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| 1 // Copyright 2012 the V8 project authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef V8_LIVEEDIT_H_ | |
| 6 #define V8_LIVEEDIT_H_ | |
| 7 | |
| 8 | |
| 9 | |
| 10 // Live Edit feature implementation. | |
| 11 // User should be able to change script on already running VM. This feature | |
| 12 // matches hot swap features in other frameworks. | |
| 13 // | |
| 14 // The basic use-case is when user spots some mistake in function body | |
| 15 // from debugger and wishes to change the algorithm without restart. | |
| 16 // | |
| 17 // A single change always has a form of a simple replacement (in pseudo-code): | |
| 18 // script.source[positions, positions+length] = new_string; | |
| 19 // Implementation first determines, which function's body includes this | |
| 20 // change area. Then both old and new versions of script are fully compiled | |
| 21 // in order to analyze, whether the function changed its outer scope | |
| 22 // expectations (or number of parameters). If it didn't, function's code is | |
| 23 // patched with a newly compiled code. If it did change, enclosing function | |
| 24 // gets patched. All inner functions are left untouched, whatever happened | |
| 25 // to them in a new script version. However, new version of code will | |
| 26 // instantiate newly compiled functions. | |
| 27 | |
| 28 | |
| 29 #include "src/allocation.h" | |
| 30 #include "src/compiler.h" | |
| 31 | |
| 32 namespace v8 { | |
| 33 namespace internal { | |
| 34 | |
| 35 // This class collects some specific information on structure of functions | |
| 36 // in a particular script. It gets called from compiler all the time, but | |
| 37 // actually records any data only when liveedit operation is in process; | |
| 38 // in any other time this class is very cheap. | |
| 39 // | |
| 40 // The primary interest of the Tracker is to record function scope structures | |
| 41 // in order to analyze whether function code maybe safely patched (with new | |
| 42 // code successfully reading existing data from function scopes). The Tracker | |
| 43 // also collects compiled function codes. | |
| 44 class LiveEditFunctionTracker { | |
| 45 public: | |
| 46 explicit LiveEditFunctionTracker(Isolate* isolate, FunctionLiteral* fun); | |
| 47 ~LiveEditFunctionTracker(); | |
| 48 void RecordFunctionInfo(Handle<SharedFunctionInfo> info, | |
| 49 FunctionLiteral* lit, Zone* zone); | |
| 50 void RecordRootFunctionInfo(Handle<Code> code); | |
| 51 | |
| 52 static bool IsActive(Isolate* isolate); | |
| 53 | |
| 54 private: | |
| 55 Isolate* isolate_; | |
| 56 }; | |
| 57 | |
| 58 | |
| 59 class LiveEdit : AllStatic { | |
| 60 public: | |
| 61 // Describes how exactly a frame has been dropped from stack. | |
| 62 enum FrameDropMode { | |
| 63 // No frame has been dropped. | |
| 64 FRAMES_UNTOUCHED, | |
| 65 // The top JS frame had been calling IC stub. IC stub mustn't be called now. | |
| 66 FRAME_DROPPED_IN_IC_CALL, | |
| 67 // The top JS frame had been calling debug break slot stub. Patch the | |
| 68 // address this stub jumps to in the end. | |
| 69 FRAME_DROPPED_IN_DEBUG_SLOT_CALL, | |
| 70 // The top JS frame had been calling some C++ function. The return address | |
| 71 // gets patched automatically. | |
| 72 FRAME_DROPPED_IN_DIRECT_CALL, | |
| 73 FRAME_DROPPED_IN_RETURN_CALL, | |
| 74 CURRENTLY_SET_MODE | |
| 75 }; | |
| 76 | |
| 77 static void InitializeThreadLocal(Debug* debug); | |
| 78 | |
| 79 static bool SetAfterBreakTarget(Debug* debug); | |
| 80 | |
| 81 MUST_USE_RESULT static MaybeHandle<JSArray> GatherCompileInfo( | |
| 82 Handle<Script> script, | |
| 83 Handle<String> source); | |
| 84 | |
| 85 static void WrapSharedFunctionInfos(Handle<JSArray> array); | |
| 86 | |
| 87 static void ReplaceFunctionCode(Handle<JSArray> new_compile_info_array, | |
| 88 Handle<JSArray> shared_info_array); | |
