lib/ExecutionEngine/Interpreter/ExternalFunctions.cpp

   1 //===-- ExternalFunctions.cpp - Implement External Functions --------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  This file contains both code to deal with invoking "external" functions, but
  10 //  also contains code that implements "exported" external functions.
  11 //
  12 //  There are currently two mechanisms for handling external functions in the
  13 //  Interpreter.  The first is to implement lle_* wrapper functions that are
  14 //  specific to well-known library functions which manually translate the
  15 //  arguments from GenericValues and make the call.  If such a wrapper does
  16 //  not exist, and libffi is available, then the Interpreter will attempt to
  17 //  invoke the function using libffi, after finding its address.
  18 //
  19 //===----------------------------------------------------------------------===//
  20
  21 #include "Interpreter.h"
  22 #include "llvm/ADT/APInt.h"
  23 #include "llvm/ADT/ArrayRef.h"
  24 #include "llvm/Config/config.h" // Detect libffi
  25 #include "llvm/ExecutionEngine/GenericValue.h"
  26 #include "llvm/IR/DataLayout.h"
  27 #include "llvm/IR/DerivedTypes.h"
  28 #include "llvm/IR/Function.h"
  29 #include "llvm/IR/Type.h"
  30 #include "llvm/Support/Casting.h"
  31 #include "llvm/Support/DynamicLibrary.h"
  32 #include "llvm/Support/ErrorHandling.h"
  33 #include "llvm/Support/ManagedStatic.h"
  34 #include "llvm/Support/Mutex.h"
  35 #include "llvm/Support/raw_ostream.h"
  36 #include <cassert>
  37 #include <cmath>
  38 #include <csignal>
  39 #include <cstdint>
  40 #include <cstdio>
  41 #include <cstring>
  42 #include <map>
  43 #include <mutex>
  44 #include <string>
  45 #include <utility>
  46 #include <vector>
  47
  48 #ifdef HAVE_FFI_CALL
  49 #ifdef HAVE_FFI_H
  50 #include <ffi.h>
  51 #define USE_LIBFFI
  52 #elif HAVE_FFI_FFI_H
  53 #include <ffi/ffi.h>
  54 #define USE_LIBFFI
  55 #endif
  56 #endif
  57
  58 using namespace llvm;
  59
  60 static ManagedStatic<sys::Mutex> FunctionsLock;
  61
  62 typedef GenericValue (*ExFunc)(FunctionType *, ArrayRef<GenericValue>);
  63 static ManagedStatic<std::map<const Function *, ExFunc> > ExportedFunctions;
  64 static ManagedStatic<std::map<std::string, ExFunc> > FuncNames;
  65
  66 #ifdef USE_LIBFFI
  67 typedef void (*RawFunc)();
  68 static ManagedStatic<std::map<const Function *, RawFunc> > RawFunctions;
  69 #endif
  70
  71 static Interpreter *TheInterpreter;
  72
  73 static char getTypeID(Type *Ty) {
  74   switch (Ty->getTypeID()) {
  75   case Type::VoidTyID:    return 'V';
  76   case Type::IntegerTyID:
  77     switch (cast<IntegerType>(Ty)->getBitWidth()) {
  78       case 1:  return 'o';
  79       case 8:  return 'B';
  80       case 16: return 'S';
  81       case 32: return 'I';
  82       case 64: return 'L';
  83       default: return 'N';
  84     }
  85   case Type::FloatTyID:   return 'F';
  86   case Type::DoubleTyID:  return 'D';
  87   case Type::PointerTyID: return 'P';
  88   case Type::FunctionTyID:return 'M';
  89   case Type::StructTyID:  return 'T';
  90   case Type::ArrayTyID:   return 'A';
  91   default: return 'U';
  92   }
  93 }
  94
  95 // Try to find address of external function given a Function object.
  96 // Please note, that interpreter doesn't know how to assemble a
  97 // real call in general case (this is JIT job), that's why it assumes,
  98 // that all external functions has the same (and pretty "general") signature.
  99 // The typical example of such functions are "lle_X_" ones.
 100 static ExFunc lookupFunction(const Function *F) {
 101   // Function not found, look it up... start by figuring out what the
 102   // composite function name should be.
