[clang][PAC] Enable the PAC dynamic_cast to final class optimization by ojhunt · Pull Request #152601 · llvm/llvm-project (original) (raw)
@llvm/pr-subscribers-clang
@llvm/pr-subscribers-clang-codegen
Author: Oliver Hunt (ojhunt)
Changes
Update the codegen for the the dynamic_cast to a final class optimization when pointer authentication is enabled.
Full diff: https://github.com/llvm/llvm-project/pull/152601.diff
5 Files Affected:
- (modified) clang/docs/ReleaseNotes.rst (+2)
- (modified) clang/lib/CodeGen/CGExprCXX.cpp (+1-2)
- (modified) clang/lib/CodeGen/ItaniumCXXABI.cpp (+39)
- (modified) clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp (-1)
- (added) clang/test/CodeGenCXX/ptrauth-dynamic-cast-exact.cpp (+128)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 0e9fcaa5fac6a..94de70329ee34 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -184,6 +184,8 @@ Bug Fixes to C++ Support
([[assume(expr)]]) creates temporary objects.
- Fix the dynamic_cast to final class optimization to correctly handle casts that are guaranteed to fail (#GH137518). +- Support the dynamic_cast to final class optimization with pointer
- authentication enabled.
Bug Fixes to AST Handling ^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp index 49d5d8acbe331..afb9ab8a55c56 100644 --- a/clang/lib/CodeGen/CGExprCXX.cpp +++ b/clang/lib/CodeGen/CGExprCXX.cpp @@ -2292,8 +2292,7 @@ llvm::Value *CodeGenFunction::EmitDynamicCast(Address ThisAddr, bool IsExact = !IsDynamicCastToVoid && CGM.getCodeGenOpts().OptimizationLevel > 0 && DestRecordTy->getAsCXXRecordDecl()->isEffectivelyFinal() &&
CGM.getCXXABI().shouldEmitExactDynamicCast(DestRecordTy) &&!getLangOpts().PointerAuthCalls;
std::optionalCGCXXABI::ExactDynamicCastInfo ExactCastInfo; if (IsExact) {CGM.getCXXABI().shouldEmitExactDynamicCast(DestRecordTy);
diff --git a/clang/lib/CodeGen/ItaniumCXXABI.cpp b/clang/lib/CodeGen/ItaniumCXXABI.cpp index 5ffc1edb9986f..f4c84c37ce72b 100644 --- a/clang/lib/CodeGen/ItaniumCXXABI.cpp +++ b/clang/lib/CodeGen/ItaniumCXXABI.cpp @@ -1745,7 +1745,14 @@ llvm::Value *ItaniumCXXABI::emitExactDynamicCast( llvm::BasicBlock *CastFail) { const CXXRecordDecl *SrcDecl = SrcRecordTy->getAsCXXRecordDecl(); const CXXRecordDecl *DestDecl = DestRecordTy->getAsCXXRecordDecl();
auto AuthenticateVTable = [&](Address ThisAddr, const CXXRecordDecl *Decl) {
if (!CGF.getLangOpts().PointerAuthCalls)
return;(void)CGF.GetVTablePtr(ThisAddr, CGF.UnqualPtrTy, Decl,
CodeGenFunction::VTableAuthMode::MustTrap);};
bool PerformPostCastAuthentication = false; llvm::Value *VTable = nullptr; if (ExactCastInfo.RequiresCastToPrimaryBase) { // Base appears in at least two different places. Find the most-derived @@ -1756,8 +1763,16 @@ llvm::Value *ItaniumCXXABI::emitExactDynamicCast( emitDynamicCastToVoid(CGF, ThisAddr, SrcRecordTy); ThisAddr = Address(PrimaryBase, CGF.VoidPtrTy, ThisAddr.getAlignment()); SrcDecl = DestDecl;
// This unauthenticated load is unavoidable, so we're relying on the
// authenticated load in the dynamic cast to void, and we'll manually
// authenticate the resulting v-table at the end of the cast check.
PerformPostCastAuthentication = CGF.getLangOpts().PointerAuthCalls;
CGPointerAuthInfo StrippingAuthInfo(0, PointerAuthenticationMode::Strip,
false, false, nullptr);Address VTablePtrPtr = ThisAddr.withElementType(CGF.VoidPtrPtrTy); VTable = CGF.Builder.CreateLoad(VTablePtrPtr, "vtable");
if (PerformPostCastAuthentication)
VTable = CGF.EmitPointerAuthAuth(StrippingAuthInfo, VTable);} else VTable = CGF.GetVTablePtr(ThisAddr, CGF.UnqualPtrTy, SrcDecl);
@@ -1774,8 +1789,32 @@ llvm::Value *ItaniumCXXABI::emitExactDynamicCast( llvm::ConstantInt::get(CGF.PtrDiffTy, -Offset); AdjustedThisPtr = CGF.Builder.CreateInBoundsGEP(CGF.CharTy, AdjustedThisPtr, OffsetConstant);
- PerformPostCastAuthentication = CGF.getLangOpts().PointerAuthCalls;
}
- if (PerformPostCastAuthentication) {
- // If we've changed the object pointer we authenticate the vtable pointer
- // of the resulting object.