| 89 | |
| 90 static void FunctionSourceUpdated(Handle<JSArray> shared_info_array); | |
| 91 | |
| 92 // Updates script field in FunctionSharedInfo. | |
| 93 static void SetFunctionScript(Handle<JSValue> function_wrapper, | |
| 94 Handle<Object> script_handle); | |
| 95 | |
| 96 static void PatchFunctionPositions(Handle<JSArray> shared_info_array, | |
| 97 Handle<JSArray> position_change_array); | |
| 98 | |
| 99 // For a script updates its source field. If old_script_name is provided | |
| 100 // (i.e. is a String), also creates a copy of the script with its original | |
| 101 // source and sends notification to debugger. | |
| 102 static Handle<Object> ChangeScriptSource(Handle<Script> original_script, | |
| 103 Handle<String> new_source, | |
| 104 Handle<Object> old_script_name); | |
| 105 | |
| 106 // In a code of a parent function replaces original function as embedded | |
| 107 // object with a substitution one. | |
| 108 static void ReplaceRefToNestedFunction(Handle<JSValue> parent_function_shared, | |
| 109 Handle<JSValue> orig_function_shared, | |
| 110 Handle<JSValue> subst_function_shared); | |
| 111 | |
| 112 // Find open generator activations, and set corresponding "result" elements to | |
| 113 // FUNCTION_BLOCKED_ACTIVE_GENERATOR. | |
| 114 static bool FindActiveGenerators(Handle<FixedArray> shared_info_array, | |
| 115 Handle<FixedArray> result, int len); | |
| 116 | |
| 117 // Checks listed functions on stack and return array with corresponding | |
| 118 // FunctionPatchabilityStatus statuses; extra array element may | |
| 119 // contain general error message. Modifies the current stack and | |
| 120 // has restart the lowest found frames and drops all other frames above | |
| 121 // if possible and if do_drop is true. | |
| 122 static Handle<JSArray> CheckAndDropActivations( | |
| 123 Handle<JSArray> shared_info_array, bool do_drop); | |
| 124 | |
| 125 // Restarts the call frame and completely drops all frames above it. | |
| 126 // Return error message or NULL. | |
| 127 static const char* RestartFrame(JavaScriptFrame* frame); | |
| 128 | |
| 129 // A copy of this is in liveedit-debugger.js. | |
| 130 enum FunctionPatchabilityStatus { | |
| 131 FUNCTION_AVAILABLE_FOR_PATCH = 1, | |
| 132 FUNCTION_BLOCKED_ON_ACTIVE_STACK = 2, | |
| 133 FUNCTION_BLOCKED_ON_OTHER_STACK = 3, | |
| 134 FUNCTION_BLOCKED_UNDER_NATIVE_CODE = 4, | |
| 135 FUNCTION_REPLACED_ON_ACTIVE_STACK = 5, | |
| 136 FUNCTION_BLOCKED_UNDER_GENERATOR = 6, | |
| 137 FUNCTION_BLOCKED_ACTIVE_GENERATOR = 7 | |
| 138 }; | |
| 139 | |
| 140 // Compares 2 strings line-by-line, then token-wise and returns diff in form | |
| 141 // of array of triplets (pos1, pos1_end, pos2_end) describing list | |
| 142 // of diff chunks. | |
| 143 static Handle<JSArray> CompareStrings(Handle<String> s1, | |
| 144 Handle<String> s2); | |
| 145 | |
| 146 // Architecture-specific constant. | |
| 147 static const bool kFrameDropperSupported; | |
| 148 | |
| 149 /** | |
| 150 * Defines layout of a stack frame that supports padding. This is a regular | |
| 151 * internal frame that has a flexible stack structure. LiveEdit can shift | |
| 152 * its lower part up the stack, taking up the 'padding' space when additional | |
| 153 * stack memory is required. | |
| 154 * Such frame is expected immediately above the topmost JavaScript frame. | |
| 155 * | |
| 156 * Stack Layout: | |
| 157 * --- Top | |
| 158 * LiveEdit routine frames | |
| 159 * --- | |
| 160 * C frames of debug handler | |
| 161 * --- | |
| 162 * ... | |
| 163 * --- | |
| 164 * An internal frame that has n padding words: | |
| 165 * - any number of words as needed by code -- upper part of frame | |
| 166 * - padding size: a Smi storing n -- current size of padding | |
| 167 * - padding: n words filled with kPaddingValue in form of Smi | |
| 168 * - 3 context/type words of a regular InternalFrame | |
| 169 * - fp | |
