Merge branch 'master' into odin-ast-changes

32 files changed, 1567 insertions, 282 deletions

diff --git a/src/array.cpp b/src/array.cpp
index ac3727978..d08bd647f 100644
--- a/src/array.cpp
+++ b/src/array.cpp
@@ -89,7 +89,9 @@ template <typename T>
 void slice_init(Slice<T> *s, gbAllocator const &allocator, isize count) {
 	GB_ASSERT(count >= 0);
 	s->data = gb_alloc_array(allocator, T, count);
-	GB_ASSERT(s->data != nullptr);
+	if (count > 0) {
+		GB_ASSERT(s->data != nullptr);
+	}
 	s->count = count;
 }
 
diff --git a/src/bug_report.cpp b/src/bug_report.cpp
index 9a1cb2254..02a2b1ba2 100644
--- a/src/bug_report.cpp
+++ b/src/bug_report.cpp
@@ -17,6 +17,11 @@
 	#include <sys/sysctl.h>

 #endif

 

+#if defined(GB_SYSTEM_OPENBSD)

+	#include <sys/sysctl.h>

+	#include <sys/utsname.h>

+#endif

+

 /*

 	NOTE(Jeroen): This prints the Windows product edition only, to be called from `print_platform_details`.

 */

@@ -242,6 +247,14 @@ void report_ram_info() {
 		if (sysctl(sysctls, 2, &ram_amount, &val_size, NULL, 0) != -1) {

 			gb_printf("%lld MiB\n", ram_amount / gb_megabytes(1));

 		}

+	#elif defined(GB_SYSTEM_OPENBSD)

+		uint64_t ram_amount;

+		size_t   val_size = sizeof(ram_amount);

+

+		int sysctls[] = { CTL_HW, HW_PHYSMEM64 };

+		if (sysctl(sysctls, 2, &ram_amount, &val_size, NULL, 0) != -1) {

+			gb_printf("%lld MiB\n", ram_amount / gb_megabytes(1));

+		}

 	#else

 		gb_printf("Unknown.\n");

 	#endif

@@ -473,11 +486,11 @@ void print_bug_report_help() {
 

 	#elif defined(GB_SYSTEM_LINUX)

 		/*

-			Try to parse `/usr/lib/os-release` for `PRETTY_NAME="Ubuntu 20.04.3 LTS`

+			Try to parse `/etc/os-release` for `PRETTY_NAME="Ubuntu 20.04.3 LTS`

 		*/

 		gbAllocator a = heap_allocator();

 

-		gbFileContents release = gb_file_read_contents(a, 1, "/usr/lib/os-release");

+		gbFileContents release = gb_file_read_contents(a, 1, "/etc/os-release");

 		defer (gb_file_free_contents(&release));

 

 		b32 found = 0;

@@ -643,6 +656,14 @@ void print_bug_report_help() {
 		} else {

 			gb_printf("macOS: Unknown\n");

 		}			

+	#elif defined(GB_SYSTEM_OPENBSD)

+		struct utsname un;

+		

+		if (uname(&un) != -1) {

+			gb_printf("%s %s %s %s\n", un.sysname, un.release, un.version, un.machine);

+		} else {

+			gb_printf("OpenBSD: Unknown\n");    

+		}

 	#else

 		gb_printf("Unknown\n");

 

@@ -657,4 +678,4 @@ void print_bug_report_help() {
 		And RAM info.

 	*/

 	report_ram_info();

-}
\ No newline at end of file
+}

diff --git a/src/build_settings.cpp b/src/build_settings.cpp
index 610e4f847..c40a70069 100644
--- a/src/build_settings.cpp
+++ b/src/build_settings.cpp
@@ -1,4 +1,4 @@
-#if defined(GB_SYSTEM_FREEBSD)
+#if defined(GB_SYSTEM_FREEBSD) || defined(GB_SYSTEM_OPENBSD)
 #include <sys/types.h>
 #include <sys/sysctl.h>
 #endif
@@ -16,6 +16,7 @@ enum TargetOsKind {
 	TargetOs_linux,
 	TargetOs_essence,
 	TargetOs_freebsd,
+	TargetOs_openbsd,
 	
 	TargetOs_wasi,
 	TargetOs_js,
@@ -53,6 +54,7 @@ String target_os_names[TargetOs_COUNT] = {
 	str_lit("linux"),
 	str_lit("essence"),
 	str_lit("freebsd"),
+	str_lit("openbsd"),
 	
 	str_lit("wasi"),
 	str_lit("js"),
@@ -354,6 +356,15 @@ gb_global TargetMetrics target_freebsd_amd64 = {
 	str_lit("e-m:w-i64:64-f80:128-n8:16:32:64-S128"),
 };
 
+gb_global TargetMetrics target_openbsd_amd64 = {
+	TargetOs_openbsd,
+	TargetArch_amd64,
+	8,
+	16,
+	str_lit("x86_64-unknown-openbsd-elf"),
+	str_lit("e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"),
+};
+
 gb_global TargetMetrics target_essence_amd64 = {
 	TargetOs_essence,
 	TargetArch_amd64,
@@ -417,6 +428,7 @@ gb_global NamedTargetMetrics named_targets[] = {
 	{ str_lit("windows_amd64"),       &target_windows_amd64  },
 	{ str_lit("freebsd_386"),         &target_freebsd_386    },
 	{ str_lit("freebsd_amd64"),       &target_freebsd_amd64  },
+	{ str_lit("openbsd_amd64"),       &target_openbsd_amd64  },
 	{ str_lit("freestanding_wasm32"), &target_freestanding_wasm32 },
 	{ str_lit("wasi_wasm32"),         &target_wasi_wasm32 },
 	{ str_lit("js_wasm32"),           &target_js_wasm32 },
@@ -722,10 +734,38 @@ String internal_odin_root_dir(void) {
 		len = readlink("/proc/curproc/exe", &path_buf[0], path_buf.count);
 #elif defined(GB_SYSTEM_DRAGONFLYBSD)
 		len = readlink("/proc/curproc/file", &path_buf[0], path_buf.count);
-#else
+#elif defined(GB_SYSTEM_LINUX)
 		len = readlink("/proc/self/exe", &path_buf[0], path_buf.count);
+#elif defined(GB_SYSTEM_OPENBSD)
+		int error;
+		int mib[] = {
+			CTL_KERN,
+			KERN_PROC_ARGS,
+			getpid(),
+			KERN_PROC_ARGV,
+		};
+		// get argv size
+		error = sysctl(mib, 4, NULL, (size_t *) &len, NULL, 0);
+		if (error == -1) {
+			// sysctl error
+			return make_string(nullptr, 0);
+		}
+		// get argv
+		char **argv = (char **)gb_malloc(len);
+		error = sysctl(mib, 4, argv, (size_t *) &len, NULL, 0);
+		if (error == -1) {
+			// sysctl error
+			gb_mfree(argv);
+			return make_string(nullptr, 0);
+		}
+		// copy argv[0] to path_buf
+		len = gb_strlen(argv[0]);
+		if(len < path_buf.count) {
+			gb_memmove(&path_buf[0], argv[0], len);
+		}
+		gb_mfree(argv);
 #endif
-		if(len == 0) {
+		if(len == 0 || len == -1) {
 			return make_string(nullptr, 0);
 		}
 		if (len < path_buf.count) {
@@ -922,6 +962,8 @@ void init_build_context(TargetMetrics *cross_target) {
 			#endif
 		#elif defined(GB_SYSTEM_FREEBSD)
 			metrics = &target_freebsd_amd64;
+		#elif defined(GB_SYSTEM_OPENBSD)
+			metrics = &target_openbsd_amd64;
 		#elif defined(GB_CPU_ARM)
 			metrics = &target_linux_arm64;
 		#else
@@ -980,6 +1022,9 @@ void init_build_context(TargetMetrics *cross_target) {
 		case TargetOs_freebsd:
 			bc->link_flags = str_lit("-arch x86-64 ");
 			break;
+		case TargetOs_openbsd:
+			bc->link_flags = str_lit("-arch x86-64 ");
+			break;
 		}
 	} else if (bc->metrics.arch == TargetArch_i386) {
 		switch (bc->metrics.os) {
diff --git a/src/check_builtin.cpp b/src/check_builtin.cpp
index d3a3103b1..aeeeb9e4d 100644
--- a/src/check_builtin.cpp
+++ b/src/check_builtin.cpp
@@ -143,6 +143,241 @@ void check_or_return_split_types(CheckerContext *c, Operand *x, String const &na
 }
 
 
+bool does_require_msgSend_stret(Type *return_type) {
+	if (return_type == nullptr) {
+		return false;
+	}
+	if (build_context.metrics.arch == TargetArch_i386 || build_context.metrics.arch == TargetArch_amd64) {
+		i64 struct_limit = type_size_of(t_uintptr) << 1;
+		return type_size_of(return_type) > struct_limit;
+	}
+	if (build_context.metrics.arch == TargetArch_arm64) {
+		return false;
+	}
+
+	// if (build_context.metrics.arch == TargetArch_arm32) {
+	// 	i64 struct_limit = type_size_of(t_uintptr);
+	// 	// NOTE(bill): This is technically wrong
+	// 	return is_type_struct(return_type) && !is_type_raw_union(return_type) && type_size_of(return_type) > struct_limit;
+	// }
+	GB_PANIC("unsupported architecture");
+	return false;
+}
+
+ObjcMsgKind get_objc_proc_kind(Type *return_type) {
+	if (return_type == nullptr) {
+		return ObjcMsg_normal;
+	}
+
+	if (build_context.metrics.arch == TargetArch_i386 || build_context.metrics.arch == TargetArch_amd64) {
+		if (is_type_float(return_type)) {
+			return ObjcMsg_fpret;
+		}
+		if (build_context.metrics.arch == TargetArch_amd64) {
+			if (is_type_complex(return_type)) {
+				// URL: https://github.com/opensource-apple/objc4/blob/cd5e62a5597ea7a31dccef089317abb3a661c154/runtime/message.h#L143-L159
+				return ObjcMsg_fpret;
+			}
+		}
+	}
+	if (build_context.metrics.arch != TargetArch_arm64) {
+		if (does_require_msgSend_stret(return_type)) {
+			return ObjcMsg_stret;
+		}
+	}
+	return ObjcMsg_normal;
+}
+
+void add_objc_proc_type(CheckerContext *c, Ast *call, Type *return_type, Slice<Type *> param_types) {
+	ObjcMsgKind kind = get_objc_proc_kind(return_type);
+
+	Scope *scope = create_scope(c->info, nullptr);
+
+	// NOTE(bill, 2022-02-08): the backend's ABI handling should handle this correctly, I hope
+	Type *params = alloc_type_tuple();
+	{
+		auto variables = array_make<Entity *>(permanent_allocator(), 0, param_types.count);
+
+		for_array(i, param_types)  {
+			Type *type = param_types[i];
+			Entity *param = alloc_entity_param(scope, blank_token, type, false, true);
+			array_add(&variables, param);
+		}
+		params->Tuple.variables = slice_from_array(variables);
+	}
+
+	Type *results = alloc_type_tuple();
+	if (return_type) {
+		auto variables = array_make<Entity *>(permanent_allocator(), 1);
+		results->Tuple.variables = slice_from_array(variables);
+		Entity *param = alloc_entity_param(scope, blank_token, return_type, false, true);
+		results->Tuple.variables[0] = param;
+	}
+
+
+	ObjcMsgData data = {};
+	data.kind = kind;
+	data.proc_type = alloc_type_proc(scope, params, param_types.count, results, results->Tuple.variables.count, false, ProcCC_CDecl);
+
+	mutex_lock(&c->info->objc_types_mutex);
+	map_set(&c->info->objc_msgSend_types, call, data);
+	mutex_unlock(&c->info->objc_types_mutex);
+
+	try_to_add_package_dependency(c, "runtime", "objc_msgSend");
+	try_to_add_package_dependency(c, "runtime", "objc_msgSend_fpret");
+	try_to_add_package_dependency(c, "runtime", "objc_msgSend_fp2ret");
+	try_to_add_package_dependency(c, "runtime", "objc_msgSend_stret");
+}
+
+bool is_constant_string(CheckerContext *c, String const &builtin_name, Ast *expr, String *name_) {
+	Operand op = {};
+	check_expr(c, &op, expr);
+	if (op.mode == Addressing_Constant && op.value.kind == ExactValue_String) {
+		if (name_) *name_ = op.value.value_string;
+		return true;
+	}
+	gbString e = expr_to_string(op.expr);
+	gbString t = type_to_string(op.type);
+	error(op.expr, "'%.*s' expected a constant string value, got %s of type %s", LIT(builtin_name), e, t);
+	gb_string_free(t);
+	gb_string_free(e);
+	return false;
+}
+
+bool check_builtin_objc_procedure(CheckerContext *c, Operand *operand, Ast *call, i32 id, Type *type_hint) {
+	String builtin_name = builtin_procs[id].name;
+
+	if (build_context.metrics.os != TargetOs_darwin) {
+		// allow on doc generation (e.g. Metal stuff)
+		if (build_context.command_kind != Command_doc && build_context.command_kind != Command_check) {
+			error(call, "'%.*s' only works on darwin", LIT(builtin_name));
+		}
+	}
+
+
+	ast_node(ce, CallExpr, call);
+	switch (id) {
+	default:
+		GB_PANIC("Implement objective built-in procedure: %.*s", LIT(builtin_name));
+		return false;
+
+	case BuiltinProc_objc_send: {
+		Type *return_type = nullptr;
+
+		Operand rt = {};
+		check_expr_or_type(c, &rt, ce->args[0]);
+		if (rt.mode == Addressing_Type) {
+			return_type = rt.type;
+		} else if (is_operand_nil(rt)) {
+			return_type = nullptr;
+		} else {
+			gbString e = expr_to_string(rt.expr);
+			error(rt.expr, "'%.*s' expected a type or nil to define the return type of the Objective-C call, got %s", LIT(builtin_name), e);
+			gb_string_free(e);
+			return false;
+		}
+
+		operand->type = return_type;
+		operand->mode = return_type ? Addressing_Value : Addressing_NoValue;
+
+		String class_name = {};
+		String sel_name = {};
+
+		Type *sel_type = t_objc_SEL;
+		Operand self = {};
+		check_expr_or_type(c, &self, ce->args[1]);
+		if (self.mode == Addressing_Type) {
+			if (!is_type_objc_object(self.type)) {
+				gbString t = type_to_string(self.type);
+				error(self.expr, "'%.*s' expected a type or value derived from intrinsics.objc_object, got type %s", LIT(builtin_name), t);
+				gb_string_free(t);
+				return false;
+			}
+			if (!has_type_got_objc_class_attribute(self.type)) {
+				gbString t = type_to_string(self.type);
+				error(self.expr, "'%.*s' expected a named type with the attribute @(obj_class=<string>) , got type %s", LIT(builtin_name), t);
+				gb_string_free(t);
+				return false;
+			}
+
+			sel_type = t_objc_Class;
+		} else if (!is_operand_value(self) || !check_is_assignable_to(c, &self, t_objc_id)) {
+			gbString e = expr_to_string(self.expr);
+			gbString t = type_to_string(self.type);
+			error(self.expr, "'%.*s' expected a type or value derived from intrinsics.objc_object, got '%s' of type %s %d", LIT(builtin_name), e, t, self.type->kind);
+			gb_string_free(t);
+			gb_string_free(e);
+			return false;
+		} else if (!is_type_pointer(self.type)) {
+			gbString e = expr_to_string(self.expr);
+			gbString t = type_to_string(self.type);
+			error(self.expr, "'%.*s' expected a pointer of a value derived from intrinsics.objc_object, got '%s' of type %s", LIT(builtin_name), e, t);
+			gb_string_free(t);
+			gb_string_free(e);
+			return false;
+		} else {
+			Type *type = type_deref(self.type);
+			if (!(type->kind == Type_Named &&
+			      type->Named.type_name != nullptr &&
+			      type->Named.type_name->TypeName.objc_class_name != "")) {
+				gbString t = type_to_string(type);
+				error(self.expr, "'%.*s' expected a named type with the attribute @(obj_class=<string>) , got type %s", LIT(builtin_name), t);
+				gb_string_free(t);
+				return false;
+			}
+		}
+
+
+		if (!is_constant_string(c, builtin_name, ce->args[2], &sel_name)) {
+			return false;
+		}
+
+		isize const arg_offset = 1;
+		auto param_types = slice_make<Type *>(permanent_allocator(), ce->args.count-arg_offset);
+		param_types[0] = t_objc_id;
+		param_types[1] = sel_type;
+
+		for (isize i = 2+arg_offset; i < ce->args.count; i++) {
+			Operand x = {};
+			check_expr(c, &x, ce->args[i]);
+			param_types[i-arg_offset] = x.type;
+		}
+
+		add_objc_proc_type(c, call, return_type, param_types);
+
+		return true;
+	} break;
+
+	case BuiltinProc_objc_find_selector: 
+	case BuiltinProc_objc_find_class: 
+	case BuiltinProc_objc_register_selector: 
+	case BuiltinProc_objc_register_class: 
+	{
+		String sel_name = {};
+		if (!is_constant_string(c, builtin_name, ce->args[0], &sel_name)) {
+			return false;
+		}
+
+		switch (id) {
+		case BuiltinProc_objc_find_selector: 
+		case BuiltinProc_objc_register_selector: 
+			operand->type = t_objc_SEL;
+			break;
+		case BuiltinProc_objc_find_class: 
+		case BuiltinProc_objc_register_class: 
+			operand->type = t_objc_Class;
+			break;
+
+		}
+		operand->mode = Addressing_Value;
+
+		try_to_add_package_dependency(c, "runtime", "objc_lookUpClass");
+		try_to_add_package_dependency(c, "runtime", "sel_registerName");
+		try_to_add_package_dependency(c, "runtime", "objc_allocateClassPair");
+		return true;
+	} break;
+	}
+}
 
 bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32 id, Type *type_hint) {
 	ast_node(ce, CallExpr, call);
@@ -179,6 +414,12 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 	case BuiltinProc_len:
 	case BuiltinProc_min:
 	case BuiltinProc_max:
+	case BuiltinProc_type_is_subtype_of:
+	case BuiltinProc_objc_send:
+	case BuiltinProc_objc_find_selector: 
+	case BuiltinProc_objc_find_class: 
+	case BuiltinProc_objc_register_selector: 
+	case BuiltinProc_objc_register_class: 
 		// NOTE(bill): The first arg may be a Type, this will be checked case by case
 		break;
 
