scott-0 created this revision.
scott-0 added a subscriber: cfe-commits.
This makes an existing optimization apply in more cases.
http://reviews.llvm.org/D12366
Files:
lib/CodeGen/CGClass.cpp
test/CodeGenCXX/destructors.cpp
Index: test/CodeGenCXX/destructors.cpp
===================================================================
--- test/CodeGenCXX/destructors.cpp
+++ test/CodeGenCXX/destructors.cpp
@@ -1,10 +1,13 @@
-// RUN: %clang_cc1 %s -triple x86_64-apple-darwin10 -emit-llvm -o - -mconstructor-aliases -fcxx-exceptions -fexceptions -O1 -disable-llvm-optzns > %t
+// RUN: %clang_cc1 -I%S %s -triple x86_64-apple-darwin10 -emit-llvm -o - -mconstructor-aliases -fcxx-exceptions -fexceptions -O1 -disable-llvm-optzns > %t
+// RUN: FileCheck --check-prefix=CHECK0 --input-file=%t %s
// RUN: FileCheck --check-prefix=CHECK1 --input-file=%t %s
// RUN: FileCheck --check-prefix=CHECK2 --input-file=%t %s
// RUN: FileCheck --check-prefix=CHECK3 --input-file=%t %s
// RUN: FileCheck --check-prefix=CHECK4 --input-file=%t %s
// RUN: FileCheck --check-prefix=CHECK5 --input-file=%t %s
+#include <typeinfo> // so we can use 'typeid'
+
struct A {
int a;
@@ -16,7 +19,14 @@
~B();
};
+// CHECK0-LABEL: @_ZN1BD1Ev = alias void (%struct.B*)* @_ZN1BD2Ev
+// CHECK0-LABEL: @_ZN1CD1Ev = alias void (%struct.C*)* @_ZN1CD2Ev
+// CHECK0-LABEL: @_ZN2TBD1Ev = alias void (%struct.TB*)* @_ZN2TBD2Ev
+// CHECK0-LABEL: @_ZN2TDD1Ev = alias void (%struct.TD*)* @_ZN2TDD2Ev
+
B::~B() { }
+// CHECK0-LABEL: define void @_ZN1BD2Ev(%struct.B* %this)
+// CHECK0: call void @_ZN1AD2Ev
// Field with non-trivial destructor
struct C {
@@ -26,6 +36,100 @@
};
C::~C() { }
+// CHECK0-LABEL: define void @_ZN1CD2Ev(%struct.C* %this)
+// CHECK0: call void @_ZN1AD1Ev
+
+struct TB {
+ virtual void f();
+ ~TB();
+ int x;
+};
+TB *tb;
+// None of these statements need the dynamic type to be correct
+// and has side-effects (or are even important to evaluate).
+TB::~TB() { ; {{}} (void)0; ({int y = 42; y; }); x; typeid(this); dynamic_cast<TB*>(tb); }
+// CHECK0-LABEL: define void @_ZN2TBD2Ev(%struct.TB* %this)
+// No need to store vptr.
+// CHECK0-NOT: @_ZTV
+// CHECK0: ret
+struct TD : TB {
+ ~TD();
+};
+TD::~TD() { ; {{}} (void)0; ({int y = 42; y; }); x; typeid(this); dynamic_cast<TD*>(tb); }
+// CHECK0-LABEL: define void @_ZN2TDD2Ev(%struct.TD* %this)
+// No need to store vptr.
+// CHECK0-NOT: @_ZTV
+// CHECK0: call void @_ZN2TBD2Ev
+// CHECK0: ret
+
+// Check cases where we must store the vptr.
+extern void g();
+struct NTD : TB {
+ ~NTD();
+};
+NTD::~NTD() { g(); }
+// CHECK0-LABEL: define void @_ZN3NTDD2Ev(%struct.NTD* %this)
+// Because we call 'g()' must to store the vptr (our
+// base doesn't need to, but that's irrelevant).
+// CHECK0: store {{.*}} @_ZTV3NTD
+// CHECK0: void @_Z1gv
+// CHECK0: call void @_ZN2TBD2Ev
+// CHECK0: ret
+
+struct NTB {
+ virtual void f();
+ ~NTB();
+ int x;
+};
+NTB::~NTB() { g(); }
+// CHECK0-LABEL: define void @_ZN3NTBD2Ev(%struct.NTB* %this)
+// Because we call 'g()' must to store the vptr.
