Add llvm libunwind callback to suppress exceptions on apple silicon

See llvm/llvm-project#49036

Author: aaronj0

lib/Interpreter/Compatibility.h

@@ -17,9 +17,11 @@
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
+#include "llvm/BinaryFormat/MachO.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/ExecutionEngine/JITSymbol.h"
 #include "llvm/ExecutionEngine/Orc/LLJIT.h"
+#include "llvm/Object/MachO.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Path.h"
 

lib/Interpreter/CppInterOp.cpp

@@ -49,6 +49,51 @@
 #include <unistd.h>
 #endif // WIN32
 
+#ifdef __APPLE__
+// Define a minimal mach header for JIT'd code, to support exceptions on osx 14
+// and later. See llvm/llvm-project#49036
+static llvm::MachO::mach_header_64 fake_mach_header = {
+    .magic = llvm::MachO::MH_MAGIC_64,
+    .cputype = llvm::MachO::CPU_TYPE_ARM64,
+    .cpusubtype = llvm::MachO::CPU_SUBTYPE_ARM64_ALL,
+    .filetype = llvm::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);
+
+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 // __APPLE__
+
 namespace Cpp {
 
   using namespace clang;
@@ -62,7 +107,12 @@ 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__
+      removeFindDynamicUnwindSections();
+#endif
+      sInterpreter.release();
+    }
   } Deleter;
 
   static compat::Interpreter& getInterp() {

unittests/CppInterOp/InterpreterTest.cpp

@@ -127,3 +127,15 @@ TEST(InterpreterTest, CodeCompletion) {
   GTEST_SKIP();
 #endif
 }
+
+TEST(InterpreterTest, InterpreterExceptions) {
+  Cpp::CreateInterpreter();
+  bool caught = false;
+  try {
+    EXPECT_TRUE(Cpp::Declare("int f() { throw; return 1; }") == 0);
+    EXPECT_TRUE(Cpp::Process("int res = f();") == 0);
+  } catch (...) {
+    caught = true;
+  }
+  EXPECT_TRUE(caught) << "Unable to catch exception coming from interpreter";
+}