From 6789fab93c288ac7262102ca791bd5aeac651173 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Fri, 18 Mar 2022 08:57:15 +0100
Subject: [PATCH] Panic function that may be redefined. Trap and stacktrace
 builtins. Bug using builtin fixed. Fixes to using $$LINE and friends.
 Produces a stacktrace on error.

---
 lib/std/builtin.c3                            |  37 +++-
 lib/std/runtime.c3                            |   1 -
 src/build/build_options.c                     |   6 +
 src/build/build_options.h                     |   2 +
 src/build/builder.c                           |   1 +
 src/build/project.c                           |   3 +
 src/compiler/compiler_internal.h              |  22 +--
 src/compiler/context.c                        |   2 +-
 src/compiler/enums.h                          |   3 +
 src/compiler/llvm_codegen.c                   |   9 +
 src/compiler/llvm_codegen_expr.c              |  39 +++-
 src/compiler/llvm_codegen_function.c          | 120 ++++++++-----
 src/compiler/llvm_codegen_internal.h          |  13 +-
 src/compiler/llvm_codegen_module.c            |  14 ++
 src/compiler/llvm_codegen_stmt.c              | 168 +++---------------
 src/compiler/parse_global.c                   |   1 -
 src/compiler/sema_expr.c                      | 112 ++++++++----
 src/compiler/sema_internal.h                  |   1 +
 src/compiler/sema_name_resolution.c           |  11 ++
 src/compiler/sema_stmts.c                     |   2 -
 src/compiler/semantic_analyser.c              |  35 ++++
 src/compiler/symtab.c                         |  30 ++--
 src/compiler/target.c                         |  27 ++-
 test/test_suite/assert/unreachable.c3t        |  37 ++--
 test/test_suite/builtins/simple_builtins.c3t  |  43 +++--
 .../from_docs/examples_forswitch.c3t          |   5 +-
 26 files changed, 433 insertions(+), 311 deletions(-)

diff --git a/lib/std/builtin.c3 b/lib/std/builtin.c3
index 46c94be29..06b60fb83 100644
--- a/lib/std/builtin.c3
+++ b/lib/std/builtin.c3
@@ -10,9 +10,44 @@ macro scope(&variable; @body) @autoimport
 	@body();
 }
 
+extern fn void printf(char*, ...);
+
+struct CallstackElement
+{
+	CallstackElement* prev;
+	char* function;
+	char* file;
+	uint line;
+}
+fn void panic(char* message, char *file, char *function, uint line) @autoimport
+{
+	CallstackElement* stack = $$stacktrace();
+	$if ($defined(libc::stderr) && $defined(libc::fprintf)):
+
+	if (stack) stack = stack.prev;
+	if (stack)
+	{
+		libc::fprintf(@libc::stderr(), "\nERROR: '%s'\n", message);
+	}
+	else
+	{
+		libc::fprintf(@libc::stderr(), "\nERROR: '%s', function %s (%s:%d)\n", message, function, file, line);
+	}
+	while (stack)
+	{
+		libc::fprintf(@libc::stderr(), "  at function %s (%s:%u)\n", stack.function, stack.file, stack.line);
+		stack = stack.prev;
+	}
+
+	$endif;
+
+	$$trap();
+}
+
 macro unreachable($string = "Unreachable statement reached.") @autoimport @noreturn
 {
-	assert(false, $string);
+	panic($string, $$FILE, $$FUNC, $$LINE);
+	$$unreachable();
 }
 
 /*
diff --git a/lib/std/runtime.c3 b/lib/std/runtime.c3
index 463d83749..e4fe95fdb 100644
--- a/lib/std/runtime.c3
+++ b/lib/std/runtime.c3
@@ -26,6 +26,5 @@ struct VarArrayHeader
     usize size;
     usize capacity;
     void *allocator;
-
 }
 
diff --git a/src/build/build_options.c b/src/build/build_options.c
index 73edbcc44..26c734c48 100644
--- a/src/build/build_options.c
+++ b/src/build/build_options.c
@@ -540,6 +540,12 @@ static void parse_option(BuildOptions *options)
 				options->no_stdlib = true;
 				return;
 			}
+			if (match_longopt("panicfn"))
+			{
+				if (at_end() || next_is_opt()) error_exit("error: --panicfn needs a function name.");
+				options->panicfn = next_arg();
+				return;
+			}
 			if (match_longopt("lib"))
 			{
 				if (at_end() || next_is_opt()) error_exit("error: --lib needs a directory.");
diff --git a/src/build/build_options.h b/src/build/build_options.h
index e9a638291..019503b34 100644
--- a/src/build/build_options.h
+++ b/src/build/build_options.h
@@ -227,6 +227,7 @@ typedef struct BuildOptions_
 	bool emit_bitcode;
 	bool test_mode;
 	bool no_stdlib;
+	const char *panicfn;
 	RelocModel reloc_model;
 	X86VectorCapability x86_vector_capability;
 	bool print_keywords;
@@ -278,6 +279,7 @@ typedef struct
 	CompilerBackend backend;
 	uint32_t symtab_size;
 	uint32_t switchrange_max_size;
+	const char *panicfn;
 	const char *cc;
 	const char *cflags;
 	const char **csource_dirs;
diff --git a/src/build/builder.c b/src/build/builder.c
index b274a62ba..0153753dc 100644
--- a/src/build/builder.c
+++ b/src/build/builder.c
@@ -163,6 +163,7 @@ static void update_build_target_from_options(BuildTarget *target, BuildOptions *
 	}
 	target->no_stdlib = options->no_stdlib;
 	target->emit_llvm = options->emit_llvm;
+	target->panicfn = options->panicfn;
 	if (options->x86_vector_capability != X86VECTOR_DEFAULT)
 	{
 		target->feature.x86_vector_capability = options->x86_vector_capability;
diff --git a/src/build/project.c b/src/build/project.c
index d3d390f82..1fa96394a 100644
--- a/src/build/project.c
+++ b/src/build/project.c
@@ -120,7 +120,9 @@ static void load_into_build_target(JSONObject *json, const char *type, BuildTarg
 	const char *cpu = get_valid_string(json, "cpu", type, false);
 	int reloc = get_valid_string_setting(json, "reloc", type, reloc_models, 0, 5, "'none', 'pic', 'PIC', 'pie' or 'PIE'.");
 	int x86vec = get_valid_string_setting(json, "x86vec", type, vector_capability, 0, 5, "none, mmx, sse, avx or avx512");
+	const char *panicfn = get_valid_string(json, "panicfn", type, false);
 
+	target->panicfn = panicfn;
 	if (cc) target->cc = cc;
 	if (cflags) target->cflags = cflags;
 	if (csource_dirs) target->csource_dirs = csource_dirs;
@@ -156,6 +158,7 @@ static void load_into_build_target(JSONObject *json, const char *type, BuildTarg
 	// Use the fact that they correspond to 0, 1, -1
 	target->feature.x86_struct_return = get_valid_bool(json, "x86-stack-struct-return", type, target->feature.x86_struct_return);
 	target->feature.soft_float = get_valid_bool(json, "soft-float", type, target->feature.soft_float);
+	target->no_stdlib = get_valid_bool(json, "nostdlib", type, false);
 
 }
 static void project_add_target(Project *project, BuildTarget *default_target,  JSONObject *json, const char *name, const char *type)
diff --git a/src/compiler/compiler_internal.h b/src/compiler/compiler_internal.h
index 6e24a0a18..9fca0defa 100644
--- a/src/compiler/compiler_internal.h
+++ b/src/compiler/compiler_internal.h
@@ -1465,6 +1465,7 @@ typedef struct
 	DeclTable symbols;
 	DeclTable generic_symbols;
 	Path std_module_path;
+	Decl *panic_fn;
 } GlobalContext;
 