 103   std::string ExtName = "lle_";
 104   FunctionType *FT = F->getFunctionType();
 105   ExtName += getTypeID(FT->getReturnType());
 106   for (Type *T : FT->params())
 107     ExtName += getTypeID(T);
 108   ExtName += ("_" + F->getName()).str();
 109
 110   sys::ScopedLock Writer(*FunctionsLock);
 111   ExFunc FnPtr = (*FuncNames)[ExtName];
 112   if (!FnPtr)
 113     FnPtr = (*FuncNames)[("lle_X_" + F->getName()).str()];
 114   if (!FnPtr)  // Try calling a generic function... if it exists...
 115     FnPtr = (ExFunc)(intptr_t)sys::DynamicLibrary::SearchForAddressOfSymbol(
 116         ("lle_X_" + F->getName()).str());
 117   if (FnPtr)
 118     ExportedFunctions->insert(std::make_pair(F, FnPtr));  // Cache for later
 119   return FnPtr;
 120 }
 121
 122 #ifdef USE_LIBFFI
 123 static ffi_type *ffiTypeFor(Type *Ty) {
 124   switch (Ty->getTypeID()) {
 125     case Type::VoidTyID: return &ffi_type_void;
 126     case Type::IntegerTyID:
 127       switch (cast<IntegerType>(Ty)->getBitWidth()) {
 128         case 8:  return &ffi_type_sint8;
 129         case 16: return &ffi_type_sint16;
 130         case 32: return &ffi_type_sint32;
 131         case 64: return &ffi_type_sint64;
 132       }
 133     case Type::FloatTyID:   return &ffi_type_float;
 134     case Type::DoubleTyID:  return &ffi_type_double;
 135     case Type::PointerTyID: return &ffi_type_pointer;
 136     default: break;
 137   }
 138   // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
 139   report_fatal_error("Type could not be mapped for use with libffi.");
 140   return NULL;
 141 }
 142
 143 static void *ffiValueFor(Type *Ty, const GenericValue &AV,
 144                          void *ArgDataPtr) {
 145   switch (Ty->getTypeID()) {
 146     case Type::IntegerTyID:
 147       switch (cast<IntegerType>(Ty)->getBitWidth()) {
 148         case 8: {
 149           int8_t *I8Ptr = (int8_t *) ArgDataPtr;
 150           *I8Ptr = (int8_t) AV.IntVal.getZExtValue();
 151           return ArgDataPtr;
 152         }
 153         case 16: {
 154           int16_t *I16Ptr = (int16_t *) ArgDataPtr;
 155           *I16Ptr = (int16_t) AV.IntVal.getZExtValue();
 156           return ArgDataPtr;
 157         }
 158         case 32: {
 159           int32_t *I32Ptr = (int32_t *) ArgDataPtr;
 160           *I32Ptr = (int32_t) AV.IntVal.getZExtValue();
 161           return ArgDataPtr;
 162         }
 163         case 64: {
 164           int64_t *I64Ptr = (int64_t *) ArgDataPtr;
 165           *I64Ptr = (int64_t) AV.IntVal.getZExtValue();
 166           return ArgDataPtr;
 167         }
 168       }
 169     case Type::FloatTyID: {
 170       float *FloatPtr = (float *) ArgDataPtr;
 171       *FloatPtr = AV.FloatVal;
 172       return ArgDataPtr;
 173     }
 174     case Type::DoubleTyID: {
 175       double *DoublePtr = (double *) ArgDataPtr;
 176       *DoublePtr = AV.DoubleVal;
 177       return ArgDataPtr;
 178     }
 179     case Type::PointerTyID: {
 180       void **PtrPtr = (void **) ArgDataPtr;
 181       *PtrPtr = GVTOP(AV);
 182       return ArgDataPtr;
 183     }
 184     default: break;
 185   }
 186   // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
 187   report_fatal_error("Type value could not be mapped for use with libffi.");
 188   return NULL;
 189 }
 190
 191 static bool ffiInvoke(RawFunc Fn, Function *F, ArrayRef<GenericValue> ArgVals,
 192                       const DataLayout &TD, GenericValue &Result) {
 193   ffi_cif cif;
 194   FunctionType *FTy = F->getFunctionType();
 195   const unsigned NumArgs = F->arg_size();
 196
 197   // TODO: We don't have type information about the remaining arguments, because
 198   // this information is never passed into ExecutionEngine::runFunction().
