stackvm.cc 19.9 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

20 21 22
/*!
 *  Copyright (c) 2017 by Contributors
 * Implementation stack VM.
23
 * \file stackvm.cc
24 25
 */
#include <dmlc/thread_local.h>
26
#include <tvm/runtime/util.h>
27
#include <tvm/runtime/c_backend_api.h>
28
#include <algorithm>
29
#include "stackvm.h"
30 31

namespace tvm {
32
namespace runtime {
33 34 35 36 37 38 39 40 41 42 43 44 45

typedef dmlc::ThreadLocalStore<StackVM::State> StackVMStateStore;

StackVM::State* StackVM::ThreadLocalState() {
  return StackVMStateStore::Get();
}

#define STACK_VM_BINOP(OP, FIELD)                                 \
  {                                                               \
    stack[sp - 1].FIELD = stack[sp - 1].FIELD OP stack[sp].FIELD; \
    sp -= 1; pc += 1;                                             \
  }

46 47
#define STACK_VM_CMPOP(OP, FIELD)                                   \
  {                                                                 \
48
    stack[sp - 1].v_int64 = stack[sp - 1].FIELD OP stack[sp].FIELD; \
49
    sp -= 1; pc += 1;                                               \
50 51 52 53
  }

#define STACK_VM_LOAD(FIELD, DST_TYPE, SRC_TYPE)                        \
  {                                                                     \
54 55 56 57
    int index = code[pc + 1].v_int;                                     \
    stack[sp]FIELD = static_cast<DST_TYPE>(                             \
        static_cast<SRC_TYPE*>(stack[sp].v_handle)[index]);             \
    pc += 2;                                                            \
58 59 60 61
  }

#define STACK_VM_STORE(FIELD, DST_TYPE)                                 \
  {                                                                     \
62 63 64 65
    int index = code[pc + 1].v_int;                                     \
    static_cast<DST_TYPE*>(stack[sp - 1].v_handle)[index] =             \
        static_cast<DST_TYPE>(stack[sp]FIELD);                          \
    sp -= 2; pc += 2;                                                   \
66 67
  }

68 69
#define STACK_VM_PRINT_CODE0(CODE)                            \
  case CODE:  {                                                     \
70 71 72 73 74 75
    os << "[" << pc << "]\t" << #CODE << std::endl; return pc + 1;  \
  }

#define STACK_VM_PRINT_CODE1(CODE)                                      \
  case CODE:  {                                                         \
    os << "[" << pc << "]\t" << #CODE << " " << code[pc + 1].v_int << "\n" \
76
       <<  "[" << pc + 1 << "]" << std::endl;                           \
77 78 79
        return pc + 2;                                                  \
  }

80 81 82 83 84 85 86 87 88 89
#define STACK_VM_PRINT_CODE2(CODE)                                      \
  case CODE:  {                                                         \
    os << "[" << pc << "]\t" << #CODE                                   \
        << " " << code[pc + 1].v_int                                    \
        << " " << code[pc + 2].v_int << "\n"                            \
       <<  "[" << pc + 1 << "]" << std::endl                            \
       <<  "[" << pc + 2 << "]" << std::endl;                           \
        return pc + 3;                                                  \
  }

90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125
#define STACK_VM_PRINT_HEAP_ACCESS(CODE)                                \
  case CODE:  {                                                         \
    os << "[" << pc << "]\t" << #CODE << " " << code[pc + 1].v_int      \
       << " " << heap_id_name[code[pc + 1].v_int] << "\n"               \
       <<  "[" << pc + 1 << "]" << std::endl;                           \
        return pc + 2;                                                  \
  }