| 170 * --- | |
| 171 * Topmost JavaScript frame | |
| 172 * --- | |
| 173 * ... | |
| 174 * --- Bottom | |
| 175 */ | |
| 176 // A size of frame base including fp. Padding words starts right above | |
| 177 // the base. | |
| 178 static const int kFrameDropperFrameSize = 4; | |
| 179 // A number of words that should be reserved on stack for the LiveEdit use. | |
| 180 // Stored on stack in form of Smi. | |
| 181 static const int kFramePaddingInitialSize = 1; | |
| 182 // A value that padding words are filled with (in form of Smi). Going | |
| 183 // bottom-top, the first word not having this value is a counter word. | |
| 184 static const int kFramePaddingValue = kFramePaddingInitialSize + 1; | |
| 185 }; | |
| 186 | |
| 187 | |
| 188 // A general-purpose comparator between 2 arrays. | |
| 189 class Comparator { | |
| 190 public: | |
| 191 // Holds 2 arrays of some elements allowing to compare any pair of | |
| 192 // element from the first array and element from the second array. | |
| 193 class Input { | |
| 194 public: | |
| 195 virtual int GetLength1() = 0; | |
| 196 virtual int GetLength2() = 0; | |
| 197 virtual bool Equals(int index1, int index2) = 0; | |
| 198 | |
| 199 protected: | |
| 200 virtual ~Input() {} | |
| 201 }; | |
| 202 | |
| 203 // Receives compare result as a series of chunks. | |
| 204 class Output { | |
| 205 public: | |
| 206 // Puts another chunk in result list. Note that technically speaking | |
| 207 // only 3 arguments actually needed with 4th being derivable. | |
| 208 virtual void AddChunk(int pos1, int pos2, int len1, int len2) = 0; | |
| 209 | |
| 210 protected: | |
| 211 virtual ~Output() {} | |
| 212 }; | |
| 213 | |
| 214 // Finds the difference between 2 arrays of elements. | |
| 215 static void CalculateDifference(Input* input, | |
| 216 Output* result_writer); | |
| 217 }; | |
| 218 | |
| 219 | |
| 220 | |
| 221 // Simple helper class that creates more or less typed structures over | |
| 222 // JSArray object. This is an adhoc method of passing structures from C++ | |
| 223 // to JavaScript. | |
| 224 template<typename S> | |
| 225 class JSArrayBasedStruct { | |
| 226 public: | |
| 227 static S Create(Isolate* isolate) { | |
| 228 Factory* factory = isolate->factory(); | |
| 229 Handle<JSArray> array = factory->NewJSArray(S::kSize_); | |
| 230 return S(array); | |
| 231 } | |
| 232 | |
| 233 static S cast(Object* object) { | |
| 234 JSArray* array = JSArray::cast(object); | |
| 235 Handle<JSArray> array_handle(array); | |
| 236 return S(array_handle); | |
| 237 } | |
| 238 | |
| 239 explicit JSArrayBasedStruct(Handle<JSArray> array) : array_(array) { | |
| 240 } | |
| 241 | |
| 242 Handle<JSArray> GetJSArray() { | |
| 243 return array_; | |
| 244 } | |
| 245 | |
| 246 Isolate* isolate() const { | |
| 247 return array_->GetIsolate(); | |
| 248 } | |
| 249 | |
| 250 protected: | |
| 251 void SetField(int field_position, Handle<Object> value) { | |
| 252 Object::SetElement(isolate(), array_, field_position, value, SLOPPY) | |
| 253 .Assert(); | |
| 254 } | |
| 255 | |
| 256 void SetSmiValueField(int field_position, int value) { | |
| 257 SetField(field_position, Handle<Smi>(Smi::FromInt(value), isolate())); | |
| 258 } | |
| 259 | |
| 260 Handle<Object> GetField(int field_position) { | |
| 261 return Object::GetElement( | |
| 262 isolate(), array_, field_position).ToHandleChecked(); | |
| 263 } | |
| 264 | |
| 265 int GetSmiValueField(int field_position) { | |
| 266 Handle<Object> res = GetField(field_position); | |
| 267 return Handle<Smi>::cast(res)->value(); | |
| 268 } | |
| 269 | |
| 270 private: | |
| 271 Handle<JSArray> array_; | |
| 272 }; | |
| 273 | |
| 274 | |
| 275 // Represents some function compilation details. This structure will be used | |
| 276 // from JavaScript. It contains Code object, which is kept wrapped | |
| 277 // into a BlindReference for sanitizing reasons. | |
