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| 1 | // | ||
| 2 | // Dis VM | ||
| 3 | // File: stack.cpp | ||
| 4 | // Author: arr | ||
| 5 | // | ||
| 6 | |||
| 7 | #include <cinttypes> | ||
| 8 | #include <runtime.h> | ||
| 9 | #include <builtin_module.h> | ||
| 10 | #include <vm_memory.h> | ||
| 11 | #include <debug.h> | ||
| 12 | #include <exceptions.h> | ||
| 13 | |||
| 14 | using namespace disvm; | ||
| 15 | using namespace disvm::runtime; | ||
| 16 | |||
| 17 | namespace | ||
| 18 | { | ||
| 19 | struct vm_stack_page | ||
| 20 | { | ||
| 21 | vm_stack_page *prev_page; | ||
| 22 | uintptr_t page_limit_addr; | ||
| 23 | vm_frame_t *page_top_frame; // Do not free. This is used as a tracking pointer. | ||
| 24 | |||
| 25 | void *stack_data() const | ||
| 26 | { | ||
| 27 | // The beginning of the stack data is at the end of the struct. | ||
| 28 | return reinterpret_cast<uint8_t *>(const_cast<vm_stack_page *>(this)) + sizeof(vm_stack_page); | ||
| 29 | } | ||
| 30 | |||
| 31 | bool contains_frame(const vm_frame_t *frame) const | ||
| 32 | { | ||
| 33 | return reinterpret_cast<uintptr_t>(stack_data()) <= reinterpret_cast<uintptr_t>(frame) && reinterpret_cast<uintptr_t>(frame) < page_limit_addr; | ||
| 34 | } | ||
| 35 | }; | ||
| 36 | |||
| 37 | struct vm_stack_layout final : public vm_alloc_t | ||
| 38 | { | ||
| 39 | static std::shared_ptr<const type_descriptor_t> type_desc() | ||
| 40 | { | ||
| 41 | static auto td = type_descriptor_t::create(0); | ||
| 42 | return td; | ||
| 43 | } | ||
| 44 | |||
| 45 | vm_stack_layout(std::size_t stack_page_size) | ||
| 46 | : vm_alloc_t(type_desc()) | ||
| 47 | , stack_page_size{ stack_page_size } | ||
| 48 | , top_frame{ nullptr } | ||
| 49 | , top_page{ nullptr } | ||
| 50 | { | ||
| 51 | new_page(); | ||
| 52 | } | ||
| 53 | |||
| 54 | ~vm_stack_layout() | ||
| 55 | { | ||
| 56 | assert(top_page != nullptr); | ||
| 57 | free_memory(top_page); | ||
| 58 | } | ||
| 59 | |||
| 60 | const std::size_t stack_page_size; | ||
| 61 | |||
| 62 | vm_stack_page *top_page; | ||
| 63 | vm_frame_t *top_frame; // Do not free. This is used as a tracking pointer. | ||
| 64 | |||
| 65 | // Create a new 'top page' and return stack data address | ||
| 66 | void *new_page() | ||
| 67 | { | ||
| 68 | auto current_stack_page = top_page; | ||
| 69 | top_page = alloc_memory<vm_stack_page>(sizeof(vm_stack_page) + stack_page_size); | ||
| 70 | |||
| 71 | // Initialize the stack allocation. | ||
| 72 | top_page->prev_page = current_stack_page; | ||
| 73 | |||
| 74 | // The top frame member is only for tracking and so is initialized to null. | ||
| 75 | top_page->page_top_frame = nullptr; | ||
| 76 | top_page->page_limit_addr = reinterpret_cast<uintptr_t>(top_page)+stack_page_size; | ||
| 77 | |||
| 78 | debug::log_msg(debug::component_trace_t::memory, debug::log_level_t::debug, "alloc: vm stack alloc: %#" PRIxPTR " %#" PRIxPTR "\n", top_page, top_page->page_limit_addr); | ||
| 79 | |||
| 80 | return top_page->stack_data(); | ||
| 81 | } | ||
| 82 | |||
| 83 | // Drop the current page and move to the previous one | ||
| 84 | void drop_page() | ||
| 85 | { | ||
| 86 | auto current_stack_page = top_page->prev_page; | ||