#define STACK_VM_PRINT_JUMP(CODE)                                     \
  case CODE:  {                                                        \
    os << "[" << pc << "]\t" << #CODE << " rel=" << code[pc + 1].v_int \
       << " to " << pc + code[pc + 1].v_int << '\n'                    \
       << "[" << pc + 1 << "]" << std::endl;                         \
    return pc + 2;                                                     \
  }


int64_t StackVM::PrintCode(std::ostream& os, int64_t pc) const {
  switch (code[pc].op_code) {
    // int
    STACK_VM_PRINT_CODE0(ADD_I64);
    STACK_VM_PRINT_CODE0(SUB_I64);
    STACK_VM_PRINT_CODE0(MUL_I64);
    STACK_VM_PRINT_CODE0(MOD_I64);
    STACK_VM_PRINT_CODE0(DIV_I64);
    STACK_VM_PRINT_CODE0(EQ_I64);
    STACK_VM_PRINT_CODE0(LT_I64);
    STACK_VM_PRINT_CODE0(LE_I64);
    // floats
    STACK_VM_PRINT_CODE0(ADD_F64);
    STACK_VM_PRINT_CODE0(SUB_F64);
    STACK_VM_PRINT_CODE0(MUL_F64);
    STACK_VM_PRINT_CODE0(DIV_F64);
    STACK_VM_PRINT_CODE0(EQ_F64);
    STACK_VM_PRINT_CODE0(LT_F64);
    STACK_VM_PRINT_CODE0(LE_F64);
126 127
    // handle.
    STACK_VM_PRINT_CODE0(EQ_HANDLE);
128 129
    // addressing load
    STACK_VM_PRINT_CODE1(ARRAY_LOAD_UINT32);
130 131 132 133 134 135 136 137 138 139 140
    STACK_VM_PRINT_CODE1(ARRAY_LOAD_INT32);
    STACK_VM_PRINT_CODE1(ARRAY_LOAD_INT64);
    STACK_VM_PRINT_CODE1(ARRAY_LOAD_FP64);
    STACK_VM_PRINT_CODE1(ARRAY_LOAD_HANDLE);
    STACK_VM_PRINT_CODE1(ARRAY_LOAD_TVMVALUE);
    STACK_VM_PRINT_CODE1(ARRAY_STORE_UINT32);
    STACK_VM_PRINT_CODE1(ARRAY_STORE_INT32);
    STACK_VM_PRINT_CODE1(ARRAY_STORE_INT64);
    STACK_VM_PRINT_CODE1(ARRAY_STORE_FP64);
    STACK_VM_PRINT_CODE1(ARRAY_STORE_HANDLE);
    STACK_VM_PRINT_CODE1(ARRAY_STORE_TVMVALUE);
141 142 143 144 145 146 147 148 149 150 151 152 153 154 155
    STACK_VM_PRINT_CODE0(NOT);
    STACK_VM_PRINT_CODE0(ADDR_ADD);
    // stack ops
    STACK_VM_PRINT_CODE1(PUSH_I64);
    STACK_VM_PRINT_CODE1(PUSH_VALUE);
    STACK_VM_PRINT_CODE0(POP);
    STACK_VM_PRINT_CODE0(SELECT);
    STACK_VM_PRINT_HEAP_ACCESS(STORE_HEAP);
    STACK_VM_PRINT_HEAP_ACCESS(LOAD_HEAP);
    STACK_VM_PRINT_CODE1(ASSERT);
    STACK_VM_PRINT_JUMP(RJUMP_IF_TRUE);
    STACK_VM_PRINT_JUMP(RJUMP_IF_FALSE);
    STACK_VM_PRINT_JUMP(RJUMP);
    STACK_VM_PRINT_CODE1(ASSERT_SP);
    // Intrinsics
156 157 158 159
    STACK_VM_PRINT_CODE2(TVM_STRUCT_GET);
    STACK_VM_PRINT_CODE2(TVM_STRUCT_SET);
    // Allocate data by 8 bytes.
    STACK_VM_PRINT_CODE1(TVM_STACK_ALLOCA_BY_8BYTE);
160 161 162
    STACK_VM_PRINT_CODE0(TVM_DEVICE_ALLOCA);
    STACK_VM_PRINT_CODE0(TVM_DEVICE_FREE);
    STACK_VM_PRINT_CODE0(TVM_THROW_LAST_ERROR);
163
    // packed function.
164 165 166 167
    case CALL_PACKED_LOWERED: {
      int call_fid = code[pc + 1].v_int;
      int begin = code[pc + 2].v_int;
      int end = code[pc + 3].v_int;
168
      os << "[" << pc << "]\tCALL_PACKED_FUNC "
169 170 171
         << " fid=" << call_fid
         << " begin=" << begin
         << " end=" << end;
172
      os << '\n';
173 174
      for (int i = 0; i < 3; ++i) {
        os << "[" << pc + 1 + i << "]" << std::endl;
175
      }
176
      return pc + 4;
177
    }
178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194
  }
  LOG(FATAL) << "unknown op code " << code[pc].op_code;
  return 0;
}

