Improve our handling of reference binding for subobjects of
temporaries. There are actually several interrelated fixes here:
- When converting an object to a base class, it's only an lvalue
cast when the original object was an lvalue and we aren't casting
pointer-to-derived to pointer-to-base. Previously, we were
misclassifying derived-to-base casts of class rvalues as lvalues,
causing various oddities (including problems with reference binding
not extending the lifetimes of some temporaries).
- Teach the code for emitting a reference binding how to look
through no-op casts and parentheses directly, since
Expr::IgnoreParenNoOpCasts is just plain wrong for this. Also, make
sure that we properly look through multiple levels of indirection
from the temporary object, but destroy the actual temporary object;
this fixes the reference-binding issue mentioned above.
- Teach Objective-C message sends to bind the result as a temporary
when needed. This is actually John's change, but it triggered the
reference-binding problem above, so it's included here. Now John
can actually test his return-slot improvements.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@104434 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 74e64e5..17d85dc 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -211,9 +211,15 @@
llvm::SmallVector<SubobjectAdjustment, 2> Adjustments;
do {
- if (const CastExpr *CE
- = dyn_cast<CastExpr>(E->IgnoreParenNoopCasts(getContext()))) {
- if (CE->getCastKind() == CastExpr::CK_DerivedToBase) {
+ if (const ParenExpr *PE = dyn_cast<ParenExpr>(E)) {
+ E = PE->getSubExpr();
+ continue;
+ }
+
+ if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
+ if ((CE->getCastKind() == CastExpr::CK_DerivedToBase ||
+ CE->getCastKind() == CastExpr::CK_UncheckedDerivedToBase) &&
+ E->getType()->isRecordType()) {
E = CE->getSubExpr();
CXXRecordDecl *Derived
= cast<CXXRecordDecl>(E->getType()->getAs<RecordType>()->getDecl());
@@ -221,9 +227,12 @@
Derived));
continue;
}
- } else if (const MemberExpr *ME
- = dyn_cast<MemberExpr>(
- E->IgnoreParenNoopCasts(getContext()))) {
+
+ if (CE->getCastKind() == CastExpr::CK_NoOp) {
+ E = CE->getSubExpr();
+ continue;
+ }
+ } else if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) {
if (ME->getBase()->isLvalue(getContext()) != Expr::LV_Valid &&
ME->getBase()->getType()->isRecordType()) {
if (FieldDecl *Field = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
@@ -234,7 +243,10 @@
}
}
}
- } while (false);
+
+ // Nothing changed.
+ break;
+ } while (true);
Val = EmitAnyExprToTemp(E, /*IsAggLocVolatile=*/false,
IsInitializer);