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Recommit Devirtualize destructor of final class. 

Original patch commited as r364100, reverted as r364359, recommitted as r365509,
reverted as r365850.

llvm-svn: 368323
This commit is contained in:
Hiroshi Yamauchi 2019-08-08 18:00:49 +00:00
parent babdfdec90
commit cb30590da1
2 changed files with 50 additions and 3 deletions
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30
clang/lib/CodeGen/CGExprCXX.cpp
View File

@ -1882,9 +1882,33 @@ static void EmitObjectDelete(CodeGenFunction &CGF,
Dtor = RD->getDestructor();
if (Dtor->isVirtual()) {
CGF.CGM.getCXXABI().emitVirtualObjectDelete(CGF, DE, Ptr, ElementType,
Dtor);
return;
bool UseVirtualCall = true;
const Expr *Base = DE->getArgument();
if (auto *DevirtualizedDtor =
dyn_cast_or_null<const CXXDestructorDecl>(
Dtor->getDevirtualizedMethod(
Base, CGF.CGM.getLangOpts().AppleKext))) {
UseVirtualCall = false;
const CXXRecordDecl *DevirtualizedClass =
DevirtualizedDtor->getParent();
if (declaresSameEntity(getCXXRecord(Base), DevirtualizedClass)) {
// Devirtualized to the class of the base type (the type of the
// whole expression).
Dtor = DevirtualizedDtor;
} else {
// Devirtualized to some other type. Would need to cast the this
// pointer to that type but we don't have support for that yet, so
// do a virtual call. FIXME: handle the case where it is
// devirtualized to the derived type (the type of the inner
// expression) as in EmitCXXMemberOrOperatorMemberCallExpr.
UseVirtualCall = true;
}
}
if (UseVirtualCall) {
CGF.CGM.getCXXABI().emitVirtualObjectDelete(CGF, DE, Ptr, ElementType,
Dtor);
return;
}
}
}
}

23
clang/test/CodeGenCXX/devirtualize-dtor-final.cpp Normal file
View File

@ -0,0 +1,23 @@
// RUN: %clang_cc1 -triple i386-unknown-unknown -std=c++11 %s -emit-llvm -o - | FileCheck %s
namespace Test1 {
struct A { virtual ~A() {} };
struct B final : A {};
struct C : A { virtual ~C() final {} };
struct D { virtual ~D() final = 0; };
// CHECK-LABEL: define void @_ZN5Test13fooEPNS_1BE
void foo(B *b) {
// CHECK: call void @_ZN5Test11BD1Ev
delete b;
}
// CHECK-LABEL: define void @_ZN5Test14foo2EPNS_1CE
void foo2(C *c) {
// CHECK: call void @_ZN5Test11CD1Ev
delete c;
}
// CHECK-LABEL: define void @_ZN5Test14evilEPNS_1DE
void evil(D *p) {
// CHECK-NOT: call void @_ZN5Test11DD1Ev
delete p;
}
}