std::ostream& operator<<(std::ostream& os, const StackVM& vm) {  // NOLINT(*)
  int64_t pc = 0;
  const int64_t code_size = static_cast<int64_t>(vm.code.size());
  os << "Program dump: code-size=" << code_size << '\n'
     << "----------begin-----------------\n";
  while (pc < code_size) {
    pc = vm.PrintCode(os, pc);
  }
  os << "----------end--------------------\n";
  return os;
}

195 196
void StackVM::Run(const runtime::TVMArgs& args,
                  runtime::ModuleNode* mod_ctx) const {
197
  StackVM::State* s = StackVM::ThreadLocalState();
198 199 200
  if (s->heap.size() < heap_size) {
    s->heap.resize(heap_size);
  }
201 202
  s->sp = 0;
  s->pc = 0;
203
  s->mod_ctx = mod_ctx;
204 205 206 207 208 209
  s->heap[0].v_handle = (void*)args.values;  // NOLINT(*)
  s->heap[1].v_handle = (void*)args.type_codes;  // NOLINT(*)
  s->heap[2].v_int64 = args.num_args;
  this->Run(s);
}

210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246
void StackVM::InitCache() {
  extern_func_cache_.clear();
  extern_func_cache_.resize(
      extern_func_name.size(), PackedFunc(nullptr));
}

void StackVM::Save(dmlc::Stream* strm) const {
  // to be endian invariant.
  std::vector<int32_t> code_copy(code.size());
  std::transform(code.begin(), code.end(), code_copy.begin(), [](Code c) {
      return c.v_int;
    });
  strm->Write(code_copy);
  strm->Write(str_data);
  strm->Write(extern_func_name);
  strm->Write(heap_id_name);
  strm->Write(heap_size);
  strm->Write(stack_size);
}

bool StackVM::Load(dmlc::Stream* strm)  {
  // to be endian invariant.
  std::vector<int32_t> code_copy;
  if (!strm->Read(&code_copy)) return false;
  code.resize(code_copy.size());
  std::transform(code_copy.begin(), code_copy.end(), code.begin(), [](int v) {
      Code code; code.v_int = v; return code;
    });
  if (!strm->Read(&str_data)) return false;
  if (!strm->Read(&extern_func_name)) return false;
  if (!strm->Read(&heap_id_name)) return false;
  if (!strm->Read(&heap_size)) return false;
  if (!strm->Read(&stack_size)) return false;
  this->InitCache();
  return true;
}

