Odin/src/tilde_stmt.cpp

gb_internal cgBranchBlocks cg_lookup_branch_blocks(cgProcedure *p, Ast *ident) {
	GB_ASSERT(ident->kind == Ast_Ident);
	Entity *e = entity_of_node(ident);
	GB_ASSERT(e->kind == Entity_Label);
	for (cgBranchBlocks const &b : p->branch_blocks) {
		if (b.label == e->Label.node) {
			return b;
		}
	}

	GB_PANIC("Unreachable");
	cgBranchBlocks empty = {};
	return empty;
}

gb_internal cgTargetList *cg_push_target_list(cgProcedure *p, Ast *label, TB_Node *break_, TB_Node *continue_, TB_Node *fallthrough_) {
	cgTargetList *tl = gb_alloc_item(permanent_allocator(), cgTargetList);
	tl->prev = p->target_list;
	tl->break_ = break_;
	tl->continue_ = continue_;
	tl->fallthrough_ = fallthrough_;
	p->target_list = tl;

	if (label != nullptr) { // Set label blocks
		GB_ASSERT(label->kind == Ast_Label);

		for (cgBranchBlocks &b : p->branch_blocks) {
			GB_ASSERT(b.label != nullptr && label != nullptr);
			GB_ASSERT(b.label->kind == Ast_Label);
			if (b.label == label) {
				b.break_    = break_;
				b.continue_ = continue_;
				return tl;
			}
		}

		GB_PANIC("Unreachable");
	}

	return tl;
}

gb_internal void cg_pop_target_list(cgProcedure *p) {
	p->target_list = p->target_list->prev;
}

gb_internal cgAddr cg_add_local(cgProcedure *p, Type *type, Entity *e, bool zero_init) {
	char const *name = "";
	if (e != nullptr && e->token.string.len > 0 && e->token.string != "_") {
		// NOTE(bill): for debugging purposes only
		name = alloc_cstring(permanent_allocator(), e->token.string);
	}

	isize size = type_size_of(type);
	TB_CharUnits alignment = cast(TB_CharUnits)type_align_of(type);
	if (is_type_matrix(type)) {
		alignment *= 2; // NOTE(bill): Just in case
	}

	TB_Node *local = tb_inst_local(p->func, cast(u32)size, alignment);

	if (zero_init) {
		bool is_volatile = false;
		TB_Node *zero  = tb_inst_uint(p->func, TB_TYPE_I8,  0);
		TB_Node *count = tb_inst_uint(p->func, TB_TYPE_I32, cast(u64)size);
		tb_inst_memset(p->func, local, zero, count, alignment, is_volatile);
	}

	return cg_addr(cg_value(local, alloc_type_pointer(type)));
}


gb_internal void cg_scope_open(cgProcedure *p, Scope *scope) {
	// TODO(bill): cg_scope_open
}

gb_internal void cg_scope_close(cgProcedure *p, cgDeferExitKind kind, TB_Node *control_region, bool pop_stack=true) {
	// TODO(bill): cg_scope_close
}

gb_internal void cg_emit_defer_stmts(cgProcedure *p, cgDeferExitKind kind, TB_Node *control_region) {
	// TODO(bill): cg_emit_defer_stmts
}

gb_internal void cg_build_stmt(cgProcedure *p, Ast *node) {
	Ast *prev_stmt = p->curr_stmt;
	defer (p->curr_stmt = prev_stmt);
	p->curr_stmt = node;

	// TODO(bill): check if last instruction was a terminating one or not

	{
		TokenPos pos = ast_token(node).pos;
		TB_FileID *file_id = map_get(&p->module->file_id_map, cast(uintptr)pos.file_id);
		if (file_id) {
			tb_inst_set_location(p->func, *file_id, pos.line);
		}
	}

	u16 prev_state_flags = p->state_flags;
	defer (p->state_flags = prev_state_flags);

	if (node->state_flags != 0) {
		u16 in = node->state_flags;
		u16 out = p->state_flags;

		if (in & StateFlag_bounds_check) {
			out |= StateFlag_bounds_check;
			out &= ~StateFlag_no_bounds_check;
		} else if (in & StateFlag_no_bounds_check) {
			out |= StateFlag_no_bounds_check;
			out &= ~StateFlag_bounds_check;
		}
		if (in & StateFlag_no_type_assert) {
			out |= StateFlag_no_type_assert;
			out &= ~StateFlag_type_assert;
		} else if (in & StateFlag_type_assert) {
			out |= StateFlag_type_assert;
			out &= ~StateFlag_no_type_assert;
		}

		p->state_flags = out;
	}

	switch (node->kind) {
	case_ast_node(bs, EmptyStmt, node);
	case_end;

	case_ast_node(us, UsingStmt, node);
	case_end;

	case_ast_node(ws, WhenStmt, node);
		cg_build_when_stmt(p, ws);
	case_end;

