llint/LowLevelInterpreter.cpp

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  25
  26 #include "config.h"
  27 #include "LowLevelInterpreter.h"
  28 #include "LLIntOfflineAsmConfig.h"
  29 #include <wtf/InlineASM.h>
  30
  31 #if !ENABLE(JIT)
  32 #include "CodeBlock.h"
  33 #include "CommonSlowPaths.h"
  34 #include "LLIntCLoop.h"
  35 #include "LLIntSlowPaths.h"
  36 #include "JSCInlines.h"
  37 #include <wtf/Assertions.h>
  38 #include <wtf/MathExtras.h>
  39
  40 using namespace JSC::LLInt;
  41
  42 // LLInt C Loop opcodes
  43 // ====================
  44 // In the implementation of the C loop, the LLint trampoline glue functions
  45 // (e.g. llint_program_prologue, llint_eval_prologue, etc) are addressed as
  46 // if they are bytecode handlers. That means the names of the trampoline
  47 // functions will be added to the OpcodeID list via the
  48 // FOR_EACH_LLINT_OPCODE_EXTENSION() macro that FOR_EACH_OPCODE_ID()
  49 // includes.
  50 //
  51 // In addition, some JIT trampoline functions which are needed by LLInt
  52 // (e.g. getHostCallReturnValue, ctiOpThrowNotCaught) are also added as
  53 // bytecodes, and the CLoop will provide bytecode handlers for them.
  54 //
  55 // In the CLoop, we can only dispatch indirectly to these bytecodes
  56 // (including the LLInt and JIT extensions). All other dispatches
  57 // (i.e. goto's) must be to a known label (i.e. local / global labels).
  58
  59
  60 // How are the opcodes named?
  61 // ==========================
  62 // Here is a table to show examples of how each of the manifestation of the
  63 // opcodes are named:
  64 //
  65 //   Type:                        Opcode            Trampoline Glue
  66 //                                ======            ===============
  67 //   [In the llint .asm files]
  68 //   llint labels:                llint_op_enter    llint_program_prologue
  69 //
  70 //   OpcodeID:                    op_enter          llint_program
  71 //                                [in Opcode.h]     [in LLIntOpcode.h]
  72 //
  73 //   When using a switch statement dispatch in the CLoop, each "opcode" is
  74 //   a case statement:
  75 //   Opcode:                      case op_enter:    case llint_program_prologue:
  76 //
  77 //   When using a computed goto dispatch in the CLoop, each opcode is a label:
  78 //   Opcode:                      op_enter:         llint_program_prologue:
  79
  80
  81 //============================================================================
  82 // Define the opcode dispatch mechanism when using the C loop:
  83 //
  84
  85 // These are for building a C Loop interpreter:
  86 #define OFFLINE_ASM_BEGIN
  87 #define OFFLINE_ASM_END
  88
  89 #if ENABLE(OPCODE_TRACING)
  90 #define TRACE_OPCODE(opcode) dataLogF("   op %s\n", #opcode)
  91 #else
  92 #define TRACE_OPCODE(opcode)
  93 #endif
  94
  95 // To keep compilers happy in case of unused labels, force usage of the label:
  96 #define USE_LABEL(label) \
  97     do { \
  98         if (false) \
  99             goto label; \
 100     } while (false)
 101
 102 #define OFFLINE_ASM_OPCODE_LABEL(opcode) DEFINE_OPCODE(opcode) USE_LABEL(opcode); TRACE_OPCODE(opcode);
 103
 104 #define OFFLINE_ASM_GLOBAL_LABEL(label)  OFFLINE_ASM_GLUE_LABEL(label)
 105
 106 #if ENABLE(COMPUTED_GOTO_OPCODES)
 107 #define OFFLINE_ASM_GLUE_LABEL(label)  label: USE_LABEL(label);
 108 #else
 109 #define OFFLINE_ASM_GLUE_LABEL(label)  case label: label: USE_LABEL(label);
 110 #endif
 111
 112 #define OFFLINE_ASM_LOCAL_LABEL(label) label: USE_LABEL(label);
 113
 114
 115 //============================================================================
 116 // Some utilities:
 117 //
 118
 119 namespace JSC {
 120 namespace LLInt {
 121
 122 #if USE(JSVALUE32_64)
 123 static double Ints2Double(uint32_t lo, uint32_t hi)
 124 {
 125     union {
 126         double dval;
 127         uint64_t ival64;
 128     } u;
 129     u.ival64 = (static_cast<uint64_t>(hi) << 32) | lo;
 130     return u.dval;
 131 }
 132
 133 static void Double2Ints(double val, uint32_t& lo, uint32_t& hi)
 134 {
 135     union {
 136         double dval;
 137         uint64_t ival64;
 138     } u;
 139     u.dval = val;
 140     hi = static_cast<uint32_t>(u.ival64 >> 32);
 141     lo = static_cast<uint32_t>(u.ival64);
 142 }
 143 #endif // USE(JSVALUE32_64)
 144
 145 } // namespace LLint
 146
 147
 148 //============================================================================
 149 // CLoopRegister is the storage for an emulated CPU register.