 199   if (ArgVals.size() > NumArgs && F->isVarArg()) {
 200     report_fatal_error("Calling external var arg function '" + F->getName()
 201                       + "' is not supported by the Interpreter.");
 202   }
 203
 204   unsigned ArgBytes = 0;
 205
 206   std::vector<ffi_type*> args(NumArgs);
 207   for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
 208        A != E; ++A) {
 209     const unsigned ArgNo = A->getArgNo();
 210     Type *ArgTy = FTy->getParamType(ArgNo);
 211     args[ArgNo] = ffiTypeFor(ArgTy);
 212     ArgBytes += TD.getTypeStoreSize(ArgTy);
 213   }
 214
 215   SmallVector<uint8_t, 128> ArgData;
 216   ArgData.resize(ArgBytes);
 217   uint8_t *ArgDataPtr = ArgData.data();
 218   SmallVector<void*, 16> values(NumArgs);
 219   for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
 220        A != E; ++A) {
 221     const unsigned ArgNo = A->getArgNo();
 222     Type *ArgTy = FTy->getParamType(ArgNo);
 223     values[ArgNo] = ffiValueFor(ArgTy, ArgVals[ArgNo], ArgDataPtr);
 224     ArgDataPtr += TD.getTypeStoreSize(ArgTy);
 225   }
 226
 227   Type *RetTy = FTy->getReturnType();
 228   ffi_type *rtype = ffiTypeFor(RetTy);
 229
 230   if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, NumArgs, rtype, args.data()) ==
 231       FFI_OK) {
 232     SmallVector<uint8_t, 128> ret;
 233     if (RetTy->getTypeID() != Type::VoidTyID)
 234       ret.resize(TD.getTypeStoreSize(RetTy));
 235     ffi_call(&cif, Fn, ret.data(), values.data());
 236     switch (RetTy->getTypeID()) {
 237       case Type::IntegerTyID:
 238         switch (cast<IntegerType>(RetTy)->getBitWidth()) {
 239           case 8:  Result.IntVal = APInt(8 , *(int8_t *) ret.data()); break;
 240           case 16: Result.IntVal = APInt(16, *(int16_t*) ret.data()); break;
 241           case 32: Result.IntVal = APInt(32, *(int32_t*) ret.data()); break;
 242           case 64: Result.IntVal = APInt(64, *(int64_t*) ret.data()); break;
 243         }
 244         break;
 245       case Type::FloatTyID:   Result.FloatVal   = *(float *) ret.data(); break;
 246       case Type::DoubleTyID:  Result.DoubleVal  = *(double*) ret.data(); break;
 247       case Type::PointerTyID: Result.PointerVal = *(void **) ret.data(); break;
 248       default: break;
 249     }
 250     return true;
 251   }
 252
 253   return false;
 254 }
 255 #endif // USE_LIBFFI
 256
 257 GenericValue Interpreter::callExternalFunction(Function *F,
 258                                                ArrayRef<GenericValue> ArgVals) {
 259   TheInterpreter = this;
 260
 261   std::unique_lock<sys::Mutex> Guard(*FunctionsLock);
 262
 263   // Do a lookup to see if the function is in our cache... this should just be a
 264   // deferred annotation!