 
@@ -1645,21 +1646,6 @@ extern const char *kw_LINE;
 extern const char *kw_LINEREAL;
 extern const char *kw_incr;
 extern const char *kw_check_assign;
-extern const char *kw_builtin_ceil;
-extern const char *kw_builtin_trunc;
-extern const char *kw_builtin_sqrt;
-extern const char *kw_builtin_cos;
-extern const char *kw_builtin_sin;
-extern const char *kw_builtin_log;
-extern const char *kw_builtin_log2;
-extern const char *kw_builtin_log10;
-extern const char *kw_builtin_max;
-extern const char *kw_builtin_min;
-extern const char *kw_builtin_pow;
-extern const char *kw_builtin_exp;
-extern const char *kw_builtin_fabs;
-extern const char *kw_builtin_fma;
-extern const char *kw_builtin_cmpxchg;
 extern const char *kw_argc;
 extern const char *kw_argv;
 extern const char *kw_mainstub;
@@ -1675,6 +1661,11 @@ INLINE Expr *exprptrzero(ExprId id)
 	return id ? exprptr(id) : NULL;
 }
 
+INLINE Type *typeinfotype(TypeInfoId id_)
+{
+	return type_infoptr(id_)->type;
+}
+
 static inline bool ast_ok(Ast *ast) { return ast == NULL || ast->ast_kind != AST_POISONED; }
 static inline bool ast_poison(Ast *ast) { ast->ast_kind = AST_POISONED; return false; }
 bool ast_is_not_empty(Ast *ast);
@@ -1987,6 +1978,7 @@ bool sema_expr_analyse_assign_right_side(SemaContext *context, Expr *expr, Type
 
 bool sema_expr_analyse_general_call(SemaContext *context, Expr *expr, Decl *decl, Expr *struct_var, bool is_macro, bool failable);
 Decl *sema_resolve_symbol_in_current_dynamic_scope(SemaContext *context, const char *symbol);
+Decl *sema_find_decl_in_modules(Module **module_list, Path *path, const char *interned_name);
 Decl *unit_resolve_parameterized_symbol(CompilationUnit *unit, NameResolve *name_resolve);
 Decl *sema_resolve_method(CompilationUnit *unit, Decl *type, const char *method_name, Decl **ambiguous_ref, Decl **private_ref);
 Decl *sema_find_extension_method_in_module(Module *module, Type *type, const char *method_name);
diff --git a/src/compiler/context.c b/src/compiler/context.c
index 26800fb13..086a049ad 100644
--- a/src/compiler/context.c
+++ b/src/compiler/context.c
@@ -133,7 +133,7 @@ void unit_register_external_symbol(CompilationUnit *unit, Decl *decl)
 
 void decl_register(Decl *decl)
 {
-	if (decl->visibility != VISIBLE_PUBLIC) return;
+	if (decl->visibility != VISIBLE_PUBLIC && decl->visibility != VISIBLE_EXTERN) return;
 	switch (decl->decl_kind)
 	{
 		case DECL_POISONED:
diff --git a/src/compiler/enums.h b/src/compiler/enums.h
index 6344b1741..6e4a07589 100644
--- a/src/compiler/enums.h
+++ b/src/compiler/enums.h
@@ -706,6 +706,9 @@ typedef enum
 
 typedef enum
 {
+	BUILTIN_UNREACHABLE,
+	BUILTIN_TRAP,
+	BUILTIN_STACKTRACE,
 	BUILTIN_CEIL,
 	BUILTIN_TRUNC,
 	BUILTIN_SQRT,
diff --git a/src/compiler/llvm_codegen.c b/src/compiler/llvm_codegen.c
index 07c0b9305..21c19fe35 100644
--- a/src/compiler/llvm_codegen.c
+++ b/src/compiler/llvm_codegen.c
@@ -850,6 +850,13 @@ void *llvm_gen(Module *module)
 	gencontext_init(gen_context, module);
 	gencontext_begin_module(gen_context);
 
+	// Declare the panic function implicitly
+	Decl *panicfn = gen_context->panicfn;
+	if (panicfn && panicfn->module != module)
+	{
+		llvm_emit_extern_decl(gen_context, panicfn);
+	}
+
 	VECEACH(module->units, j)
 	{
 		CompilationUnit *unit = module->units[j];
@@ -857,11 +864,13 @@ void *llvm_gen(Module *module)
 		gen_context->debug.compile_unit = unit->llvm.debug_compile_unit;
 		gen_context->debug.file = unit->llvm.debug_file;
 
+
 		VECEACH(unit->external_symbol_list, i)
 		{
 			Decl *d = unit->external_symbol_list[i];
 			// Avoid duplicating symbol
 			if (d->module == unit->module) continue;
+			if (d == panicfn) continue;
 			llvm_emit_extern_decl(gen_context, unit->external_symbol_list[i]);
 		}
 		VECEACH(unit->methods, i)
diff --git a/src/compiler/llvm_codegen_expr.c b/src/compiler/llvm_codegen_expr.c
index f36d3f86a..dc6bf1d75 100644
--- a/src/compiler/llvm_codegen_expr.c
+++ b/src/compiler/llvm_codegen_expr.c
@@ -3590,8 +3590,7 @@ static inline void llvm_emit_force_unwrap_expr(GenContext *c, BEValue *be_value,
 		// TODO, we should add info about the error.
 		SourceSpan loc = expr->span;
 		File *file = source_file_by_id(loc.file_id);
-		llvm_emit_debug_output(c, "Runtime error force unwrap!", file->name, c->cur_func_decl->extname, loc.row ? loc.row : 1);
-		llvm_emit_call_intrinsic(c, intrinsic_id.trap, NULL, 0, NULL, 0);
+		llvm_emit_panic(c, "Runtime error force unwrap!", file->name, c->cur_func_decl->extname, loc.row ? loc.row : 1);
 		LLVMBuildUnreachable(c->builder);
 		c->current_block = NULL;
 		c->current_block_is_target = NULL;
@@ -4213,12 +4212,12 @@ static void llvm_emit_intrinsic_expr(GenContext *c, unsigned intrinsic, BEValue
 	LLVMValueRef arg_results[4];
 	for (unsigned i = 0; i < arguments; i++)
 	{
-		llvm_emit_expr(c, be_value, expr->call_expr.arguments[0]);
+		llvm_emit_expr(c, be_value, expr->call_expr.arguments[i]);
 		llvm_value_rvalue(c, be_value);
 		arg_results[i] = be_value->value;
 	}
-	LLVMTypeRef call_type = llvm_get_type(c, expr->type);
-	LLVMValueRef result = llvm_emit_call_intrinsic(c, intrinsic, &call_type, 1, arg_results, arguments);
+	LLVMTypeRef call_type = expr->type == type_void ? NULL : llvm_get_type(c, expr->type);
+	LLVMValueRef result = llvm_emit_call_intrinsic(c, intrinsic, &call_type, call_type ? 1 : 0, arg_results, arguments);
 	llvm_value_set(be_value, result, expr->type);
 }
 