 150 // It defines the policy of how ints smaller than intptr_t are packed into the
 151 // pseudo register, as well as hides endianness differences.
 152
 153 struct CLoopRegister {
 154     CLoopRegister() { i = static_cast<intptr_t>(0xbadbeef0baddbeef); }
 155     union {
 156         intptr_t i;
 157         uintptr_t u;
 158 #if USE(JSVALUE64)
 159 #if CPU(BIG_ENDIAN)
 160         struct {
 161             int32_t i32padding;
 162             int32_t i32;
 163         };
 164         struct {
 165             uint32_t u32padding;
 166             uint32_t u32;
 167         };
 168         struct {
 169             int8_t i8padding[7];
 170             int8_t i8;
 171         };
 172         struct {
 173             uint8_t u8padding[7];
 174             uint8_t u8;
 175         };
 176 #else // !CPU(BIG_ENDIAN)
 177         struct {
 178             int32_t i32;
 179             int32_t i32padding;
 180         };
 181         struct {
 182             uint32_t u32;
 183             uint32_t u32padding;
 184         };
 185         struct {
 186             int8_t i8;
 187             int8_t i8padding[7];
 188         };
 189         struct {
 190             uint8_t u8;
 191             uint8_t u8padding[7];
 192         };
 193 #endif // !CPU(BIG_ENDIAN)
 194 #else // !USE(JSVALUE64)
 195         int32_t i32;
 196         uint32_t u32;
 197
 198 #if CPU(BIG_ENDIAN)
 199         struct {
 200             int8_t i8padding[3];
 201             int8_t i8;
 202         };
 203         struct {
 204             uint8_t u8padding[3];
 205             uint8_t u8;
 206         };
 207
 208 #else // !CPU(BIG_ENDIAN)
 209         struct {
 210             int8_t i8;
 211             int8_t i8padding[3];
 212         };
 213         struct {
 214             uint8_t u8;
 215             uint8_t u8padding[3];
 216         };
 217 #endif // !CPU(BIG_ENDIAN)
 218 #endif // !USE(JSVALUE64)
 219
 220         intptr_t* ip;
 221         int8_t* i8p;
 222         void* vp;
 223         CallFrame* callFrame;
 224         ExecState* execState;
 225         void* instruction;
 226         VM* vm;
 227         JSCell* cell;
 228         ProtoCallFrame* protoCallFrame;
 229         NativeFunction nativeFunc;
 230 #if USE(JSVALUE64)
 231         int64_t i64;
 232         uint64_t u64;
 233         EncodedJSValue encodedJSValue;
 234         double castToDouble;
 235 #endif
 236         Opcode opcode;
 237     };
 238
 239     operator ExecState*() { return execState; }
 240     operator Instruction*() { return reinterpret_cast<Instruction*>(instruction); }
 241     operator VM*() { return vm; }
 242     operator ProtoCallFrame*() { return protoCallFrame; }
 243     operator Register*() { return reinterpret_cast<Register*>(vp); }
 244     operator JSCell*() { return cell; }
 245
 246 #if USE(JSVALUE64)
 247     inline void clearHighWord() { i32padding = 0; }
 248 #else
 249     inline void clearHighWord() { }
 250 #endif
 251 };
 252
 253 //============================================================================
 254 // The llint C++ interpreter loop:
 255 //
 256
 257 JSValue CLoop::execute(OpcodeID entryOpcodeID, void* executableAddress, VM* vm, ProtoCallFrame* protoCallFrame, bool isInitializationPass)
 258 {
 259     #define CAST reinterpret_cast
 260     #define SIGN_BIT32(x) ((x) & 0x80000000)
 261
 262     // One-time initialization of our address tables. We have to put this code
 263     // here because our labels are only in scope inside this function. The
 264     // caller (or one of its ancestors) is responsible for ensuring that this
 265     // is only called once during the initialization of the VM before threads
 266     // are at play.
