Author: vedantk Date: Thu Oct 20 13:44:14 2016 New Revision: 284766 URL: http://llvm.org/viewvc/llvm-project?rev=284766&view=rev Log: [CodeGen] Devirtualize calls to methods marked final in a derived class
If we see a virtual method call to Base::foo() but can infer that the object is an instance of Derived, and that 'foo' is marked 'final' in Derived, we can devirtualize the call to Derived::foo(). Differential Revision: https://reviews.llvm.org/D25813 Modified: cfe/trunk/lib/CodeGen/CGClass.cpp cfe/trunk/test/CodeGenCXX/devirtualize-virtual-function-calls-final.cpp cfe/trunk/test/CodeGenCXX/ubsan-devirtualized-calls.cpp Modified: cfe/trunk/lib/CodeGen/CGClass.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGClass.cpp?rev=284766&r1=284765&r2=284766&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CGClass.cpp (original) +++ cfe/trunk/lib/CodeGen/CGClass.cpp Thu Oct 20 13:44:14 2016 @@ -2873,6 +2873,11 @@ CodeGenFunction::CanDevirtualizeMemberFu if (getLangOpts().AppleKext) return false; + // If the member function is marked 'final', we know that it can't be + // overridden and can therefore devirtualize it. + if (MD->hasAttr<FinalAttr>()) + return true; + // If the most derived class is marked final, we know that no subclass can // override this member function and so we can devirtualize it. For example: // @@ -2883,14 +2888,17 @@ CodeGenFunction::CanDevirtualizeMemberFu // b->f(); // } // - const CXXRecordDecl *MostDerivedClassDecl = Base->getBestDynamicClassType(); - if (MostDerivedClassDecl->hasAttr<FinalAttr>()) - return true; + if (const CXXRecordDecl *BestDynamicDecl = Base->getBestDynamicClassType()) { + if (BestDynamicDecl->hasAttr<FinalAttr>()) + return true; - // If the member function is marked 'final', we know that it can't be - // overridden and can therefore devirtualize it. - if (MD->hasAttr<FinalAttr>()) - return true; + // There may be a method corresponding to MD in a derived class. If that + // method is marked final, we can devirtualize it. + const CXXMethodDecl *DevirtualizedMethod = + MD->getCorrespondingMethodInClass(BestDynamicDecl); + if (DevirtualizedMethod->hasAttr<FinalAttr>()) + return true; + } // Similarly, if the class itself is marked 'final' it can't be overridden // and we can therefore devirtualize the member function call. Modified: cfe/trunk/test/CodeGenCXX/devirtualize-virtual-function-calls-final.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/devirtualize-virtual-function-calls-final.cpp?rev=284766&r1=284765&r2=284766&view=diff ============================================================================== --- cfe/trunk/test/CodeGenCXX/devirtualize-virtual-function-calls-final.cpp (original) +++ cfe/trunk/test/CodeGenCXX/devirtualize-virtual-function-calls-final.cpp Thu Oct 20 13:44:14 2016 @@ -225,3 +225,19 @@ namespace Test9 { return -static_cast<RA&>(*x); } } + +namespace Test10 { + struct A { + virtual int f(); + }; + + struct B : A { + int f() final; + }; + + // CHECK-LABEL: define i32 @_ZN6Test101fEPNS_1BE + int f(B *b) { + // CHECK: call i32 @_ZN6Test101B1fEv + return static_cast<A *>(b)->f(); + } +} Modified: cfe/trunk/test/CodeGenCXX/ubsan-devirtualized-calls.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/ubsan-devirtualized-calls.cpp?rev=284766&r1=284765&r2=284766&view=diff ============================================================================== --- cfe/trunk/test/CodeGenCXX/ubsan-devirtualized-calls.cpp (original) +++ cfe/trunk/test/CodeGenCXX/ubsan-devirtualized-calls.cpp Thu Oct 20 13:44:14 2016 @@ -16,9 +16,6 @@ struct Derived2 final : Base1, Base2 { void f1() override {} }; -// PR13127 documents some missed devirtualization opportunities, including -// devirt for methods marked 'final'. We can enable the checks