+// CHECK0: store {{.*}} @_ZTV3NTB
+// CHECK0: void @_Z1gv
+// CHECK0: ret
+
+struct TD2 : NTB {
+ virtual void f();
+ ~TD2();
+};
+NTB *ntb;
+TD2::~TD2() { ; {{}} (void)0; ({int y = 42; y; }); x; /*@@@typeid(this); dynamic_cast<TD*>(ntb);*/ }
+// CHECK0-LABEL: define void @_ZN3TD2D2Ev(%struct.TD2* %this)
+// We don't need to store the vptr (our base does need to,
+// but that's irrelevant).
+// CHECK0-NOT: @_ZTV
+// CHECK0: call void @_ZN3NTBD2Ev
+// CHECK0: ret
+
+// More cases we must store the vptr.
+struct NT2 {
+ virtual void f();
+ ~NT2();
+};
+NT2* nt2;
+NT2::~NT2() { nt2->f(); }
+// CHECK0-LABEL: define void @_ZN3NT2D2Ev(%struct.NT2* %this)
+// CHECK0: store {{.*}} @_ZTV3NT2
+// CHECK0: ret
+
+struct NT3 {
+ virtual void f();
+ ~NT3();
+};
+const std::type_info *ti;
+NT3::~NT3() { ti = &typeid(this); }
+// CHECK0-LABEL: define void @_ZN3NT3D2Ev(%struct.NT3* %this)
+// CHECK0: store {{.*}} @_ZTV3NT3
+// CHECK0: ret
+
+struct NT4 : TB {
+ virtual void f();
+ ~NT4();
+};
+NT4::~NT4() { dynamic_cast<NT4&>(*tb); }
+// CHECK0-LABEL: define void @_ZN3NT4D2Ev(%struct.NT4* %this)
+// CHECK0: store {{.*}} @_ZTV3NT4
+// CHECK0: ret
namespace PR7526 {
extern void foo();
Index: lib/CodeGen/CGClass.cpp
===================================================================
--- lib/CodeGen/CGClass.cpp
+++ lib/CodeGen/CGClass.cpp
@@ -20,6 +20,7 @@
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/RecordLayout.h"
+#include "clang/AST/SideEffectFinder.h"
#include "clang/AST/StmtCXX.h"
#include "clang/Basic/TargetBuiltins.h"
#include "clang/CodeGen/CGFunctionInfo.h"
@@ -1351,12 +1352,52 @@
return HasTrivialDestructorBody(Context, FieldClassDecl, FieldClassDecl);
}
+namespace {
+ /// \brief Detect if any sub-Expr is possibly sensitive to dynamic types.
+ class DynamicTypeSensitivityDetector :
+ public ConstEvaluatedExprVisitor<DynamicTypeSensitivityDetector>
+ {
+ typedef ConstEvaluatedExprVisitor<DynamicTypeSensitivityDetector> Inherited;
+ bool Sensitive;
+
+ public:
+ explicit DynamicTypeSensitivityDetector(const ASTContext &Context)
+ : Inherited(Context), Sensitive(false) { }
+
+ bool isSensitive() const { return Sensitive; }
+
+ void VisitCallExpr(const Expr *E) {
+ Sensitive = true;
+ }
+ void VisitCXXTypeidExpr(const Expr *E) {
+ Sensitive = true;
+ }
+ void VisitExpr(const Expr *E) {
+ if (E->getStmtClass() == Stmt::CXXTypeidExprClass ||
+ E->getStmtClass() == Stmt::CXXDynamicCastExprClass) {
+ Sensitive = true;
+ }
+ if (!Sensitive)
+ Inherited::VisitExpr(E);
+ }
+ };
+}
+
/// CanSkipVTablePointerInitialization - Check whether we need to initialize
/// any vtable pointers before calling this destructor.
static bool CanSkipVTablePointerInitialization(ASTContext &Context,
const CXXDestructorDecl *Dtor) {
- if (!Dtor->hasTrivialBody())
- return false;
+ // We only need the vtable ptr for the body if it is sensitive to the
+ // dynamic type of '*this' and potentially has side-effects.
+ const Stmt *Body = Dtor->getBody();
+ DynamicTypeSensitivityDetector Detector(Context);
+ Detector.Visit(Body);
+ if (Detector.isSensitive()) {
+ SideEffectFinder Finder(Context, true);
+ Finder.Visit(Body);
+ if (Finder.hasSideEffects())
+ return false;
+ }
// Check the fields.
const CXXRecordDecl *ClassDecl = Dtor->getParent();
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