 267     if (UNLIKELY(isInitializationPass)) {
 268 #if ENABLE(COMPUTED_GOTO_OPCODES)
 269         Opcode* opcodeMap = LLInt::opcodeMap();
 270         #define OPCODE_ENTRY(__opcode, length) \
 271             opcodeMap[__opcode] = bitwise_cast<void*>(&&__opcode);
 272         FOR_EACH_OPCODE_ID(OPCODE_ENTRY)
 273         #undef OPCODE_ENTRY
 274
 275         #define LLINT_OPCODE_ENTRY(__opcode, length) \
 276             opcodeMap[__opcode] = bitwise_cast<void*>(&&__opcode);
 277
 278         FOR_EACH_LLINT_NATIVE_HELPER(LLINT_OPCODE_ENTRY)
 279         #undef LLINT_OPCODE_ENTRY
 280 #endif
 281         // Note: we can only set the exceptionInstructions after we have
 282         // initialized the opcodeMap above. This is because getCodePtr()
 283         // can depend on the opcodeMap.
 284         Instruction* exceptionInstructions = LLInt::exceptionInstructions();
 285         for (int i = 0; i < maxOpcodeLength + 1; ++i)
 286             exceptionInstructions[i].u.pointer =
 287                 LLInt::getCodePtr(llint_throw_from_slow_path_trampoline);
 288
 289         return JSValue();
 290     }
 291
 292     // Define the pseudo registers used by the LLINT C Loop backend:
 293     ASSERT(sizeof(CLoopRegister) == sizeof(intptr_t));
 294
 295     union CLoopDoubleRegister {
 296         double d;
 297 #if USE(JSVALUE64)
 298         int64_t castToInt64;
 299 #endif
 300     };
 301
 302     // The CLoop llint backend is initially based on the ARMv7 backend, and
 303     // then further enhanced with a few instructions from the x86 backend to
 304     // support building for X64 targets. Hence, the shape of the generated
 305     // code and the usage convention of registers will look a lot like the
 306     // ARMv7 backend's.
 307     //
 308     // For example, on a 32-bit build:
 309     // 1. Outgoing args will be set up as follows:
 310     //    arg1 in t0 (r0 on ARM)
 311     //    arg2 in t1 (r1 on ARM)
 312     // 2. 32 bit return values will be in t0 (r0 on ARM).
 313     // 3. 64 bit return values (e.g. doubles) will be in t0,t1 (r0,r1 on ARM).
 314     //
 315     // But instead of naming these simulator registers based on their ARM
 316     // counterparts, we'll name them based on their original llint asm names.
 317     // This will make it easier to correlate the generated code with the
 318     // original llint asm code.
 319     //
 320     // On a 64-bit build, it more like x64 in that the registers are 64 bit.
 321     // Hence:
 322     // 1. Outgoing args are still the same: arg1 in t0, arg2 in t1, etc.
 323     // 2. 32 bit result values will be in the low 32-bit of t0.
 324     // 3. 64 bit result values will be in t0.