 265   std::map<const Function *, ExFunc>::iterator FI = ExportedFunctions->find(F);
 266   if (ExFunc Fn = (FI == ExportedFunctions->end()) ? lookupFunction(F)
 267                                                    : FI->second) {
 268     Guard.unlock();
 269     return Fn(F->getFunctionType(), ArgVals);
 270   }
 271
 272 #ifdef USE_LIBFFI
 273   std::map<const Function *, RawFunc>::iterator RF = RawFunctions->find(F);
 274   RawFunc RawFn;
 275   if (RF == RawFunctions->end()) {
 276     RawFn = (RawFunc)(intptr_t)
 277       sys::DynamicLibrary::SearchForAddressOfSymbol(F->getName());
 278     if (!RawFn)
 279       RawFn = (RawFunc)(intptr_t)getPointerToGlobalIfAvailable(F);
 280     if (RawFn != 0)
 281       RawFunctions->insert(std::make_pair(F, RawFn));  // Cache for later
 282   } else {
 283     RawFn = RF->second;
 284   }
 285
 286   Guard.unlock();
 287
 288   GenericValue Result;
 289   if (RawFn != 0 && ffiInvoke(RawFn, F, ArgVals, getDataLayout(), Result))
 290     return Result;
 291 #endif // USE_LIBFFI
 292
 293   if (F->getName() == "__main")
 294     errs() << "Tried to execute an unknown external function: "
 295       << *F->getType() << " __main\n";
 296   else
 297     report_fatal_error("Tried to execute an unknown external function: " +
 298                        F->getName());
 299 #ifndef USE_LIBFFI
 300   errs() << "Recompiling LLVM with --enable-libffi might help.\n";
 301 #endif
 302   return GenericValue();
 303 }
 304
 305 //===----------------------------------------------------------------------===//
 306 //  Functions "exported" to the running application...
 307 //
 308
 309 // void atexit(Function*)
 310 static GenericValue lle_X_atexit(FunctionType *FT,
 311                                  ArrayRef<GenericValue> Args) {
 312   assert(Args.size() == 1);
 313   TheInterpreter->addAtExitHandler((Function*)GVTOP(Args[0]));
 314   GenericValue GV;
 315   GV.IntVal = 0;
 316   return GV;
 317 }
 318
 319 // void exit(int)
 320 static GenericValue lle_X_exit(FunctionType *FT, ArrayRef<GenericValue> Args) {
 321   TheInterpreter->exitCalled(Args[0]);
 322   return GenericValue();
 323 }
 324
 325 // void abort(void)
 326 static GenericValue lle_X_abort(FunctionType *FT, ArrayRef<GenericValue> Args) {
 327   //FIXME: should we report or raise here?
 328   //report_fatal_error("Interpreted program raised SIGABRT");
 329   raise (SIGABRT);
 330   return GenericValue();
 331 }
 332
 333 // int sprintf(char *, const char *, ...) - a very rough implementation to make
 334 // output useful.
 335 static GenericValue lle_X_sprintf(FunctionType *FT,
 336                                   ArrayRef<GenericValue> Args) {
 337   char *OutputBuffer = (char *)GVTOP(Args[0]);
 338   const char *FmtStr = (const char *)GVTOP(Args[1]);
 339   unsigned ArgNo = 2;
 340
 341   // printf should return # chars printed.  This is completely incorrect, but
 342   // close enough for now.
 343   GenericValue GV;
 344   GV.IntVal = APInt(32, strlen(FmtStr));
 345   while (true) {
 346     switch (*FmtStr) {
 347     case 0: return GV;             // Null terminator...
 348     default:                       // Normal nonspecial character
 349       sprintf(OutputBuffer++, "%c", *FmtStr++);
 350       break;
 351     case '\\': {                   // Handle escape codes
 352       sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1));
 353       FmtStr += 2; OutputBuffer += 2;
 354       break;
 355     }
 356     case '%': {                    // Handle format specifiers
 357       char FmtBuf[100] = "", Buffer[1000] = "";
 358       char *FB = FmtBuf;
 359       *FB++ = *FmtStr++;
 360       char Last = *FB++ = *FmtStr++;
 361       unsigned HowLong = 0;
 362       while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' &&
 363              Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' &&
 364              Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' &&
 365              Last != 'p' && Last != 's' && Last != '%') {
 366         if (Last == 'l' || Last == 'L') HowLong++;  // Keep track of l's
 367         Last = *FB++ = *FmtStr++;
 368       }
 369       *FB = 0;
 370
 371       switch (Last) {
 372       case '%':
 373         memcpy(Buffer, "%", 2); break;
 374       case 'c':
 375         sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
 376         break;
 377       case 'd': case 'i':
 378       case 'u': case 'o':
 379       case 'x': case 'X':
 380         if (HowLong >= 1) {
 381           if (HowLong == 1 &&
 382               TheInterpreter->getDataLayout().getPointerSizeInBits() == 64 &&
 383               sizeof(long) < sizeof(int64_t)) {
 384             // Make sure we use %lld with a 64 bit argument because we might be
 385             // compiling LLI on a 32 bit compiler.
