[clang] 485c80e - [PAC] Ignore noexcept on function type when computing discriminator of member function pointers (#109056)
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Tue Jan 21 09:03:54 PST 2025
Author: Akira Hatanaka
Date: 2025-01-21T09:03:50-08:00
New Revision: 485c80e1188192a4bb2a8cbddccdca82a6e33b81
URL: https://github.com/llvm/llvm-project/commit/485c80e1188192a4bb2a8cbddccdca82a6e33b81
DIFF: https://github.com/llvm/llvm-project/commit/485c80e1188192a4bb2a8cbddccdca82a6e33b81.diff
LOG: [PAC] Ignore noexcept on function type when computing discriminator of member function pointers (#109056)
This fixes a bug where a member function pointer signed using a function type with noexcept as the discriminator was being authenticated using a function type without noexcept.
Fixes https://github.com/llvm/llvm-project/issues/106487.
Added:
Modified:
clang/lib/AST/ASTContext.cpp
clang/test/CodeGenCXX/ptrauth-member-function-pointer.cpp
Removed:
################################################################################
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 155dbcfcaeed31..a4ba9fd0553464 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -3503,6 +3503,34 @@ uint16_t ASTContext::getPointerAuthTypeDiscriminator(QualType T) {
encodeTypeForFunctionPointerAuth(*this, Out, T);
} else {
T = T.getUnqualifiedType();
+ // Calls to member function pointers don't need to worry about
+ // language interop or the laxness of the C type compatibility rules.
+ // We just mangle the member pointer type directly, which is
+ // implicitly much stricter about type matching. However, we do
+ // strip any top-level exception specification before this mangling.
+ // C++23 requires calls to work when the function type is convertible
+ // to the pointer type by a function pointer conversion, which can
+ // change the exception specification. This does not technically
+ // require the exception specification to not affect representation,
+ // because the function pointer conversion is still always a direct
+ // value conversion and therefore an opportunity to resign the
+ // pointer. (This is in contrast to e.g. qualification conversions,
+ // which can be applied in nested pointer positions, effectively
+ // requiring qualified and unqualified representations to match.)
+ // However, it is pragmatic to ignore exception specifications
+ // because it allows a certain amount of `noexcept` mismatching
+ // to not become a visible ODR problem. This also leaves some
+ // room for the committee to add laxness to function pointer
+ // conversions in future standards.
+ if (auto *MPT = T->getAs<MemberPointerType>())
+ if (MPT->isMemberFunctionPointer()) {
+ QualType PointeeType = MPT->getPointeeType();
+ if (PointeeType->castAs<FunctionProtoType>()->getExceptionSpecType() !=
+ EST_None) {
+ QualType FT = getFunctionTypeWithExceptionSpec(PointeeType, EST_None);
+ T = getMemberPointerType(FT, MPT->getClass());
+ }
+ }
std::unique_ptr<MangleContext> MC(createMangleContext());
MC->mangleCanonicalTypeName(T, Out);
}
diff --git a/clang/test/CodeGenCXX/ptrauth-member-function-pointer.cpp b/clang/test/CodeGenCXX/ptrauth-member-function-pointer.cpp
index 0a9ac3fa510f56..e9436f11b5106e 100644
--- a/clang/test/CodeGenCXX/ptrauth-member-function-pointer.cpp
+++ b/clang/test/CodeGenCXX/ptrauth-member-function-pointer.cpp
@@ -1,10 +1,12 @@
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -o - %s | FileCheck -check-prefixes=CHECK,NODEBUG,DARWIN %s
+// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++17 -O1 -disable-llvm-passes -o - %s | FileCheck -check-prefixes=CHECK,NODEBUG,DARWIN,CXX17 %s
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -debug-info-kind=limited -o - %s | FileCheck -check-prefixes=CHECK,DARWIN %s
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -stack-protector 1 -o - %s | FileCheck %s -check-prefix=STACK-PROT
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -stack-protector 2 -o - %s | FileCheck %s -check-prefix=STACK-PROT
// RUN: %clang_cc1 -triple arm64-apple-ios -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -stack-protector 3 -o - %s | FileCheck %s -check-prefix=STACK-PROT
// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -o - %s | FileCheck -check-prefixes=CHECK,NODEBUG,ELF %s
+// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++17 -O1 -disable-llvm-passes -o - %s | FileCheck -check-prefixes=CHECK,NODEBUG,ELF,CXX17 %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -debug-info-kind=limited -o - %s | FileCheck -check-prefixes=CHECK,ELF %s
// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -stack-protector 1 -o - %s | FileCheck %s -check-prefix=STACK-PROT