 325
 326     CLoopRegister t0, t1, t2, t3, t5, t7, sp, cfr, lr, pc;
 327 #if USE(JSVALUE64)
 328     CLoopRegister pcBase, tagTypeNumber, tagMask;
 329 #endif
 330     CLoopDoubleRegister d0, d1;
 331
 332     lr.opcode = getOpcode(llint_return_to_host);
 333     sp.vp = vm->interpreter->stack().topOfStack() + 1;
 334     cfr.callFrame = vm->topCallFrame;
 335 #ifndef NDEBUG
 336     void* startSP = sp.vp;
 337     CallFrame* startCFR = cfr.callFrame;
 338 #endif
 339
 340     // Initialize the incoming args for doVMEntryToJavaScript:
 341     t0.vp = executableAddress;
 342     t1.vm = vm;
 343     t2.protoCallFrame = protoCallFrame;
 344
 345 #if USE(JSVALUE64)
 346     // For the ASM llint, JITStubs takes care of this initialization. We do
 347     // it explicitly here for the C loop:
 348     tagTypeNumber.i = 0xFFFF000000000000;
 349     tagMask.i = 0xFFFF000000000002;
 350 #endif // USE(JSVALUE64)
 351
 352     // Interpreter variables for value passing between opcodes and/or helpers:
 353     NativeFunction nativeFunc = 0;
 354     JSValue functionReturnValue;
 355     Opcode opcode = getOpcode(entryOpcodeID);
 356
 357 #define PUSH(cloopReg) \
 358     do { \
 359         sp.ip--; \
 360         *sp.ip = cloopReg.i; \
 361     } while (false)
 362
 363 #define POP(cloopReg) \
 364     do { \
 365         cloopReg.i = *sp.ip; \
 366         sp.ip++; \
 367     } while (false)
 368
 369 #if ENABLE(OPCODE_STATS)
 370 #define RECORD_OPCODE_STATS(__opcode) OpcodeStats::recordInstruction(__opcode)
 371 #else
 372 #define RECORD_OPCODE_STATS(__opcode)
 373 #endif
 374
 375 #if USE(JSVALUE32_64)
 376 #define FETCH_OPCODE() pc.opcode
 377 #else // USE(JSVALUE64)
 378 #define FETCH_OPCODE() *bitwise_cast<Opcode*>(pcBase.i8p + pc.i * 8)
 379 #endif // USE(JSVALUE64)
 380
 381 #define NEXT_INSTRUCTION() \
 382     do {                         \
 383         opcode = FETCH_OPCODE(); \
 384         DISPATCH_OPCODE();       \
 385     } while (false)
 386
 387 #if ENABLE(COMPUTED_GOTO_OPCODES)
 388
 389     //========================================================================
 390     // Loop dispatch mechanism using computed goto statements:
 391
 392     #define DISPATCH_OPCODE() goto *opcode
 393
 394     #define DEFINE_OPCODE(__opcode) \
 395         __opcode: \
 396             RECORD_OPCODE_STATS(__opcode);
 397
 398     // Dispatch to the current PC's bytecode:
 399     DISPATCH_OPCODE();
 400
 401 #else // !ENABLE(COMPUTED_GOTO_OPCODES)
 402     //========================================================================
 403     // Loop dispatch mechanism using a C switch statement:
 404
 405     #define DISPATCH_OPCODE() goto dispatchOpcode
 406
 407     #define DEFINE_OPCODE(__opcode) \
 408         case __opcode: \
 409         __opcode: \
 410             RECORD_OPCODE_STATS(__opcode);
 411
 412     // Dispatch to the current PC's bytecode:
 413     dispatchOpcode:
 414     switch (opcode)
 415
 416 #endif // !ENABLE(COMPUTED_GOTO_OPCODES)
 417
 418     //========================================================================
 419     // Bytecode handlers:
 420     {
 421         // This is the file generated by offlineasm, which contains all of the
 422         // bytecode handlers for the interpreter, as compiled from
 423         // LowLevelInterpreter.asm and its peers.
 424
 425         #include "LLIntAssembly.h"
 426
 427         OFFLINE_ASM_GLUE_LABEL(llint_return_to_host)
 428         {
 429             ASSERT(startSP == sp.vp);
 430             ASSERT(startCFR == cfr.callFrame);
 431 #if USE(JSVALUE32_64)
 432             return JSValue(t1.i, t0.i); // returning JSValue(tag, payload);
 433 #else
 434             return JSValue::decode(t0.encodedJSValue);
 435 #endif
 436         }
 437
 438         // In the ASM llint, getHostCallReturnValue() is a piece of glue
 439         // function provided by the JIT (see jit/JITOperations.cpp).
 440         // We simulate it here with a pseduo-opcode handler.