247 248 249
void StackVM::Run(State* s) const {
  int64_t sp = s->sp;
  int64_t pc = s->pc;
250
  int64_t alloca_sp = s->sp;
251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277
  std::vector<TVMValue>& stack = s->stack;
  std::vector<TVMValue>& heap = s->heap;
  if (stack.size() < stack_size) {
    stack.resize(stack_size);
  }
  int64_t stack_cap = static_cast<int64_t>(stack_size - 4);
  if (heap.size() < heap_size) {
    heap.resize(heap_size);
  }
  const int64_t code_size = static_cast<int64_t>(code.size());
  while (pc < code_size) {
    switch (code[pc].op_code) {
      case ADD_I64: STACK_VM_BINOP(+, v_int64); break;
      case SUB_I64: STACK_VM_BINOP(-, v_int64); break;
      case MUL_I64: STACK_VM_BINOP(*, v_int64); break;
      case DIV_I64: STACK_VM_BINOP(/, v_int64); break;
      case MOD_I64: STACK_VM_BINOP(%, v_int64); break;
      case EQ_I64: STACK_VM_CMPOP(==, v_int64); break;
      case LT_I64: STACK_VM_CMPOP(<, v_int64); break;
      case LE_I64: STACK_VM_CMPOP(<=, v_int64); break;
      case ADD_F64: STACK_VM_BINOP(+, v_float64); break;
      case SUB_F64: STACK_VM_BINOP(-, v_float64); break;
      case MUL_F64: STACK_VM_BINOP(*, v_float64); break;
      case DIV_F64: STACK_VM_BINOP(/, v_float64); break;
      case EQ_F64: STACK_VM_CMPOP(==, v_float64); break;
      case LT_F64: STACK_VM_CMPOP(<, v_float64); break;
      case LE_F64: STACK_VM_CMPOP(<=, v_float64); break;
278
      case EQ_HANDLE: STACK_VM_CMPOP(==, v_handle); break;
279
      // addressing
280 281 282 283 284 285 286 287 288 289 290 291 292 293
      case ARRAY_LOAD_UINT32: STACK_VM_LOAD(.v_int64, int64_t, uint32_t); break;
      case ARRAY_LOAD_INT32: STACK_VM_LOAD(.v_int64, int64_t, int32_t); break;
      case ARRAY_LOAD_INT64: STACK_VM_LOAD(.v_int64, int64_t, int64_t); break;
      case ARRAY_LOAD_FP64: STACK_VM_LOAD(.v_float64, double, double); break;
      case ARRAY_LOAD_HANDLE: STACK_VM_LOAD(.v_handle, void*, void*); break;
      case ARRAY_LOAD_TVMVALUE: STACK_VM_LOAD(, TVMValue, TVMValue); break;
      // store
      case ARRAY_STORE_UINT32: STACK_VM_STORE(.v_int64, uint32_t); break;
      case ARRAY_STORE_INT32: STACK_VM_STORE(.v_int64, int32_t); break;
      case ARRAY_STORE_INT64: STACK_VM_STORE(.v_int64, int64_t); break;
      case ARRAY_STORE_FP64: STACK_VM_STORE(.v_float64, double); break;
      case ARRAY_STORE_HANDLE: STACK_VM_STORE(.v_handle, void*); break;
      case ARRAY_STORE_TVMVALUE: STACK_VM_STORE(, TVMValue); break;
      // add
294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375
      case ADDR_ADD: {
        stack[sp - 1].v_handle = (char*)(stack[sp - 1].v_handle) + stack[sp].v_int64;  // NOLINT(*)
        sp = sp - 1;
        pc = pc + 1;
        break;
      }
      case NOT: {
        stack[sp].v_int64 = !stack[sp].v_int64;
        pc += 1;
        break;
      }
      case PUSH_I64: {
        stack[sp + 1].v_int64 = code[pc + 1].v_int;
        sp += 1;
        pc += 2;
        break;
      }
      case PUSH_VALUE: {
        int relpos = code[pc + 1].v_int;
        CHECK_LE(relpos, 0);
        stack[sp + 1] = stack[sp + relpos];
        sp += 1;
        pc += 2;
        break;
      }
      case POP: {
        sp -= 1;
        pc += 1;
        break;
      }
      case SELECT: {
        stack[sp - 2] = (stack[sp].v_int64 ? stack[sp - 2] : stack[sp - 1]);
        sp -= 2;
        pc += 1;
        break;
      }
      case LOAD_HEAP: {
        stack[sp + 1] = heap[code[pc + 1].v_int];
        sp += 1;
        pc += 2;
        break;
      }
      case STORE_HEAP: {
        heap[code[pc + 1].v_int] = stack[sp];
        sp -= 1;
        pc += 2;
        break;
      }
      case ASSERT: {
        CHECK(stack[sp].v_int64) << str_data[code[pc + 1].v_int];
        sp -= 1;
        pc += 2;
        break;
      }
