[llvm-branch-commits] [clang] release/21.x: [clang][PAC] Fix PAC codegen for final class dynamic_cast optimization (#152227) (PR #152586)

[via llvm-branch-commits]

https://github.com/llvmbot created https://github.com/llvm/llvm-project/pull/152586

Backport 726847829553079a13b1b7104f2c2db9dcda9c1d

Requested by: @ojhunt

>From 789c9330fa0195dc5f9cdada51ae0f187197d562 Mon Sep 17 00:00:00 2001
From: Oliver Hunt <oliver at apple.com>
Date: Tue, 5 Aug 2025 17:41:55 -0700
Subject: [PATCH] [clang][PAC] Fix PAC codegen for final class dynamic_cast
 optimization (#152227)

The codegen for the final class dynamic_cast optimization fails to
consider pointer authentication. This change resolves this be simply
disabling the optimization when pointer authentication enabled.

(cherry picked from commit 726847829553079a13b1b7104f2c2db9dcda9c1d)
---
 clang/lib/CodeGen/CGExprCXX.cpp                       | 3 ++-
 clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index 359e30cb8f5cd..912b1d72c7e23 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -2313,7 +2313,8 @@ llvm::Value *CodeGenFunction::EmitDynamicCast(Address ThisAddr,
   bool IsExact = !IsDynamicCastToVoid &&
                  CGM.getCodeGenOpts().OptimizationLevel > 0 &&
                  DestRecordTy->getAsCXXRecordDecl()->isEffectivelyFinal() &&
-                 CGM.getCXXABI().shouldEmitExactDynamicCast(DestRecordTy);
+                 CGM.getCXXABI().shouldEmitExactDynamicCast(DestRecordTy) &&
+                 !getLangOpts().PointerAuthCalls;
 
   // C++ [expr.dynamic.cast]p4:
   //   If the value of v is a null pointer value in the pointer case, the result
diff --git a/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp b/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp
index 9a8ce1997a7f9..19c2a9bd0497e 100644
--- a/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp
+++ b/clang/test/CodeGenCXX/dynamic-cast-exact-disabled.cpp
@@ -3,6 +3,7 @@
 // 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 { };