 441         OFFLINE_ASM_GLUE_LABEL(getHostCallReturnValue)
 442         {
 443             // The part in getHostCallReturnValueWithExecState():
 444             JSValue result = vm->hostCallReturnValue;
 445 #if USE(JSVALUE32_64)
 446             t1.i = result.tag();
 447             t0.i = result.payload();
 448 #else
 449             t0.encodedJSValue = JSValue::encode(result);
 450 #endif
 451             opcode = lr.opcode;
 452             DISPATCH_OPCODE();
 453         }
 454
 455 #if !ENABLE(COMPUTED_GOTO_OPCODES)
 456     default:
 457         ASSERT(false);
 458 #endif
 459
 460     } // END bytecode handler cases.
 461
 462 #if ENABLE(COMPUTED_GOTO_OPCODES)
 463     // Keep the compiler happy so that it doesn't complain about unused
 464     // labels for the LLInt trampoline glue. The labels are automatically
 465     // emitted by label macros above, and some of them are referenced by
 466     // the llint generated code. Since we can't tell ahead of time which
 467     // will be referenced and which will be not, we'll just passify the
 468     // compiler on all such labels:
 469     #define LLINT_OPCODE_ENTRY(__opcode, length) \
 470         UNUSED_LABEL(__opcode);
 471         FOR_EACH_OPCODE_ID(LLINT_OPCODE_ENTRY);
 472     #undef LLINT_OPCODE_ENTRY
 473 #endif
 474
 475     #undef NEXT_INSTRUCTION
 476     #undef DEFINE_OPCODE
 477     #undef CHECK_FOR_TIMEOUT
 478     #undef CAST
 479     #undef SIGN_BIT32
 480
 481     return JSValue(); // to suppress a compiler warning.
 482 } // Interpreter::llintCLoopExecute()
 483
 484 } // namespace JSC
 485
 486 #elif !OS(WINDOWS)
 487
 488 //============================================================================
 489 // Define the opcode dispatch mechanism when using an ASM loop:
 490 //
 491
 492 // These are for building an interpreter from generated assembly code:
 493 #define OFFLINE_ASM_BEGIN   asm (
 494 #define OFFLINE_ASM_END     );
 495
 496 #define OFFLINE_ASM_OPCODE_LABEL(__opcode) OFFLINE_ASM_LOCAL_LABEL(llint_##__opcode)
 497 #define OFFLINE_ASM_GLUE_LABEL(__opcode)   OFFLINE_ASM_LOCAL_LABEL(__opcode)
 498
 499 #if CPU(ARM_THUMB2)
 500 #define OFFLINE_ASM_GLOBAL_LABEL(label)          \
 501     ".text\n"                                    \
 502     ".align 4\n"                                 \
 503     ".globl " SYMBOL_STRING(label) "\n"          \
 504     HIDE_SYMBOL(label) "\n"                      \
 505     ".thumb\n"                                   \
 506     ".thumb_func " THUMB_FUNC_PARAM(label) "\n"  \
 507     SYMBOL_STRING(label) ":\n"
 508 #elif CPU(ARM64)
 509 #define OFFLINE_ASM_GLOBAL_LABEL(label)         \
 510     ".text\n"                                   \
 511     ".align 4\n"                                \
 512     ".globl " SYMBOL_STRING(label) "\n"         \
 513     HIDE_SYMBOL(label) "\n"                     \
 514     SYMBOL_STRING(label) ":\n"
 515 #else
 516 #define OFFLINE_ASM_GLOBAL_LABEL(label)         \
 517     ".text\n"                                   \
 518     ".globl " SYMBOL_STRING(label) "\n"         \
 519     HIDE_SYMBOL(label) "\n"                     \
 520     SYMBOL_STRING(label) ":\n"
 521 #endif
 522
 523 #define OFFLINE_ASM_LOCAL_LABEL(label)   LOCAL_LABEL_STRING(label) ":\n"
 524
 525 // This is a file generated by offlineasm, which contains all of the assembly code
 526 // for the interpreter, as compiled from LowLevelInterpreter.asm.
 527 #include "LLIntAssembly.h"
 528
 529 #endif // ENABLE(JIT)