| 278 class FunctionInfoWrapper : public JSArrayBasedStruct<FunctionInfoWrapper> { | |
| 279 public: | |
| 280 explicit FunctionInfoWrapper(Handle<JSArray> array) | |
| 281 : JSArrayBasedStruct<FunctionInfoWrapper>(array) { | |
| 282 } | |
| 283 | |
| 284 void SetInitialProperties(Handle<String> name, int start_position, | |
| 285 int end_position, int param_num, int literal_count, | |
| 286 int parent_index); | |
| 287 | |
| 288 void SetFunctionCode(Handle<Code> function_code, | |
| 289 Handle<HeapObject> code_scope_info); | |
| 290 | |
| 291 void SetFunctionScopeInfo(Handle<Object> scope_info_array) { | |
| 292 this->SetField(kFunctionScopeInfoOffset_, scope_info_array); | |
| 293 } | |
| 294 | |
| 295 void SetSharedFunctionInfo(Handle<SharedFunctionInfo> info); | |
| 296 | |
| 297 int GetLiteralCount() { | |
| 298 return this->GetSmiValueField(kLiteralNumOffset_); | |
| 299 } | |
| 300 | |
| 301 int GetParentIndex() { | |
| 302 return this->GetSmiValueField(kParentIndexOffset_); | |
| 303 } | |
| 304 | |
| 305 Handle<Code> GetFunctionCode(); | |
| 306 | |
| 307 MaybeHandle<TypeFeedbackVector> GetFeedbackVector(); | |
| 308 | |
| 309 Handle<Object> GetCodeScopeInfo(); | |
| 310 | |
| 311 int GetStartPosition() { | |
| 312 return this->GetSmiValueField(kStartPositionOffset_); | |
| 313 } | |
| 314 | |
| 315 int GetEndPosition() { return this->GetSmiValueField(kEndPositionOffset_); } | |
| 316 | |
| 317 private: | |
| 318 static const int kFunctionNameOffset_ = 0; | |
| 319 static const int kStartPositionOffset_ = 1; | |
| 320 static const int kEndPositionOffset_ = 2; | |
| 321 static const int kParamNumOffset_ = 3; | |
| 322 static const int kCodeOffset_ = 4; | |
| 323 static const int kCodeScopeInfoOffset_ = 5; | |
| 324 static const int kFunctionScopeInfoOffset_ = 6; | |
| 325 static const int kParentIndexOffset_ = 7; | |
| 326 static const int kSharedFunctionInfoOffset_ = 8; | |
| 327 static const int kLiteralNumOffset_ = 9; | |
| 328 static const int kSize_ = 10; | |
| 329 | |
| 330 friend class JSArrayBasedStruct<FunctionInfoWrapper>; | |
| 331 }; | |
| 332 | |
| 333 | |
| 334 // Wraps SharedFunctionInfo along with some of its fields for passing it | |
| 335 // back to JavaScript. SharedFunctionInfo object itself is additionally | |
| 336 // wrapped into BlindReference for sanitizing reasons. | |
| 337 class SharedInfoWrapper : public JSArrayBasedStruct<SharedInfoWrapper> { | |
| 338 public: | |
| 339 static bool IsInstance(Handle<JSArray> array) { | |
| 340 if (array->length() != Smi::FromInt(kSize_)) return false; | |
| 341 Handle<Object> element( | |
| 342 Object::GetElement(array->GetIsolate(), | |
| 343 array, | |
| 344 kSharedInfoOffset_).ToHandleChecked()); | |
| 345 if (!element->IsJSValue()) return false; | |
| 346 return Handle<JSValue>::cast(element)->value()->IsSharedFunctionInfo(); | |
| 347 } | |
| 348 | |
| 349 explicit SharedInfoWrapper(Handle<JSArray> array) | |
| 350 : JSArrayBasedStruct<SharedInfoWrapper>(array) { | |
| 351 } | |
| 352 | |
| 353 void SetProperties(Handle<String> name, | |
| 354 int start_position, | |
| 355 int end_position, | |
| 356 Handle<SharedFunctionInfo> info); | |
| 357 | |
| 358 Handle<SharedFunctionInfo> GetInfo(); | |
| 359 | |
| 360 private: | |
| 361 static const int kFunctionNameOffset_ = 0; | |
| 362 static const int kStartPositionOffset_ = 1; | |
| 363 static const int kEndPositionOffset_ = 2; | |
| 364 static const int kSharedInfoOffset_ = 3; | |
| 365 static const int kSize_ = 4; | |
| 366 | |
| 367 friend class JSArrayBasedStruct<SharedInfoWrapper>; | |
| 368 }; | |
| 369 | |
| 370 } } // namespace v8::internal | |
| 371 | |
| 372 #endif /* V*_LIVEEDIT_H_ */ | |
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Chromium Code Reviews
Issue 1265923002:
Debugger: move implementation to a separate folder. (Closed)
Base URL: https://chromium.googlesource.com/v8/v8.git@master