@@ -4377,7 +4376,11 @@ unsigned llvm_get_intrinsic(BuiltinFunction func)
 	switch (func)
 	{
 		case BUILTIN_NONE:
+		case BUILTIN_UNREACHABLE:
+		case BUILTIN_STACKTRACE:
 			UNREACHABLE
+		case BUILTIN_TRAP:
+			return intrinsic_id.trap;
 		case BUILTIN_CEIL:
 			return intrinsic_id.ceil;
 		case BUILTIN_TRUNC:
@@ -4431,6 +4434,25 @@ LLVMAtomicOrdering llvm_atomic_ordering(Atomicity atomicity)
 void llvm_emit_builtin_call(GenContext *c, BEValue *result_value, Expr *expr)
 {
 	BuiltinFunction func = exprptr(expr->call_expr.function)->builtin_expr.builtin;
+	if (func == BUILTIN_UNREACHABLE)
+	{
+		llvm_value_set(result_value, LLVMBuildUnreachable(c->builder), type_void);
+		c->current_block = NULL;
+		c->current_block_is_target = NULL;
+		LLVMBasicBlockRef after_unreachable = llvm_basic_block_new(c, "after.unreachable");
+		llvm_emit_block(c, after_unreachable);
+		return;
+	}
+	if (func == BUILTIN_STACKTRACE)
+	{
+		if (!c->debug.enable_stacktrace)
+		{
+			llvm_value_set(result_value, llvm_get_zero(c, type_voidptr), type_voidptr);
+			return;
+		}
+		llvm_value_set(result_value, llvm_emit_bitcast(c, c->debug.stack_slot, type_voidptr), type_voidptr);
+		return;
+	}
 	if (func == BUILTIN_VOLATILE_STORE)
 	{
 		BEValue value;
@@ -4482,11 +4504,18 @@ void llvm_add_call_attributes(GenContext *c, LLVMValueRef call_value, int start_
 }
 void llvm_emit_call_expr(GenContext *c, BEValue *result_value, Expr *expr)
 {
+
 	if (expr->call_expr.is_builtin)
 	{
 		llvm_emit_builtin_call(c, result_value, expr);
 		return;
 	}
+
+	if (c->debug.stack_slot_row)
+	{
+		llvm_store(c, c->debug.stack_slot_row, llvm_const_int(c, type_uint, expr->span.row), type_abi_alignment(type_uint));
+	}
+
 	LLVMTypeRef func_type;
 	LLVMValueRef func;
 	BEValue temp_value;
diff --git a/src/compiler/llvm_codegen_function.c b/src/compiler/llvm_codegen_function.c
index 3b9e40a51..2ae2e5a1b 100644
--- a/src/compiler/llvm_codegen_function.c
+++ b/src/compiler/llvm_codegen_function.c
@@ -402,62 +402,98 @@ void llvm_emit_return_implicit(GenContext *c)
 	llvm_emit_return_abi(c, NULL, &value);
 }
 
-void llvm_emit_function_body(GenContext *context, Decl *decl)
+void llvm_emit_function_body(GenContext *c, Decl *decl)
 {
 	DEBUG_LOG("Generating function %s.", decl->extname);
 	assert(decl->backend_ref);
 
-	bool emit_debug = llvm_use_debug(context);
-	LLVMValueRef prev_function = context->function;
-	LLVMBuilderRef prev_builder = context->builder;
+	bool emit_debug = llvm_use_debug(c);
+	LLVMValueRef prev_function = c->function;
+	LLVMBuilderRef prev_builder = c->builder;
 
-	context->error_var = NULL;
-	context->catch_block = NULL;
 
-	context->function = decl->backend_ref;
+	c->error_var = NULL;
+	c->catch_block = NULL;
+
+	c->function = decl->backend_ref;
 	if (emit_debug)
 	{
-		context->debug.function = LLVMGetSubprogram(context->function);
+		c->debug.function = LLVMGetSubprogram(c->function);
+		if (c->debug.enable_stacktrace)
+		{
+			scratch_buffer_clear();
+			scratch_buffer_append(decl->module->name->module);
+			scratch_buffer_append("::");
+			scratch_buffer_append(decl->name ? decl->name : "anon");
+			c->debug.func_name = llvm_emit_zstring(c, scratch_buffer_to_string());
+
+			File *file = source_file_by_id(decl->span.file_id);
+			c->debug.file_name = llvm_emit_zstring(c, file->name);
+		}
 	}
 
-	context->cur_func_decl = decl;
+	c->cur_func_decl = decl;
 
-	LLVMBasicBlockRef entry = LLVMAppendBasicBlockInContext(context->context, context->function, "entry");
-	context->current_block = entry;
-	context->current_block_is_target = true;
-	context->block_return_exit = NULL;
-	context->in_block = 0;
-	context->builder = LLVMCreateBuilderInContext(context->context);
-	LLVMPositionBuilderAtEnd(context->builder, entry);
+	LLVMBasicBlockRef entry = LLVMAppendBasicBlockInContext(c->context, c->function, "entry");
+	c->current_block = entry;
+	c->current_block_is_target = true;
+	c->block_return_exit = NULL;
+	c->in_block = 0;
+	c->builder = LLVMCreateBuilderInContext(c->context);
+	LLVMPositionBuilderAtEnd(c->builder, entry);
 
-	LLVMValueRef alloca_point = LLVMBuildAlloca(context->builder, LLVMInt32TypeInContext(context->context), "alloca_point");
-	context->alloca_point = alloca_point;
+	LLVMValueRef alloca_point = LLVMBuildAlloca(c->builder, LLVMInt32TypeInContext(c->context), "alloca_point");
+	c->alloca_point = alloca_point;
 
 	FunctionPrototype *prototype = decl->type->func.prototype;
 	unsigned arg = 0;
 
 	if (emit_debug)
 	{
-		llvm_debug_scope_push(context, context->debug.function);
+		llvm_debug_scope_push(c, c->debug.function);
+		if (c->debug.enable_stacktrace)
+		{
+			LLVMTypeRef slot_type = c->debug.stack_type;
+			LLVMTypeRef ptr_to_slot_type = LLVMPointerType(slot_type, 0);
+			if (!c->debug.last_ptr)
+			{
+				LLVMValueRef last_stack = c->debug.last_ptr = LLVMAddGlobal(c->module, ptr_to_slot_type, ".$last_stack");
+				LLVMSetThreadLocal(last_stack, true);
+				LLVMSetInitializer(last_stack, LLVMConstNull(ptr_to_slot_type));
+				LLVMSetVisibility(last_stack, LLVMDefaultVisibility);
+				LLVMSetLinkage(last_stack, LLVMWeakODRLinkage);
+			}
+			AlignSize alignment = llvm_abi_alignment(c, slot_type);
+			c->debug.stack_slot = llvm_emit_alloca(c, slot_type, alignment, ".$stackslot");
+			AlignSize align_to_use;
+			LLVMValueRef prev_ptr = llvm_emit_struct_gep_raw(c, c->debug.stack_slot, slot_type, 0, alignment, &align_to_use);
+			llvm_store(c, prev_ptr, LLVMBuildLoad2(c->builder, ptr_to_slot_type, c->debug.last_ptr, ""), align_to_use);
+			LLVMValueRef func_name = llvm_emit_struct_gep_raw(c, c->debug.stack_slot, slot_type, 1, alignment, &align_to_use);
+			llvm_store(c, func_name, c->debug.func_name, align_to_use);
+			LLVMValueRef file_name = llvm_emit_struct_gep_raw(c, c->debug.stack_slot, slot_type, 2, alignment, &align_to_use);
+			llvm_store(c, file_name, c->debug.file_name, align_to_use);
+			c->debug.stack_slot_row = llvm_emit_struct_gep_raw(c, c->debug.stack_slot, slot_type, 3, alignment, &align_to_use);
+			llvm_store(c, c->debug.last_ptr, c->debug.stack_slot, type_alloca_alignment(type_voidptr));
+		}
 	}
 
-	context->failable_out = NULL;
-	context->return_out = NULL;
+	c->failable_out = NULL;
+	c->return_out = NULL;
 	if (prototype->ret_abi_info->kind == ABI_ARG_INDIRECT)
 	{
 		if (prototype->is_failable)
 		{
-			context->failable_out = LLVMGetParam(context->function, arg++);
+			c->failable_out = LLVMGetParam(c->function, arg++);
 		}
 		else
 		{
-			context->return_out = LLVMGetParam(context->function, arg++);
+			c->return_out = LLVMGetParam(c->function, arg++);
 		}
 	}
 	if (prototype->ret_by_ref_abi_info)
 	{
-		assert(!context->return_out);
-		context->return_out = LLVMGetParam(context->function, arg++);
+		assert(!c->return_out);
+		c->return_out = LLVMGetParam(c->function, arg++);
 	}
 
 
@@ -466,49 +502,49 @@ void llvm_emit_function_body(GenContext *context, Decl *decl)
 		// Generate LLVMValueRef's for all parameters, so we can use them as local vars in code
 		VECEACH(decl->func_decl.function_signature.params, i)
 		{
-			llvm_emit_parameter(context, decl->func_decl.function_signature.params[i], prototype->abi_args[i], &arg, i);
+			llvm_emit_parameter(c, decl->func_decl.function_signature.params[i], prototype->abi_args[i], &arg, i);
 		}
 	}
 
