[PATCH 0/3] MR8112: Enable compiler exceptions on Clang for 64-bit MSVC targets.

[Jacek Caban (＠jacek)]

Only 64-bit targets for now. Enabling this on 32-bit x86 requires additional work, as we need to provide exception helpers for modules that don’t link against msvcrt/ucrt. LLVM currently does not support `__try`/`__except` on 32-bit ARM.

While `__try`/`__except` is generally available on the MinGW target with `-fms-extensions`, `-fasync-exceptions` is currently supported only on the MSVC target. For that reason, I did not enable it for the MinGW target.

[PATCH 1/3] ntdll: Mark IsBadStringPtr functions as noinline.

[Jacek Caban]

From: Jacek Caban

Without this, the compiler may inline them into dispatch_exception. When compiler
exceptions are enabled, this causes a handler to be set up for dispatch_exception,
which is unintended. A side effect of this is that EXCEPTION_NESTED_CALL may be
cleared when a nested exception is dispatched.

This fixes test_nested_exception test on aarch64 when compiler exceptions are used.
---
 dlls/ntdll/exception.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dlls/ntdll/exception.c b/dlls/ntdll/exception.c
index bf4a53e1b6e..2284333668a 100644
--- a/dlls/ntdll/exception.c
+++ b/dlls/ntdll/exception.c
@@ -465,7 +465,7 @@ void __cdecl __wine_spec_unimplemented_stub( const char *module, const char *fun
  *
  * IsBadStringPtrA replacement for ntdll, to catch exception in debug traces.
  */
-BOOL WINAPI IsBadStringPtrA( LPCSTR str, UINT_PTR max )
+BOOL DECLSPEC_NOINLINE WINAPI IsBadStringPtrA( LPCSTR str, UINT_PTR max )
 {
     if (!str) return TRUE;
     __TRY
@@ -486,7 +486,7 @@ BOOL WINAPI IsBadStringPtrA( LPCSTR str, UINT_PTR max )
  *
  * IsBadStringPtrW replacement for ntdll, to catch exception in debug traces.
  */
-BOOL WINAPI IsBadStringPtrW( LPCWSTR str, UINT_PTR max )
+BOOL DECLSPEC_NOINLINE WINAPI IsBadStringPtrW( LPCWSTR str, UINT_PTR max )
 {
     if (!str) return TRUE;
     __TRY

[PATCH 2/3] configure: Enable -fasync-exceptions when supported.

[Jacek Caban]

From: Jacek Caban

This affects Clang in MSVC mode. By default, Clang treats __try/__except as regular
exceptions, assuming that memory access doesn’t throw. As a result, it may
incorrectly move code outside the exception handler or optimize away the handler
entirely. MSVC always treats __try/__except as meaningful. Work around the issue
by explicitly enabling -fasync-exceptions.

See https://github.com/llvm/llvm-project/issues/62606 more context.
---
 configure.ac | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/configure.ac b/configure.ac
index 2dcf3111f49..e900ea20493 100644
--- a/configure.ac
+++ b/configure.ac
@@ -540,6 +540,7 @@ This is an error since --enable-archs=$wine_arch was requested.])])
     WINE_TRY_PE_CFLAGS([-fno-strict-aliasing])
     dnl clang needs to be told to fail on unknown options
     WINE_TRY_PE_CFLAGS([-Werror=unknown-warning-option],[CFLAGS="$CFLAGS -Werror=unknown-warning-option"])
+    WINE_TRY_PE_CFLAGS([-Werror=unused-command-line-argument],[CFLAGS="$CFLAGS -Werror=unused-command-line-argument"])
     WINE_TRY_PE_CFLAGS([-Werror=ignored-optimization-argument],[CFLAGS="$CFLAGS -Werror=ignored-optimization-argument"])
     WINE_TRY_PE_CFLAGS([-Wdeclaration-after-statement])
     WINE_TRY_PE_CFLAGS([-Wempty-body])
@@ -558,6 +559,7 @@ This is an error since --enable-archs=$wine_arch was requested.])])
     WINE_TRY_PE_CFLAGS([-Wabsolute-value])
     WINE_TRY_PE_CFLAGS([-Wenum-enum-conversion],[:],WINE_TRY_PE_CFLAGS([-Wenum-conversion]))
     WINE_TRY_PE_CFLAGS([-ffunction-sections])
+    WINE_TRY_PE_CFLAGS([-fasync-exceptions])

dnl clang had broken -fms-hotpatch support before version 18 (https://github.com/llvm/llvm-project/pull/77245)
     WINE_TRY_PE_CFLAGS([-fms-hotpatch -DMIN_CLANG_VERSION=18],

[PATCH 3/3] include: Enable compiler exceptions on Clang for 64-bit MSVC targets.

[Jacek Caban]

From: Jacek Caban

---
 dlls/winecrt0/exception.c | 6 ++++++
 include/excpt.h           | 8 ++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/dlls/winecrt0/exception.c b/dlls/winecrt0/exception.c
index 58cf91172ac..ab4224cf4c2 100644
--- a/dlls/winecrt0/exception.c
+++ b/dlls/winecrt0/exception.c
@@ -18,6 +18,12 @@
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */

+#include "excpt.h"
+#undef USE_COMPILER_EXCEPTIONS
+#undef GetExceptionInformation
+#undef GetExceptionCode
+#undef AbnormalTermination
+
 #include <stdarg.h>
 #include "winternl.h"
 #include "wine/exception.h"
diff --git a/include/excpt.h b/include/excpt.h
index 3369f3b1547..17c7409c636 100644
--- a/include/excpt.h
+++ b/include/excpt.h
@@ -38,7 +38,11 @@ typedef enum _EXCEPTION_DISPOSITION
 #define EXCEPTION_CONTINUE_EXECUTION    -1

-#if defined(_MSC_VER) && defined(USE_COMPILER_EXCEPTIONS)
+#if !defined(USE_COMPILER_EXCEPTIONS) && defined(_MSC_VER) && !defined(__i386__) && !defined(__arm__) && (!defined(__clang_major__) || __clang_major__ >= 19)
+#define USE_COMPILER_EXCEPTIONS
+#endif
+
+#ifdef USE_COMPILER_EXCEPTIONS
 #define GetExceptionCode    _exception_code
 #define GetExceptionInformation (struct _EXCEPTION_POINTERS *)_exception_info
 #define AbnormalTermination _abnormal_termination
@@ -46,6 +50,6 @@ typedef enum _EXCEPTION_DISPOSITION
 unsigned long __cdecl _exception_code(void);
 void * __cdecl _exception_info(void);
 int __cdecl _abnormal_termination(void);
-#endif /* defined(_MSC_VER) && defined(USE_COMPILER_EXCEPTIONS) */
+#endif /* USE_COMPILER_EXCEPTIONS */

#endif /* __WINE_EXCPT_H */