@@ -202,7 +443,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		break;
 	}
 
-	String builtin_name = builtin_procs[id].name;;
+	String builtin_name = builtin_procs[id].name;
 
 
 	if (ce->args.count > 0) {
@@ -219,6 +460,13 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		GB_PANIC("Implement built-in procedure: %.*s", LIT(builtin_name));
 		break;
 
+	case BuiltinProc_objc_send:
+	case BuiltinProc_objc_find_selector: 
+	case BuiltinProc_objc_find_class: 
+	case BuiltinProc_objc_register_selector: 
+	case BuiltinProc_objc_register_class: 
+		return check_builtin_objc_procedure(c, operand, call, id, type_hint);
+
 	case BuiltinProc___entry_point:
 		operand->mode = Addressing_NoValue;
 		operand->type = nullptr;
@@ -858,7 +1106,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		
 		Selection sel = lookup_field(type, field_name, false);
 		if (sel.entity == nullptr) {
-			gbString type_str = type_to_string(type);
+			gbString type_str = type_to_string_shorthand(type);
 			error(ce->args[0],
 			      "'%s' has no field named '%.*s'", type_str, LIT(field_name));
 			gb_string_free(type_str);
@@ -870,7 +1118,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 			return false;
 		}
 		if (sel.indirect) {
-			gbString type_str = type_to_string(type);
+			gbString type_str = type_to_string_shorthand(type);
 			error(ce->args[0],
 			      "Field '%.*s' is embedded via a pointer in '%s'", LIT(field_name), type_str);
 			gb_string_free(type_str);
@@ -931,7 +1179,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 		
 		Selection sel = lookup_field(type, field_name, false);
 		if (sel.entity == nullptr) {
-			gbString type_str = type_to_string(type);
+			gbString type_str = type_to_string_shorthand(type);
 			error(ce->args[0],
 			      "'%s' has no field named '%.*s'", type_str, LIT(field_name));
 			gb_string_free(type_str);
@@ -943,7 +1191,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 			return false;
 		}
 		if (sel.indirect) {
-			gbString type_str = type_to_string(type);
+			gbString type_str = type_to_string_shorthand(type);
 			error(ce->args[0],
 			      "Field '%.*s' is embedded via a pointer in '%s'", LIT(field_name), type_str);
 			gb_string_free(type_str);
@@ -3258,6 +3506,7 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 			case TargetOs_linux:
 			case TargetOs_essence:
 			case TargetOs_freebsd:
+			case TargetOs_openbsd:
 				switch (build_context.metrics.arch) {
 				case TargetArch_i386:
 				case TargetArch_amd64:
@@ -3344,9 +3593,11 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 	case BuiltinProc_type_is_simple_compare:
 	case BuiltinProc_type_is_dereferenceable:
 	case BuiltinProc_type_is_valid_map_key:
+	case BuiltinProc_type_is_valid_matrix_elements:
 	case BuiltinProc_type_is_named:
 	case BuiltinProc_type_is_pointer:
 	case BuiltinProc_type_is_array:
+	case BuiltinProc_type_is_enumerated_array:
 	case BuiltinProc_type_is_slice:
 	case BuiltinProc_type_is_dynamic_array:
 	case BuiltinProc_type_is_map:
@@ -3354,10 +3605,9 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 	case BuiltinProc_type_is_union:
 	case BuiltinProc_type_is_enum:
 	case BuiltinProc_type_is_proc:
-	case BuiltinProc_type_is_bit_field:
-	case BuiltinProc_type_is_bit_field_value:
 	case BuiltinProc_type_is_bit_set:
 	case BuiltinProc_type_is_simd_vector:
+	case BuiltinProc_type_is_matrix:
 	case BuiltinProc_type_is_specialized_polymorphic_record:
 	case BuiltinProc_type_is_unspecialized_polymorphic_record:
 	case BuiltinProc_type_has_nil:
@@ -3725,6 +3975,31 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 
 		break;
 
+	case BuiltinProc_type_is_subtype_of:
+		{
+			Operand op_src = {};
+			Operand op_dst = {};
+
+			check_expr_or_type(c, &op_src, ce->args[0]);
+			if (op_src.mode != Addressing_Type) {
+				gbString e = expr_to_string(op_src.expr);
+				error(op_src.expr, "'%.*s' expects a type, got %s", LIT(builtin_name), e);
+				gb_string_free(e);
+				return false;
+			}
+			check_expr_or_type(c, &op_dst, ce->args[1]);
+			if (op_dst.mode != Addressing_Type) {
+				gbString e = expr_to_string(op_dst.expr);
+				error(op_dst.expr, "'%.*s' expects a type, got %s", LIT(builtin_name), e);
+				gb_string_free(e);
+				return false;
+			}
+
+			operand->value = exact_value_bool(is_type_subtype_of(op_src.type, op_dst.type));
+			operand->mode = Addressing_Constant;
+			operand->type = t_untyped_bool;
+		} break;
+
 	case BuiltinProc_type_field_index_of:
 		{
 			Operand op = {};
@@ -3814,6 +4089,20 @@ bool check_builtin_procedure(CheckerContext *c, Operand *operand, Ast *call, i32
 			operand->type = t_hasher_proc;
 			break;
 		}
+
+	case BuiltinProc_constant_utf16_cstring:
+		{
+			String value = {};
+			if (!is_constant_string(c, builtin_name, ce->args[0], &value)) {
+				return false;
+			}
+			operand->mode = Addressing_Value;
+			operand->type = alloc_type_multi_pointer(t_u16);
+			operand->value = {};
+			break;
+		}
+
+
 	}
 
 	return true;
diff --git a/src/check_decl.cpp b/src/check_decl.cpp
index f6dade812..3fdd944f9 100644
--- a/src/check_decl.cpp
+++ b/src/check_decl.cpp
@@ -174,6 +174,10 @@ void check_init_constant(CheckerContext *ctx, Entity *e, Operand *operand) {
 		return;
 	}
 
+	if (is_type_proc(e->type)) {
+		error(e->token, "Illegal declaration of a constant procedure value");
+	}
+
 	e->parent_proc_decl = ctx->curr_proc_decl;
 
 	e->Constant.value = operand->value;
@@ -338,6 +342,13 @@ void check_type_decl(CheckerContext *ctx, Entity *e, Ast *init_expr, Type *def)
 	if (decl != nullptr) {
 		AttributeContext ac = {};
 		check_decl_attributes(ctx, decl->attributes, type_decl_attribute, &ac);
+		if (e->kind == Entity_TypeName && ac.objc_class != "") {
+			e->TypeName.objc_class_name = ac.objc_class;
+
+			if (type_size_of(e->type) > 0) {
+				error(e->token, "@(objc_class) marked type must be of zero size");
+			}
+		}
 	}
 
 
@@ -819,6 +830,63 @@ void check_proc_decl(CheckerContext *ctx, Entity *e, DeclInfo *d) {
 	}
 	e->Procedure.optimization_mode = cast(ProcedureOptimizationMode)ac.optimization_mode;
 
+	if (ac.objc_name.len || ac.objc_is_class_method || ac.objc_type) {
+		if (ac.objc_name.len == 0 && ac.objc_is_class_method) {
+			error(e->token, "@(objc_name) is required with @(objc_is_class_method)");
+		} else if (ac.objc_type == nullptr) {
+			error(e->token, "@(objc_name) requires that @(objc_type) to be set");
+		} else if (ac.objc_name.len == 0 && ac.objc_type) {
+			error(e->token, "@(objc_name) is required with @(objc_type)");
+		} else {
+			Type *t = ac.objc_type;
+			if (t->kind == Type_Named) {
+				Entity *tn = t->Named.type_name;
+
+				GB_ASSERT(tn->kind == Entity_TypeName);
+
+				if (tn->scope != e->scope) {
+					error(e->token, "@(objc_name) attribute may only be applied to procedures and types within the same scope");
+				} else {
+					mutex_lock(&global_type_name_objc_metadata_mutex);
+					defer (mutex_unlock(&global_type_name_objc_metadata_mutex));
+
+					if (!tn->TypeName.objc_metadata) {
+						tn->TypeName.objc_metadata = create_type_name_obj_c_metadata();
+					}
+					auto *md = tn->TypeName.objc_metadata;
+					mutex_lock(md->mutex);
+					defer (mutex_unlock(md->mutex));
+
+					if (!ac.objc_is_class_method) {
+						bool ok = true;
+						for (TypeNameObjCMetadataEntry const &entry : md->value_entries) {
+							if (entry.name == ac.objc_name) {
+								error(e->token, "Previous declaration of @(objc_name=\"%.*s\")", LIT(ac.objc_name));
+								ok = false;
+								break;
+							}
+						}
+						if (ok) {
+							array_add(&md->value_entries, TypeNameObjCMetadataEntry{ac.objc_name, e});
+						}
+					} else {
+						bool ok = true;
+						for (TypeNameObjCMetadataEntry const &entry : md->type_entries) {
+							if (entry.name == ac.objc_name) {
+								error(e->token, "Previous declaration of @(objc_name=\"%.*s\")", LIT(ac.objc_name));
+								ok = false;
+								break;
+							}
+						}
+						if (ok) {
+							array_add(&md->type_entries, TypeNameObjCMetadataEntry{ac.objc_name, e});
+						}
+					}
+				}
+			}
+		}
+	}
+
 
 	switch (e->Procedure.optimization_mode) {
 	case ProcedureOptimizationMode_None:
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 3f31ac810..614da2368 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -132,6 +132,62 @@ void check_did_you_mean_print(DidYouMeanAnswers *d, char const *prefix = "") {
 	}
 }
 
+void populate_check_did_you_mean_objc_entity(StringSet *set, Entity *e, bool is_type) {
+	if (e->kind != Entity_TypeName) {
+		return;
+	}
+	if (e->TypeName.objc_metadata == nullptr) {
+		return;
+	}
+	TypeNameObjCMetadata *objc_metadata = e->TypeName.objc_metadata;
+	Type *t = base_type(e->type);
+	GB_ASSERT(t->kind == Type_Struct);
+
+	if (is_type) {
+		for_array(i, objc_metadata->type_entries) {
+			String name = objc_metadata->type_entries[i].name;
+			string_set_add(set, name);
+		}
+	} else {
+		for_array(i, objc_metadata->value_entries) {
+			String name = objc_metadata->value_entries[i].name;
+			string_set_add(set, name);
+		}
+	}
+
+	for_array(i, t->Struct.fields) {
+		Entity *f = t->Struct.fields[i];
+		if (f->flags & EntityFlag_Using && f->type != nullptr) {
+			if (f->type->kind == Type_Named && f->type->Named.type_name) {
+				populate_check_did_you_mean_objc_entity(set, f->type->Named.type_name, is_type);
+			}
+		}
+	}
+}
+
+
+void check_did_you_mean_objc_entity(String const &name, Entity *e, bool is_type, char const *prefix = "") {
+	ERROR_BLOCK();
+	GB_ASSERT(e->kind == Entity_TypeName);
+	GB_ASSERT(e->TypeName.objc_metadata != nullptr);
+	auto *objc_metadata = e->TypeName.objc_metadata;
+	mutex_lock(objc_metadata->mutex);
+	defer (mutex_unlock(objc_metadata->mutex));
+
+	StringSet set = {};
+	string_set_init(&set, heap_allocator());
+	defer (string_set_destroy(&set));
+	populate_check_did_you_mean_objc_entity(&set, e, is_type);
+
+
+	DidYouMeanAnswers d = did_you_mean_make(heap_allocator(), set.entries.count, name);
+	defer (did_you_mean_destroy(&d));
+	for_array(i, set.entries) {
+		did_you_mean_append(&d, set.entries[i].value);
+	}
+	check_did_you_mean_print(&d, prefix);
+}
+
 void check_did_you_mean_type(String const &name, Array<Entity *> const &fields, char const *prefix = "") {
 	ERROR_BLOCK();
 
@@ -144,6 +200,7 @@ void check_did_you_mean_type(String const &name, Array<Entity *> const &fields,
 	check_did_you_mean_print(&d, prefix);
 }
 
+
 void check_did_you_mean_type(String const &name, Slice<Entity *> const &fields, char const *prefix = "") {
 	ERROR_BLOCK();
 
@@ -228,42 +285,6 @@ void check_scope_decls(CheckerContext *c, Slice<Ast *> const &nodes, isize reser
 	}
 }
 
-
-isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isize level = 0, bool src_is_ptr = false) {
-	Type *prev_src = src;
-	src = type_deref(src);
-	if (!src_is_ptr) {
-		src_is_ptr = src != prev_src;
-	}
-	src = base_type(src);
-
-	if (!is_type_struct(src)) {
-		return 0;
-	}
-
-	for_array(i, src->Struct.fields) {
-		Entity *f = src->Struct.fields[i];
-		if (f->kind != Entity_Variable || (f->flags&EntityFlag_Using) == 0) {
-			continue;
-		}
-
-		if (are_types_identical(f->type, dst)) {
-			return level+1;
-		}
-		if (src_is_ptr && is_type_pointer(dst)) {
-			if (are_types_identical(f->type, type_deref(dst))) {
-				return level+1;
-			}
-		}
-		isize nested_level = check_is_assignable_to_using_subtype(f->type, dst, level+1, src_is_ptr);
-		if (nested_level > 0) {
-			return nested_level;
-		}
-	}
-
-	return 0;
-}
-
 bool find_or_generate_polymorphic_procedure(CheckerContext *old_c, Entity *base_entity, Type *type,
                                             Array<Operand> *param_operands, Ast *poly_def_node, PolyProcData *poly_proc_data) {
 	///////////////////////////////////////////////////////////////////////////////
@@ -4449,14 +4470,19 @@ Entity *check_selector(CheckerContext *c, Operand *operand, Ast *node, Type *typ
 
 	if (entity == nullptr) {
 		gbString op_str   = expr_to_string(op_expr);
-		gbString type_str = type_to_string(operand->type);
+		gbString type_str = type_to_string_shorthand(operand->type);
 		gbString sel_str  = expr_to_string(selector);
 		error(op_expr, "'%s' of type '%s' has no field '%s'", op_str, type_str, sel_str);
 
 		if (operand->type != nullptr && selector->kind == Ast_Ident) {
 			String const &name = selector->Ident.token.string;
 			Type *bt = base_type(operand->type);
-			if (bt->kind == Type_Struct) {
+			if (operand->type->kind == Type_Named &&
+			    operand->type->Named.type_name &&
+			    operand->type->Named.type_name->kind == Entity_TypeName &&
+			    operand->type->Named.type_name->TypeName.objc_metadata) {
+				check_did_you_mean_objc_entity(name, operand->type->Named.type_name, operand->mode == Addressing_Type);
+			} else if (bt->kind == Type_Struct) {
 				check_did_you_mean_type(name, bt->Struct.fields);
 			} else if (bt->kind == Type_Enum) {
 				check_did_you_mean_type(name, bt->Enum.fields);
@@ -4485,7 +4511,7 @@ Entity *check_selector(CheckerContext *c, Operand *operand, Ast *node, Type *typ
 		}
 
 		gbString op_str   = expr_to_string(op_expr);
-		gbString type_str = type_to_string(operand->type);
+		gbString type_str = type_to_string_shorthand(operand->type);
 		gbString sel_str  = expr_to_string(selector);
 		error(op_expr, "Cannot access non-constant field '%s' from '%s'", sel_str, op_str);
 		gb_string_free(sel_str);
@@ -4510,7 +4536,7 @@ Entity *check_selector(CheckerContext *c, Operand *operand, Ast *node, Type *typ
 		}
 
 		gbString op_str   = expr_to_string(op_expr);
-		gbString type_str = type_to_string(operand->type);
+		gbString type_str = type_to_string_shorthand(operand->type);
 		gbString sel_str  = expr_to_string(selector);
 		error(op_expr, "Cannot access non-constant field '%s' from '%s'", sel_str, op_str);
 		gb_string_free(sel_str);
@@ -4523,7 +4549,7 @@ Entity *check_selector(CheckerContext *c, Operand *operand, Ast *node, Type *typ
 
 	if (expr_entity != nullptr && is_type_polymorphic(expr_entity->type)) {
 		gbString op_str   = expr_to_string(op_expr);
-		gbString type_str = type_to_string(operand->type);
+		gbString type_str = type_to_string_shorthand(operand->type);
 		gbString sel_str  = expr_to_string(selector);
 		error(op_expr, "Cannot access field '%s' from non-specialized polymorphic type '%s'", sel_str, op_str);
 		gb_string_free(sel_str);
@@ -6432,10 +6458,10 @@ ExprKind check_call_expr(CheckerContext *c, Operand *operand, Ast *call, Ast *pr
 		return builtin_procs[id].kind;
 	}
 