| 87 | assert(current_stack_page != nullptr); | ||
| 88 | |||
| 89 | free_memory(top_page); | ||
| 90 | debug::log_msg(debug::component_trace_t::memory, debug::log_level_t::debug, "free: vm stack alloc\n"); | ||
| 91 | |||
| 92 | // Set the top page | ||
| 93 | top_page = current_stack_page; | ||
| 94 | } | ||
| 95 | }; | ||
| 96 | } | ||
| 97 | |||
| 98 | vm_frame_t::vm_frame_t(std::shared_ptr<const type_descriptor_t> &td) | ||
| 99 | : frame_type{ std::move(td) } | ||
| 100 | { | ||
| 101 | assert(frame_type != nullptr); | ||
| 102 | |||
| 103 | // Initialize the new frame | ||
| 104 | init_memory(*frame_type, base()); | ||
| 105 | |||
| 106 | prev_pc() = runtime_constants::invalid_program_counter; | ||
| 107 | prev_frame() = nullptr; | ||
| 108 | prev_module_ref() = nullptr; | ||
| 109 | |||
| 110 | if (debug::is_component_tracing_enabled<debug::component_trace_t::memory>()) | ||
| 111 | debug::log_msg(debug::component_trace_t::memory, debug::log_level_t::debug, "init: vm frame: %#" PRIxPTR " %d\n", this, frame_type->size_in_bytes); | ||
| 112 | } | ||
| 113 | |||
| 114 | vm_frame_t::~vm_frame_t() | ||
| 115 | { | ||
| 116 | dec_ref_count_and_free(prev_module_ref()); | ||
| 117 | |||
| 118 | destroy_memory(*frame_type, base()); | ||
| 119 | |||
| 120 | if (debug::is_component_tracing_enabled<debug::component_trace_t::memory>()) | ||
| 121 | debug::log_msg(debug::component_trace_t::memory, debug::log_level_t::debug, "destroy: vm frame: %#" PRIxPTR "\n", this); | ||
| 122 | } | ||
| 123 | |||
| 124 | void vm_frame_t::copy_frame_contents(const vm_frame_t &other) | ||
| 125 | { | ||
| 126 | auto this_frame_base = reinterpret_cast<uint8_t *>(base()); | ||
| 127 | auto this_frame_contents = this_frame_base + sizeof(vm_frame_base_alloc_t); | ||
| 128 | |||
| 129 | auto other_frame_base = reinterpret_cast<uint8_t *>(other.base()); | ||
| 130 | auto other_frame_contents = other_frame_base + sizeof(vm_frame_base_alloc_t); | ||
| 131 | |||
| 132 | assert(frame_type->size_in_bytes > sizeof(vm_frame_base_alloc_t)); | ||
| 133 | std::memcpy(this_frame_contents, other_frame_contents, frame_type->size_in_bytes - sizeof(vm_frame_base_alloc_t)); | ||
| 134 | |||
| 135 | inc_ref_count_in_memory(*frame_type, this_frame_base); | ||
| 136 | } | ||
| 137 | |||
| 138 | pointer_t vm_frame_t::base() const | ||
| 139 | { | ||
| 140 | // The beginning of the frame data is at the end of the frame struct. | ||
| 141 | return reinterpret_cast<pointer_t>(reinterpret_cast<uint8_t *>(const_cast<vm_frame_t *>(this)) + sizeof(vm_frame_t)); | ||
| 142 | } | ||
| 143 | |||
| 144 | vm_pc_t &vm_frame_t::prev_pc() const | ||
| 145 | { | ||
| 146 | return base<vm_frame_base_alloc_t>().p_pc; | ||
| 147 | } | ||
| 148 | |||
| 149 | vm_frame_t *&vm_frame_t::prev_frame() const | ||
| 150 | { | ||
| 151 | return base<vm_frame_base_alloc_t>().p_fp; | ||
| 152 | } | ||
| 153 | |||
| 154 | vm_module_ref_t *&vm_frame_t::prev_module_ref() const | ||
| 155 | { | ||
| 156 | return base<vm_frame_base_alloc_t>().p_mr; | ||
| 157 | } | ||
| 158 | |||
| 159 | pointer_t vm_frame_t::fixed_point_register_1() const | ||
| 160 | { | ||
| 161 | const auto offset = runtime_constants::fixed_point_register_1_frame_offset; | ||