      case RJUMP_IF_TRUE: {
        if (stack[sp].v_int64) {
          pc += code[pc + 1].v_int;
        } else {
          pc += 2;
        }
        break;
      }
      case RJUMP_IF_FALSE: {
        if (!stack[sp].v_int64) {
          pc += code[pc + 1].v_int;
        } else {
          pc += 2;
        }
        break;
      }
      case RJUMP: {
        pc += code[pc + 1].v_int;
        break;
      }
      case ASSERT_SP: {
        int64_t expected = code[pc + 1].v_int;
        CHECK_EQ(sp, expected)
            << "sp assertion failed, expected="
            << expected << " now=" << sp << ", pc=" << pc;
        pc += 2;
        break;
      }
376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392
      case CALL_PACKED_LOWERED: {
        // call packed function.
        TVMValue* value_stack = static_cast<TVMValue*>(stack[sp - 1].v_handle);
        int* type_stack = static_cast<int*>(stack[sp].v_handle);
        int call_fid = code[pc + 1].v_int;
        int begin = code[pc + 2].v_int;
        int end = code[pc + 3].v_int;
        int num_args = end - begin;
        static_assert(sizeof(Code) == sizeof(int) &&
                      alignof(Code) == alignof(int), "asusmption");
        runtime::TVMRetValue rv;
        GetExtern(s, call_fid).CallPacked(
            runtime::TVMArgs(value_stack + begin, type_stack + begin, num_args), &rv);
        sp = sp - 1;
        stack[sp] = rv.value();
        pc += 4;
        break;
393
      }
394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445
      // intrinsics
      case TVM_STRUCT_GET: {
        using namespace ir;
        int index = code[pc + 1].v_int;
        int kind = code[pc + 2].v_int;
        TVMArray* arr = static_cast<TVMArray*>(stack[sp].v_handle);
        switch (kind) {
          case intrinsic::kArrData: {
            stack[sp].v_handle = arr[index].data; break;
          }
          case intrinsic::kArrShape: {
            stack[sp].v_handle = arr[index].shape; break;
          }
          case intrinsic::kArrStrides: {
            stack[sp].v_handle = arr[index].strides; break;
          }
          case intrinsic::kArrNDim: {
            stack[sp].v_int64 = arr[index].ndim; break;
          }
          case intrinsic::kArrTypeCode: {
            stack[sp].v_int64 = static_cast<int64_t>(
                arr[index].dtype.code); break;
          }
          case intrinsic::kArrTypeBits: {
            stack[sp].v_int64 = static_cast<int64_t>(
                arr[index].dtype.bits); break;
          }
          case intrinsic::kArrTypeLanes: {
            stack[sp].v_int64 = static_cast<int64_t>(
                arr[index].dtype.lanes); break;
          }
          case intrinsic::kArrByteOffset: {
            stack[sp].v_int64 = static_cast<int64_t>(
                arr[index].byte_offset); break;
          }
          case intrinsic::kArrDeviceId: {
            stack[sp].v_int64 = arr[index].ctx.device_id; break;
          }
          case intrinsic::kArrDeviceType: {
            stack[sp].v_int64 = static_cast<int64_t>(
                arr[index].ctx.device_type); break;
          }
          case intrinsic::kArrAddr: {
            stack[sp].v_handle = arr + index; break;
          }
          case intrinsic::kTVMValueContent: {
            stack[sp] = static_cast<TVMValue*>(stack[sp].v_handle)[index]; break;
          }
          default: LOG(FATAL) << "unhandled get " << kind;
        }
        pc = pc + 3;
        break;
446
      }
447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499
      case TVM_STRUCT_SET: {
        using namespace ir;
        int index = code[pc + 1].v_int;
        int kind = code[pc + 2].v_int;
        TVMArray* arr = static_cast<TVMArray*>(stack[sp - 1].v_handle);
        switch (kind) {
          case intrinsic::kArrData: {