-	Entity *e = entity_of_node(operand->expr);
+	Entity *initial_entity = entity_of_node(operand->expr);
 
-	if (e != nullptr && e->kind == Entity_Procedure) {
-		if (e->Procedure.deferred_procedure.entity != nullptr) {
+	if (initial_entity != nullptr && initial_entity->kind == Entity_Procedure) {
+		if (initial_entity->Procedure.deferred_procedure.entity != nullptr) {
 			call->viral_state_flags |= ViralStateFlag_ContainsDeferredProcedure;
 		}
 	}
@@ -9810,6 +9836,9 @@ gbString write_expr_to_string(gbString str, Ast *node, bool shorthand) {
 		if (f->flags&FieldFlag_const) {
 			str = gb_string_appendc(str, "#const ");
 		}
+		if (f->flags&FieldFlag_subtype) {
+			str = gb_string_appendc(str, "#subtype ");
+		}
 
 		for_array(i, f->names) {
 			Ast *name = f->names[i];
diff --git a/src/check_type.cpp b/src/check_type.cpp
index 6d3e32466..64fb67723 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -144,6 +144,7 @@ void check_struct_fields(CheckerContext *ctx, Ast *node, Slice<Entity *> *fields
 		}
 
 		bool is_using = (p->flags&FieldFlag_using) != 0;
+		bool is_subtype = (p->flags&FieldFlag_subtype) != 0;
 
 		for_array(j, p->names) {
 			Ast *name = p->names[j];
@@ -158,6 +159,9 @@ void check_struct_fields(CheckerContext *ctx, Ast *node, Slice<Entity *> *fields
 			Entity *field = alloc_entity_field(ctx->scope, name_token, type, is_using, field_src_index);
 			add_entity(ctx, ctx->scope, name, field);
 			field->Variable.field_group_index = field_group_index;
+			if (is_subtype) {
+				field->flags |= EntityFlag_Subtype;
+			}
 
 			if (j == 0) {
 				field->Variable.docs = docs;
@@ -194,6 +198,20 @@ void check_struct_fields(CheckerContext *ctx, Ast *node, Slice<Entity *> *fields
 
 			populate_using_entity_scope(ctx, node, p, type);
 		}
+
+		if (is_subtype && p->names.count > 0) {
+			Type *first_type = fields_array[fields_array.count-1]->type;
+			Type *t = base_type(type_deref(first_type));
+
+			if (!does_field_type_allow_using(t) &&
+			    p->names.count >= 1 &&
+			    p->names[0]->kind == Ast_Ident) {
+				Token name_token = p->names[0]->Ident.token;
+				gbString type_str = type_to_string(first_type);
+				error(name_token, "'subtype' cannot be applied to the field '%.*s' of type '%s'", LIT(name_token.string), type_str);
+				gb_string_free(type_str);
+			}
+		}
 	}
 	
 	*fields = slice_from_array(fields_array);
@@ -323,6 +341,10 @@ void add_polymorphic_record_entity(CheckerContext *ctx, Ast *node, Type *named_t
 	}
 
 	named_type->Named.type_name = e;
+	GB_ASSERT(original_type->kind == Type_Named);
+	e->TypeName.objc_class_name = original_type->Named.type_name->TypeName.objc_class_name;
+	// TODO(bill): Is this even correct? Or should the metadata be copied?
+	e->TypeName.objc_metadata = original_type->Named.type_name->TypeName.objc_metadata;
 
 	mutex_lock(&ctx->info->gen_types_mutex);
 	auto *found_gen_types = map_get(&ctx->info->gen_types, original_type);
@@ -1906,6 +1928,25 @@ bool check_procedure_type(CheckerContext *ctx, Type *type, Ast *proc_type_node,
 		c->scope->flags &= ~ScopeFlag_ContextDefined;
 	}
 
+	TargetArchKind arch = build_context.metrics.arch;
+	switch (cc) {
+	case ProcCC_StdCall:
+	case ProcCC_FastCall:
+		if (arch != TargetArch_i386 && arch != TargetArch_amd64) {
+			error(proc_type_node, "Invalid procedure calling convention \"%s\" for target architecture, expected either i386 or amd64, got %.*s",
+			      proc_calling_convention_strings[cc], LIT(target_arch_names[arch]));
+		}
+		break;
+	case ProcCC_Win64:
+	case ProcCC_SysV:
+		if (arch != TargetArch_amd64) {
+			error(proc_type_node, "Invalid procedure calling convention \"%s\" for target architecture, expected amd64, got %.*s",
+			      proc_calling_convention_strings[cc], LIT(target_arch_names[arch]));
+		}
+		break;
+	}
+
+
 	bool variadic = false;
 	isize variadic_index = -1;
 	bool success = true;
diff --git a/src/checker.cpp b/src/checker.cpp
index b62ef7c4c..5a7ece263 100644
--- a/src/checker.cpp
+++ b/src/checker.cpp
@@ -4,7 +4,7 @@
 void check_expr(CheckerContext *c, Operand *operand, Ast *expression);
 void check_expr_or_type(CheckerContext *c, Operand *operand, Ast *expression, Type *type_hint=nullptr);
 void add_comparison_procedures_for_fields(CheckerContext *c, Type *t);
-
+Type *check_type(CheckerContext *ctx, Ast *e);
 
 bool is_operand_value(Operand o) {
 	switch (o.mode) {
@@ -225,8 +225,8 @@ bool decl_info_has_init(DeclInfo *d) {
 Scope *create_scope(CheckerInfo *info, Scope *parent, isize init_elements_capacity=DEFAULT_SCOPE_CAPACITY) {
 	Scope *s = gb_alloc_item(permanent_allocator(), Scope);
 	s->parent = parent;
-	string_map_init(&s->elements, permanent_allocator(), init_elements_capacity);
-	ptr_set_init(&s->imported, permanent_allocator(), 0);
+	string_map_init(&s->elements, heap_allocator(), init_elements_capacity);
+	ptr_set_init(&s->imported, heap_allocator(), 0);
 	mutex_init(&s->mutex);
 
 	if (parent != nullptr && parent != builtin_pkg->scope) {
@@ -733,12 +733,25 @@ void add_package_dependency(CheckerContext *c, char const *package_name, char co
 	String n = make_string_c(name);
 	AstPackage *p = get_core_package(&c->checker->info, make_string_c(package_name));
 	Entity *e = scope_lookup(p->scope, n);
-	e->flags |= EntityFlag_Used;
 	GB_ASSERT_MSG(e != nullptr, "%s", name);
 	GB_ASSERT(c->decl != nullptr);
+	e->flags |= EntityFlag_Used;
+	add_dependency(c->info, c->decl, e);
+}
+
+void try_to_add_package_dependency(CheckerContext *c, char const *package_name, char const *name) {
+	String n = make_string_c(name);
+	AstPackage *p = get_core_package(&c->checker->info, make_string_c(package_name));
+	Entity *e = scope_lookup(p->scope, n);
+	if (e == nullptr) {
+		return;
+	}
+	GB_ASSERT(c->decl != nullptr);
+	e->flags |= EntityFlag_Used;
 	add_dependency(c->info, c->decl, e);
 }
 
+
 void add_declaration_dependency(CheckerContext *c, Entity *e) {
 	if (e == nullptr) {
 		return;
@@ -841,6 +854,17 @@ void add_global_enum_constant(Slice<Entity *> const &fields, char const *name, i
 	GB_PANIC("Unfound enum value for global constant: %s %lld", name, cast(long long)value);
 }
 
+Type *add_global_type_name(Scope *scope, String const &type_name, Type *backing_type) {
+	Entity *e = alloc_entity_type_name(scope, make_token_ident(type_name), nullptr, EntityState_Resolved);
+	Type *named_type = alloc_type_named(type_name, backing_type, e);
+	e->type = named_type;
+	set_base_type(named_type, backing_type);
+	if (scope_insert(scope, e)) {
+		compiler_error("double declaration of %.*s", LIT(e->token.string));
+	}
+	return named_type;
+}
+
 
 void init_universal(void) {
 	BuildContext *bc = &build_context;
@@ -870,11 +894,43 @@ void init_universal(void) {
 	add_global_bool_constant("false", false);
 
 	// TODO(bill): Set through flags in the compiler
-	add_global_string_constant("ODIN_OS",      bc->ODIN_OS);
-	add_global_string_constant("ODIN_ARCH",    bc->ODIN_ARCH);
 	add_global_string_constant("ODIN_VENDOR",  bc->ODIN_VENDOR);
 	add_global_string_constant("ODIN_VERSION", bc->ODIN_VERSION);
 	add_global_string_constant("ODIN_ROOT",    bc->ODIN_ROOT);
+
+	{
+		GlobalEnumValue values[TargetOs_COUNT] = {
+			{"Unknown",      TargetOs_Invalid},
+			{"Windows",      TargetOs_windows},
+			{"Darwin",       TargetOs_darwin},
+			{"Linux",        TargetOs_linux},
+			{"Essence",      TargetOs_essence},
+			{"FreeBSD",      TargetOs_freebsd},
+			{"OpenBSD",      TargetOs_openbsd},
+			{"WASI",         TargetOs_wasi},
+			{"JS",           TargetOs_js},
+			{"Freestanding", TargetOs_freestanding},
+		};
+
+		auto fields = add_global_enum_type(str_lit("Odin_OS_Type"), values, gb_count_of(values));
+		add_global_enum_constant(fields, "ODIN_OS", bc->metrics.os);
+		add_global_string_constant("ODIN_OS_STRING", target_os_names[bc->metrics.os]);
+	}
+
+	{
+		GlobalEnumValue values[TargetArch_COUNT] = {
+			{"Unknown", TargetArch_Invalid},
+			{"amd64",   TargetArch_amd64},
+			{"i386",    TargetArch_i386},
+			{"arm64",   TargetArch_arm64},
+			{"wasm32",  TargetArch_wasm32},
+			{"wasm64",  TargetArch_wasm64},
+		};
+
+		auto fields = add_global_enum_type(str_lit("Odin_Arch_Type"), values, gb_count_of(values));
+		add_global_enum_constant(fields, "ODIN_ARCH", bc->metrics.arch);
+		add_global_string_constant("ODIN_ARCH_STRING", target_arch_names[bc->metrics.arch]);
+	}
 	
 	{
 		GlobalEnumValue values[BuildMode_COUNT] = {
@@ -889,7 +945,6 @@ void init_universal(void) {
 		add_global_enum_constant(fields, "ODIN_BUILD_MODE", bc->build_mode);
 	}
 
-	add_global_string_constant("ODIN_ENDIAN_STRING", target_endian_names[target_endians[bc->metrics.arch]]);
 	{
 		GlobalEnumValue values[TargetEndian_COUNT] = {
 			{"Unknown", TargetEndian_Invalid},
@@ -900,6 +955,7 @@ void init_universal(void) {
 
 		auto fields = add_global_enum_type(str_lit("Odin_Endian_Type"), values, gb_count_of(values));
 		add_global_enum_constant(fields, "ODIN_ENDIAN", target_endians[bc->metrics.arch]);
+		add_global_string_constant("ODIN_ENDIAN_STRING", target_endian_names[target_endians[bc->metrics.arch]]);
 	}
 
 	{
@@ -985,6 +1041,17 @@ void init_universal(void) {
 	t_f64_ptr      = alloc_type_pointer(t_f64);
 	t_u8_slice     = alloc_type_slice(t_u8);
 	t_string_slice = alloc_type_slice(t_string);
+
+	// intrinsics types for objective-c stuff
+	{
+		t_objc_object   = add_global_type_name(intrinsics_pkg->scope, str_lit("objc_object"),   alloc_type_struct());
+		t_objc_selector = add_global_type_name(intrinsics_pkg->scope, str_lit("objc_selector"), alloc_type_struct());
+		t_objc_class    = add_global_type_name(intrinsics_pkg->scope, str_lit("objc_class"),    alloc_type_struct());
+
+		t_objc_id       = alloc_type_pointer(t_objc_object);
+		t_objc_SEL      = alloc_type_pointer(t_objc_selector);
+		t_objc_Class    = alloc_type_pointer(t_objc_class);
+	}
 }
 
 
@@ -1041,6 +1108,9 @@ void init_checker_info(CheckerInfo *i) {
 	semaphore_init(&i->collect_semaphore);
 
 	mpmc_init(&i->intrinsics_entry_point_usage, a, 1<<10); // just waste some memory here, even if it probably never used
+
+	mutex_init(&i->objc_types_mutex);
+	map_init(&i->objc_msgSend_types, a);
 }
 
 void destroy_checker_info(CheckerInfo *i) {
@@ -1073,6 +1143,9 @@ void destroy_checker_info(CheckerInfo *i) {
 	mutex_destroy(&i->type_and_value_mutex);
 	mutex_destroy(&i->identifier_uses_mutex);
 	mutex_destroy(&i->foreign_mutex);
+
+	mutex_destroy(&i->objc_types_mutex);
+	map_destroy(&i->objc_msgSend_types);
 }
 
 CheckerContext make_checker_context(Checker *c) {
@@ -2712,6 +2785,14 @@ ExactValue check_decl_attribute_value(CheckerContext *c, Ast *value) {
 	return ev;
 }
 
+Type *check_decl_attribute_type(CheckerContext *c, Ast *value) {
+	if (value != nullptr) {
+		return check_type(c, value);
+	}
+	return nullptr;
+}
+
+
 #define ATTRIBUTE_USER_TAG_NAME "tag"
 
 
@@ -3011,6 +3092,42 @@ DECL_ATTRIBUTE_PROC(proc_decl_attribute) {
 			error(elem, "Expected a string for '%.*s'", LIT(name));
 		}
 		return true;
+	} else if (name == "objc_name") {
+		ExactValue ev = check_decl_attribute_value(c, value);
+		if (ev.kind == ExactValue_String) {
+			if (string_is_valid_identifier(ev.value_string)) {
+				ac->objc_name = ev.value_string;
+			} else {
+				error(elem, "Invalid identifier for '%.*s', got '%.*s'", LIT(name), LIT(ev.value_string));
+			}
+		} else {
+			error(elem, "Expected a string value for '%.*s'", LIT(name));
+		}
+		return true;
+	} else if (name == "objc_is_class_method") {
+		ExactValue ev = check_decl_attribute_value(c, value);
+		if (ev.kind == ExactValue_Bool) {
+			ac->objc_is_class_method = ev.value_bool;
+		} else {
+			error(elem, "Expected a boolean value for '%.*s'", LIT(name));
+		}
+		return true;
+	} else if (name == "objc_type") {
+		if (value == nullptr) {
+			error(elem, "Expected a type for '%.*s'", LIT(name));
+		} else {
+			Type *objc_type = check_type(c, value);
+			if (objc_type != nullptr) {
+				if (!has_type_got_objc_class_attribute(objc_type)) {
+					gbString t = type_to_string(objc_type);
+					error(value, "'%.*s' expected a named type with the attribute @(obj_class=<string>), got type %s", LIT(name), t);
+					gb_string_free(t);
+				} else {
+					ac->objc_type = objc_type;
+				}
+			}
+		}
+		return true;
 	}
 	return false;
 }
@@ -3161,6 +3278,14 @@ DECL_ATTRIBUTE_PROC(type_decl_attribute) {
 	} else if (name == "private") {
 		// NOTE(bill): Handled elsewhere `check_collect_value_decl`
 		return true;
+	} else if (name == "objc_class") {
+		ExactValue ev = check_decl_attribute_value(c, value);
+		if (ev.kind != ExactValue_String || ev.value_string == "") {
+			error(elem, "Expected a non-empty string value for '%.*s'", LIT(name));
+		} else {
+			ac->objc_class = ev.value_string;
+		}
+		return true;
 	}
 	return false;
 }
@@ -3477,11 +3602,11 @@ void check_collect_value_decl(CheckerContext *c, Ast *decl) {
 	if (entity_visibility_kind == EntityVisiblity_Public &&
 	    (c->scope->flags&ScopeFlag_File) &&
 	    c->scope->file) {
-	    	if (c->scope->file->flags & AstFile_IsPrivatePkg) {
-			entity_visibility_kind = EntityVisiblity_PrivateToPackage;
-	    	} else if (c->scope->file->flags & AstFile_IsPrivateFile) {
+	    	if (c->scope->file->flags & AstFile_IsPrivateFile) {
 			entity_visibility_kind = EntityVisiblity_PrivateToFile;
-		}
+		} else if (c->scope->file->flags & AstFile_IsPrivatePkg) {
+			entity_visibility_kind = EntityVisiblity_PrivateToPackage;
+	    	}
 	}
 
 	if (entity_visibility_kind != EntityVisiblity_Public && !(c->scope->flags&ScopeFlag_File)) {
diff --git a/src/checker.hpp b/src/checker.hpp
index 9a8753efd..552e6aca7 100644
--- a/src/checker.hpp
+++ b/src/checker.hpp
@@ -118,6 +118,11 @@ struct AttributeContext {
 	bool    init                : 1;
 	bool    set_cold            : 1;
 	u32 optimization_mode; // ProcedureOptimizationMode
+
+	String  objc_class;
+	String  objc_name;
+	bool    objc_is_class_method;
+	Type *  objc_type;
 };
 