| 162 | assert(offset < frame_type->size_in_bytes); | ||
| 163 | |||
| 164 | auto p = reinterpret_cast<uint8_t *>(base()) + offset; | ||
| 165 | return reinterpret_cast<pointer_t>(p); | ||
| 166 | } | ||
| 167 | |||
| 168 | pointer_t vm_frame_t::fixed_point_register_2() const | ||
| 169 | { | ||
| 170 | const auto offset = runtime_constants::fixed_point_register_2_frame_offset; | ||
| 171 | assert(offset < frame_type->size_in_bytes); | ||
| 172 | |||
| 173 | auto p = reinterpret_cast<uint8_t *>(base()) + offset; | ||
| 174 | return reinterpret_cast<pointer_t>(p); | ||
| 175 | } | ||
| 176 | |||
| 177 | vm_stack_t::vm_stack_t(std::size_t stack_extent) | ||
| 178 | : _mem{ std::make_unique<vm_stack_layout>(stack_extent) } | ||
| 179 | { | ||
| 180 | assert(stack_extent != 0); | ||
| 181 | debug::log_msg(debug::component_trace_t::memory, debug::log_level_t::debug, "init: vm stack\n"); | ||
| 182 | } | ||
| 183 | |||
| 184 | vm_stack_t::~vm_stack_t() | ||
| 185 | { | ||
| 186 | while (nullptr != pop_frame()) | ||
| 187 | { | ||
| 188 | // Pop all frames off the stack | ||
| 189 | } | ||
| 190 | |||
| 191 | // Free stack memory | ||
| 192 | _mem->release(); | ||
| 193 | _mem.reset(); | ||
| 194 | |||
| 195 | debug::log_msg(debug::component_trace_t::memory, debug::log_level_t::debug, "destroy: vm stack\n"); | ||
| 196 | } | ||
| 197 | |||
| 198 | vm_frame_t *vm_stack_t::alloc_frame(std::shared_ptr<const type_descriptor_t> frame_type) | ||
| 199 | { | ||
| 200 | assert(frame_type != nullptr); | ||
| 201 | assert(sizeof(vm_frame_base_alloc_t) < frame_type->size_in_bytes && "Requested frame size less than VM frame base size"); | ||
| 202 | |||
| 203 | auto layout = dynamic_cast<vm_stack_layout *>(_mem.get()); | ||
| 204 | |||
| 205 | auto page_top_frame = layout->top_page->page_top_frame; | ||
| 206 | const auto new_frame_size = sizeof(vm_frame_t) + frame_type->size_in_bytes; | ||
| 207 | if (layout->stack_page_size < new_frame_size) | ||
| 208 | throw vm_system_exception{ "Requested stack frame larger than stack page" }; | ||
| 209 | |||
| 210 | vm_frame_t *new_frame; | ||
| 211 | if (page_top_frame == nullptr) | ||
| 212 | { | ||
| 213 | new_frame = ::new(layout->top_page->stack_data())vm_frame_t{ frame_type }; | ||
| 214 | } | ||
| 215 | else | ||
| 216 | { | ||
| 217 | auto current_page_top_frame_addr = reinterpret_cast<std::size_t>(page_top_frame); | ||
| 218 | auto new_frame_addr_maybe = current_page_top_frame_addr + (sizeof(vm_frame_t) + page_top_frame->frame_type->size_in_bytes); | ||
| 219 | |||
| 220 | // If the new frame is not going to fit on the current page, create a new page. | ||
| 221 | if ((new_frame_addr_maybe + new_frame_size) >= layout->top_page->page_limit_addr) | ||
| 222 | new_frame_addr_maybe = reinterpret_cast<uintptr_t>(layout->new_page()); | ||
| 223 | |||
| 224 | new_frame = ::new(reinterpret_cast<void *>(new_frame_addr_maybe))vm_frame_t{ frame_type }; | ||
| 225 | } | ||
| 226 | |||
| 227 | // Record the top frame on the page | ||
| 228 | layout->top_page->page_top_frame = new_frame; | ||
| 229 | |||
| 230 | return new_frame; | ||
| 231 | } | ||
| 232 | |||
| 233 | vm_frame_t *vm_stack_t::push_frame() | ||
| 234 | { | ||