-	LLVMSetCurrentDebugLocation2(context->builder, NULL);
+	LLVMSetCurrentDebugLocation2(c->builder, NULL);
 
 	assert(decl->func_decl.body);
 	AstId current = astptr(decl->func_decl.body)->compound_stmt.first_stmt;
 	while (current)
 	{
-		llvm_emit_stmt(context, ast_next(&current));
+		llvm_emit_stmt(c, ast_next(&current));
 	}
 
-	if (context->current_block && llvm_basic_block_is_unused(context->current_block))
+	if (c->current_block && llvm_basic_block_is_unused(c->current_block))
 	{
-		LLVMBasicBlockRef prev_block = LLVMGetPreviousBasicBlock(context->current_block);
-		LLVMDeleteBasicBlock(context->current_block);
-		context->current_block = prev_block;
-		LLVMPositionBuilderAtEnd(context->builder, context->current_block);
+		LLVMBasicBlockRef prev_block = LLVMGetPreviousBasicBlock(c->current_block);
+		LLVMDeleteBasicBlock(c->current_block);
+		c->current_block = prev_block;
+		LLVMPositionBuilderAtEnd(c->builder, c->current_block);
 	}
 	// Insert a return (and defer) if needed.
-	if (context->current_block && !LLVMGetBasicBlockTerminator(context->current_block))
+	if (c->current_block && !LLVMGetBasicBlockTerminator(c->current_block))
 	{
-		llvm_emit_return_implicit(context);
+		llvm_emit_return_implicit(c);
 	}
 
 	// erase alloca point
 	if (LLVMGetInstructionParent(alloca_point))
 	{
-		context->alloca_point = NULL;
+		c->alloca_point = NULL;
 		LLVMInstructionEraseFromParent(alloca_point);
 	}
 
-	LLVMDisposeBuilder(context->builder);
-	context->builder = NULL;
+	LLVMDisposeBuilder(c->builder);
+	c->builder = NULL;
 
-	if (llvm_use_debug(context))
+	if (llvm_use_debug(c))
 	{
-		llvm_debug_scope_pop(context);
+		llvm_debug_scope_pop(c);
 	}
 
-	context->builder = prev_builder;
-	context->function = prev_function;
+	c->builder = prev_builder;
+	c->function = prev_function;
 }
 
 static void llvm_emit_param_attributes(GenContext *c, LLVMValueRef function, ABIArgInfo *info, bool is_return, int index, int last_index)
diff --git a/src/compiler/llvm_codegen_internal.h b/src/compiler/llvm_codegen_internal.h
index 88510e39f..8436e8e29 100644
--- a/src/compiler/llvm_codegen_internal.h
+++ b/src/compiler/llvm_codegen_internal.h
@@ -51,6 +51,7 @@ typedef struct
 typedef struct
 {
 	unsigned runtime_version : 8;
+	bool enable_stacktrace : 1;
 	LLVMDIBuilderRef builder;
 	LLVMMetadataRef file;
 	LLVMMetadataRef compile_unit;
@@ -58,6 +59,12 @@ typedef struct
 	SourceSpan current_range;
 	LLVMMetadataRef *lexical_block_stack;
 	LLVMMetadataRef inlined_at;
+	LLVMValueRef func_name;
+	LLVMValueRef file_name;
+	LLVMValueRef last_ptr;
+	LLVMTypeRef stack_type;
+	LLVMValueRef stack_slot;
+	LLVMValueRef stack_slot_row;
 } DebugContext;
 
 
@@ -78,6 +85,7 @@ typedef struct
 	LLVMValueRef error_var;
 	LLVMTypeRef bool_type;
 	LLVMTypeRef byte_type;
+	Decl *panicfn;
 	Decl *cur_code_decl;
 	Decl *cur_func_decl;
 	TypeInfo *current_return_type;
@@ -97,7 +105,6 @@ typedef struct
 	BEValue retval;
 	int in_block;
 	bool current_block_is_target : 1;
-	bool did_call_stack_save : 1;
 	LLVMTypeRef type_data_definitions[TYPE_KINDS];
 	SourceSpan last_emitted_loc;
 } GenContext;
@@ -202,6 +209,7 @@ LLVMAttributeRef LLVMCreateTypeAttribute(LLVMContextRef C, unsigned KindID,
 										 LLVMTypeRef type_ref);
 #endif
 
+
 // BE value
 void llvm_value_addr(GenContext *c, BEValue *value);
 static inline bool llvm_value_is_addr(BEValue *value) { return value->kind == BE_ADDRESS || value->kind == BE_ADDRESS_FAILABLE; }
@@ -305,11 +313,12 @@ void llvm_store_zero(GenContext *c, BEValue *ref);
 void llvm_emit_memcpy(GenContext *c, LLVMValueRef dest, unsigned dest_align, LLVMValueRef source, unsigned src_align, uint64_t len);
 void llvm_emit_memcpy_to_decl(GenContext *c, Decl *decl, LLVMValueRef source, unsigned source_alignment);
 void llvm_emit_stmt(GenContext *c, Ast *ast);
+LLVMValueRef llvm_emit_zstring(GenContext *c, const char *str);
 static inline LLVMValueRef llvm_emit_store(GenContext *context, Decl *decl, LLVMValueRef value);
 void llvm_emit_panic_on_true(GenContext *c, LLVMValueRef value, const char *panic_name, SourceSpan loc);
 void llvm_emit_panic_if_true(GenContext *c, BEValue *value, const char *panic_name, SourceSpan loc);
 void llvm_emit_ptr_from_array(GenContext *c, BEValue *value);
-void llvm_emit_debug_output(GenContext *c, const char *message, const char *file, const char *func, unsigned line);
+void llvm_emit_panic(GenContext *c, const char *message, const char *file, const char *func, unsigned line);
 void llvm_emit_return_abi(GenContext *c, BEValue *return_value, BEValue *failable);
 void llvm_emit_return_implicit(GenContext *c);
 void llvm_emit_struct_member_ref(GenContext *c, BEValue *struct_ref, BEValue *member_ref, unsigned member_id);
diff --git a/src/compiler/llvm_codegen_module.c b/src/compiler/llvm_codegen_module.c
index b86c5a61d..66db28cd0 100644
--- a/src/compiler/llvm_codegen_module.c
+++ b/src/compiler/llvm_codegen_module.c
@@ -13,6 +13,7 @@ void gencontext_begin_module(GenContext *c)
 	c->ir_filename = strformat("%s.ll", result);
 	c->object_filename = strformat("%s%s", result, get_object_extension());
 
+	c->panicfn = global_context.panic_fn;
 	c->module = LLVMModuleCreateWithNameInContext(c->code_module->name->module, c->context);
 	c->machine = llvm_target_machine_create();
 	c->target_data = LLVMCreateTargetDataLayout(c->machine);
@@ -60,10 +61,23 @@ void gencontext_begin_module(GenContext *c)
 		global_context.type[i]->backend_debug_type = NULL;
 		global_context.type[i]->backend_typeid = NULL;
 	}
+	if (c->panicfn) c->panicfn->backend_ref = NULL;
+
 	if (active_target.debug_info != DEBUG_INFO_NONE)
 	{
 		c->debug.runtime_version = 1;
 		c->debug.builder = LLVMCreateDIBuilder(c->module);
+		if (active_target.debug_info == DEBUG_INFO_FULL && active_target.feature.safe_mode)
+		{
+			c->debug.stack_type = LLVMStructCreateNamed(c->context, ".$callstack");
+			LLVMTypeRef types[4] = { LLVMPointerType(c->debug.stack_type, 0),
+									 LLVMPointerType(c->byte_type, 0),
+									 LLVMPointerType(c->byte_type, 0),
+									 llvm_get_type(c, type_uint) };
+			LLVMStructSetBody(c->debug.stack_type, types, 4, false);
+			c->debug.last_ptr = NULL;
+			c->debug.enable_stacktrace = true;
+		}
 	}
 }
 