- llvm::BasicBlock *NonNullBlock = CGF.Builder.GetInsertBlock();
- llvm::BasicBlock *PostCastAuthSuccess =
CGF.createBasicBlock("dynamic_cast.postauth.success");- llvm::BasicBlock *PostCastAuthComplete =
CGF.createBasicBlock("dynamic_cast.postauth.complete");- CGF.Builder.CreateCondBr(Success, PostCastAuthSuccess,
PostCastAuthComplete);- CGF.EmitBlock(PostCastAuthSuccess);
- Address AdjustedThisAddr =
Address(AdjustedThisPtr, CGF.IntPtrTy, CGF.getPointerAlign());- AuthenticateVTable(AdjustedThisAddr, DestDecl);
- CGF.EmitBranch(PostCastAuthComplete);
- CGF.EmitBlock(PostCastAuthComplete);
- llvm::PHINode *PHI = CGF.Builder.CreatePHI(AdjustedThisPtr->getType(), 2);
- PHI->addIncoming(AdjustedThisPtr, PostCastAuthSuccess);
- llvm::Value *NullValue =
llvm::Constant::getNullValue(AdjustedThisPtr->getType());- PHI->addIncoming(NullValue, NonNullBlock);
- AdjustedThisPtr = PHI;
- } CGF.Builder.CreateCondBr(Success, CastSuccess, CastFail); return AdjustedThisPtr; } diff --git a/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp b/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp index 3156e1bb21b1e..bf202d14c3398 100644 --- a/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp +++ b/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp @@ -3,7 +3,6 @@ // RUN: %clang_cc1 -I%S %s -triple x86_64-apple-darwin10 -O1 -fvisibility=hidden -emit-llvm -std=c++11 -o - | FileCheck %s --check-prefixes=CHECK,INEXACT // RUN: %clang_cc1 -I%S %s -triple x86_64-apple-darwin10 -O1 -fapple-kext -emit-llvm -std=c++11 -o - | FileCheck %s --check-prefixes=CHECK,INEXACT // RUN: %clang_cc1 -I%S %s -triple x86_64-apple-darwin10 -O1 -fno-assume-unique-vtables -emit-llvm -std=c++11 -o - | FileCheck %s --check-prefixes=CHECK,INEXACT -// RUN: %clang_cc1 -I%S %s -triple arm64e-apple-darwin10 -O1 -fptrauth-calls -emit-llvm -std=c++11 -o - | FileCheck %s --check-prefixes=CHECK,INEXACT
struct A { virtual ~A(); }; struct B final : A { }; diff --git a/clang/test/CodeGenCXX/ptrauth-dynamic-cast-exact.cpp b/clang/test/CodeGenCXX/ptrauth-dynamic-cast-exact.cpp new file mode 100644 index 0000000000000..1710ca5563380 --- /dev/null +++ b/clang/test/CodeGenCXX/ptrauth-dynamic-cast-exact.cpp @@ -0,0 +1,128 @@ +// RUN: %clang_cc1 -I%S %s -triple arm64e-apple-darwin10 -O1 -fptrauth-calls -fptrauth-vtable-pointer-address-discrimination -fptrauth-vtable-pointer-type-discrimination -emit-llvm -std=c++11 -o - | FileCheck %s --check-prefixes=CHECK + +struct A {
- virtual ~A(); +}; +struct B {
- int foo;
- virtual ~B(); +}; +struct C final : A, B {
- virtual void f(){}; +}; +struct D final : B, A {
- virtual void f(){}; +};
- +struct Offset {
- virtual ~Offset(); +}; +struct E {
- virtual ~E(); +}; +struct F final : Offset, E { +}; +struct G {
- virtual ~G();
- int g; +}; +struct H : E {
- int h; +}; +struct I : E {