 AttributeContext make_attribute_context(String link_prefix) {
@@ -267,6 +272,17 @@ struct UntypedExprInfo {
 typedef PtrMap<Ast *, ExprInfo *> UntypedExprInfoMap; 
 typedef MPMCQueue<ProcInfo *> ProcBodyQueue;
 
+enum ObjcMsgKind : u32 {
+	ObjcMsg_normal,
+	ObjcMsg_fpret,
+	ObjcMsg_fp2ret,
+	ObjcMsg_stret,
+};
+struct ObjcMsgData {
+	ObjcMsgKind kind;
+	Type *proc_type;
+};
+
 // CheckerInfo stores all the symbol information for a type-checked program
 struct CheckerInfo {
 	Checker *checker;
@@ -340,7 +356,8 @@ struct CheckerInfo {
 
 	MPMCQueue<Ast *> intrinsics_entry_point_usage;
 
-
+	BlockingMutex objc_types_mutex;
+	PtrMap<Ast *, ObjcMsgData> objc_msgSend_types;
 };
 
 struct CheckerContext {
diff --git a/src/checker_builtin_procs.hpp b/src/checker_builtin_procs.hpp
index e8f5174c0..cba952ddf 100644
--- a/src/checker_builtin_procs.hpp
+++ b/src/checker_builtin_procs.hpp
@@ -213,8 +213,6 @@ BuiltinProc__type_simple_boolean_begin,
 	BuiltinProc_type_is_union,
 	BuiltinProc_type_is_enum,
 	BuiltinProc_type_is_proc,
-	BuiltinProc_type_is_bit_field,
-	BuiltinProc_type_is_bit_field_value,
 	BuiltinProc_type_is_bit_set,
 	BuiltinProc_type_is_simd_vector,
 	BuiltinProc_type_is_matrix,
@@ -243,6 +241,8 @@ BuiltinProc__type_simple_boolean_end,
 	BuiltinProc_type_polymorphic_record_parameter_count,
 	BuiltinProc_type_polymorphic_record_parameter_value,
 
+	BuiltinProc_type_is_subtype_of,
+
 	BuiltinProc_type_field_index_of,
 
 	BuiltinProc_type_equal_proc,
@@ -252,6 +252,15 @@ BuiltinProc__type_end,
 
 	BuiltinProc___entry_point,
 
+	BuiltinProc_objc_send,
+	BuiltinProc_objc_find_selector,
+	BuiltinProc_objc_find_class,
+	BuiltinProc_objc_register_selector,
+	BuiltinProc_objc_register_class,
+
+	BuiltinProc_constant_utf16_cstring,
+
+
 	BuiltinProc_COUNT,
 };
 gb_global BuiltinProc builtin_procs[BuiltinProc_COUNT] = {
@@ -466,8 +475,6 @@ gb_global BuiltinProc builtin_procs[BuiltinProc_COUNT] = {
 	{STR_LIT("type_is_union"),             1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 	{STR_LIT("type_is_enum"),              1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 	{STR_LIT("type_is_proc"),              1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
-	{STR_LIT("type_is_bit_field"),         1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
-	{STR_LIT("type_is_bit_field_value"),   1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 	{STR_LIT("type_is_bit_set"),           1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 	{STR_LIT("type_is_simd_vector"),       1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 	{STR_LIT("type_is_matrix"),            1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
@@ -495,6 +502,8 @@ gb_global BuiltinProc builtin_procs[BuiltinProc_COUNT] = {
 	{STR_LIT("type_polymorphic_record_parameter_count"), 1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 	{STR_LIT("type_polymorphic_record_parameter_value"), 2, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 
+	{STR_LIT("type_is_subtype_of"), 2, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+
 	{STR_LIT("type_field_index_of"), 2, false, Expr_Expr, BuiltinProcPkg_intrinsics},
 
 	{STR_LIT("type_equal_proc"),  1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
@@ -504,4 +513,14 @@ gb_global BuiltinProc builtin_procs[BuiltinProc_COUNT] = {
 	{STR_LIT(""), 0, false, Expr_Stmt, BuiltinProcPkg_intrinsics},
 
 	{STR_LIT("__entry_point"), 0, false, Expr_Stmt, BuiltinProcPkg_intrinsics},
+
+	{STR_LIT("objc_send"),   3, true,  Expr_Expr, BuiltinProcPkg_intrinsics},
+
+	{STR_LIT("objc_find_selector"),     1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+	{STR_LIT("objc_find_class"),        1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+	{STR_LIT("objc_register_selector"), 1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+	{STR_LIT("objc_register_class"),    1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+
+	{STR_LIT("constant_utf16_cstring"), 1, false, Expr_Expr, BuiltinProcPkg_intrinsics},
+
 };
diff --git a/src/common.cpp b/src/common.cpp
index ab2a46118..aaacda04b 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -848,7 +848,7 @@ ReadDirectoryError read_directory(String path, Array<FileInfo> *fi) {
 
 	return ReadDirectory_None;
 }
-#elif defined(GB_SYSTEM_LINUX) || defined(GB_SYSTEM_OSX) || defined(GB_SYSTEM_FREEBSD)
+#elif defined(GB_SYSTEM_LINUX) || defined(GB_SYSTEM_OSX) || defined(GB_SYSTEM_FREEBSD) || defined(GB_SYSTEM_OPENBSD)
 
 #include <dirent.h>
 
@@ -1021,7 +1021,7 @@ LoadedFileError load_file_32(char const *fullpath, LoadedFile *memory_mapped_fil
 	#endif
 	}
 	
-	gbFileContents fc = gb_file_read_contents(heap_allocator(), true, fullpath);
+	gbFileContents fc = gb_file_read_contents(permanent_allocator(), true, fullpath);
 
 	if (fc.size > I32_MAX) {
 		err = LoadedFile_FileTooLarge;
diff --git a/src/common_memory.cpp b/src/common_memory.cpp
index 096c35b5c..953462077 100644
--- a/src/common_memory.cpp
+++ b/src/common_memory.cpp
@@ -139,6 +139,7 @@ struct PlatformMemoryBlock {
 };
 
 
+gb_global std::atomic<isize> global_platform_memory_total_usage;
 gb_global PlatformMemoryBlock global_platform_memory_block_sentinel;
 
 PlatformMemoryBlock *platform_virtual_memory_alloc(isize total_size);
@@ -158,10 +159,17 @@ void platform_virtual_memory_protect(void *memory, isize size);
 
 	PlatformMemoryBlock *platform_virtual_memory_alloc(isize total_size) {
 		PlatformMemoryBlock *pmblock = (PlatformMemoryBlock *)VirtualAlloc(0, total_size, MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE);
-		GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
+		if (pmblock == nullptr) {
+			gb_printf_err("Out of Virtual memory, oh no...\n");
+			gb_printf_err("Requested: %lld bytes\n", cast(long long)total_size);
+			gb_printf_err("Total Usage: %lld bytes\n", cast(long long)global_platform_memory_total_usage);
+			GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
+		}
+		global_platform_memory_total_usage += total_size;
 		return pmblock;
 	}
 	void platform_virtual_memory_free(PlatformMemoryBlock *block) {
+		global_platform_memory_total_usage -= block->total_size;
 		GB_ASSERT(VirtualFree(block, 0, MEM_RELEASE));
 	}
 	void platform_virtual_memory_protect(void *memory, isize size) {
@@ -180,11 +188,18 @@ void platform_virtual_memory_protect(void *memory, isize size);
 	
 	PlatformMemoryBlock *platform_virtual_memory_alloc(isize total_size) {
 		PlatformMemoryBlock *pmblock = (PlatformMemoryBlock *)mmap(nullptr, total_size, PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
-		GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
+		if (pmblock == nullptr) {
+			gb_printf_err("Out of Virtual memory, oh no...\n");
+			gb_printf_err("Requested: %lld bytes\n", cast(long long)total_size);
+			gb_printf_err("Total Usage: %lld bytes\n", cast(long long)global_platform_memory_total_usage);
+			GB_ASSERT_MSG(pmblock != nullptr, "Out of Virtual Memory, oh no...");
+		}
+		global_platform_memory_total_usage += total_size;
 		return pmblock;
 	}
 	void platform_virtual_memory_free(PlatformMemoryBlock *block) {
 		isize size = block->total_size;
+		global_platform_memory_total_usage -= size;
 		munmap(block, size);
 	}
 	void platform_virtual_memory_protect(void *memory, isize size) {
diff --git a/src/docs_writer.cpp b/src/docs_writer.cpp
index 0474ce8ff..2c5186c39 100644
--- a/src/docs_writer.cpp
+++ b/src/docs_writer.cpp
@@ -683,40 +683,7 @@ OdinDocTypeIndex odin_doc_type(OdinDocWriter *w, Type *type) {
 			types[1] = odin_doc_type(w, type->Proc.results);
 			doc_type.types = odin_write_slice(w, types, gb_count_of(types));
 
-			String calling_convention = {};
-			switch (type->Proc.calling_convention) {
-			case ProcCC_Invalid:
-				// no need
-				break;
-			case ProcCC_Odin:
-				if (default_calling_convention() != ProcCC_Odin) {
-					calling_convention = str_lit("odin");
-				}
-				break;
-			case ProcCC_Contextless:
-				if (default_calling_convention() != ProcCC_Contextless) {
-					calling_convention = str_lit("contextless");
-				}
-				break;
-			case ProcCC_CDecl:
-				calling_convention = str_lit("cdecl");
-				break;
-			case ProcCC_StdCall:
-				calling_convention = str_lit("stdcall");
-				break;
-			case ProcCC_FastCall:
-				calling_convention = str_lit("fastcall");
-				break;
-			case ProcCC_None:
-				calling_convention = str_lit("none");
-				break;
-			case ProcCC_Naked:
-				calling_convention = str_lit("naked");
-				break;
-			case ProcCC_InlineAsm:
-				calling_convention = str_lit("inline-assembly");
-				break;
-			}
+			String calling_convention = make_string_c(proc_calling_convention_strings[type->Proc.calling_convention]);
 			doc_type.calling_convention = odin_doc_write_string(w, calling_convention);
 		}
 		break;
diff --git a/src/entity.cpp b/src/entity.cpp
index 8327a517e..f5720293f 100644
--- a/src/entity.cpp
+++ b/src/entity.cpp
@@ -74,6 +74,7 @@ enum EntityFlag : u64 {
 
 	EntityFlag_Test          = 1ull<<30,
 	EntityFlag_Init          = 1ull<<31,
+	EntityFlag_Subtype       = 1ull<<32,
 	
 	EntityFlag_CustomLinkName = 1ull<<40,
 	EntityFlag_CustomLinkage_Internal = 1ull<<41,
@@ -86,6 +87,10 @@ enum EntityFlag : u64 {
 	EntityFlag_Overridden    = 1ull<<63,
 };
 
+enum : u64 {
+	EntityFlags_IsSubtype = EntityFlag_Using|EntityFlag_Subtype,
+};
+
 enum EntityState : u32 {
 	EntityState_Unresolved = 0,
 	EntityState_InProgress = 1,
@@ -122,6 +127,28 @@ enum ProcedureOptimizationMode : u32 {
 	ProcedureOptimizationMode_Speed,
 };
 
+
+BlockingMutex global_type_name_objc_metadata_mutex;
+
+struct TypeNameObjCMetadataEntry {
+	String name;
+	Entity *entity;
+};
+struct TypeNameObjCMetadata {
+	BlockingMutex *mutex;
+	Array<TypeNameObjCMetadataEntry> type_entries;
+	Array<TypeNameObjCMetadataEntry> value_entries;
+};
+
+TypeNameObjCMetadata *create_type_name_obj_c_metadata() {
+	TypeNameObjCMetadata *md = gb_alloc_item(permanent_allocator(), TypeNameObjCMetadata);
+	md->mutex = gb_alloc_item(permanent_allocator(), BlockingMutex);
+	mutex_init(md->mutex);
+	array_init(&md->type_entries,  heap_allocator());
+	array_init(&md->value_entries, heap_allocator());
+	return md;
+}
+
 // An Entity is a named "thing" in the language
 struct Entity {
 	EntityKind  kind;
@@ -186,6 +213,8 @@ struct Entity {
 			Type * type_parameter_specialization;
 			String ir_mangled_name;
 			bool   is_type_alias;
+			String objc_class_name;
+			TypeNameObjCMetadata *objc_metadata;
 		} TypeName;
 		struct {
 			u64     tags;
diff --git a/src/exact_value.cpp b/src/exact_value.cpp
index fd90278e5..f6df48951 100644
--- a/src/exact_value.cpp
+++ b/src/exact_value.cpp
@@ -50,9 +50,9 @@ struct ExactValue {
 	union {
 		bool           value_bool;
 		String         value_string;
-		BigInt         value_integer; // NOTE(bill): This must be an integer and not a pointer
+		BigInt         value_integer;
 		f64            value_float;
-		i64            value_pointer;
+		i64            value_pointer; // NOTE(bill): This must be an integer and not a pointer
 		Complex128    *value_complex;
 		Quaternion256 *value_quaternion;
 		Ast *          value_compound;
@@ -630,6 +630,9 @@ void match_exact_values(ExactValue *x, ExactValue *y) {
 	case ExactValue_Bool:
 	case ExactValue_String:
 	case ExactValue_Quaternion:
+	case ExactValue_Pointer:
+	case ExactValue_Procedure:
+	case ExactValue_Typeid:
 		return;
 
 	case ExactValue_Integer:
@@ -671,9 +674,6 @@ void match_exact_values(ExactValue *x, ExactValue *y) {
 			return;
 		}
 		break;
-
-	case ExactValue_Procedure:
-		return;
 	}
 
 	compiler_error("match_exact_values: How'd you get here? Invalid ExactValueKind %d", x->kind);
@@ -932,6 +932,17 @@ bool compare_exact_values(TokenKind op, ExactValue x, ExactValue y) {
 		break;
 	}
 
+	case ExactValue_Pointer: {
+		switch (op) {
+		case Token_CmpEq: return x.value_pointer == y.value_pointer;
+		case Token_NotEq: return x.value_pointer != y.value_pointer;
+		case Token_Lt:    return x.value_pointer <  y.value_pointer;
+		case Token_LtEq:  return x.value_pointer <= y.value_pointer;
+		case Token_Gt:    return x.value_pointer >  y.value_pointer;
+		case Token_GtEq:  return x.value_pointer >= y.value_pointer;
+		}
+	}
+
 	case ExactValue_Typeid:
 		switch (op) {
 		case Token_CmpEq: return are_types_identical(x.value_typeid, y.value_typeid);
diff --git a/src/gb/gb.h b/src/gb/gb.h
index d9bf09436..b72a893f7 100644
--- a/src/gb/gb.h
+++ b/src/gb/gb.h
@@ -79,6 +79,10 @@ extern "C" {
 		#ifndef GB_SYSTEM_FREEBSD
 		#define GB_SYSTEM_FREEBSD 1
 		#endif
+	#elif defined(__OpenBSD__)
+		#ifndef GB_SYSTEM_OPENBSD
+		#define GB_SYSTEM_OPENBSD 1
+		#endif
 	#else
 		#error This UNIX operating system is not supported
 	#endif
@@ -199,7 +203,7 @@ extern "C" {
 	#endif
 	#include <stdlib.h> // NOTE(bill): malloc on linux
 	#include <sys/mman.h>
-	#if !defined(GB_SYSTEM_OSX) && !defined(__FreeBSD__)
+	#if !defined(GB_SYSTEM_OSX) && !defined(__FreeBSD__) && !defined(__OpenBSD__)
 		#include <sys/sendfile.h>
 	#endif
 	#include <sys/stat.h>
@@ -235,6 +239,12 @@ extern "C" {
 	#define sendfile(out, in, offset, count) sendfile(out, in, offset, count, NULL, NULL, 0)
 #endif
 
