Merge branch 'fix/llvm-trap-windows' into feature/llvm-osr

lib/llvm-backend/cpp/object_loader.cpp

@@ -1,6 +1,7 @@
 #include "object_loader.hh"
 #include <iostream>
 #include <memory>
+#include <setjmp.h>
 
 extern "C" void __register_frame(uint8_t *);
 extern "C" void __deregister_frame(uint8_t *);
@@ -12,6 +13,54 @@ MemoryManager::~MemoryManager()  {
   callbacks.dealloc_memory(read_section.base, read_section.size);
   callbacks.dealloc_memory(readwrite_section.base, readwrite_section.size);
 }
+void unwinding_setjmp(jmp_buf stack_out, void (*func)(void *), void *userdata) {
+  if(setjmp(stack_out)) {
+
+  } else {
+    func(userdata);
+  }
+}
+
+[[noreturn]]
+void unwinding_longjmp(jmp_buf stack_in) {
+  longjmp(stack_in, 42);
+}
+
+struct UnwindPoint {
+    UnwindPoint *prev;
+    jmp_buf stack;
+    std::function<void()> *f;
+    std::unique_ptr<std::exception> exception;
+};
+
+static thread_local UnwindPoint *unwind_state = nullptr;
+
+static void unwind_payload(void *_point) {
+    UnwindPoint *point = (UnwindPoint *) _point;
+    (*point->f)();
+}
+
+void catch_unwind(std::function<void()>&& f) {
+    UnwindPoint current;
+    current.prev = unwind_state;
+    current.f = &f;
+    unwind_state = &current;
+
+    unwinding_setjmp(current.stack, unwind_payload, (void *) &current);
+    if(current.exception) {
+        throw *current.exception;
+    }
+}
+
+void unsafe_unwind(std::exception *exception) {
+    UnwindPoint *state = unwind_state;
+    if(state) {
+        state->exception.reset(exception);
+        unwinding_longjmp(state->stack);
+    } else {
+        abort();
+    }
+}
 
 uint8_t *MemoryManager::allocateCodeSection(uintptr_t size, unsigned alignment,
                                       unsigned section_id,

lib/llvm-backend/cpp/object_loader.hh

@@ -5,6 +5,8 @@
 #include <exception>
 #include <iostream>
 #include <sstream>
+#include <setjmp.h>
+#include <functional>
 
 #include <llvm/ExecutionEngine/RuntimeDyld.h>
 
@@ -104,11 +106,14 @@ private:
   size_t stack_map_size = 0;
 };
 
-struct WasmException {
+struct WasmException: std::exception {
 public:
   virtual std::string description() const noexcept = 0;
 };
 
+void catch_unwind(std::function<void()>&& f);
+[[noreturn]] void unsafe_unwind(std::exception *exception);
+
 struct UncatchableException : WasmException {
 public:
   virtual std::string description() const noexcept override {
@@ -234,27 +239,29 @@ result_t module_load(const uint8_t *mem_ptr, size_t mem_size,
   return RESULT_OK;
 }
 
-[[noreturn]] void throw_trap(WasmTrap::Type ty) { throw WasmTrap(ty); }
+[[noreturn]] void throw_trap(WasmTrap::Type ty) { unsafe_unwind(new WasmTrap(ty)); }
 
 void module_delete(WasmModule *module) { delete module; }
 
 // Throw a fat pointer that's assumed to be `*mut dyn Any` on the rust
 // side.
 [[noreturn]] void throw_any(size_t data, size_t vtable) {
-  throw UserException(data, vtable);
+  unsafe_unwind(new UserException(data, vtable));
 }
 
 // Throw a pointer that's assumed to be codegen::BreakpointHandler on the
 // rust side.
 [[noreturn]] void throw_breakpoint(uintptr_t callback) {
-  throw BreakpointException(callback);
+  unsafe_unwind(new BreakpointException(callback));
 }
 
 bool invoke_trampoline(trampoline_t trampoline, void *ctx, void *func,
                        void *params, void *results, WasmTrap::Type *trap_out,
                        box_any_t *user_error, void *invoke_env) noexcept {
   try {
-    trampoline(ctx, func, params, results);
+    catch_unwind([trampoline, ctx, func, params, results]() {
+        trampoline(ctx, func, params, results);
+    });
     return true;
   } catch (const WasmTrap &e) {
     *trap_out = e.type;