diff --git a/src/compiler/llvm_codegen_stmt.c b/src/compiler/llvm_codegen_stmt.c
index 2667edb8a..ce03b0b78 100644
--- a/src/compiler/llvm_codegen_stmt.c
+++ b/src/compiler/llvm_codegen_stmt.c
@@ -420,7 +420,8 @@ void llvm_emit_for_stmt(GenContext *c, Ast *ast)
 		{
 			SourceSpan loc = ast->span;
 			File  *file = source_file_by_id(loc.file_id);
-			llvm_emit_debug_output(c, "Infinite loop found", file->name, c->cur_func_decl->extname, loc.row ? loc.row : 1);
+
+			llvm_emit_panic(c, "Infinite loop found", file->name, c->cur_func_decl->extname, loc.row ? loc.row : 1);
 			LLVMBuildUnreachable(c->builder);
 			LLVMBasicBlockRef block = llvm_basic_block_new(c, "unreachable_block");
 			c->current_block = NULL;
@@ -928,19 +929,6 @@ static inline void llvm_emit_assume(GenContext *c, Expr *expr)
 static inline void llvm_emit_assert_stmt(GenContext *c, Ast *ast)
 {
 	ExprId exprid = ast->assert_stmt.expr;
-	if (!exprid)
-	{
-		File *file = source_file_by_id(ast->span.file_id);
-		unsigned row = ast->span.row;
-		llvm_emit_debug_output(c, "Unreachable statement reached.", file->name, c->cur_func_decl->extname, row ? row : 1);
-		llvm_emit_call_intrinsic(c, intrinsic_id.trap, NULL, 0, NULL, 0);
-		LLVMBuildUnreachable(c->builder);
-		LLVMBasicBlockRef block = llvm_basic_block_new(c, "unreachable_block");
-		c->current_block = NULL;
-		c->current_block_is_target = false;
-		llvm_emit_block(c, block);
-		return;
-	}
 	Expr *assert_expr = exprptr(exprid);
 
 	if (active_target.feature.safe_mode)
@@ -964,8 +952,7 @@ static inline void llvm_emit_assert_stmt(GenContext *c, Ast *ast)
 			error = "Assert violation";
 		}
 		File  *file = source_file_by_id(loc.file_id);
-		llvm_emit_debug_output(c, error, file->name, c->cur_func_decl->name, loc.row ? loc.row : 1);
-		llvm_emit_call_intrinsic(c, intrinsic_id.trap, NULL, 0, NULL, 0);
+		llvm_emit_panic(c, error, file->name, c->cur_func_decl->name, loc.row ? loc.row : 1);
 		llvm_emit_br(c, on_ok);
 		llvm_emit_block(c, on_ok);
 	}
@@ -1032,7 +1019,7 @@ void gencontext_emit_expr_stmt(GenContext *c, Ast *ast)
 	llvm_emit_expr(c, &value, ast->expr_stmt);
 }
 
-static LLVMValueRef llvm_emit_string(GenContext *c, const char *str)
+LLVMValueRef llvm_emit_zstring(GenContext *c, const char *str)
 {
 	LLVMTypeRef char_type = llvm_get_type(c, type_char);
 	unsigned len = (unsigned)strlen(str);
@@ -1047,129 +1034,30 @@ static LLVMValueRef llvm_emit_string(GenContext *c, const char *str)
 	                                              1, &alignment);
 	return LLVMBuildBitCast(c->builder, string, LLVMPointerType(char_type, 0), "");
 }
-void llvm_emit_debug_output(GenContext *c, const char *message, const char *file, const char *func, unsigned line)
+
+
+void llvm_emit_panic(GenContext *c, const char *message, const char *file, const char *func, unsigned line)
 {
+	if (c->debug.stack_slot_row)
+	{
+		llvm_store(c, c->debug.stack_slot_row, llvm_const_int(c, type_uint, line), type_abi_alignment(type_uint));
+	}
+
+	Decl *panicfn = c->panicfn;
+	if (!panicfn)
+	{
+		llvm_emit_call_intrinsic(c, intrinsic_id.trap, NULL, 0, NULL, 0);
+		return;
+	}
 	LLVMTypeRef char_ptr_type = llvm_get_ptr_type(c, type_char);
-	LLVMTypeRef cint_type = llvm_get_type(c, type_cint);
-	const char *name;
-	int file_index;
-	int line_index;
-	int expr_index;
-	int func_index = -1;
-	OsType os = platform_target.os;
-	if (platform_target.arch == ARCH_TYPE_WASM32 || platform_target.arch == ARCH_TYPE_WASM64) os = OS_TYPE_WASI;
-	switch (os)
-	{
-		case OS_TYPE_WIN32:
-			name = "_assert";
-			expr_index = 0;
-			file_index = 1;
-			line_index = 2;
-			break;
-		case OS_DARWIN_TYPES:
-			name = "__assert_rtn";
-			func_index = 0;
-			expr_index = 3;
-			file_index = 1;
-			line_index = 2;
-			break;
-		case OS_TYPE_SOLARIS:
-			name = "__assert_c99";
-			expr_index = 0;
-			file_index = 1;
-			line_index = 2;
-			func_index = 3;
-			break;
-		case OS_TYPE_LINUX:
-		case OS_TYPE_WASI:
-			name = "__assert_fail";
-			expr_index = 0;
-			file_index = 1;
-			line_index = 2;
-			func_index = 3;
-			break;
-		case OS_TYPE_OPENBSD:
-			name = "__assert2";
-			file_index = 0;
-			line_index = 1;
-			func_index = 2;
-			expr_index = 3;
-			break;
-		default:
-			name = "__assert";
-			expr_index = 0;
-			file_index = 1;
-			line_index = 2;
-			func_index = -1;
-			break;
-	}
-
-	LLVMTypeRef type;
-	LLVMTypeRef void_type = LLVMVoidTypeInContext(c->context);
-	switch (os)
-	{
-		case OS_TYPE_WIN32:
-		case OS_TYPE_FREE_BSD:
-		case OS_TYPE_DRAGON_FLY:
-		{
-			LLVMTypeRef args[3] = { char_ptr_type, char_ptr_type, cint_type };
-			type = LLVMFunctionType(void_type, args, 3, false);
-			break;
-		}
-		case OS_DARWIN_TYPES:
-		case OS_TYPE_WASI:
-		case OS_TYPE_LINUX:
-		case OS_TYPE_SOLARIS:
-		{
-			LLVMTypeRef args[4] = { char_ptr_type, char_ptr_type, cint_type, char_ptr_type };
-			type = LLVMFunctionType(void_type, args, 4, false);
-			break;
-		}
-		case OS_TYPE_OPENBSD:
-		{
-			LLVMTypeRef args[4] = { char_ptr_type, cint_type, char_ptr_type, char_ptr_type };
-			type = LLVMFunctionType(void_type, args, 4, false);
-			break;
-		}
-		case OS_TYPE_NETBSD:
-		{
-			LLVMTypeRef args[3] = { char_ptr_type, cint_type, char_ptr_type };
-			type = LLVMFunctionType(void_type, args, 3, false);
-			break;
-		}
-		default:
-		{
-			LLVMTypeRef args[3] = { char_ptr_type, char_ptr_type, cint_type };
-			type = LLVMFunctionType(void_type, args, 3, false);
-			break;
-		}
-	}
-	LLVMValueRef assert_func = LLVMGetNamedFunction(c->module, name);
-	if (!assert_func)
-	{
-		assert_func = LLVMAddFunction(c->module, name, type);
-	}
-
-	LLVMValueRef args[4];
-
-	if (func_index == -1)
-	{
-		scratch_buffer_clear();
-		scratch_buffer_append(file);
-		scratch_buffer_append(" : ");
-		scratch_buffer_append(func);
-		file = scratch_buffer_to_string();
-	}
-	else
-	{
-		args[func_index] = llvm_emit_string(c, func);
-	}
-	args[file_index] = llvm_emit_string(c, file);
-	args[expr_index] = llvm_emit_string(c, message);
-	args[line_index] = llvm_const_int(c, type_cint, line);
-
-	LLVMBuildCall2(c->builder, type, assert_func, args, func_index > -1 ? 4 : 3, "");
+	LLVMValueRef args[4] = {
+			llvm_emit_zstring(c, message),
+			llvm_emit_zstring(c, file),
+			func ? llvm_emit_zstring(c, func) : LLVMConstNull(char_ptr_type),
+			llvm_const_int(c, type_uint, line)
+	};
 