+#if defined(GB_SYSTEM_OPENBSD)
+	#include <stdio.h>
+	#include <pthread_np.h>
+	#define lseek64 lseek
+#endif
+    
 #if defined(GB_SYSTEM_UNIX)
 	#include <semaphore.h>
 #endif
@@ -783,6 +793,13 @@ typedef struct gbAffinity {
 	isize thread_count;
 	isize threads_per_core;
 } gbAffinity;
+#elif defined(GB_SYSTEM_OPENBSD)
+typedef struct gbAffinity {
+	b32   is_accurate;
+	isize core_count;
+	isize thread_count;
+	isize threads_per_core;
+} gbAffinity;
 #else
 #error TODO(bill): Unknown system
 #endif
@@ -3682,6 +3699,30 @@ isize gb_affinity_thread_count_for_core(gbAffinity *a, isize core) {
 	GB_ASSERT(0 <= core && core < a->core_count);
 	return a->threads_per_core;
 }
+
+#elif defined(GB_SYSTEM_OPENBSD)
+#include <unistd.h>
+
+void gb_affinity_init(gbAffinity *a) {
+	a->core_count       = sysconf(_SC_NPROCESSORS_ONLN);
+	a->threads_per_core = 1;
+	a->is_accurate      = a->core_count > 0;
+	a->core_count       = a->is_accurate ? a->core_count : 1;
+	a->thread_count     = a->core_count;
+}
+
+void gb_affinity_destroy(gbAffinity *a) {
+	gb_unused(a);
+}
+
+b32 gb_affinity_set(gbAffinity *a, isize core, isize thread_index) {
+	return true;
+}
+
+isize gb_affinity_thread_count_for_core(gbAffinity *a, isize core) {
+	GB_ASSERT(0 <= core && core < a->core_count);
+	return a->threads_per_core;
+}
 #else
 #error TODO(bill): Unknown system
 #endif
@@ -6025,7 +6066,7 @@ gbFileTime gb_file_last_write_time(char const *filepath) {
 gb_inline b32 gb_file_copy(char const *existing_filename, char const *new_filename, b32 fail_if_exists) {
 #if defined(GB_SYSTEM_OSX)
 	return copyfile(existing_filename, new_filename, NULL, COPYFILE_DATA) == 0;
-#else
+#elif defined(GB_SYSTEM_LINUX) || defined(GB_SYSTEM_FREEBSD)
 	isize size;
 	int existing_fd = open(existing_filename, O_RDONLY, 0);
 	int new_fd      = open(new_filename, O_WRONLY|O_CREAT, 0666);
@@ -6042,6 +6083,49 @@ gb_inline b32 gb_file_copy(char const *existing_filename, char const *new_filena
 	close(existing_fd);
 
 	return size == stat_existing.st_size;
+#else
+	int new_flags = O_WRONLY | O_CREAT;
+	if (fail_if_exists) {
+		new_flags |= O_EXCL;
+	}
+	int existing_fd = open(existing_filename, O_RDONLY, 0);
+	int new_fd      = open(new_filename, new_flags, 0666);
+
+	struct stat stat_existing;
+	if (fstat(existing_fd, &stat_existing) == -1) {
+		return 0;
+	}
+
+	size_t bsize = stat_existing.st_blksize > BUFSIZ ? stat_existing.st_blksize : BUFSIZ;
+	char *buf = (char *)malloc(bsize);
+	if (buf == NULL) {
+		close(new_fd);
+		close(existing_fd);
+		return 0;
+	}
+
+	isize size = 0;
+	ssize_t nread, nwrite, offset;
+	while ((nread = read(existing_fd, buf, bsize)) != -1 && nread != 0) {
+		for (offset = 0; nread; nread -= nwrite, offset += nwrite) {
+			if ((nwrite = write(new_fd, buf + offset, nread)) == -1 || nwrite == 0) {
+				free(buf);
+				close(new_fd);
+				close(existing_fd);
+				return 0;
+			}
+			size += nwrite;
+		}
+	}
+	
+	free(buf);
+	close(new_fd);
+	close(existing_fd);
+
+	if (nread == -1) {
+		return 0;
+	}
+	return size == stat_existing.st_size;
 #endif
 }
 
@@ -6093,6 +6177,7 @@ gbFileContents gb_file_read_contents(gbAllocator a, b32 zero_terminate, char con
 }
 
 void gb_file_free_contents(gbFileContents *fc) {
+    if (fc == NULL || fc->size == 0) return;
 	GB_ASSERT_NOT_NULL(fc->data);
 	gb_free(fc->allocator, fc->data);
 	fc->data = NULL;
diff --git a/src/llvm_abi.cpp b/src/llvm_abi.cpp
index 310df6639..0244b73d6 100644
--- a/src/llvm_abi.cpp
+++ b/src/llvm_abi.cpp
@@ -1184,6 +1184,12 @@ LB_ABI_INFO(lb_get_abi_info) {
 			ft->calling_convention = calling_convention;
 			return ft;
 		}
+	case ProcCC_Win64:
+		GB_ASSERT(build_context.metrics.arch == TargetArch_amd64);
+		return lbAbiAmd64Win64::abi_info(c, arg_types, arg_count, return_type, return_is_defined, calling_convention);
+	case ProcCC_SysV:
+		GB_ASSERT(build_context.metrics.arch == TargetArch_amd64);
+		return lbAbiAmd64SysV::abi_info(c, arg_types, arg_count, return_type, return_is_defined, calling_convention);
 	}
 
 	switch (build_context.metrics.arch) {
diff --git a/src/llvm_backend.cpp b/src/llvm_backend.cpp
index 304effb7f..3b11f95a2 100644
--- a/src/llvm_backend.cpp
+++ b/src/llvm_backend.cpp
@@ -652,7 +652,54 @@ lbProcedure *lb_create_startup_type_info(lbModule *m) {
 	return p;
 }
 
-lbProcedure *lb_create_startup_runtime(lbModule *main_module, lbProcedure *startup_type_info, Array<lbGlobalVariable> &global_variables) { // Startup Runtime
+lbProcedure *lb_create_objc_names(lbModule *main_module) {
+	if (build_context.metrics.os != TargetOs_darwin) {
+		return nullptr;
+	}
+	Type *proc_type = alloc_type_proc(nullptr, nullptr, 0, nullptr, 0, false, ProcCC_CDecl);
+	lbProcedure *p = lb_create_dummy_procedure(main_module, str_lit("__$init_objc_names"), proc_type);
+	p->is_startup = true;
+	return p;
+}
+
+void lb_finalize_objc_names(lbProcedure *p) {
+	if (p == nullptr) {
+		return;
+	}
+	lbModule *m = p->module;
+
+	LLVMPassManagerRef default_function_pass_manager = LLVMCreateFunctionPassManagerForModule(m->mod);
+	lb_populate_function_pass_manager(m, default_function_pass_manager, false, build_context.optimization_level);
+	LLVMFinalizeFunctionPassManager(default_function_pass_manager);
+
+
+	auto args = array_make<lbValue>(permanent_allocator(), 1);
+
+	LLVMSetLinkage(p->value, LLVMInternalLinkage);
+	lb_begin_procedure_body(p);
+	for_array(i, m->objc_classes.entries) {
+		auto const &entry = m->objc_classes.entries[i];
+		String name = entry.key.string;
+		args[0] = lb_const_value(m, t_cstring, exact_value_string(name));
+		lbValue ptr = lb_emit_runtime_call(p, "objc_lookUpClass", args);
+		lb_addr_store(p, entry.value, ptr);
+	}
+
+	for_array(i, m->objc_selectors.entries) {
+		auto const &entry = m->objc_selectors.entries[i];
+		String name = entry.key.string;
+		args[0] = lb_const_value(m, t_cstring, exact_value_string(name));
+		lbValue ptr = lb_emit_runtime_call(p, "sel_registerName", args);
+		lb_addr_store(p, entry.value, ptr);
+	}
+
+	lb_end_procedure_body(p);
+
+	lb_run_function_pass_manager(default_function_pass_manager, p);
+
+}
+
+lbProcedure *lb_create_startup_runtime(lbModule *main_module, lbProcedure *startup_type_info, lbProcedure *objc_names, Array<lbGlobalVariable> &global_variables) { // Startup Runtime
 	LLVMPassManagerRef default_function_pass_manager = LLVMCreateFunctionPassManagerForModule(main_module->mod);
 	lb_populate_function_pass_manager(main_module, default_function_pass_manager, false, build_context.optimization_level);
 	LLVMFinalizeFunctionPassManager(default_function_pass_manager);
@@ -666,6 +713,10 @@ lbProcedure *lb_create_startup_runtime(lbModule *main_module, lbProcedure *start
 
 	LLVMBuildCall2(p->builder, LLVMGetElementType(lb_type(main_module, startup_type_info->type)), startup_type_info->value, nullptr, 0, "");
 
+	if (objc_names) {
+		LLVMBuildCall2(p->builder, LLVMGetElementType(lb_type(main_module, objc_names->type)), objc_names->value, nullptr, 0, "");
+	}
+
 	for_array(i, global_variables) {
 		auto *var = &global_variables[i];
 		if (var->is_initialized) {
@@ -1244,6 +1295,11 @@ void lb_generate_code(lbGenerator *gen) {
 		reloc_mode = LLVMRelocPIC;
 	}
 
+	if (build_context.metrics.os == TargetOs_openbsd) {
+		// Always use PIC for OpenBSD: it defaults to PIE
+		reloc_mode = LLVMRelocPIC;
+	}
+
 	for_array(i, gen->modules.entries) {
 		target_machines[i] = LLVMCreateTargetMachine(
 			target, target_triple, llvm_cpu,
@@ -1570,8 +1626,10 @@ void lb_generate_code(lbGenerator *gen) {
 	TIME_SECTION("LLVM Runtime Type Information Creation");
 	lbProcedure *startup_type_info = lb_create_startup_type_info(default_module);
 
+	lbProcedure *objc_names = lb_create_objc_names(default_module);
+
 	TIME_SECTION("LLVM Runtime Startup Creation (Global Variables)");
-	lbProcedure *startup_runtime = lb_create_startup_runtime(default_module, startup_type_info, global_variables);
+	lbProcedure *startup_runtime = lb_create_startup_runtime(default_module, startup_type_info, objc_names, global_variables);
 	gb_unused(startup_runtime);
 
 	TIME_SECTION("LLVM Global Procedures and Types");
@@ -1650,6 +1708,8 @@ void lb_generate_code(lbGenerator *gen) {
 		}
 	}
 
+	lb_finalize_objc_names(objc_names);
+
 	if (build_context.ODIN_DEBUG) {
 		TIME_SECTION("LLVM Debug Info Complete Types and Finalize");
 		for_array(j, gen->modules.entries) {
@@ -1662,6 +1722,7 @@ void lb_generate_code(lbGenerator *gen) {
 	}
 
 
+
 	TIME_SECTION("LLVM Function Pass");
 	for_array(i, gen->modules.entries) {
 		lbModule *m = gen->modules.entries[i].value;
diff --git a/src/llvm_backend.hpp b/src/llvm_backend.hpp
index d7093bc63..f2bcfaff6 100644
--- a/src/llvm_backend.hpp
+++ b/src/llvm_backend.hpp
@@ -144,6 +144,9 @@ struct lbModule {
 	PtrMap<void *, LLVMMetadataRef> debug_values; 
 
 	Array<lbIncompleteDebugType> debug_incomplete_types;
+
+	StringMap<lbAddr> objc_classes;
+	StringMap<lbAddr> objc_selectors;
 };
 
 struct lbGenerator {
@@ -293,7 +296,6 @@ struct lbProcedure {
 
 
 bool lb_init_generator(lbGenerator *gen, Checker *c);
-void lb_generate_module(lbGenerator *gen);
 
 String lb_mangle_name(lbModule *m, Entity *e);
 String lb_get_entity_name(lbModule *m, Entity *e, String name = {});
@@ -366,7 +368,7 @@ lbContextData *lb_push_context_onto_stack(lbProcedure *p, lbAddr ctx);
 lbContextData *lb_push_context_onto_stack_from_implicit_parameter(lbProcedure *p);
 
 
-lbAddr lb_add_global_generated(lbModule *m, Type *type, lbValue value={});
+lbAddr lb_add_global_generated(lbModule *m, Type *type, lbValue value={}, Entity **entity_=nullptr);
 lbAddr lb_add_local(lbProcedure *p, Type *type, Entity *e=nullptr, bool zero_init=true, i32 param_index=0, bool force_no_init=false);
 
 void lb_add_foreign_library_path(lbModule *m, Entity *e);
@@ -546,6 +548,10 @@ lbCallingConventionKind const lb_calling_convention_map[ProcCC_MAX] = {
 	lbCallingConvention_C,            // ProcCC_None,
 	lbCallingConvention_C,            // ProcCC_Naked,
 	lbCallingConvention_C,            // ProcCC_InlineAsm,
+
+	lbCallingConvention_Win64,        // ProcCC_Win64,
+	lbCallingConvention_X86_64_SysV,  // ProcCC_SysV,
+
 };
 
 enum : LLVMDWARFTypeEncoding {
diff --git a/src/llvm_backend_const.cpp b/src/llvm_backend_const.cpp
index 5862a7add..8f17a1cfb 100644
--- a/src/llvm_backend_const.cpp
+++ b/src/llvm_backend_const.cpp
@@ -115,8 +115,8 @@ LLVMValueRef llvm_const_cast(LLVMValueRef val, LLVMTypeRef dst) {
 
 
 lbValue lb_const_ptr_cast(lbModule *m, lbValue value, Type *t) {
-	GB_ASSERT(is_type_pointer(value.type));
-	GB_ASSERT(is_type_pointer(t));
+	GB_ASSERT(is_type_internally_pointer_like(value.type));
+	GB_ASSERT(is_type_internally_pointer_like(t));
 	GB_ASSERT(lb_is_const(value));
 
 	lbValue res = {};
@@ -175,7 +175,7 @@ LLVMValueRef llvm_const_array(LLVMTypeRef elem_type, LLVMValueRef *values, isize
 }
 
 LLVMValueRef llvm_const_slice(lbModule *m, lbValue data, lbValue len) {
-	GB_ASSERT(is_type_pointer(data.type));
+	GB_ASSERT(is_type_pointer(data.type) || is_type_multi_pointer(data.type));
 	GB_ASSERT(are_types_identical(len.type, t_int));
 	LLVMValueRef vals[2] = {
 		data.value,
@@ -568,7 +568,7 @@ lbValue lb_const_value(lbModule *m, Type *type, ExactValue value, bool allow_loc
 		}
 
 	case ExactValue_Integer:
-		if (is_type_pointer(type)) {
+		if (is_type_pointer(type) || is_type_multi_pointer(type)) {
 			LLVMTypeRef t = lb_type(m, original_type);
 			LLVMValueRef i = lb_big_int_to_llvm(m, t_uintptr, &value.value_integer);
 			res.value = LLVMConstIntToPtr(i, t);
diff --git a/src/llvm_backend_debug.cpp b/src/llvm_backend_debug.cpp
index f60096aad..b91f32bfc 100644
--- a/src/llvm_backend_debug.cpp
+++ b/src/llvm_backend_debug.cpp
@@ -958,15 +958,15 @@ void lb_add_debug_local_variable(lbProcedure *p, LLVMValueRef ptr, Type *type, T
 	);
 
 	LLVMValueRef storage = ptr;
-	LLVMValueRef instr = ptr;
+	LLVMBasicBlockRef block = p->decl_block->block;
 	LLVMMetadataRef llvm_debug_loc = lb_debug_location_from_token_pos(p, token.pos);
 	LLVMMetadataRef llvm_expr = LLVMDIBuilderCreateExpression(m->debug_builder, nullptr, 0);
 	lb_set_llvm_metadata(m, ptr, llvm_expr);
-	LLVMDIBuilderInsertDeclareBefore(m->debug_builder, storage, var_info, llvm_expr, llvm_debug_loc, instr);
+	LLVMDIBuilderInsertDeclareAtEnd(m->debug_builder, storage, var_info, llvm_expr, llvm_debug_loc, block);
 }
 
 
-void lb_add_debug_param_variable(lbProcedure *p, LLVMValueRef ptr, Type *type, Token const &token, unsigned arg_number) {
+void lb_add_debug_param_variable(lbProcedure *p, LLVMValueRef ptr, Type *type, Token const &token, unsigned arg_number, lbBlock *block) {
 	if (p->debug_info == nullptr) {
 		return;
 	}
@@ -1020,19 +1020,14 @@ void lb_add_debug_param_variable(lbProcedure *p, LLVMValueRef ptr, Type *type, T
 	);
 