- int i; +}; +struct J : virtual E {
- int j; +}; +struct K : virtual E {
- int k; +}; +struct L final : G, H, I, J, K {
- int l; +}; +struct M final: G, private H { int m; };
- +// CHECK-LABEL: @_Z10exact_to_CP1A +C *exact_to_C(A *a) {
- // CHECK: [[UNAUTHED_VPTR:%.*]] = load ptr, ptr %a, align 8
- // CHECK: [[VPTR_ADDRI:%.*]] = ptrtoint ptr %a to i64
- // CHECK: [[VPTR_ADDR_DISC:%.*]] = tail call i64 @llvm.ptrauth.blend(i64 [[VPTR_ADDRI]], i64 62866)
- // CHECK: [[UNAUTHED_VPTRI:%.*]] = ptrtoint ptr [[UNAUTHED_VPTR]] to i64
- // CHECK: [[AUTHED_VPTRI:%.*]] = tail call i64 @llvm.ptrauth.auth(i64 [[UNAUTHED_VPTRI]], i32 2, i64 [[VPTR_ADDR_DISC]])
- // CHECK: [[IS_EXPECTED:%.*]] = icmp eq i64 [[AUTHED_VPTRI]], ptrtoint (ptr getelementptr inbounds nuw inrange(-16, 24) (i8, ptr @_ZTV1C, i64 16) to i64)
- // CHECK: br i1 [[IS_EXPECTED]], label %dynamic_cast.end, label %dynamic_cast.null
- // CHECK: [[NULL_CHECKED_RESULT:%.*]] = phi ptr [ %a, %dynamic_cast.notnull ], [ null, %dynamic_cast.null ]
- // CHECK: ret ptr [[NULL_CHECKED_RESULT]]
- return dynamic_cast<C*>(a); +}
- +// CHECK-LABEL: @_Z9exact_t_DP1A +D *exact_t_D(A *a) {
- // CHECK: dynamic_cast.notnull:
- // CHECK: [[SRC_UNAUTHED_VPTR:%.*]] = load ptr, ptr %a
- // CHECK: [[SRC_VPTR_ADDRI:%.*]] = ptrtoint ptr %a to i64
- // CHECK: [[SRC_VPTR_DISC:%.*]] = tail call i64 @llvm.ptrauth.blend(i64 [[SRC_VPTR_ADDRI]], i64 62866)
- // CHECK: [[SRC_UNAUTHED_VPTRI:%.*]] = ptrtoint ptr [[SRC_UNAUTHED_VPTR]] to i64
- // CHECK: [[SRC_AUTHED_VPTRI:%.*]] = tail call i64 @llvm.ptrauth.auth(i64 [[SRC_UNAUTHED_VPTRI]], i32 2, i64 [[SRC_VPTR_DISC]])
- // CHECK: [[SUCCESS:%.*]] = icmp eq i64 [[SRC_AUTHED_VPTRI]], ptrtoint (ptr getelementptr inbounds nuw inrange(-16, 16) (i8, ptr @_ZTV1D, i64 56) to i64)
- // CHECK: br i1 [[SUCCESS]], label %dynamic_cast.postauth.success, label %dynamic_cast.postauth.complete
- // CHECK: dynamic_cast.postauth.success:
- // CHECK: [[ADJUSTED_THIS:%.*]] = getelementptr inbounds i8, ptr %a, i64 -16
- // CHECK: [[ADJUSTED_UNAUTHED_VPTR:%.*]] = load ptr, ptr [[ADJUSTED_THIS]]
- // CHECK: [[ADJUSTED_VPTR_ADDRI:%.*]] = ptrtoint ptr [[ADJUSTED_THIS]] to i64
- // CHECK: [[ADJUSTED_VPTR_DISC:%.*]] = tail call i64 @llvm.ptrauth.blend(i64 [[ADJUSTED_VPTR_ADDRI]], i64 28965)
- // CHECK: [[ADJUSTED_UNAUTHED_VPTRI:%.*]] = ptrtoint ptr [[ADJUSTED_UNAUTHED_VPTR]] to i64
- // CHECK: [[ADJUSTED_AUTHED_VPTRI:%.*]] = tail call i64 @llvm.ptrauth.auth(i64 [[ADJUSTED_UNAUTHED_VPTRI]], i32 2, i64 [[ADJUSTED_VPTR_DISC]])
- // CHECK: [[ADJUSTED_AUTHED_VPTR:%.*]] = inttoptr i64 [[ADJUSTED_AUTHED_VPTRI]] to ptr
- // CHECK: br label %dynamic_cast.postauth.complete
- // CHECK: dynamic_cast.postauth.complete:
- // CHECK: [[AUTHED_ADJUSTED_THIS:%.*]] = phi ptr [ [[ADJUSTED_THIS]], %dynamic_cast.postauth.success ], [ null, %dynamic_cast.notnull ]