marked 'PR13127' -// if we implement this in the frontend. struct Derived3 : Base1 { void f1() override /* nofinal */ {} }; @@ -30,10 +27,10 @@ struct Derived4 final : Base1 { // CHECK: [[UBSAN_TI_DERIVED1_1:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived1 to i8* // CHECK: [[UBSAN_TI_DERIVED2_1:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived2 to i8* // CHECK: [[UBSAN_TI_DERIVED2_2:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived2 to i8* -// PR13127: [[UBSAN_TI_DERIVED3:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived3 to i8* -// PR13127: [[UBSAN_TI_BASE1:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI5Base1 to i8* -// PR13127: [[UBSAN_TI_DERIVED4_1:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived4 to i8* -// PR13127: [[UBSAN_TI_DERIVED4_2:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived4 to i8* +// CHECK: [[UBSAN_TI_DERIVED3:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived3 to i8* +// CHECK: [[UBSAN_TI_BASE1:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI5Base1 to i8* +// CHECK: [[UBSAN_TI_DERIVED4_1:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived4 to i8* +// CHECK: [[UBSAN_TI_DERIVED4_2:@[0-9]+]] = private unnamed_addr global {{.*}} i8* bitcast {{.*}} @_ZTI8Derived4 to i8* // CHECK-LABEL: define void @_Z2t1v void t1() { @@ -59,26 +56,26 @@ void t3() { // CHECK-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED2_2]] {{.*}}, i{{[0-9]+}} %[[D2_2]] } -// PR13127-LABEL: define void @_Z2t4v +// CHECK-LABEL: define void @_Z2t4v void t4() { Base1 p; Derived3 *badp = static_cast<Derived3 *>(&p); //< Check that &p isa Derived3. - // PR13127: %[[P1:[0-9]+]] = ptrtoint %struct.Derived3* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize - // PR13127-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED3]] {{.*}}, i{{[0-9]+}} %[[P1]] + // CHECK: %[[P1:[0-9]+]] = ptrtoint %struct.Derived3* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize + // CHECK-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED3]] {{.*}}, i{{[0-9]+}} %[[P1]] static_cast<Base1 *>(badp)->f1(); //< No devirt, test 'badp isa Base1'. - // PR13127: %[[BADP1:[0-9]+]] = ptrtoint %struct.Base1* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize - // PR13127-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_BASE1]] {{.*}}, i{{[0-9]+}} %[[BADP1]] + // CHECK: %[[BADP1:[0-9]+]] = ptrtoint %struct.Base1* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize + // CHECK-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_BASE1]] {{.*}}, i{{[0-9]+}} %[[BADP1]] } -// PR13127-LABEL: define void @_Z2t5v +// CHECK-LABEL: define void @_Z2t5v void t5() { Base1 p; Derived4 *badp = static_cast<Derived4 *>(&p); //< Check that &p isa Derived4. - // PR13127: %[[P1:[0-9]+]] = ptrtoint %struct.Derived4* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize - // PR13127-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED4_1]] {{.*}}, i{{[0-9]+}} %[[P1]] + // CHECK: %[[P1:[0-9]+]] = ptrtoint %struct.Derived4* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize + // CHECK-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED4_1]] {{.*}}, i{{[0-9]+}} %[[P1]] static_cast<Base1 *>(badp)->f1(); //< Devirt Base1::f1 to Derived4::f1. - // PR13127: %[[BADP1:[0-9]+]] = ptrtoint %struct.Derived4* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize - // PR13127-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED4_2]] {{.*}}, i{{[0-9]+}} %[[BADP1]] + // CHECK: %[[BADP1:[0-9]+]] = ptrtoint %struct.Derived4* {{%[0-9]+}} to i{{[0-9]+}}, !nosanitize + // CHECK-NEXT: call void @__ubsan_handle_dynamic_type_cache{{[_a-z]*}}({{.*}} [[UBSAN_TI_DERIVED4_2]] {{.*}}, i{{[0-9]+}} %[[BADP1]] } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