 	LLVMValueRef storage = ptr;
-	LLVMValueRef instr = ptr;
-	LLVMBasicBlockRef block = p->decl_block->block;
 	LLVMMetadataRef llvm_debug_loc = lb_debug_location_from_token_pos(p, token.pos);
 	LLVMMetadataRef llvm_expr = LLVMDIBuilderCreateExpression(m->debug_builder, nullptr, 0);
 	lb_set_llvm_metadata(m, ptr, llvm_expr);
-	if (LLVMIsAAllocaInst(instr)) {
-		LLVMDIBuilderInsertDeclareBefore(m->debug_builder, storage, var_info, llvm_expr, llvm_debug_loc, instr);
-	} else {
-		// NOTE(bill, 2022-02-01): For parameter values, you must insert them at the end of the decl block
-		// The reason is that if the parameter is at index 0 and a pointer, there is not such things as an
-		// instruction "before" it.
-		LLVMDIBuilderInsertDeclareAtEnd(m->debug_builder, storage, var_info, llvm_expr, llvm_debug_loc, block);
-	}
+
+	// NOTE(bill, 2022-02-01): For parameter values, you must insert them at the end of the decl block
+	// The reason is that if the parameter is at index 0 and a pointer, there is not such things as an
+	// instruction "before" it.
+	LLVMDIBuilderInsertDbgValueAtEnd(m->debug_builder, storage, var_info, llvm_expr, llvm_debug_loc, block->block);
 }
 
 
@@ -1055,5 +1050,10 @@ void lb_add_debug_context_variable(lbProcedure *p, lbAddr const &ctx) {
 	token.string = str_lit("context");
 	token.pos = pos;
 
-	lb_add_debug_local_variable(p, ctx.addr.value, t_context, token);
+	LLVMValueRef ptr = ctx.addr.value;
+	while (LLVMIsABitCastInst(ptr)) {
+		ptr = LLVMGetOperand(ptr, 0);
+	}
+
+	lb_add_debug_local_variable(p, ptr, t_context, token);
 }
diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index 29a86d116..844deb43c 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -3303,9 +3303,9 @@ lbAddr lb_build_addr(lbProcedure *p, Ast *expr) {
 	case_end;
 
 	case_ast_node(se, SelectorExpr, expr);
-		Ast *sel = unparen_expr(se->selector);
-		if (sel->kind == Ast_Ident) {
-			String selector = sel->Ident.token.string;
+		Ast *sel_node = unparen_expr(se->selector);
+		if (sel_node->kind == Ast_Ident) {
+			String selector = sel_node->Ident.token.string;
 			TypeAndValue tav = type_and_value_of_expr(se->expr);
 
 			if (tav.mode == Addressing_Invalid) {
@@ -3320,7 +3320,12 @@ lbAddr lb_build_addr(lbProcedure *p, Ast *expr) {
 
 			Type *type = base_type(tav.type);
 			if (tav.mode == Addressing_Type) { // Addressing_Type
-				GB_PANIC("Unreachable");
+				Selection sel = lookup_field(tav.type, selector, true);
+				if (sel.pseudo_field) {
+					GB_ASSERT(sel.entity->kind == Entity_Procedure);
+					return lb_addr(lb_find_value_from_entity(p->module, sel.entity));
+				}
+				GB_PANIC("Unreachable %.*s", LIT(selector));
 			}
 
 			if (se->swizzle_count > 0) {
@@ -3347,6 +3352,11 @@ lbAddr lb_build_addr(lbProcedure *p, Ast *expr) {
 
 			Selection sel = lookup_field(type, selector, false);
 			GB_ASSERT(sel.entity != nullptr);
+			if (sel.pseudo_field) {
+				GB_ASSERT(sel.entity->kind == Entity_Procedure);
+				Entity *e = entity_of_node(sel_node);
+				return lb_addr(lb_find_value_from_entity(p->module, e));
+			}
 
 			{
 				lbAddr addr = lb_build_addr(p, se->expr);
diff --git a/src/llvm_backend_general.cpp b/src/llvm_backend_general.cpp
index 2fc21b534..1c98aa77f 100644
--- a/src/llvm_backend_general.cpp
+++ b/src/llvm_backend_general.cpp
@@ -72,6 +72,9 @@ void lb_init_module(lbModule *m, Checker *c) {
 
 	map_init(&m->debug_values, a);
 	array_init(&m->debug_incomplete_types, a, 0, 1024);
+
+	string_map_init(&m->objc_classes, a);
+	string_map_init(&m->objc_selectors, a);
 }
 
 bool lb_init_generator(lbGenerator *gen, Checker *c) {
@@ -2450,7 +2453,7 @@ lbValue lb_find_procedure_value_from_entity(lbModule *m, Entity *e) {
 	return {};
 }
 
-lbAddr lb_add_global_generated(lbModule *m, Type *type, lbValue value) {
+lbAddr lb_add_global_generated(lbModule *m, Type *type, lbValue value, Entity **entity_) {
 	GB_ASSERT(type != nullptr);
 	type = default_type(type);
 
@@ -2476,6 +2479,9 @@ lbAddr lb_add_global_generated(lbModule *m, Type *type, lbValue value) {
 
 	lb_add_entity(m, e, g);
 	lb_add_member(m, name, g);
+
+	if (entity_) *entity_ = e;
+
 	return lb_addr(g);
 }
 
diff --git a/src/llvm_backend_opt.cpp b/src/llvm_backend_opt.cpp
index 8f1c7ad59..d36bdec0b 100644
--- a/src/llvm_backend_opt.cpp
+++ b/src/llvm_backend_opt.cpp
@@ -56,7 +56,7 @@ LLVMBool lb_must_preserve_predicate_callback(LLVMValueRef value, void *user_data
 #endif
 
 void lb_basic_populate_function_pass_manager(LLVMPassManagerRef fpm, i32 optimization_level) {
-	if (optimization_level == 0 && build_context.ODIN_DEBUG) {
+	if (false && optimization_level == 0 && build_context.ODIN_DEBUG) {
 		LLVMAddMergedLoadStoreMotionPass(fpm);
 	} else {
 		LLVMAddPromoteMemoryToRegisterPass(fpm);
diff --git a/src/llvm_backend_proc.cpp b/src/llvm_backend_proc.cpp
index 7a6fac603..7ead77c2c 100644
--- a/src/llvm_backend_proc.cpp
+++ b/src/llvm_backend_proc.cpp
@@ -57,6 +57,7 @@ void lb_mem_copy_non_overlapping(lbProcedure *p, lbValue dst, lbValue src, lbVal
 	LLVMBuildCall(p->builder, ip, args, gb_count_of(args), "");
 }
 
+
 lbProcedure *lb_create_procedure(lbModule *m, Entity *entity, bool ignore_body) {
 	GB_ASSERT(entity != nullptr);
 	GB_ASSERT(entity->kind == Entity_Procedure);
@@ -163,14 +164,6 @@ lbProcedure *lb_create_procedure(lbModule *m, Entity *entity, bool ignore_body)
 		break;
 	}
 
-
-
-	// lbCallingConventionKind cc_kind = lbCallingConvention_C;
-	// // TODO(bill): Clean up this logic
-	// if (build_context.metrics.os != TargetOs_js)  {
-	// 	cc_kind = lb_calling_convention_map[pt->Proc.calling_convention];
-	// }
-	// LLVMSetFunctionCallConv(p->value, cc_kind);
 	lbValue proc_value = {p->value, p->type};
 	lb_add_entity(m, entity,  proc_value);
 	lb_add_member(m, p->name, proc_value);
@@ -480,9 +473,8 @@ void lb_begin_procedure_body(lbProcedure *p) {
 				} else if (arg_type->kind == lbArg_Direct) {
 					if (e->token.string.len != 0 && !is_blank_ident(e->token.string)) {
 						LLVMTypeRef param_type = lb_type(p->module, e->type);
-						LLVMValueRef value = LLVMGetParam(p->value, param_offset+param_index);
-
-						value = OdinLLVMBuildTransmute(p, value, param_type);
+						LLVMValueRef original_value = LLVMGetParam(p->value, param_offset+param_index);
+						LLVMValueRef value = OdinLLVMBuildTransmute(p, original_value, param_type);
 
 						lbValue param = {};
 						param.value = value;
@@ -491,7 +483,16 @@ void lb_begin_procedure_body(lbProcedure *p) {
 						lbValue ptr = lb_address_from_load_or_generate_local(p, param);
 						GB_ASSERT(LLVMIsAAllocaInst(ptr.value));
 						lb_add_entity(p->module, e, ptr);
-						lb_add_debug_param_variable(p, ptr.value, e->type, e->token, param_index+1);
+
+						lbBlock *block = p->decl_block;
+						if (original_value != value) {
+							block = p->curr_block;
+						}
+						LLVMValueRef debug_storage_value = value;
+						if (original_value != value && LLVMIsALoadInst(value)) {
+							debug_storage_value = LLVMGetOperand(value, 0);
+						}
+						lb_add_debug_param_variable(p, debug_storage_value, e->type, e->token, param_index+1, block);
 					}
 				} else if (arg_type->kind == lbArg_Indirect) {
 					if (e->token.string.len != 0 && !is_blank_ident(e->token.string)) {
@@ -499,7 +500,7 @@ void lb_begin_procedure_body(lbProcedure *p) {
 						ptr.value = LLVMGetParam(p->value, param_offset+param_index);
 						ptr.type = alloc_type_pointer(e->type);
 						lb_add_entity(p->module, e, ptr);
-						lb_add_debug_param_variable(p, ptr.value, e->type, e->token, param_index+1);
+						lb_add_debug_param_variable(p, ptr.value, e->type, e->token, param_index+1, p->decl_block);
 					}
 				}
 			}
@@ -2106,6 +2107,85 @@ lbValue lb_build_builtin_proc(lbProcedure *p, Ast *expr, TypeAndValue const &tv,
 			res.type = t_uintptr;
 			return res;
 		}
+
+	case BuiltinProc_objc_send:
+		return lb_handle_objc_send(p, expr);
+
+	case BuiltinProc_objc_find_selector:     return lb_handle_objc_find_selector(p, expr);
+	case BuiltinProc_objc_find_class:        return lb_handle_objc_find_class(p, expr);
+	case BuiltinProc_objc_register_selector: return lb_handle_objc_register_selector(p, expr);
+	case BuiltinProc_objc_register_class:    return lb_handle_objc_register_class(p, expr);
+
+
+	case BuiltinProc_constant_utf16_cstring:
+		{
+			auto const encode_surrogate_pair = [](Rune r, u16 *r1, u16 *r2) {
+				if (r < 0x10000 || r > 0x10ffff) {
+					*r1 = 0xfffd;
+					*r2 = 0xfffd;
+				} else {
+					r -= 0x10000;
+					*r1 = 0xd800 + ((r>>10)&0x3ff);
+					*r2 = 0xdc00 + (r&0x3ff);
+				}
+			};
+
+			lbModule *m = p->module;
+
+			auto tav = type_and_value_of_expr(ce->args[0]);
+			GB_ASSERT(tav.value.kind == ExactValue_String);
+			String value = tav.value.value_string;
+
+			LLVMTypeRef llvm_u16 = lb_type(m, t_u16);
+
+			isize max_len = value.len*2 + 1;
+			LLVMValueRef *buffer = gb_alloc_array(temporary_allocator(), LLVMValueRef, max_len);
+			isize n = 0;
+			while (value.len > 0) {
+				Rune r = 0;
+				isize w = gb_utf8_decode(value.text, value.len, &r);
+				value.text += w;
+				value.len  -= w;
+				if ((0 <= r && r < 0xd800) || (0xe000 <= r && r < 0x10000)) {
+					buffer[n++] = LLVMConstInt(llvm_u16, cast(u16)r, false);
+				} else if (0x10000 <= r && r <= 0x10ffff) {
+					u16 r1, r2;
+					encode_surrogate_pair(r, &r1, &r2);
+					buffer[n++] = LLVMConstInt(llvm_u16, r1, false);
+					buffer[n++] = LLVMConstInt(llvm_u16, r2, false);
+				} else {
+					buffer[n++] = LLVMConstInt(llvm_u16, 0xfffd, false);
+				}
+			}
+
+			buffer[n++] = LLVMConstInt(llvm_u16, 0, false);
+
+			LLVMValueRef array = LLVMConstArray(llvm_u16, buffer, cast(unsigned int)n);
+
+			char *name = nullptr;
+			{
+				isize max_len = 7+8+1;
+				name = gb_alloc_array(permanent_allocator(), char, max_len);
+				u32 id = m->gen->global_array_index.fetch_add(1);
+				isize len = gb_snprintf(name, max_len, "csbs$%x", id);
+				len -= 1;
+			}
+			LLVMValueRef global_data = LLVMAddGlobal(m->mod, LLVMTypeOf(array), name);
+			LLVMSetInitializer(global_data, array);
+			LLVMSetLinkage(global_data, LLVMInternalLinkage);
+
+
+
+			LLVMValueRef indices[] = {
+				LLVMConstInt(lb_type(m, t_u32), 0, false),
+				LLVMConstInt(lb_type(m, t_u32), 0, false),
+			};
+			lbValue res = {};
+			res.type = tv.type;
+			res.value = LLVMBuildInBoundsGEP(p->builder, global_data, indices, gb_count_of(indices), "");
+			return res;
+
+		}
 	}
 