+	LLVMBuildCall2(c->builder, llvm_get_type(c, panicfn->type), panicfn->backend_ref, args, 4, "");
 }
 
 void llvm_emit_panic_if_true(GenContext *c, BEValue *value, const char *panic_name, SourceSpan loc)
@@ -1180,8 +1068,7 @@ void llvm_emit_panic_if_true(GenContext *c, BEValue *value, const char *panic_na
 	llvm_emit_cond_br(c, value, panic_block, ok_block);
 	llvm_emit_block(c, panic_block);
 	File  *file = source_file_by_id(loc.file_id);
-	llvm_emit_debug_output(c, panic_name, file->name, c->cur_func_decl->name, loc.row);
-	llvm_emit_call_intrinsic(c, intrinsic_id.trap, NULL, 0, NULL, 0);
+	llvm_emit_panic(c, panic_name, file->name, c->cur_func_decl->name, loc.row);
 	llvm_emit_br(c, ok_block);
 	llvm_emit_block(c, ok_block);
 }
@@ -1195,8 +1082,7 @@ void llvm_emit_panic_on_true(GenContext *c, LLVMValueRef value, const char *pani
 	llvm_value_set_bool(&be_value, value);
 	llvm_emit_cond_br(c, &be_value, panic_block, ok_block);
 	llvm_emit_block(c, panic_block);
-	llvm_emit_debug_output(c, panic_name, file->name, c->cur_func_decl->name, loc.row ? loc.row : 1);
-	llvm_emit_call_intrinsic(c, intrinsic_id.trap, NULL, 0, NULL, 0);
+	llvm_emit_panic(c, panic_name, file->name, c->cur_func_decl->name, loc.row ? loc.row : 1);
 	llvm_emit_br(c, ok_block);
 	llvm_emit_block(c, ok_block);
 }
diff --git a/src/compiler/parse_global.c b/src/compiler/parse_global.c
index 4d4130a26..41bafebb3 100644
--- a/src/compiler/parse_global.c
+++ b/src/compiler/parse_global.c
@@ -2092,7 +2092,6 @@ static inline bool parse_doc_contract(ParseContext *c, AstId **docs_ref, DocDire
 	ASSIGN_EXPR_OR_RET(ast->doc_stmt.contract.decl_exprs, parse_expression_list(c, kind == DOC_DIRECTIVE_CHECKED), false);
 	const char *end = start;
 	while (*++end != '\n' && *end != '\0') end++;
-	end--;
 	if (end > c->data.lex_start) end = c->data.lex_start;
 	while (end[-1] == ' ') end--;
 	scratch_buffer_clear();
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
index 42b228932..d0ce99372 100644
--- a/src/compiler/sema_expr.c
+++ b/src/compiler/sema_expr.c
@@ -67,51 +67,18 @@ const char *ct_eval_expr(SemaContext *c, const char *expr_type, Expr *inner, Tok
 		SEMA_ERROR(inner, "'%s' expects a constant string as the argument.", expr_type);
 		return ct_eval_error;
 	}
-	const char *string = inner->const_expr.string.chars;
-	ArraySize len = inner->const_expr.string.len;
-
-	ArraySize path_end = 0;
-	for (ArraySize i = 0; i < len; i++)
-	{
-		char ch = string[i];
-		if (!is_alphanum_(ch))
-		{
-			if (ch == ':' && i > 0 && string[i + 1] == ':')
-			{
-				path_end = i;
-				i++;
-			}
-			else
-			{
-				SEMA_ERROR(inner, "A valid name was expected here.");
-				return ct_eval_error;
-			}
-		}
-	}
-	if (path_end > 0)
-	{
-		*path_ref = path_create_from_string(string, path_end, inner->span);
-		string += path_end + 2;
-		len -= path_end + 2;
-	}
-	if (len == 0)
+	const char *interned_version = NULL;
+	if (!splitpathref(inner->const_expr.string.chars, inner->const_expr.string.len, path_ref, &interned_version, type))
 	{
 		SEMA_ERROR(inner, "A valid name was expected here.");
 		return ct_eval_error;
 	}
-	const char *interned_version = symtab_find(string, len, fnv1a(string, len), type);
-	if (!interned_version)
+	if (*path_ref) (*path_ref)->span = inner->span;
+	if (*type == TOKEN_INVALID_TOKEN)
 	{
 		if (report_missing)
 		{
-			if (*path_ref)
-			{
-				SEMA_ERROR(inner, "'%s::%.*s' could not be found, did you spell it right?", (*path_ref)->module, (int)len, string);
-			}
-			else
-			{
-				SEMA_ERROR(inner, "'%.*s' could not be found, did you spell it right?", (int)len, string);
-			}
+			SEMA_ERROR(inner, "'%s' could not be found, did you spell it right?", interned_version);
 			return ct_eval_error;
 		}
 		return NULL;
@@ -2209,6 +2176,10 @@ static inline unsigned builtin_expected_args(BuiltinFunction func)
 {
 	switch (func)
 	{
+		case BUILTIN_UNREACHABLE:
+		case BUILTIN_TRAP:
+		case BUILTIN_STACKTRACE:
+			return 0;
 		case BUILTIN_CEIL:
 		case BUILTIN_TRUNC:
 		case BUILTIN_SQRT:
@@ -2271,6 +2242,13 @@ static inline bool sema_expr_analyse_builtin_call(SemaContext *context, Expr *ex
 	Type *rtype = NULL;
 	switch (func)
 	{
+		case BUILTIN_UNREACHABLE:
+		case BUILTIN_TRAP:
+			rtype = type_void;
+			break;
+		case BUILTIN_STACKTRACE:
+			rtype = type_voidptr;
+			break;
 		case BUILTIN_CEIL:
 		case BUILTIN_TRUNC:
 		case BUILTIN_SQRT:
@@ -6221,7 +6199,7 @@ static inline bool sema_expr_analyse_compiler_const(SemaContext *context, Expr *
 	const char *string = expr->builtin_expr.ident;
 	if (string == kw_FILE)
 	{
-		expr_rewrite_to_string(expr, context->unit->file->name);
+		expr_rewrite_to_string(expr, context->compilation_unit->file->name);
 		return true;
 	}
 	if (string == kw_FUNC)
@@ -7314,3 +7292,59 @@ bool sema_analyse_inferred_expr(SemaContext *context, Type *infer_type, Expr *ex
 	return true;
 }
 
