind), Parent(0), Type(Type)
+ {
+ LocAndNRVO.Location = Loc.getRawEncoding();
+ LocAndNRVO.NRVO = NRVO;
+ }
/// \brief Create the initialization entity for a member subobject.
InitializedEntity(FieldDecl *Member, const InitializedEntity *Parent)
@@ -152,14 +162,14 @@
/// \brief Create the initialization entity for the result of a function.
static InitializedEntity InitializeResult(SourceLocation ReturnLoc,
- QualType Type) {
- return InitializedEntity(EK_Result, ReturnLoc, Type);
+ QualType Type, bool NRVO) {
+ return InitializedEntity(EK_Result, ReturnLoc, Type, NRVO);
}
/// \brief Create the initialization entity for an exception object.
static InitializedEntity InitializeException(SourceLocation ThrowLoc,
- QualType Type) {
- return InitializedEntity(EK_Exception, ThrowLoc, Type);
+ QualType Type, bool NRVO) {
+ return InitializedEntity(EK_Exception, ThrowLoc, Type, NRVO);
}
/// \brief Create the initialization entity for an object allocated via new.
@@ -208,6 +218,10 @@
/// initialized.
DeclaratorDecl *getDecl() const;
+ /// \brief Determine whether this initialization allows the named return
+ /// value optimization, which also applies to thrown objects.
+ bool allowsNRVO() const;
+
/// \brief Retrieve the base specifier.
CXXBaseSpecifier *getBaseSpecifier() const {
assert(getKind() == EK_Base && "Not a base specifier");
@@ -224,14 +238,14 @@
/// the result of a function call.
SourceLocation getReturnLoc() const {
assert(getKind() == EK_Result && "No 'return' location!");
- return SourceLocation::getFromRawEncoding(Location);
+ return SourceLocation::getFromRawEncoding(LocAndNRVO.Location);
}
/// \brief Determine the location of the 'throw' keyword when initializing
/// an exception object.
SourceLocation getThrowLoc() const {
assert(getKind() == EK_Exception && "No 'throw' location!");
- return SourceLocation::getFromRawEncoding(Location);
+ return SourceLocation::getFromRawEncoding(LocAndNRVO.Location);
}
/// \brief If this is already the initializer for an array or vector