            arr[index].data = stack[sp].v_handle; break;
          }
          case intrinsic::kArrShape: {
            arr[index].shape = static_cast<int64_t*>(stack[sp].v_handle);
            break;
          }
          case intrinsic::kArrStrides: {
            arr[index].strides = static_cast<int64_t*>(stack[sp].v_handle);
            break;
          }
          case intrinsic::kArrNDim: {
            arr[index].ndim = static_cast<int>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kArrTypeCode: {
            arr[index].dtype.code = static_cast<uint8_t>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kArrTypeBits: {
            arr[index].dtype.bits = static_cast<uint8_t>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kArrTypeLanes: {
            arr[index].dtype.lanes = static_cast<uint16_t>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kArrByteOffset: {
            arr[index].byte_offset = static_cast<uint64_t>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kArrDeviceId: {
            arr[index].ctx.device_id = static_cast<int>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kArrDeviceType: {
            arr[index].ctx.device_type = static_cast<DLDeviceType>(stack[sp].v_int64);
            break;
          }
          case intrinsic::kTVMValueContent: {
            static_cast<TVMValue*>(stack[sp - 1].v_handle)[index] = stack[sp]; break;
          }
          default: LOG(FATAL) << "unhandled tvm_struct_set " << kind;
        }
        sp -= 2;
        pc += 3;
        break;
500
      }
501 502 503 504 505 506 507 508 509 510
      // alloca
      case TVM_STACK_ALLOCA_BY_8BYTE: {
        static_assert(sizeof(TVMValue) == 8, "invariance");
        int num = code[pc + 1].v_int;
        void* addr = &stack[sp] + 1;
        sp = sp + num + 1;
        alloca_sp = sp - 1;
        stack[sp].v_handle = addr;
        pc = pc + 2;
        break;
511
      }
512
      case TVM_DEVICE_ALLOCA: {
513 514 515 516 517 518 519 520 521
        int device_type = static_cast<int>(stack[sp - 4].v_int64);
        int device_id = static_cast<int>(stack[sp - 3].v_int64);
        size_t nbytes = static_cast<size_t>(stack[sp - 2].v_int64);
        int dtype_code_hint = static_cast<int>(stack[sp - 1].v_int64);
        int dtype_bits_hint = static_cast<int>(stack[sp].v_int64);
        void* ptr = TVMBackendAllocWorkspace(device_type, device_id, nbytes,
                                             dtype_code_hint, dtype_bits_hint);
        stack[sp - 4].v_handle = ptr;
        sp = sp - 4;
522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538
        pc = pc + 1;
        break;
      }
      case TVM_DEVICE_FREE: {
        int device_type = static_cast<int>(stack[sp - 2].v_int64);
        int device_id = static_cast<int>(stack[sp - 1].v_int64);
        void* ptr = stack[sp].v_handle;
        int ret = TVMBackendFreeWorkspace(device_type, device_id, ptr);
        stack[sp - 2].v_int64 = ret;
        sp = sp - 2;
        pc = pc + 1;
        break;
      }
      case TVM_THROW_LAST_ERROR: {
        LOG(FATAL) << TVMGetLastError();
        break;
      }
539
    }
540
    CHECK_GE(sp, alloca_sp) << "touch allocated space";
541 542 543 544
    CHECK_LT(sp, stack_cap) << "Stack overflow";
  }
}

545
const PackedFunc& StackVM::GetExtern(State* s, int fid) const {
546 547 548
  CHECK_LT(static_cast<size_t>(fid), extern_func_cache_.size());
  // allow race write in this, since write is idempotent
  PackedFunc& f = extern_func_cache_[fid];
549
  if (f == nullptr) {
550
    CHECK(s->mod_ctx != nullptr)
551
        << "No local context is set in stackvm";
552
    const PackedFunc* pf = s->mod_ctx->GetFuncFromEnv(extern_func_name[fid]);
553 554 555 556 557 558
    CHECK(pf != nullptr);
    f = *pf;
  }
  return f;
}

559
}  // namespace runtime
560
}  // namespace tvm