 	GB_PANIC("Unhandled built-in procedure %.*s", LIT(builtin_procs[id].name));
diff --git a/src/llvm_backend_utility.cpp b/src/llvm_backend_utility.cpp
index 7e2bd7daa..98b7e07f0 100644
--- a/src/llvm_backend_utility.cpp
+++ b/src/llvm_backend_utility.cpp
@@ -1819,3 +1819,175 @@ void lb_set_wasm_export_attributes(LLVMValueRef value, String export_name) {
 	LLVMSetVisibility(value, LLVMDefaultVisibility);
 	LLVMAddTargetDependentFunctionAttr(value, "wasm-export-name",   alloc_cstring(permanent_allocator(), export_name));
 }
+
+
+lbValue lb_lookup_runtime_procedure(lbModule *m, String const &name);
+
+
+lbAddr lb_handle_objc_find_or_register_selector(lbProcedure *p, String const &name) {
+	lbAddr *found = string_map_get(&p->module->objc_selectors, name);
+	if (found) {
+		return *found;
+	} else {
+		lbModule *default_module = &p->module->gen->default_module;
+		Entity *e = nullptr;
+		lbAddr default_addr = lb_add_global_generated(default_module, t_objc_SEL, {}, &e);
+
+		lbValue ptr = lb_find_value_from_entity(p->module, e);
+		lbAddr local_addr = lb_addr(ptr);
+
+		string_map_set(&default_module->objc_selectors, name, default_addr);
+		if (default_module != p->module) {
+			string_map_set(&p->module->objc_selectors, name, local_addr);
+		}
+		return local_addr;
+	}
+}
+
+lbValue lb_handle_objc_find_selector(lbProcedure *p, Ast *expr) {
+	ast_node(ce, CallExpr, expr);
+
+	auto tav = ce->args[0]->tav;
+	GB_ASSERT(tav.value.kind == ExactValue_String);
+	String name = tav.value.value_string;
+	return lb_addr_load(p, lb_handle_objc_find_or_register_selector(p, name));
+}
+
+lbValue lb_handle_objc_register_selector(lbProcedure *p, Ast *expr) {
+	ast_node(ce, CallExpr, expr);
+	lbModule *m = p->module;
+
+	auto tav = ce->args[0]->tav;
+	GB_ASSERT(tav.value.kind == ExactValue_String);
+	String name = tav.value.value_string;
+	lbAddr dst = lb_handle_objc_find_or_register_selector(p, name);
+
+	auto args = array_make<lbValue>(permanent_allocator(), 1);
+	args[0] = lb_const_value(m, t_cstring, exact_value_string(name));
+	lbValue ptr = lb_emit_runtime_call(p, "sel_registerName", args);
+	lb_addr_store(p, dst, ptr);
+
+	return lb_addr_load(p, dst);
+}
+
+lbAddr lb_handle_objc_find_or_register_class(lbProcedure *p, String const &name) {
+	lbAddr *found = string_map_get(&p->module->objc_classes, name);
+	if (found) {
+		return *found;
+	} else {
+		lbModule *default_module = &p->module->gen->default_module;
+		Entity *e = nullptr;
+		lbAddr default_addr = lb_add_global_generated(default_module, t_objc_SEL, {}, &e);
+
+		lbValue ptr = lb_find_value_from_entity(p->module, e);
+		lbAddr local_addr = lb_addr(ptr);
+
+		string_map_set(&default_module->objc_classes, name, default_addr);
+		if (default_module != p->module) {
+			string_map_set(&p->module->objc_classes, name, local_addr);
+		}
+		return local_addr;
+	}
+}
+
+lbValue lb_handle_objc_find_class(lbProcedure *p, Ast *expr) {
+	ast_node(ce, CallExpr, expr);
+
+	auto tav = ce->args[0]->tav;
+	GB_ASSERT(tav.value.kind == ExactValue_String);
+	String name = tav.value.value_string;
+	return lb_addr_load(p, lb_handle_objc_find_or_register_class(p, name));
+}
+
+lbValue lb_handle_objc_register_class(lbProcedure *p, Ast *expr) {
+	ast_node(ce, CallExpr, expr);
+	lbModule *m = p->module;
+
+	auto tav = ce->args[0]->tav;
+	GB_ASSERT(tav.value.kind == ExactValue_String);
+	String name = tav.value.value_string;
+	lbAddr dst = lb_handle_objc_find_or_register_class(p, name);
+
+	auto args = array_make<lbValue>(permanent_allocator(), 3);
+	args[0] = lb_const_nil(m, t_objc_Class);
+	args[1] = lb_const_nil(m, t_objc_Class);
+	args[2] = lb_const_int(m, t_uint, 0);
+	lbValue ptr = lb_emit_runtime_call(p, "objc_allocateClassPair", args);
+	lb_addr_store(p, dst, ptr);
+
+	return lb_addr_load(p, dst);
+}
+
+
+lbValue lb_handle_objc_id(lbProcedure *p, Ast *expr) {
+	TypeAndValue const &tav = type_and_value_of_expr(expr);
+	if (tav.mode == Addressing_Type) {
+		Type *type = tav.type;
+		GB_ASSERT_MSG(type->kind == Type_Named, "%s", type_to_string(type));
+		Entity *e = type->Named.type_name;
+		GB_ASSERT(e->kind == Entity_TypeName);
+		String name = e->TypeName.objc_class_name;
+
+		lbAddr *found = string_map_get(&p->module->objc_classes, name);
+		if (found) {
+			return lb_addr_load(p, *found);
+		} else {
+			lbModule *default_module = &p->module->gen->default_module;
+			Entity *e = nullptr;
+			lbAddr default_addr = lb_add_global_generated(default_module, t_objc_Class, {}, &e);
+
+			lbValue ptr = lb_find_value_from_entity(p->module, e);
+			lbAddr local_addr = lb_addr(ptr);
+
+			string_map_set(&default_module->objc_classes, name, default_addr);
+			if (default_module != p->module) {
+				string_map_set(&p->module->objc_classes, name, local_addr);
+			}
+			return lb_addr_load(p, local_addr);
+		}
+	}
+
+	return lb_build_expr(p, expr);
+}
+
+lbValue lb_handle_objc_send(lbProcedure *p, Ast *expr) {
+	ast_node(ce, CallExpr, expr);
+
+	lbModule *m = p->module;
+	CheckerInfo *info = m->info;
+	ObjcMsgData data = map_must_get(&info->objc_msgSend_types, expr);
+	GB_ASSERT(data.proc_type != nullptr);
+
+	GB_ASSERT(ce->args.count >= 3);
+	auto args = array_make<lbValue>(permanent_allocator(), 0, ce->args.count-1);
+
+	lbValue id = lb_handle_objc_id(p, ce->args[1]);
+	Ast *sel_expr = ce->args[2];
+	GB_ASSERT(sel_expr->tav.value.kind == ExactValue_String);
+	lbValue sel = lb_addr_load(p, lb_handle_objc_find_or_register_selector(p, sel_expr->tav.value.value_string));
+
+	array_add(&args, id);
+	array_add(&args, sel);
+	for (isize i = 3; i < ce->args.count; i++) {
+		lbValue arg = lb_build_expr(p, ce->args[i]);
+		array_add(&args, arg);
+	}
+
+
+	lbValue the_proc = {};
+	switch (data.kind) {
+	default:
+		GB_PANIC("unhandled ObjcMsgKind %u", data.kind);
+		break;
+	case ObjcMsg_normal: the_proc = lb_lookup_runtime_procedure(m, str_lit("objc_msgSend"));        break;
+	case ObjcMsg_fpret:  the_proc = lb_lookup_runtime_procedure(m, str_lit("objc_msgSend_fpret"));  break;
+	case ObjcMsg_fp2ret: the_proc = lb_lookup_runtime_procedure(m, str_lit("objc_msgSend_fp2ret")); break;
+	case ObjcMsg_stret:  the_proc = lb_lookup_runtime_procedure(m, str_lit("objc_msgSend_stret"));  break;
+	}
+
+	the_proc = lb_emit_conv(p, the_proc, data.proc_type);
+
+	return lb_emit_call(p, the_proc, args);
+}
+
+
diff --git a/src/main.cpp b/src/main.cpp
index fe56d451f..f8a3e6f85 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -463,7 +463,8 @@ i32 linker_stage(lbGenerator *gen) {
 			#endif
 			link_settings = gb_string_appendc(link_settings, "-Wl,-init,'_odin_entry_point' ");
 			link_settings = gb_string_appendc(link_settings, "-Wl,-fini,'_odin_exit_point' ");
-		} else {
+		} else if (build_context.metrics.os != TargetOs_openbsd) {
+			// OpenBSD defaults to PIE executable. do not pass -no-pie for it.
 			link_settings = gb_string_appendc(link_settings, "-no-pie ");
 		}
 		if (build_context.out_filepath.len > 0) {
@@ -485,7 +486,7 @@ i32 linker_stage(lbGenerator *gen) {
 				// NOTE: If you change this (although this minimum is as low as you can go with Odin working)
 				//       make sure to also change the 'mtriple' param passed to 'opt'
 				#if defined(GB_CPU_ARM)
-				" -mmacosx-version-min=11.0.0 "
+				" -mmacosx-version-min=12.0.0 "
 				#else
 				" -mmacosx-version-min=10.8.0 "
 				#endif
@@ -572,50 +573,21 @@ void usage(String argv0) {
 	print_usage_line(0, "Usage:");
 	print_usage_line(1, "%.*s command [arguments]", LIT(argv0));
 	print_usage_line(0, "Commands:");
-	print_usage_line(1, "build     compile .odin file, or directory of .odin files, as an executable.");
-	print_usage_line(1, "          one must contain the program's entry point, all must be in the same package.");
-	print_usage_line(1, "run       same as 'build', but also then runs the newly compiled executable.");
-	print_usage_line(1, "check     parse and type check .odin file");
-	print_usage_line(1, "query     parse, type check, and output a .json file containing information about the program");
-	print_usage_line(1, "doc       generate documentation .odin file, or directory of .odin files");
-	print_usage_line(1, "version   print version");
-	print_usage_line(1, "report    print information useful to reporting a bug");
+	print_usage_line(1, "build             compile .odin file, or directory of .odin files, as an executable.");
+	print_usage_line(1, "                  one must contain the program's entry point, all must be in the same package.");
+	print_usage_line(1, "run               same as 'build', but also then runs the newly compiled executable.");
+	print_usage_line(1, "check             parse, and type check an .odin file, or directory of .odin files");
+	print_usage_line(1, "query             parse, type check, and output a .json file containing information about the program");
+	print_usage_line(1, "strip-semicolon   parse, type check, and remove unneeded semicolons from the entire program");
+	print_usage_line(1, "test              build ands runs procedures with the attribute @(test) in the initial package");
+	print_usage_line(1, "doc               generate documentation .odin file, or directory of .odin files");
+	print_usage_line(1, "version           print version");
+	print_usage_line(1, "report            print information useful to reporting a bug");
 	print_usage_line(0, "");
 	print_usage_line(0, "For further details on a command, use -help after the command name");
 	print_usage_line(1, "e.g. odin build -help");
 }
 
-
-bool string_is_valid_identifier(String str) {
-	if (str.len <= 0) return false;
-
-	isize rune_count = 0;
-
-	isize w = 0;
-	isize offset = 0;
-	while (offset < str.len) {
-		Rune r = 0;
-		w = utf8_decode(str.text, str.len, &r);
-		if (r == GB_RUNE_INVALID) {
-			return false;
-		}
-
-		if (rune_count == 0) {
-			if (!rune_is_letter(r)) {
-				return false;
-			}
-		} else {
-			if (!rune_is_letter(r) && !rune_is_digit(r)) {
-				return false;
-			}
-		}
-		rune_count += 1;
-		offset += w;
-	}
-
-	return true;
-}
-
 enum BuildFlagKind {
 	BuildFlag_Invalid,
 
@@ -1851,6 +1823,7 @@ void print_show_help(String const arg0, String const &command) {
 		print_usage_line(1, "          one must contain the program's entry point, all must be in the same package.");
 	} else if (command == "run") {
 		print_usage_line(1, "run       same as 'build', but also then runs the newly compiled executable.");
+		print_usage_line(1, "          append an empty flag and then the args, '-- <args>', to specify args for the output.");
 	} else if (command == "check") {
 		print_usage_line(1, "check     parse and type check .odin file(s)");
 	} else if (command == "test") {
@@ -2447,6 +2420,7 @@ int main(int arg_count, char const **arg_ptr) {
 	virtual_memory_init();
 	mutex_init(&fullpath_mutex);
 	mutex_init(&hash_exact_value_mutex);
+	mutex_init(&global_type_name_objc_metadata_mutex);
 
 	init_string_buffer_memory();
 	init_string_interner();
@@ -2606,7 +2580,7 @@ int main(int arg_count, char const **arg_ptr) {
 	// NOTE(bill): add 'shared' directory if it is not already set
 	if (!find_library_collection_path(str_lit("shared"), nullptr)) {
 		add_library_collection(str_lit("shared"),
-							   get_fullpath_relative(heap_allocator(), odin_root_dir(), str_lit("shared")));
+			get_fullpath_relative(heap_allocator(), odin_root_dir(), str_lit("shared")));
 	}
 
 
diff --git a/src/parser.cpp b/src/parser.cpp
index 0914c77ca..f70afe346 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -57,6 +57,9 @@ isize ast_node_size(AstKind kind) {
 	return align_formula_isize(gb_size_of(AstCommonStuff) + ast_variant_sizes[kind], gb_align_of(void *));
 
 }
+
+gb_global std::atomic<isize> global_total_node_memory_allocated;
+
 // NOTE(bill): And this below is why is I/we need a new language! Discriminated unions are a pain in C/C++
 Ast *alloc_ast_node(AstFile *f, AstKind kind) {
 	gbAllocator a = ast_allocator(f);
@@ -66,6 +69,9 @@ Ast *alloc_ast_node(AstFile *f, AstKind kind) {
 	Ast *node = cast(Ast *)gb_alloc(a, size);
 	node->kind = kind;
 	node->file_id = f ? f->id : 0;
+
+	global_total_node_memory_allocated += size;
+
 	return node;
 }
 
@@ -3009,64 +3015,62 @@ i32 token_precedence(AstFile *f, TokenKind t) {
 
 Ast *parse_binary_expr(AstFile *f, bool lhs, i32 prec_in) {
 	Ast *expr = parse_unary_expr(f, lhs);
-	for (i32 prec = token_precedence(f, f->curr_token.kind); prec >= prec_in; prec--) {
-		for (;;) {
-			Token op = f->curr_token;
-			i32 op_prec = token_precedence(f, op.kind);
-			if (op_prec != prec) {
-				// NOTE(bill): This will also catch operators that are not valid "binary" operators
-				break;
+	for (;;) {
+		Token op = f->curr_token;
+		i32 op_prec = token_precedence(f, op.kind);
+		if (op_prec < prec_in) {
+			// NOTE(bill): This will also catch operators that are not valid "binary" operators
+			break;
+		}
+		Token prev = f->prev_token;
+		switch (op.kind) {
+		case Token_if:
+		case Token_when:
+			if (prev.pos.line < op.pos.line) {
+				// NOTE(bill): Check to see if the `if` or `when` is on the same line of the `lhs` condition
+				goto loop_end;
 			}
-			Token prev = f->prev_token;
+			break;
+		}
+		expect_operator(f); // NOTE(bill): error checks too
+
+		if (op.kind == Token_Question) {
+			Ast *cond = expr;
+			// Token_Question
+			Ast *x = parse_expr(f, lhs);
+			Token token_c = expect_token(f, Token_Colon);
+			Ast *y = parse_expr(f, lhs);
+			expr = ast_ternary_if_expr(f, x, cond, y);
+		} else if (op.kind == Token_if || op.kind == Token_when) {
+			Ast *x = expr;
+			Ast *cond = parse_expr(f, lhs);
+			Token tok_else = expect_token(f, Token_else);
+			Ast *y = parse_expr(f, lhs);
+
 			switch (op.kind) {
 			case Token_if:
+				expr = ast_ternary_if_expr(f, x, cond, y);
+				break;
 			case Token_when:
-				if (prev.pos.line < op.pos.line) {
-					// NOTE(bill): Check to see if the `if` or `when` is on the same line of the `lhs` condition
-					goto loop_end;
-				}
+				expr = ast_ternary_when_expr(f, x, cond, y);
 				break;
 			}
-			expect_operator(f); // NOTE(bill): error checks too
-
-			if (op.kind == Token_Question) {
-				Ast *cond = expr;
-				// Token_Question
-				Ast *x = parse_expr(f, lhs);
-				Token token_c = expect_token(f, Token_Colon);
-				Ast *y = parse_expr(f, lhs);
-				expr = ast_ternary_if_expr(f, x, cond, y);
-			} else if (op.kind == Token_if || op.kind == Token_when) {
-				Ast *x = expr;
-				Ast *cond = parse_expr(f, lhs);
-				Token tok_else = expect_token(f, Token_else);
-				Ast *y = parse_expr(f, lhs);
-				
-				switch (op.kind) {
-				case Token_if:
-					expr = ast_ternary_if_expr(f, x, cond, y);
-					break;
-				case Token_when:
-					expr = ast_ternary_when_expr(f, x, cond, y);
-					break;
-				}
+		} else {
+			Ast *right = parse_binary_expr(f, false, op_prec+1);
+			if (right == nullptr) {
+				syntax_error(op, "Expected expression on the right-hand side of the binary operator '%.*s'", LIT(op.string));
+			}
+			if (op.kind == Token_or_else) {
+				// NOTE(bill): easier to handle its logic different with its own AST kind
+				expr = ast_or_else_expr(f, expr, op, right);
 			} else {
-				Ast *right = parse_binary_expr(f, false, prec+1);
-				if (right == nullptr) {
-					syntax_error(op, "Expected expression on the right-hand side of the binary operator '%.*s'", LIT(op.string));
-				}
-				if (op.kind == Token_or_else) {
-					// NOTE(bill): easier to handle its logic different with its own AST kind
-					expr = ast_or_else_expr(f, expr, op, right);	
-				} else {
-					expr = ast_binary_expr(f, op, expr, right);
-				}
+				expr = ast_binary_expr(f, op, expr, right);
 			}
-
-			lhs = false;
 		}
-		loop_end:;
+
+		lhs = false;
 	}
+	loop_end:;
 	return expr;
 }
 
@@ -3412,12 +3416,18 @@ ProcCallingConvention string_to_calling_convention(String s) {
 	if (s == "fast")        return ProcCC_FastCall;
 	if (s == "none")        return ProcCC_None;
 	if (s == "naked")       return ProcCC_Naked;
+
+	if (s == "win64")	return ProcCC_Win64;
+	if (s == "sysv")        return ProcCC_SysV;
+
 	if (s == "system") {
 		if (build_context.metrics.os == TargetOs_windows) {
 			return ProcCC_StdCall;
 		}
 		return ProcCC_CDecl;
 	}
+
+
 	return ProcCC_Invalid;
 }
 
@@ -3504,12 +3514,13 @@ enum FieldPrefixKind : i32 {
 	FieldPrefix_Unknown = -1,
 	FieldPrefix_Invalid = 0,
 
-	FieldPrefix_using,
+	FieldPrefix_using, // implies #subtype
 	FieldPrefix_const,
 	FieldPrefix_no_alias,
 	FieldPrefix_c_vararg,
 	FieldPrefix_auto_cast,
 	FieldPrefix_any_int,
+	FieldPrefix_subtype, // does not imply `using` semantics
 };
 
 struct ParseFieldPrefixMapping {
@@ -3526,6 +3537,7 @@ gb_global ParseFieldPrefixMapping parse_field_prefix_mappings[] = {
 	{str_lit("c_vararg"),   Token_Hash,      FieldPrefix_c_vararg,  FieldFlag_c_vararg},
 	{str_lit("const"),      Token_Hash,      FieldPrefix_const,     FieldFlag_const},
 	{str_lit("any_int"),    Token_Hash,      FieldPrefix_any_int,   FieldFlag_any_int},
+	{str_lit("subtype"),    Token_Hash,      FieldPrefix_subtype,   FieldFlag_subtype},
 };
 
 
@@ -4843,12 +4855,6 @@ ParseFileError init_ast_file(AstFile *f, String fullpath, TokenPos *err_pos) {
 	f->prev_token = f->tokens[f->prev_token_index];
 	f->curr_token = f->tokens[f->curr_token_index];
 
-	isize const page_size = 4*1024;
-	isize block_size = 2*f->tokens.count*gb_size_of(Ast);
-	block_size = ((block_size + page_size-1)/page_size) * page_size;
-	block_size = gb_clamp(block_size, page_size, DEFAULT_MINIMUM_BLOCK_SIZE);
-	f->arena.minimum_block_size = block_size;
-
 	array_init(&f->comments, heap_allocator(), 0, 0);
 	array_init(&f->imports,  heap_allocator(), 0, 0);
 