- // CHECK: br i1 [[SUCCESS]], label %dynamic_cast.end, label %dynamic_cast.null
- // CHECK: dynamic_cast.null:
- // CHECK: br label %dynamic_cast.end
- // CHECK: dynamic_cast.end:
- // CHECK: [[RESULT:%.*]] = phi ptr [ [[AUTHED_ADJUSTED_THIS]], %dynamic_cast.postauth.complete ], [ null, %dynamic_cast.null ]
- // CHECK: ret ptr [[RESULT]]
- return dynamic_cast<D*>(a); +}
- +// CHECK-LABEL: @_Z11exact_multiP1E +L *exact_multi(E *e) {
- // CHECK: dynamic_cast.notnull:
- // CHECK: [[VTABLE_ADDR:%.*]] = load ptr, ptr %e, align 8
- // CHECK: [[THIS_ADDRI:%.*]] = ptrtoint ptr %e to i64
- // CHECK: [[VTABLE_DISC:%.*]] = tail call i64 @llvm.ptrauth.blend(i64 [[THIS_ADDRI]], i64 12810)
- // CHECK: [[VTABLE_ADDRI:%.*]] = ptrtoint ptr [[VTABLE_ADDR]] to i64
- // CHECK: [[AUTHED_VTABLEI:%.*]] = tail call i64 @llvm.ptrauth.auth(i64 [[VTABLE_ADDRI]], i32 2, i64 [[VTABLE_DISC]])
- // CHECK: [[AUTHED_VTABLE:%.*]] = inttoptr i64 [[AUTHED_VTABLEI]] to ptr
- // CHECK: [[PRIMARY_BASE_OFFSET:%.*]] = getelementptr inbounds i8, ptr [[AUTHED_VTABLE]], i64 -16
- // CHECK: %offset.to.top = load i64, ptr [[PRIMARY_BASE_OFFSET]]
- // CHECK: [[ADJUSTED_THIS:%.*]] = getelementptr inbounds i8, ptr %e, i64 %offset.to.top
- // CHECK: [[ADJUSTED_THIS_VTABLE:%.*]] = load ptr, ptr [[ADJUSTED_THIS]]
- // CHECK: [[ADJUSTED_THIS_VTABLEI:%.*]] = ptrtoint ptr [[ADJUSTED_THIS_VTABLE]] to i64
- // CHECK: [[ADJUSTED_THIS_STRIPPED_VTABLEI:%.*]] = tail call i64 @llvm.ptrauth.strip(i64 [[ADJUSTED_THIS_VTABLEI]], i32 0)
- // CHECK: [[SUCCESS:%.*]] = icmp eq i64 [[ADJUSTED_THIS_STRIPPED_VTABLEI]], ptrtoint (ptr getelementptr inbounds nuw inrange(-24, 16) (i8, ptr @_ZTV1L, i64 24) to i64)
- // CHECK: br i1 [[SUCCESS]], label %dynamic_cast.postauth.success, label %dynamic_cast.postauth.complete
- // CHECK: dynamic_cast.postauth.success:
- // CHECK: [[ADJUSTED_THISI:%.*]] = ptrtoint ptr [[ADJUSTED_THIS]] to i64
- // CHECK: [[DEST_DISC:%.*]] = tail call i64 @llvm.ptrauth.blend(i64 [[ADJUSTED_THISI]], i64 41434)
- // CHECK: tail call i64 @llvm.ptrauth.auth(i64 [[ADJUSTED_THIS_VTABLEI]], i32 2, i64 [[DEST_DISC]])
- // CHECK: br label %dynamic_cast.postauth.complete
- // CHECK: dynamic_cast.postauth.complete:
- // CHECK: [[AUTHED_ADJUSTED_THIS:%.*]] = phi ptr [ [[ADJUSTED_THIS]], %dynamic_cast.postauth.success ], [ null, %dynamic_cast.notnull ]
- // CHECK: br i1 [[SUCCESS]], label %dynamic_cast.end, label %dynamic_cast.null
- // CHECK: dynamic_cast.null:
- // CHECK: br label %dynamic_cast.end
- // CHECK: dynamic_cast.end:
- // CHECK: [[RESULT:%.*]] = phi ptr [ [[AUTHED_ADJUSTED_THIS]], %dynamic_cast.postauth.complete ], [ null, %dynamic_cast.null ]
- // CHECK: ret ptr [[RESULT]]
- return dynamic_cast<L*>(e); +}
- +// CHECK-LABEL: @_Z19exact_invalid_multiP1H +M exact_invalid_multi(H d) {
- // CHECK: entry:
- // CHECK-NEXT: ret ptr null
- return dynamic_cast<M*>(d); +}