[libunwind] [libunwind] [SEH] Set NonVolatileRegisters before calling a personality function (PR #137951)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libunwind

Author: Martin Storsjö (mstorsjo)

<details>
<summary>Changes</summary>

The CRT __C_specific_handler function uses this for restoring registers before calling the filter function.

This fixes the libunwind/libcxxabi forced unwind testcases on ARM and AArch64.

---
Full diff: https://github.com/llvm/llvm-project/pull/137951.diff


1 Files Affected:

- (modified) libunwind/src/Unwind-seh.cpp (+5) 


``````````diff
diff --git a/libunwind/src/Unwind-seh.cpp b/libunwind/src/Unwind-seh.cpp
index b2bb119ed6d29..f6525af07e25f 100644
--- a/libunwind/src/Unwind-seh.cpp
+++ b/libunwind/src/Unwind-seh.cpp
@@ -212,6 +212,11 @@ __libunwind_seh_personality(int version, _Unwind_Action state,
   ms_exc.ExceptionInformation[2] = state;
   DISPATCHER_CONTEXT *disp_ctx =
       __unw_seh_get_disp_ctx((unw_cursor_t *)context);
+#if defined(__aarch64__)
+  disp_ctx->NonVolatileRegisters = (PBYTE)&disp_ctx->ContextRecord->X19;
+#elif defined(__arm__)
+  disp_ctx->NonVolatileRegisters = (PBYTE)&disp_ctx->ContextRecord->R4;
+#endif
   _LIBUNWIND_TRACE_UNWINDING("__libunwind_seh_personality() calling "
                              "LanguageHandler %p(%p, %p, %p, %p)",
                              (void *)disp_ctx->LanguageHandler, (void *)&ms_exc,

``````````

</details>


https://github.com/llvm/llvm-project/pull/137951