[mono][aot] Type load checks do not fail at compile time but produce a runtime exception

src/mono/mono/metadata/jit-icall-reg.h

@@ -312,6 +312,7 @@ MONO_JIT_ICALL (mono_throw_bad_image) \
 MONO_JIT_ICALL (mono_throw_not_supported) \
 MONO_JIT_ICALL (mono_throw_platform_not_supported) \
 MONO_JIT_ICALL (mono_throw_invalid_program) \
+MONO_JIT_ICALL (mono_throw_type_load) \
 MONO_JIT_ICALL (mono_trace_enter_method) \
 MONO_JIT_ICALL (mono_trace_leave_method) \
 MONO_JIT_ICALL (mono_trace_tail_method) \

src/mono/mono/mini/aot-compiler.c

@@ -9580,7 +9580,13 @@ compile_method (MonoAotCompile *acfg, MonoMethod *method)
 		mono_atomic_inc_i32 (&acfg->stats.genericcount);
 		return;
 	}
-	if (cfg->exception_type != MONO_EXCEPTION_NONE) {
+	if (cfg->exception_type == MONO_EXCEPTION_TYPE_LOAD) {
+		// Clear the exception, method-to-ir has already replaced the INITOBJ of the invalid
+		// type with a THROW.
+		cfg->exception_type = MONO_EXCEPTION_NONE;
+		// TODO: log this?
+	}
+	else if (cfg->exception_type != MONO_EXCEPTION_NONE) {
 		/* Some instances cannot be JITted due to constraints etc. */
 		if (!method->is_inflated)
 			report_loader_error (acfg, cfg->error, FALSE, "Unable to compile method '%s' due to: '%s'.\n", mono_method_get_full_name (method), mono_error_get_message (cfg->error));

src/mono/mono/mini/jit-icalls.c

@@ -1688,6 +1688,14 @@ mono_throw_invalid_program (const char *msg)
 	mono_error_set_pending_exception (error);
 }
 
+void
+mono_throw_type_load (void)
+{
+	ERROR_DECL (error);
+	mono_error_set_generic_error (error, "System", "TypeLoadException", "");
+	mono_error_set_pending_exception (error);
+}
+
 void
 mono_dummy_jit_icall (void)
 {

src/mono/mono/mini/jit-icalls.h

@@ -234,6 +234,8 @@ ICALL_EXPORT void mono_throw_platform_not_supported (void);
 
 ICALL_EXPORT void mono_throw_invalid_program (const char *msg);
 
+ICALL_EXPORT void mono_throw_type_load (void);
+
 ICALL_EXPORT void mono_dummy_jit_icall (void);
 
 ICALL_EXPORT void mono_dummy_jit_icall_val (gpointer ptr);

src/mono/mono/mini/method-to-ir.c

@@ -166,8 +166,12 @@ mono_tailcall_print (const char *format, ...)
 	} while (0)
 
 #define TYPE_LOAD_ERROR(klass) do { \
-		cfg->exception_ptr = klass; \
-		LOAD_ERROR;					\
+		if (cfg->compile_aot) { \
+			mono_emit_jit_icall (cfg, mono_throw_type_load, NULL); \
+		} else { \
+			cfg->exception_ptr = klass; \
+			LOAD_ERROR; \
+		} \
 	} while (0)
 