+bool splitpathref(const char *string, ArraySize len, Path **path_ref, const char **ident_ref, TokenType *type_ref)
+{
+	ArraySize path_end = 0;
+	*path_ref = NULL;
+	for (ArraySize i = 0; i < len; i++)
+	{
+		char ch = string[i];
+		if (!is_alphanum_(ch))
+		{
+			if (ch == ':' && i > 0 && string[i + 1] == ':')
+			{
+				path_end = i;
+				i++;
+			}
+			else
+			{
+				return false;
+			}
+		}
+	}
+	if (path_end > 0)
+	{
+		*path_ref = path_create_from_string(string, path_end, INVALID_SPAN);
+		string += path_end + 2;
+		len -= path_end + 2;
+	}
+	while (len > 0)
+	{
+		char c = string[0];
+		if (c != ' ' && c != '\t') break;
+		len--;
+		string++;
+	}
+	if (len == 0) return false;
+	uint32_t hash = FNV1_SEED;
+	for (size_t i = 0; i < len; i++)
+	{
+		char c = string[i];
+		if (!is_alphanum_(c)) return false;
+		hash = FNV1a(c, hash);
+	}
+	*ident_ref = symtab_find(string, len, hash, type_ref);
+	if (!*ident_ref)
+	{
+		scratch_buffer_clear();
+		if (*path_ref)
+		{
+			scratch_buffer_append_len((*path_ref)->module, (*path_ref)->len);
+			scratch_buffer_append("::");
+		}
+		scratch_buffer_append_len(string, len);
+		*ident_ref = scratch_buffer_to_string();
+		*type_ref = TOKEN_INVALID_TOKEN;
+	}
+	return true;
+}
\ No newline at end of file
diff --git a/src/compiler/sema_internal.h b/src/compiler/sema_internal.h
index bcdf2f67e..d1b19f6a4 100644
--- a/src/compiler/sema_internal.h
+++ b/src/compiler/sema_internal.h
@@ -42,6 +42,7 @@ void context_pop_defers_and_replace_ast(SemaContext *context, Ast *ast);
 void context_change_scope_for_label(SemaContext *context, Decl *label);
 void context_change_scope_with_flags(SemaContext *context, ScopeFlags flags);
 bool sema_analyse_defer_stmt_body(SemaContext *context, Ast *statement, Ast *body);
+bool splitpathref(const char *string, ArraySize len, Path **path_ref, const char **ident_ref, TokenType *type_ref);
 
 #define PUSH_X(ast, X) AstId _old_##X##_defer = context->X##_defer; AstId _old_##X = context->X##_target; context->X##_target = ast ? astid(ast) : 0; context->X##_defer = context->active_scope.defer_last
 #define POP_X(X) context->X##_target = _old_##X; context->X##_defer = _old_##X##_defer
diff --git a/src/compiler/sema_name_resolution.c b/src/compiler/sema_name_resolution.c
index 6048c0dd9..7846c743a 100644
--- a/src/compiler/sema_name_resolution.c
+++ b/src/compiler/sema_name_resolution.c
@@ -104,6 +104,17 @@ static inline bool sema_is_path_found(Module **modules, Path *path, bool want_ge
 	return false;
 }
 
+Decl *sema_find_decl_in_modules(Module **module_list, Path *path, const char *interned_name)
+{
+	bool path_found = false;
+	VECEACH(module_list, i)
+	{
+		Module *module = module_list[i];
+		Decl *decl = sema_find_decl_in_module(module, path, interned_name, &path_found);
+		if (decl) return decl;
+	}
+	return NULL;
+}
 static Decl *sema_find_decl_in_global(DeclTable *table, Module **module_list, NameResolve *name_resolve, bool want_generic)
 {
 	const char *symbol = name_resolve->symbol;
diff --git a/src/compiler/sema_stmts.c b/src/compiler/sema_stmts.c
index a0c254c55..0fa852f87 100644
--- a/src/compiler/sema_stmts.c
+++ b/src/compiler/sema_stmts.c
@@ -2159,8 +2159,6 @@ bool sema_analyse_assert_stmt(SemaContext *context, Ast *statement)
 				}
 				return false;
 			}
-
-			statement->assert_stmt.expr = 0;
 			context->active_scope.jump_end = true;
 		}
 	}
diff --git a/src/compiler/semantic_analyser.c b/src/compiler/semantic_analyser.c
index c1e45cd3a..a253f6408 100644
--- a/src/compiler/semantic_analyser.c
+++ b/src/compiler/semantic_analyser.c
@@ -318,6 +318,41 @@ void sema_analysis_run(void)
 	{
 		sema_analyze_to_stage(stage);
 	}
+
+	if (active_target.panicfn || !active_target.no_stdlib)
+	{
+		const char *panicfn = active_target.panicfn ? active_target.panicfn : "std::builtin::panic";
+		Path *path;
+		const char *ident;
+		TokenType type;
+		if (!splitpathref(panicfn, strlen(panicfn), &path, &ident, &type) || path == NULL)
+		{
+			error_exit("'%s' is not a valid panic function.", panicfn);
+		}
+		Decl *decl = sema_find_decl_in_modules(global_context.module_list, path, ident);
+		if (!decl)
+		{
+			error_exit("Panic function '%s::%s' could not be found.", path->module, ident);
+		}
+		if (decl->decl_kind != DECL_FUNC)
+		{
+			error_exit("'%s::%s' is not a function.", path->module, ident);
+		}
+		Decl **params = decl->func_decl.function_signature.params;
+		if (vec_size(params) != 4 || params[0]->type != type_get_ptr(type_char)
+			|| params[1]->type != type_get_ptr(type_char)
+			|| params[2]->type != type_get_ptr(type_char)
+			|| params[3]->type != type_uint
+			|| typeinfotype(decl->func_decl.function_signature.returntype) != type_void)
+		{
+			error_exit("Expected panic function to have the signature fn void(char*, char*, uint, uint).");
+		}
+		global_context.panic_fn = decl;
+	}
+	else
+	{
+		global_context.panic_fn = NULL;
+	}
 	compiler_sema_time = bench_mark();
 
 }
diff --git a/src/compiler/symtab.c b/src/compiler/symtab.c
index 225da31fb..5d67fb29b 100644
--- a/src/compiler/symtab.c
+++ b/src/compiler/symtab.c
@@ -83,21 +83,6 @@ const char *kw_LINE;
 const char *kw_LINEREAL;
 const char *kw_incr;
 const char *kw_check_assign;
-const char *kw_builtin_ceil;
-const char *kw_builtin_trunc;
-const char *kw_builtin_sqrt;
-const char *kw_builtin_cos;
-const char *kw_builtin_sin;
-const char *kw_builtin_log;
-const char *kw_builtin_log2;
-const char *kw_builtin_log10;
-const char *kw_builtin_max;
-const char *kw_builtin_min;
-const char *kw_builtin_pow;
-const char *kw_builtin_exp;
-const char *kw_builtin_fabs;
-const char *kw_builtin_fma;
-const char *kw_builtin_cmpxchg;
 const char *kw_argc;
 const char *kw_argv;
 const char *kw_mainstub;;
@@ -140,8 +125,14 @@ void symtab_init(uint32_t capacity)
 	}
 
 	// Init some constant idents
-	TokenType type = TOKEN_IDENT;
 #define KW_DEF(x) symtab_add(x, sizeof(x) - 1, fnv1a(x, sizeof(x) - 1), &type)
+	TokenType type = TOKEN_CONST_IDENT;
+	kw_LINE = KW_DEF("LINE");
+	kw_LINEREAL = KW_DEF("LINEREAL");
+	kw_FILE = KW_DEF("FILE");
+	kw_FUNC = KW_DEF("FUNC");
+
+	type = TOKEN_IDENT;
 	kw_sizeof = KW_DEF("sizeof");
 	kw_in = KW_DEF("in");
 	kw_out = KW_DEF("out");
@@ -171,10 +162,6 @@ void symtab_init(uint32_t capacity)
 	kw_require = KW_DEF("require");
 	kw_std = KW_DEF("std");
 	kw_values = KW_DEF("values");
-	kw_LINE = KW_DEF("LINE");
-	kw_LINEREAL = KW_DEF("LINEREAL");
-	kw_FILE = KW_DEF("FILE");
-	kw_FUNC = KW_DEF("FUNC");
 	kw_incr = KW_DEF("incr");
 	kw_check_assign = KW_DEF("check_assign");
 
@@ -182,6 +169,9 @@ void symtab_init(uint32_t capacity)
 	kw_argv = KW_DEF("_$argv");
 	kw_mainstub = KW_DEF("_$mainstub");
 
