From b4d1ddb99e1305f6ea6217e7570dda2a94b16e51 Mon Sep 17 00:00:00 2001
From: Richard-Qin-X <richard.qin.001@gmail.com>
Date: Sat, 1 Aug 2026 13:01:07 +0800
Subject: [CMake] Match LLVM EH and RTTI defaults

Disable C++ exceptions and RTTI by default while retaining explicit, validated opt-in switches. Replace the arena's exception syntax with an RAII construction guard so both configurations share one implementation.
---
 backend/CMakeLists.txt                      |  6 ++++++
 backend/cmake/modules/RCCBackendBuild.cmake | 12 ++++++++++++
 backend/lib/CodeGen/MachineFunction.cpp     | 17 +++++++----------
 3 files changed, 25 insertions(+), 10 deletions(-)

(limited to 'backend')

diff --git a/backend/CMakeLists.txt b/backend/CMakeLists.txt
index 2d5cc82..0f983d0 100644
--- a/backend/CMakeLists.txt
+++ b/backend/CMakeLists.txt
@@ -44,6 +44,12 @@ include(RCCBackendDeveloperTools)
 option(RCC_BACKEND_BUILD_TESTS "Build RCC Backend tests" "${BUILD_TESTING}")
 option(RCC_BACKEND_WARNINGS_AS_ERRORS "Treat compiler warnings as errors" OFF)
 option(RCC_BACKEND_ENABLE_CLANG_TIDY "Run clang-tidy during each compilation" OFF)
+option(RCC_BACKEND_ENABLE_EH "Enable C++ exception handling" OFF)
+option(RCC_BACKEND_ENABLE_RTTI "Enable C++ run-time type information" OFF)
+
+if(RCC_BACKEND_ENABLE_EH AND NOT RCC_BACKEND_ENABLE_RTTI)
+  message(FATAL_ERROR "RCC Backend exception handling requires RTTI")
+endif()
 
 rcc_backend_initialize_toolchain()
 
diff --git a/backend/cmake/modules/RCCBackendBuild.cmake b/backend/cmake/modules/RCCBackendBuild.cmake
index 79e7bb1..52e3a71 100644
--- a/backend/cmake/modules/RCCBackendBuild.cmake
+++ b/backend/cmake/modules/RCCBackendBuild.cmake
@@ -70,6 +70,18 @@ function(rcc_backend_configure_target Target)
       -Wformat=2
   )
 
+  if(RCC_BACKEND_ENABLE_EH)
+    target_compile_options("${Target}" PRIVATE -fexceptions)
+  else()
+    target_compile_options("${Target}" PRIVATE -fno-exceptions)
+  endif()
+
+  if(RCC_BACKEND_ENABLE_RTTI)
+    target_compile_options("${Target}" PRIVATE -frtti)
+  else()
+    target_compile_options("${Target}" PRIVATE -fno-rtti)
+  endif()
+
   if(RCC_BACKEND_WARNINGS_AS_ERRORS)
     target_compile_options("${Target}" PRIVATE -Werror)
   endif()
diff --git a/backend/lib/CodeGen/MachineFunction.cpp b/backend/lib/CodeGen/MachineFunction.cpp
index e19c115..fc1508c 100644
--- a/backend/lib/CodeGen/MachineFunction.cpp
+++ b/backend/lib/CodeGen/MachineFunction.cpp
@@ -35,16 +35,13 @@ public:
   [[nodiscard]] ObjectT *create(ArgumentTs &&...Arguments) {
     void *Storage = Resource.allocate(sizeof(ObjectT), alignof(ObjectT));
     ObjectT *Object = ::new (Storage) ObjectT(std::forward<ArgumentTs>(Arguments)...);
-    try {
-      Destructors.push_back(DestructorRecord{
-          Object,
-          [](void *RawObject) noexcept { std::destroy_at(static_cast<ObjectT *>(RawObject)); },
-      });
-    } catch (...) {
-      std::destroy_at(Object);
-      throw;
-    }
-    return Object;
+    auto DestroyObject = [](ObjectT *TypedObject) noexcept { std::destroy_at(TypedObject); };
+    std::unique_ptr<ObjectT, decltype(DestroyObject)> ConstructionGuard(Object, DestroyObject);
+    Destructors.push_back(DestructorRecord{
+        Object,
+        [](void *RawObject) noexcept { std::destroy_at(static_cast<ObjectT *>(RawObject)); },
+    });
+    return ConstructionGuard.release();
   }
 
 private:
-- 
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