 #define CHECK_CFG_ERROR do {\
@@ -9898,8 +9902,16 @@ mono_method_to_ir (MonoCompile *cfg, MonoMethod *method, MonoBasicBlock *start_b
 			else {
 				klass = NULL;
 				field = mono_field_from_token_checked (image, token, &klass, generic_context, cfg->error);
-				if (!field)
-					CHECK_TYPELOAD (klass);
+				if (!field) {
+					if (cfg->compile_aot && (!klass || mono_class_has_failure (klass))) {
+						clear_cfg_error (cfg);
+						cfg->exception_type = MONO_EXCEPTION_NONE;
+						mono_emit_jit_icall (cfg, mono_throw_type_load, NULL);
+						break;
+					} else {
+						CHECK_TYPELOAD (klass);
+					}
+				}
 				CHECK_CFG_ERROR;
 			}
 			if (!dont_verify && !cfg->skip_visibility && !mono_method_can_access_field (method, field))
@@ -11855,11 +11867,23 @@ mono_method_to_ir (MonoCompile *cfg, MonoMethod *method, MonoBasicBlock *start_b
 		case MONO_CEE_INITOBJ:
 			--sp;
 			klass = mini_get_class (method, token, generic_context);
-			CHECK_TYPELOAD (klass);
+
+			if (cfg->compile_aot) {
+				// In AOT we replace initobj of invalid types with a throw.
+				if (!klass || mono_class_has_failure (klass)) {
+					mono_emit_jit_icall (cfg, mono_throw_type_load, NULL);
+					inline_costs += 10;
+					break;
+				}
+			} else {
+				CHECK_TYPELOAD (klass);
+			}
+
 			if (mini_class_is_reference (klass))
 				MONO_EMIT_NEW_STORE_MEMBASE_IMM (cfg, OP_STORE_MEMBASE_IMM, sp [0]->dreg, 0, 0);
 			else
 				mini_emit_initobj (cfg, *sp, NULL, klass);
+
 			inline_costs += 1;
 			break;
 		case MONO_CEE_CONSTRAINED_:

src/mono/mono/mini/mini-runtime.c

@@ -5139,6 +5139,7 @@ register_icalls (void)
 	register_icall (mono_throw_not_supported, mono_icall_sig_void, FALSE);
 	register_icall (mono_throw_platform_not_supported, mono_icall_sig_void, FALSE);
 	register_icall (mono_throw_invalid_program, mono_icall_sig_void_ptr, FALSE);
+	register_icall (mono_throw_type_load, mono_icall_sig_void, FALSE);
 	register_icall_no_wrapper (mono_dummy_jit_icall, mono_icall_sig_void);
 	//register_icall_no_wrapper (mono_dummy_jit_icall_val, mono_icall_sig_void_ptr);
 	register_icall_no_wrapper (mini_init_method_rgctx, mono_icall_sig_void_ptr_ptr);

src/mono/mono/mini/mini.c

@@ -3491,6 +3491,9 @@ mini_method_compile (MonoMethod *method, guint32 opts, JitFlags flags, int parts
 	 */
 	mono_compile_create_vars (cfg);
 
+	if (cfg->exception_type == MONO_EXCEPTION_TYPE_LOAD)
+		cfg->exception_type = MONO_EXCEPTION_NONE;
+
 	mono_cfg_dump_create_context (cfg);
 	mono_cfg_dump_begin_group (cfg);
 
@@ -3706,6 +3709,9 @@ mini_method_compile (MonoMethod *method, guint32 opts, JitFlags flags, int parts
 	}
 #endif
 
+	if (cfg->exception_type == MONO_EXCEPTION_TYPE_LOAD)
+		cfg->exception_type = MONO_EXCEPTION_NONE;
+
 	/* after SSA translation */
 	if (parts == 2) {
 		if (MONO_METHOD_COMPILE_END_ENABLED ())

src/tests/issues.targets

@@ -2405,15 +2405,6 @@
         <ExcludeList Include="$(XunitTestBinBase)/Loader/classloader/explicitlayout/objrefandnonobjrefoverlap/case9/**">
             <Issue>expected failure: overlapped structs fail at AOT compile time, not runtime</Issue>
         </ExcludeList>
-        <ExcludeList Include = "$(XunitTestBinBase)/Loader/classloader/explicitlayout/NestedStructs/case03/**">
-            <Issue>expected failure: overlapped structs fail at AOT compile time, not runtime</Issue>
-        </ExcludeList>
-        <ExcludeList Include = "$(XunitTestBinBase)/Loader/classloader/explicitlayout/NestedStructs/case04/**">
-            <Issue>expected failure: overlapped structs fail at AOT compile time, not runtime</Issue>
-        </ExcludeList>
-        <ExcludeList Include = "$(XunitTestBinBase)/Loader/classloader/explicitlayout/NestedStructs/case05/**">
-            <Issue>expected failure: overlapped structs fail at AOT compile time, not runtime</Issue>
-        </ExcludeList>
         <ExcludeList Include = "$(XunitTestBinBase)/Loader/classloader/RefFields/Validate/**">
             <Issue>expected failure: unsupported type with ref field fails at AOT compile time, not runtime</Issue>
         </ExcludeList>