| 235 | auto layout = dynamic_cast<vm_stack_layout *>(_mem.get()); | ||
| 236 | |||
| 237 | auto current_top_frame = layout->top_frame; | ||
| 238 | auto new_top_frame = layout->top_page->page_top_frame; | ||
| 239 | new_top_frame->prev_frame() = current_top_frame; | ||
| 240 | |||
| 241 | layout->top_frame = new_top_frame; | ||
| 242 | |||
| 243 | if (debug::is_component_tracing_enabled<debug::component_trace_t::stack>()) | ||
| 244 | debug::log_msg(debug::component_trace_t::stack, debug::log_level_t::debug, "update: push vm frame: %#" PRIxPTR "\n", new_top_frame); | ||
| 245 | |||
| 246 | return new_top_frame; | ||
| 247 | } | ||
| 248 | |||
| 249 | vm_frame_t *vm_stack_t::pop_frame() | ||
| 250 | { | ||
| 251 | auto layout = dynamic_cast<vm_stack_layout *>(_mem.get()); | ||
| 252 | |||
| 253 | auto current_frame = layout->top_frame; | ||
| 254 | if (current_frame == nullptr) | ||
| 255 | return nullptr; | ||
| 256 | |||
| 257 | { | ||
| 258 | // Dispose of the current top frame and update the current frame. | ||
| 259 | auto previous_frame = current_frame; | ||
| 260 | current_frame = previous_frame->prev_frame(); | ||
| 261 | |||
| 262 | // Call destructor on previous frame since we allocated | ||
| 263 | // the frame on the stack page. | ||
| 264 | previous_frame->~vm_frame_t(); | ||
| 265 | } | ||
| 266 | |||
| 267 | layout->top_frame = current_frame; | ||
| 268 | layout->top_page->page_top_frame = current_frame; | ||
| 269 | |||
| 270 | // Check if the stack page is no longer needed. | ||
| 271 | if (current_frame != nullptr) | ||
| 272 | { | ||
| 273 | // Clean up the stack page allocation if the current frame is on a previous page | ||
| 274 | if (!layout->top_page->contains_frame(current_frame)) | ||
| 275 | { | ||
| 276 | layout->drop_page(); | ||
| 277 | |||
| 278 | // Ensure the current frame is in the new page. | ||
| 279 | assert(layout->top_page->contains_frame(current_frame)); | ||
| 280 | } | ||
| 281 | } | ||
| 282 | |||
| 283 | if (debug::is_component_tracing_enabled<debug::component_trace_t::stack>()) | ||
| 284 | debug::log_msg(debug::component_trace_t::stack, debug::log_level_t::debug, "update: pop vm frame: %#" PRIxPTR "\n", current_frame); | ||
| 285 | |||
| 286 | return current_frame; | ||
| 287 | } | ||
| 288 | |||
| 289 | vm_frame_t *vm_stack_t::peek_frame() const | ||
| 290 | { | ||
| 291 | auto layout = dynamic_cast<vm_stack_layout *>(_mem.get()); | ||
| 292 | return layout->top_frame; | ||
| 293 | } | ||
| 294 | |||
| 295 | void vm_stack_t::walk_stack(vm_stack_walk_callback_t callback) const | ||
| 296 | { | ||
| 297 | if (callback == nullptr) | ||
| 298 | return; | ||
| 299 | |||
| 300 | auto layout = dynamic_cast<vm_stack_layout *>(_mem.get()); | ||
| 301 | auto current_page = layout->top_page; | ||
| 302 | auto current_frame = layout->top_frame; | ||
| 303 | |||
| 304 | while (current_page != nullptr && current_frame != nullptr) | ||
| 305 | { | ||
| 306 | if (!callback(current_frame, current_page)) | ||
| 307 | break; | ||
| 308 | |||
| 309 | current_frame = current_frame->prev_frame(); | ||
| 310 | |||
| 311 | if (!current_page->contains_frame(current_frame)) | ||
| 312 | current_page = current_page->prev_page; | ||
| 313 | } | ||
| 314 | } | ||