// RUN: %clang_cc1 -triple aarch64-linux-gnu -fptrauth-calls -fptrauth-intrinsics -emit-llvm -std=c++11 -O1 -disable-llvm-passes -stack-protector 2 -o - %s | FileCheck %s -check-prefix=STACK-PROT
@@ -20,6 +22,10 @@
// CHECK: @__const._Z13testArrayInitv.c0 = private unnamed_addr constant %struct.Class0 { { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN5Base011nonvirtual0Ev, i32 0, i64 35591) to i64), i64 0 } }, align 8
// CHECK: @__const._Z13testArrayInitv.c1 = private unnamed_addr constant %struct.Class0 { { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN5Base08virtual1Ev_vfpthunk_, i32 0, i64 35591) to i64), i64 0 } }, align 8
+// CHECK: @_ZN22testNoexceptConversion6mfptr1E = global { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN22testNoexceptConversion1S19nonvirtual_noexceptEv, i32 0, i64 [[TYPEDISC3:.*]]) to i64), i64 0 },
+// CHECK: @_ZN22testNoexceptConversion6mfptr2E = global { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN22testNoexceptConversion1S16virtual_noexceptEv_vfpthunk_, i32 0, i64 [[TYPEDISC3]]) to i64), i64 0 },
+// CHECK: @_ZN22testNoexceptConversion15mfptr3_noexceptE = global { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN22testNoexceptConversion1S19nonvirtual_noexceptEv, i32 0, i64 [[TYPEDISC3]]) to i64), i64 0 },
+
// CHECK: @_ZTV5Base0 = unnamed_addr constant { [5 x ptr] } { [5 x ptr] [ptr null, ptr @_ZTI5Base0,
// CHECK-SAME: ptr ptrauth (ptr @_ZN5Base08virtual1Ev, i32 0, i64 55600, ptr getelementptr inbounds ({ [5 x ptr] }, ptr @_ZTV5Base0, i32 0, i32 0, i32 2)),
// CHECK-SAME: ptr ptrauth (ptr @_ZN5Base08virtual3Ev, i32 0, i64 53007, ptr getelementptr inbounds ({ [5 x ptr] }, ptr @_ZTV5Base0, i32 0, i32 0, i32 3)),
@@ -77,6 +83,9 @@ struct Derived1 : Base0, Base1 {
};
typedef void (Base0::*MethodTy0)();
+#if __cplusplus >= 201703L
+typedef void (Base0::*NoExceptMethodTy0)() noexcept;
+#endif
typedef void (Base0::*VariadicMethodTy0)(int, ...);
typedef void (Derived0::*MethodTy1)();
@@ -293,6 +302,16 @@ void test1(Base0 *a0, MethodTy0 a1) {
(a0->*a1)();
}
+// CXX17: define{{.*}} void @_Z14test1_noexceptP5Base0MS_DoFvvE(
+// CXX17: %[[V14:.*]] = phi ptr [ %{{.*}}, {{.*}} ], [ %{{.*}}, {{.*}} ]
+// CXX17: %[[V15:.*]] = phi i64 [ 0, {{.*}} ], [ [[TYPEDISC0]], {{.*}} ]
+// CXX17: call void %[[V14]](ptr noundef nonnull align {{[0-9]+}} dereferenceable(8) %{{.*}}) {{.*}}[ "ptrauth"(i32 0, i64 %[[V15]]) ]
+#if __cplusplus >= 201703L
+void test1_noexcept(Base0 *a0, NoExceptMethodTy0 a1) {
+ (a0->*a1)();
+}
+#endif
+
// CHECK: define{{.*}} void @_Z15testConversion0M5Base0FvvEM8Derived0FvvE([2 x i64] %[[METHOD0_COERCE:.*]], [2 x i64] %[[METHOD1_COERCE:.*]])
// CHECK: %[[METHOD0:.*]] = alloca { i64, i64 }, align 8
// CHECK: %[[METHOD1:.*]] = alloca { i64, i64 }, align 8
@@ -438,3 +457,47 @@ void testArrayInit() {
void testConvertNull() {
VariadicMethodTy0 t = (VariadicMethodTy0)(MethodTy0{});
}
+
+namespace testNoexceptConversion {
+
+// CHECK-LABEL: define internal void @__cxx_global_var_init()
+// CHECK: %[[V0:.*]] = load { i64, i64 }, ptr @_ZN22testNoexceptConversion15mfptr0_noexceptE, align 8
+// CHECK: store { i64, i64 } %[[V0]], ptr @_ZN22testNoexceptConversion6mfptr4E, align 8
+
+// CHECK: define {{.*}}void @_ZN22testNoexceptConversion5test0Ev()
+// CHECK: %[[P0:.*]] = alloca { i64, i64 }, align 8
+// CHECK: store { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN22testNoexceptConversion1S19nonvirtual_noexceptEv, i32 0, i64 [[TYPEDISC3]]) to i64), i64 0 }, ptr %[[P0]], align 8,
+
+// CHECK: define {{.*}}void @_ZN22testNoexceptConversion5test1Ev()
+// CHECK: %[[P0:.*]] = alloca { i64, i64 }, align 8
+// CHECK: store { i64, i64 } { i64 ptrtoint (ptr ptrauth (ptr @_ZN22testNoexceptConversion1S16virtual_noexceptEv_vfpthunk_, i32 0, i64 [[TYPEDISC3]]) to i64), i64 0 }, ptr %[[P0]], align 8,
+
+// CHECK: define {{.*}}void @_ZN22testNoexceptConversion5test2Ev()
+// CHECK: %[[P0:.*]] = alloca { i64, i64 }, align 8
+// CHECK: %[[V0:.*]] = load { i64, i64 }, ptr @_ZN22testNoexceptConversion15mfptr0_noexceptE, align 8
+// CHECK: store { i64, i64 } %[[V0]], ptr %[[P0]], align 8,
+
+struct S {
+ void nonvirtual_noexcept() noexcept;
+ virtual void virtual_noexcept() noexcept;
+};
+
+void (S::*mfptr0_noexcept)() noexcept;
+void (S::*mfptr1)() = &S::nonvirtual_noexcept;
+void (S::*mfptr2)() = &S::virtual_noexcept;
+void (S::*mfptr3_noexcept)() noexcept = &S::nonvirtual_noexcept;
+void (S::*mfptr4)() = mfptr0_noexcept;
+
+void test0() {
+ void (S::*p0)() = &S::nonvirtual_noexcept;
+}
+
+void test1() {
+ void (S::*p0)() = &S::virtual_noexcept;
+}
+
+void test2() {
+ void (S::*p0)() = mfptr0_noexcept;
+}
+
+}
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