	case_ast_node(bs, BlockStmt, node);
		TB_Node *done = nullptr;
		if (bs->label != nullptr) {
			done = tb_inst_region(p->func);
			tb_inst_set_region_name(done, -1, "block.done");
			cgTargetList *tl = cg_push_target_list(p, bs->label, done, nullptr, nullptr);
			tl->is_block = true;
		}

		cg_scope_open(p, bs->scope);
		cg_build_stmt_list(p, bs->stmts);
		cg_scope_close(p, cgDeferExit_Default, nullptr);

		if (done != nullptr) {
			tb_inst_goto(p->func, done);
			tb_inst_set_control(p->func, done);
		}

		if (bs->label != nullptr) {
			cg_pop_target_list(p);
		}
	case_end;

	case_ast_node(vd, ValueDecl, node);
		if (!vd->is_mutable) {
			return;
		}

		bool is_static = false;
		if (vd->names.count > 0) {
			for (Ast *name : vd->names) {
				if (!is_blank_ident(name)) {
					GB_ASSERT(name->kind == Ast_Ident);
					Entity *e = entity_of_node(name);
					TokenPos pos = ast_token(name).pos;
					GB_ASSERT_MSG(e != nullptr, "\n%s missing entity for %.*s", token_pos_to_string(pos), LIT(name->Ident.token.string));
					if (e->flags & EntityFlag_Static) {
						// NOTE(bill): If one of the entities is static, they all are
						is_static = true;
						break;
					}
				}
			}
		}
		if (is_static) {
			GB_PANIC("TODO(bill): build static variables");
			return;
		}

		TEMPORARY_ALLOCATOR_GUARD();

		auto const &values = vd->values;
		if (values.count == 0) {
			for (Ast *name : vd->names) {
				if (!is_blank_ident(name)) {
					Entity *e = entity_of_node(name);
					bool zero_init = true;
					cgAddr addr = cg_add_local(p, e->type, e, zero_init);
					gb_unused(addr);
				}
			}
		} else {
			GB_PANIC("TODO multiple variables");
		}
	case_end;

	case_ast_node(bs, BranchStmt, node);
		TB_Node *prev_block = tb_inst_get_control(p->func);

		TB_Node *block = nullptr;

		if (bs->label != nullptr) {
			cgBranchBlocks bb = cg_lookup_branch_blocks(p, bs->label);
			switch (bs->token.kind) {
			case Token_break:    block = bb.break_;    break;
			case Token_continue: block = bb.continue_; break;
			case Token_fallthrough:
				GB_PANIC("fallthrough cannot have a label");
				break;
			}
		} else {
			for (cgTargetList *t = p->target_list; t != nullptr && block == nullptr; t = t->prev) {
				if (t->is_block) {
					continue;
				}

				switch (bs->token.kind) {
				case Token_break:       block = t->break_;       break;
				case Token_continue:    block = t->continue_;    break;
				case Token_fallthrough: block = t->fallthrough_; break;
				}
			}
		}
		if (block != nullptr) {
			cg_emit_defer_stmts(p, cgDeferExit_Branch, block);
		}


		tb_inst_goto(p->func, block);
		tb_inst_set_control(p->func, block);
		tb_inst_unreachable(p->func);

		tb_inst_set_control(p->func, prev_block);
	case_end;

	default:
		GB_PANIC("TODO cg_build_stmt %.*s", LIT(ast_strings[node->kind]));
		break;
	}
}


gb_internal void cg_build_stmt_list(cgProcedure *p, Slice<Ast *> const &stmts) {
	for (Ast *stmt : stmts) {
		switch (stmt->kind) {
		case_ast_node(vd, ValueDecl, stmt);
			// TODO(bill)
			// cg_build_constant_value_decl(p, vd);
		case_end;
		case_ast_node(fb, ForeignBlockDecl, stmt);
			ast_node(block, BlockStmt, fb->body);
			cg_build_stmt_list(p, block->stmts);
		case_end;
		}
	}
	for (Ast *stmt : stmts) {
		cg_build_stmt(p, stmt);
	}
}


gb_internal void cg_build_when_stmt(cgProcedure *p, AstWhenStmt *ws) {
	TypeAndValue tv = type_and_value_of_expr(ws->cond);
	GB_ASSERT(is_type_boolean(tv.type));
	GB_ASSERT(tv.value.kind == ExactValue_Bool);
	if (tv.value.value_bool) {
		cg_build_stmt_list(p, ws->body->BlockStmt.stmts);
	} else if (ws->else_stmt) {
		switch (ws->else_stmt->kind) {
		case Ast_BlockStmt:
			cg_build_stmt_list(p, ws->else_stmt->BlockStmt.stmts);
			break;
		case Ast_WhenStmt:
			cg_build_when_stmt(p, &ws->else_stmt->WhenStmt);
			break;
		default:
			GB_PANIC("Invalid 'else' statement in 'when' statement");
			break;
		}
	}
}