+	builtin_list[BUILTIN_TRAP] = KW_DEF("trap");
+	builtin_list[BUILTIN_UNREACHABLE] = KW_DEF("unreachable");
+	builtin_list[BUILTIN_STACKTRACE] = KW_DEF("stacktrace");
 	builtin_list[BUILTIN_CEIL] = KW_DEF("ceil");
 	builtin_list[BUILTIN_TRUNC] = KW_DEF("trunc");
 	builtin_list[BUILTIN_SIN] = KW_DEF("sin");
diff --git a/src/compiler/target.c b/src/compiler/target.c
index cf356e17b..ac37db205 100644
--- a/src/compiler/target.c
+++ b/src/compiler/target.c
@@ -263,6 +263,30 @@ static AlignSize os_arch_max_alignment_of_tls(OsType os, ArchType arch, Environm
 	return 0;
 }
 
+static bool os_target_use_thread_local(OsType os)
+{
+	switch (os)
+	{
+		case OS_UNSUPPORTED:
+			return false;
+		case OS_TYPE_UNKNOWN:
+		case OS_TYPE_NONE:
+			return false;
+		case OS_TYPE_FREE_BSD:
+		case OS_TYPE_IOS:
+		case OS_TYPE_LINUX:
+		case OS_TYPE_MACOSX:
+		case OS_TYPE_NETBSD:
+		case OS_TYPE_OPENBSD:
+		case OS_TYPE_WIN32:
+		case OS_TYPE_TVOS:
+		case OS_TYPE_WATCHOS:
+		case OS_TYPE_WASI:
+			return true;
+	}
+	UNREACHABLE
+}
+
 static bool os_target_signed_c_char_type(OsType os, ArchType arch)
 {
 	switch (arch)
@@ -1293,11 +1317,10 @@ void target_setup(BuildTarget *target)
 	// TLS should not be supported for:
 	// ARM Cygwin
 	// NVPTX
-	platform_target.tls_supported = true;
+	platform_target.tls_supported = os_target_use_thread_local(platform_target.os);
 	platform_target.big_endian = arch_big_endian(platform_target.arch);
 	platform_target.width_pointer = arch_pointer_bit_width(platform_target.os, platform_target.arch);
 	platform_target.alloca_address_space = 0;
-
 	platform_target.object_format = object_format_from_os(platform_target.os);
 
 	platform_target.int128 = os_target_supports_int128(platform_target.os, platform_target.arch);
diff --git a/test/test_suite/assert/unreachable.c3t b/test/test_suite/assert/unreachable.c3t
index 0ea68332d..dcd444acb 100644
--- a/test/test_suite/assert/unreachable.c3t
+++ b/test/test_suite/assert/unreachable.c3t
@@ -15,22 +15,27 @@ fn void test()
 
 // #expect: unreachable.ll
 
-    %x = alloca i32
-    %0 = call i32 @unreachable.foo()
-    store i32 %0, i32* %x
-    %1 = load i32, i32* %x
-    %gt = icmp sgt i32 %1, 0
-    br i1 %gt, label %if.then, label %if.exit
 
-if.then:
-    ret void
+define void @unreachable.test() #0 {
+entry:
+  %x = alloca i32, align 4
+  %0 = call i32 @unreachable.foo()
+  store i32 %0, i32* %x, align 4
+  %1 = load i32, i32* %x, align 4
+  %gt = icmp sgt i32 %1, 0
+  br i1 %gt, label %if.then, label %if.exit
 
-if.exit:
-    call void @llvm.trap()
-    unreachable
+if.then:                                          ; preds = %entry
+  ret void
+
+if.exit:                                          ; preds = %entry
+  call void @"std::builtin.panic"(i8* getelementptr inbounds ([31 x i8], [31 x i8]* @.str, i32 0, i32 0), i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.1, i32 0, i32 0), i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.2, i32 0, i32 0), i32 11)
+  unreachable
+
+after.unreachable:                                ; No predecessors!
+  %2 = load i32, i32* %x, align 4
+  %add = add i32 %2, 1
+  store i32 %add, i32* %x, align 4
+  ret void
+}
 
-unreachable_block:
-    %2 = load i32, i32* %x
-    %add = add i32 %2, 1
-    store i32 %add, i32* %x
-    ret void
diff --git a/test/test_suite/builtins/simple_builtins.c3t b/test/test_suite/builtins/simple_builtins.c3t
index 761ce25ad..b2c394d87 100644
--- a/test/test_suite/builtins/simple_builtins.c3t
+++ b/test/test_suite/builtins/simple_builtins.c3t
@@ -28,31 +28,30 @@ entry:
   %sy = alloca i32, align 4
   %1 = call double @llvm.ceil.f64(double %0)
   store double %1, double* %d, align 8
-  %2 = call double @llvm.maxnum.f64(double 1.000000e+00, double 1.000000e+00)
-  store double %2, double* %e, align 8
-  %3 = load double, double* %d, align 8
+  %2 = load double, double* %d, align 8
+  %3 = call double @llvm.maxnum.f64(double 1.000000e+00, double %2)
+  store double %3, double* %e, align 8
   %4 = load double, double* %d, align 8
-  %5 = load double, double* %d, align 8
-  %6 = call double @llvm.fma.f64(double %3, double %4, double %5)
-  store double %6, double* %f, align 8
+  %5 = call double @llvm.fma.f64(double %4, double 2.000000e+00, double 3.000000e+00)
+  store double %5, double* %f, align 8
   store i32 13, i32* %xeb, align 4
-  %7 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 0
+  %6 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 0
+  store i32 0, i32* %6, align 4
+  %7 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 1
   store i32 0, i32* %7, align 4
-  %8 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 1
+  %8 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 2
   store i32 0, i32* %8, align 4
-  %9 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 2
-  store i32 0, i32* %9, align 4
-  %10 = load volatile i32, i32* %xeb, align 4
-  store i32 %10, i32* %sy, align 4
-  %11 = load i32, i32* %sy, align 4
-  %add = add i32 %11, 1
+  %9 = load volatile i32, i32* %xeb, align 4
+  store i32 %9, i32* %sy, align 4
+  %10 = load i32, i32* %sy, align 4
+  %add = add i32 %10, 1
   store volatile i32 %add, i32* %xeb, align 4
-  %12 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 2
-  %13 = load i32, i32* %sy, align 4
-  %add1 = add i32 %13, 2
-  store volatile i32 %add1, i32* %12, align 4
-  %14 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 2
-  %15 = load volatile i32, i32* %14, align 4
-  store i32 %15, i32* %sy, align 4
+  %11 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 2
+  %12 = load i32, i32* %sy, align 4
+  %add1 = add i32 %12, 2
+  store volatile i32 %add1, i32* %11, align 4
+  %13 = getelementptr inbounds [3 x i32], [3 x i32]* %abcd, i64 0, i64 2
+  %14 = load volatile i32, i32* %13, align 4
+  store i32 %14, i32* %sy, align 4
   ret i32 1
-}
\ No newline at end of file
+}
diff --git a/test/test_suite/from_docs/examples_forswitch.c3t b/test/test_suite/from_docs/examples_forswitch.c3t
index 943041707..775f547d6 100644
--- a/test/test_suite/from_docs/examples_forswitch.c3t
+++ b/test/test_suite/from_docs/examples_forswitch.c3t
@@ -110,8 +110,11 @@ loop.body:                                        ; preds = %loop.cond
   br label %loop.cond
 
 loop.exit:                                        ; preds = %loop.cond
-  call void @__assert_rtn(i8* getelementptr inbounds ([21 x i8], [21 x i8]* @0, i64 0, i64 0), i8* getelementptr inbounds ([22 x i8], [22 x i8]* @1, i64 0, i64 0), i32 14, i8* getelementptr inbounds ([20 x i8], [20 x i8]* @2, i64 0, i64 0))
+  call void @"std::builtin.panic"(i8* getelementptr inbounds ([20 x i8], [20 x i8]* @0, i64 0, i64 0), i8* getelementptr inbounds ([22 x i8], [22 x i8]* @1, i64 0, i64 0), i8* getelementptr inbounds ([21 x i8], [21 x i8]* @2, i64 0, i64 0), i32 14)
   unreachable
+
+unreachable_block:                                ; No predecessors!
+  ret void
 }
 
 ; Function Attrs: nounwind