@@ -5713,6 +5719,22 @@ ParseFileError parse_packages(Parser *p, String init_filename) {
 			error_line("Expected either a directory or a .odin file, got '%.*s'\n", LIT(init_filename));
 			return ParseFile_WrongExtension;
 		}
+	} else if (init_fullpath.len != 0) {
+		String path = init_fullpath;
+		if (path[path.len-1] == '/') {
+			path.len -= 1;
+		}
+		if ((build_context.command_kind & Command__does_build) &&
+		    build_context.build_mode == BuildMode_Executable) {
+			String short_path = filename_from_path(path);
+			char *cpath = alloc_cstring(heap_allocator(), short_path);
+			defer (gb_free(heap_allocator(), cpath));
+
+			if (gb_file_exists(cpath)) {
+			    	error_line("Please specify the executable name with -out:<string> as a directory exists with the same name in the current working directory");
+			    	return ParseFile_DirectoryAlreadyExists;
+			}
+		}
 	}
 	
 
diff --git a/src/parser.hpp b/src/parser.hpp
index ff0df0382..c33d1520b 100644
--- a/src/parser.hpp
+++ b/src/parser.hpp
@@ -46,6 +46,7 @@ enum ParseFileError {
 	ParseFile_InvalidToken,
 	ParseFile_GeneralError,
 	ParseFile_FileTooLarge,
+	ParseFile_DirectoryAlreadyExists,
 
 	ParseFile_Count,
 };
@@ -97,8 +98,6 @@ struct AstFile {
 	AstPackage * pkg;
 	Scope *      scope;
 
-	Arena  arena;
-
 	Ast *        pkg_decl;
 	String       fullpath;
 	Tokenizer    tokenizer;
@@ -249,12 +248,30 @@ enum ProcCallingConvention : i32 {
 
 	ProcCC_InlineAsm   = 8,
 
+	ProcCC_Win64       = 9,
+	ProcCC_SysV        = 10,
+
+
 	ProcCC_MAX,
 
 
 	ProcCC_ForeignBlockDefault = -1,
 };
 
+char const *proc_calling_convention_strings[ProcCC_MAX] = {
+	"",
+	"odin",
+	"contextless",
+	"cdecl",
+	"stdcall",
+	"fastcall",
+	"none",
+	"naked",
+	"inlineasm",
+	"win64",
+	"sysv",
+};
+
 ProcCallingConvention default_calling_convention(void) {
 	return ProcCC_Odin;
 }
@@ -282,6 +299,7 @@ enum FieldFlag : u32 {
 	FieldFlag_auto_cast = 1<<4,
 	FieldFlag_const     = 1<<5,
 	FieldFlag_any_int   = 1<<6,
+	FieldFlag_subtype   = 1<<7,
 
 	// Internal use by the parser only
 	FieldFlag_Tags      = 1<<10,
@@ -289,7 +307,7 @@ enum FieldFlag : u32 {
 
 	// Parameter List Restrictions
 	FieldFlag_Signature = FieldFlag_ellipsis|FieldFlag_using|FieldFlag_no_alias|FieldFlag_c_vararg|FieldFlag_auto_cast|FieldFlag_const|FieldFlag_any_int,
-	FieldFlag_Struct    = FieldFlag_using|FieldFlag_Tags,
+	FieldFlag_Struct    = FieldFlag_using|FieldFlag_subtype|FieldFlag_Tags,
 };
 
 enum StmtAllowFlag {
@@ -782,10 +800,10 @@ gb_inline bool is_ast_when_stmt(Ast *node) {
 	return node->kind == Ast_WhenStmt;
 }
 
-gb_global gb_thread_local Arena global_ast_arena = {};
+gb_global gb_thread_local Arena global_thread_local_ast_arena = {};
 
 gbAllocator ast_allocator(AstFile *f) {
-	Arena *arena = f ? &f->arena : &global_ast_arena;
+	Arena *arena = &global_thread_local_ast_arena;
 	return arena_allocator(arena);
 }
 
diff --git a/src/string.cpp b/src/string.cpp
index eb6058f78..bcaf23b9b 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -781,3 +781,34 @@ i32 unquote_string(gbAllocator a, String *s_, u8 quote=0, bool has_carriage_retu
 	return 2;
 }
 
+
+
+bool string_is_valid_identifier(String str) {
+	if (str.len <= 0) return false;
+
+	isize rune_count = 0;
+
+	isize w = 0;
+	isize offset = 0;
+	while (offset < str.len) {
+		Rune r = 0;
+		w = utf8_decode(str.text, str.len, &r);
+		if (r == GB_RUNE_INVALID) {
+			return false;
+		}
+
+		if (rune_count == 0) {
+			if (!rune_is_letter(r)) {
+				return false;
+			}
+		} else {
+			if (!rune_is_letter(r) && !rune_is_digit(r)) {
+				return false;
+			}
+		}
+		rune_count += 1;
+		offset += w;
+	}
+
+	return true;
+}
diff --git a/src/threading.cpp b/src/threading.cpp
index 50d0dfed1..63e3415b2 100644
--- a/src/threading.cpp
+++ b/src/threading.cpp
@@ -486,7 +486,7 @@ void thread_set_name(Thread *t, char const *name) {
 #elif defined(GB_SYSTEM_OSX)
 	// TODO(bill): Test if this works
 	pthread_setname_np(name);
-#elif defined(GB_SYSTEM_FREEBSD)
+#elif defined(GB_SYSTEM_FREEBSD) || defined(GB_SYSTEM_OPENBSD)
 	pthread_set_name_np(t->posix_handle, name);
 #else
 	// TODO(bill): Test if this works
diff --git a/src/types.cpp b/src/types.cpp
index 9ee6ba359..58ccdf5b9 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -393,6 +393,7 @@ struct Selection {
 	bool       indirect; // Set if there was a pointer deref anywhere down the line
 	u8 swizzle_count;    // maximum components = 4
 	u8 swizzle_indices;  // 2 bits per component, representing which swizzle index
+	bool pseudo_field;
 };
 Selection empty_selection = {0};
 
@@ -685,6 +686,16 @@ gb_global Type *t_map_header                     = nullptr;
 gb_global Type *t_equal_proc  = nullptr;
 gb_global Type *t_hasher_proc = nullptr;
 
+gb_global Type *t_objc_object   = nullptr;
+gb_global Type *t_objc_selector = nullptr;
+gb_global Type *t_objc_class    = nullptr;
+
+gb_global Type *t_objc_id    = nullptr;
+gb_global Type *t_objc_SEL   = nullptr;
+gb_global Type *t_objc_Class = nullptr;
+
+
+
 gb_global RecursiveMutex g_type_mutex;
 
 struct TypePath;
@@ -692,7 +703,7 @@ struct TypePath;
 i64      type_size_of         (Type *t);
 i64      type_align_of        (Type *t);
 i64      type_offset_of       (Type *t, i32 index);
-gbString type_to_string       (Type *type);
+gbString type_to_string       (Type *type, bool shorthand=false);
 i64      type_size_of_internal(Type *t, TypePath *path);
 void     init_map_internal_types(Type *type);
 Type *   bit_set_to_int(Type *t);
@@ -2323,7 +2334,7 @@ String lookup_subtype_polymorphic_field(Type *dst, Type *src) {
 	GB_ASSERT(is_type_struct(src) || is_type_union(src));
 	for_array(i, src->Struct.fields) {
 		Entity *f = src->Struct.fields[i];
-		if (f->kind == Entity_Variable && f->flags & EntityFlag_Using) {
+		if (f->kind == Entity_Variable && f->flags & EntityFlags_IsSubtype) {
 			if (are_types_identical(dst, f->type)) {
 				return f->token.string;
 			}
@@ -2332,7 +2343,7 @@ String lookup_subtype_polymorphic_field(Type *dst, Type *src) {
 					return f->token.string;
 				}
 			}
-			if (is_type_struct(f->type)) {
+			if ((f->flags & EntityFlag_Using) != 0 && is_type_struct(f->type)) {
 				String name = lookup_subtype_polymorphic_field(dst, f->type);
 				if (name.len > 0) {
 					return name;
@@ -2478,9 +2489,9 @@ bool are_types_identical_internal(Type *x, Type *y, bool check_tuple_names) {
 					if (xf->token.string != yf->token.string) {
 						return false;
 					}
-					bool xf_is_using = (xf->flags&EntityFlag_Using) != 0;
-					bool yf_is_using = (yf->flags&EntityFlag_Using) != 0;
-					if (xf_is_using ^ yf_is_using) {
+					u64 xf_flags = (xf->flags&EntityFlags_IsSubtype);
+					u64 yf_flags = (yf->flags&EntityFlags_IsSubtype);
+					if (xf_flags != yf_flags) {
 						return false;
 					}
 				}
@@ -2612,6 +2623,17 @@ i64 union_tag_size(Type *u) {
 
 	// TODO(bill): Is this an okay approach?
 	i64 max_align = 1;
+
+	if (u->Union.variants.count < 1ull<<8) {
+		max_align = 1;
+	} else if (u->Union.variants.count < 1ull<<16) {
+		max_align = 2;
+	} else if (u->Union.variants.count < 1ull<<32) {
+		max_align = 4;
+	} else {
+		GB_PANIC("how many variants do you have?!");
+	}
+
 	for_array(i, u->Union.variants) {
 		Type *variant_type = u->Union.variants[i];
 		i64 align = type_align_of(variant_type);
@@ -2772,6 +2794,7 @@ Selection lookup_field_from_index(Type *type, i64 index) {
 }
 
 Entity *scope_lookup_current(Scope *s, String const &name);
+bool has_type_got_objc_class_attribute(Type *t);
 
 Selection lookup_field_with_selection(Type *type_, String field_name, bool is_type, Selection sel, bool allow_blank_ident) {
 	GB_ASSERT(type_ != nullptr);
@@ -2784,9 +2807,40 @@ Selection lookup_field_with_selection(Type *type_, String field_name, bool is_ty
 	bool is_ptr = type != type_;
 	sel.indirect = sel.indirect || is_ptr;
 
+	Type *original_type = type;
+
 	type = base_type(type);
 
 	if (is_type) {
+		if (has_type_got_objc_class_attribute(original_type) && original_type->kind == Type_Named) {
+			Entity *e = original_type->Named.type_name;
+			GB_ASSERT(e->kind == Entity_TypeName);
+			if (e->TypeName.objc_metadata) {
+				auto *md = e->TypeName.objc_metadata;
+				mutex_lock(md->mutex);
+				defer (mutex_unlock(md->mutex));
+				for (TypeNameObjCMetadataEntry const &entry : md->type_entries) {
+					GB_ASSERT(entry.entity->kind == Entity_Procedure);
+					if (entry.name == field_name) {
+						sel.entity = entry.entity;
+						sel.pseudo_field = true;
+						return sel;
+					}
+				}
+			}
+			if (type->kind == Type_Struct) {
+				for_array(i, type->Struct.fields) {
+					Entity *f = type->Struct.fields[i];
+					if (f->flags&EntityFlag_Using) {
+						sel = lookup_field_with_selection(f->type, field_name, is_type, sel, allow_blank_ident);
+						if (sel.entity) {
+							return sel;
+						}
+					}
+				}
+			}
+		}
+
 		if (is_type_enum(type)) {
 			// NOTE(bill): These may not have been added yet, so check in case
 			for_array(i, type->Enum.fields) {
@@ -2833,6 +2887,24 @@ Selection lookup_field_with_selection(Type *type_, String field_name, bool is_ty
 	} else if (type->kind == Type_Union) {
 
 	} else if (type->kind == Type_Struct) {
+		if (has_type_got_objc_class_attribute(original_type) && original_type->kind == Type_Named) {
+			Entity *e = original_type->Named.type_name;
+			GB_ASSERT(e->kind == Entity_TypeName);
+			if (e->TypeName.objc_metadata) {
+				auto *md = e->TypeName.objc_metadata;
+				mutex_lock(md->mutex);
+				defer (mutex_unlock(md->mutex));
+				for (TypeNameObjCMetadataEntry const &entry : md->value_entries) {
+					GB_ASSERT(entry.entity->kind == Entity_Procedure);
+					if (entry.name == field_name) {
+						sel.entity = entry.entity;
+						sel.pseudo_field = true;
+						return sel;
+					}
+				}
+			}
+		}
+
 		for_array(i, type->Struct.fields) {
 			Entity *f = type->Struct.fields[i];
 			if (f->kind != Entity_Variable || (f->flags & EntityFlag_Field) == 0) {
@@ -3738,6 +3810,61 @@ i64 type_offset_of_from_selection(Type *type, Selection sel) {
 	return offset;
 }
 
+isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isize level = 0, bool src_is_ptr = false) {
+	Type *prev_src = src;
+	src = type_deref(src);
+	if (!src_is_ptr) {
+		src_is_ptr = src != prev_src;
+	}
+	src = base_type(src);
+
+	if (!is_type_struct(src)) {
+		return 0;
+	}
+
+	for_array(i, src->Struct.fields) {
+		Entity *f = src->Struct.fields[i];
+		if (f->kind != Entity_Variable || (f->flags&EntityFlags_IsSubtype) == 0) {
+			continue;
+		}
+
+		if (are_types_identical(f->type, dst)) {
+			return level+1;
+		}
+		if (src_is_ptr && is_type_pointer(dst)) {
+			if (are_types_identical(f->type, type_deref(dst))) {
+				return level+1;
+			}
+		}
+		isize nested_level = check_is_assignable_to_using_subtype(f->type, dst, level+1, src_is_ptr);
+		if (nested_level > 0) {
+			return nested_level;
+		}
+	}
+
+	return 0;
+}
+
+bool is_type_subtype_of(Type *src, Type *dst) {
+	if (are_types_identical(src, dst)) {
+		return true;
+	}
+
+	return 0 < check_is_assignable_to_using_subtype(src, dst, 0, is_type_pointer(src));
+}
+
+
+bool has_type_got_objc_class_attribute(Type *t) {
+	return t->kind == Type_Named && t->Named.type_name != nullptr && t->Named.type_name->TypeName.objc_class_name != "";
+}
+
+
+
+bool is_type_objc_object(Type *t) {
+	bool internal_check_is_assignable_to(Type *src, Type *dst);
+
+	return internal_check_is_assignable_to(t, t_objc_object);
+}
 
 Type *get_struct_field_type(Type *t, isize index) {
 	t = base_type(type_deref(t));
@@ -3809,7 +3936,7 @@ Type *alloc_type_proc_from_types(Type **param_types, unsigned param_count, Type
 
 
 
-gbString write_type_to_string(gbString str, Type *type) {
+gbString write_type_to_string(gbString str, Type *type, bool shorthand=false) {
 	if (type == nullptr) {
 		return gb_string_appendc(str, "<no type>");
 	}
@@ -3924,15 +4051,21 @@ gbString write_type_to_string(gbString str, Type *type) {
 		if (type->Struct.is_raw_union) str = gb_string_appendc(str, " #raw_union");
 		if (type->Struct.custom_align != 0) str = gb_string_append_fmt(str, " #align %d", cast(int)type->Struct.custom_align);
 		str = gb_string_appendc(str, " {");
-		for_array(i, type->Struct.fields) {
-			Entity *f = type->Struct.fields[i];
-			GB_ASSERT(f->kind == Entity_Variable);
-			if (i > 0) {
-				str = gb_string_appendc(str, ", ");
+
+
+		if (shorthand && type->Struct.fields.count > 16) {
+			str = gb_string_append_fmt(str, "%lld fields...", cast(long long)type->Struct.fields.count);
+		} else {
+			for_array(i, type->Struct.fields) {
+				Entity *f = type->Struct.fields[i];
+				GB_ASSERT(f->kind == Entity_Variable);
+				if (i > 0) {
+					str = gb_string_appendc(str, ", ");
+				}
+				str = gb_string_append_length(str, f->token.string.text, f->token.string.len);
+				str = gb_string_appendc(str, ": ");
+				str = write_type_to_string(str, f->type);
 			}
-			str = gb_string_append_length(str, f->token.string.text, f->token.string.len);
-			str = gb_string_appendc(str, ": ");
-			str = write_type_to_string(str, f->type);
 		}
 		str = gb_string_append_rune(str, '}');
 	} break;
@@ -4107,13 +4240,16 @@ gbString write_type_to_string(gbString str, Type *type) {
 }
 
 
-gbString type_to_string(Type *type, gbAllocator allocator) {
-	return write_type_to_string(gb_string_make(allocator, ""), type);
+gbString type_to_string(Type *type, gbAllocator allocator, bool shorthand=false) {
+	return write_type_to_string(gb_string_make(allocator, ""), type, shorthand);
 }
-gbString type_to_string(Type *type) {
-	return write_type_to_string(gb_string_make(heap_allocator(), ""), type);
+gbString type_to_string(Type *type, bool shorthand) {
+	return write_type_to_string(gb_string_make(heap_allocator(), ""), type, shorthand);
 }
 
+gbString type_to_string_shorthand(Type *type) {
+	return type_to_string(type, true);
+}