Add llvm libunwind callback to suppress exceptions on apple silicon

Author: aaronj0

lib/Interpreter/Compatibility.h

@@ -103,6 +103,43 @@ createClangInterpreter(std::vector<const char*>& args) {
   bool CudaEnabled = !gpu_args.empty();
 #endif
 
+#ifdef __APPLE__
+  // Define a minimal mach header for JIT'd code.
+  static MachO::mach_header_64 fake_mach_header = {
+      .magic = MachO::MH_MAGIC_64,
+      .cputype = MachO::CPU_TYPE_ARM64,
+      .cpusubtype = MachO::CPU_SUBTYPE_ARM64_ALL,
+      .filetype = MachO::MH_DYLIB,
+      .ncmds = 0,
+      .sizeofcmds = 0,
+      .flags = 0,
+      .reserved = 0};
+
+  // Declare libunwind SPI types and functions.
+  struct unw_dynamic_unwind_sections {
+    uintptr_t dso_base;
+    uintptr_t dwarf_section;
+    size_t dwarf_section_length;
+    uintptr_t compact_unwind_section;
+    size_t compact_unwind_section_length;
+  };
+
+  int find_dynamic_unwind_sections(uintptr_t addr,
+                                   unw_dynamic_unwind_sections * info) {
+    info->dso_base = (uintptr_t)&fake_mach_header;
+    info->dwarf_section = 0;
+    info->dwarf_section_length = 0;
+    info->compact_unwind_section = 0;
+    info->compact_unwind_section_length = 0;
+    return 1;
+  }
+
+  // Typedef for callback above.
+  typedef int (*unw_find_dynamic_unwind_sections)(
+      uintptr_t addr, struct unw_dynamic_unwind_sections * info);
+
+#endif
+
   clang::IncrementalCompilerBuilder CB;
   CB.SetCompilerArgs({args.begin(), it});
 
@@ -151,6 +188,15 @@ createClangInterpreter(std::vector<const char*>& args) {
   return std::move(*innerOrErr);
 }
 
+#ifdef __APPLE__
+inline void removeFindDynamicUnwindSections() {
+  if (auto* unw_remove_find_dynamic_unwind_sections = (int (*)(
+          unw_find_dynamic_unwind_sections find_dynamic_unwind_sections))
+          dlsym(RTLD_DEFAULT, "__unw_remove_find_dynamic_unwind_sections"))
+    unw_remove_find_dynamic_unwind_sections(find_dynamic_unwind_sections);
+}
+#endif
+
 inline void maybeMangleDeclName(const clang::GlobalDecl& GD,
                                 std::string& mangledName) {
   // copied and adapted from CodeGen::CodeGenModule::getMangledName

lib/Interpreter/CppInterOp.cpp

@@ -62,7 +62,12 @@ namespace Cpp {
   // This might fix the issue https://reviews.llvm.org/D107087
   // FIXME: For now we just leak the Interpreter.
   struct InterpDeleter {
-    ~InterpDeleter() { sInterpreter.release(); }
+    ~InterpDeleter() {
+#ifdef __APPLE__
+      sInterpreter.removeFindDynamicUnwindSections();
+#endif
+      sInterpreter.release();
+    }
   } Deleter;
 
   static compat::Interpreter& getInterp() {