 386             unsigned Size = strlen(FmtBuf);
 387             FmtBuf[Size] = FmtBuf[Size-1];
 388             FmtBuf[Size+1] = 0;
 389             FmtBuf[Size-1] = 'l';
 390           }
 391           sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
 392         } else
 393           sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
 394         break;
 395       case 'e': case 'E': case 'g': case 'G': case 'f':
 396         sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break;
 397       case 'p':
 398         sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break;
 399       case 's':
 400         sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break;
 401       default:
 402         errs() << "<unknown printf code '" << *FmtStr << "'!>";
 403         ArgNo++; break;
 404       }
 405       size_t Len = strlen(Buffer);
 406       memcpy(OutputBuffer, Buffer, Len + 1);
 407       OutputBuffer += Len;
 408       }
 409       break;
 410     }
 411   }
 412   return GV;
 413 }
 414
 415 // int printf(const char *, ...) - a very rough implementation to make output
 416 // useful.
 417 static GenericValue lle_X_printf(FunctionType *FT,
 418                                  ArrayRef<GenericValue> Args) {
 419   char Buffer[10000];
 420   std::vector<GenericValue> NewArgs;
 421   NewArgs.push_back(PTOGV((void*)&Buffer[0]));
 422   NewArgs.insert(NewArgs.end(), Args.begin(), Args.end());
 423   GenericValue GV = lle_X_sprintf(FT, NewArgs);
 424   outs() << Buffer;
 425   return GV;
 426 }
 427
 428 // int sscanf(const char *format, ...);
 429 static GenericValue lle_X_sscanf(FunctionType *FT,
 430                                  ArrayRef<GenericValue> args) {
 431   assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!");
 432
 433   char *Args[10];
 434   for (unsigned i = 0; i < args.size(); ++i)
 435     Args[i] = (char*)GVTOP(args[i]);
 436
 437   GenericValue GV;
 438   GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4],
 439                     Args[5], Args[6], Args[7], Args[8], Args[9]));
 440   return GV;
 441 }
 442
 443 // int scanf(const char *format, ...);
 444 static GenericValue lle_X_scanf(FunctionType *FT, ArrayRef<GenericValue> args) {
 445   assert(args.size() < 10 && "Only handle up to 10 args to scanf right now!");
 446
 447   char *Args[10];
 448   for (unsigned i = 0; i < args.size(); ++i)
 449     Args[i] = (char*)GVTOP(args[i]);
 450
 451   GenericValue GV;
 452   GV.IntVal = APInt(32, scanf( Args[0], Args[1], Args[2], Args[3], Args[4],
 453                     Args[5], Args[6], Args[7], Args[8], Args[9]));
 454   return GV;
 455 }
 456
 457 // int fprintf(FILE *, const char *, ...) - a very rough implementation to make
 458 // output useful.
 459 static GenericValue lle_X_fprintf(FunctionType *FT,
 460                                   ArrayRef<GenericValue> Args) {
 461   assert(Args.size() >= 2);
 462   char Buffer[10000];
 463   std::vector<GenericValue> NewArgs;
 464   NewArgs.push_back(PTOGV(Buffer));
 465   NewArgs.insert(NewArgs.end(), Args.begin()+1, Args.end());
 466   GenericValue GV = lle_X_sprintf(FT, NewArgs);
 467
 468   fputs(Buffer, (FILE *) GVTOP(Args[0]));
 469   return GV;
 470 }
 471
 472 static GenericValue lle_X_memset(FunctionType *FT,
 473                                  ArrayRef<GenericValue> Args) {
 474   int val = (int)Args[1].IntVal.getSExtValue();
 475   size_t len = (size_t)Args[2].IntVal.getZExtValue();
 476   memset((void *)GVTOP(Args[0]), val, len);
 477   // llvm.memset.* returns void, lle_X_* returns GenericValue,
 478   // so here we return GenericValue with IntVal set to zero
 479   GenericValue GV;
 480   GV.IntVal = 0;
 481   return GV;
 482 }
 483
 484 static GenericValue lle_X_memcpy(FunctionType *FT,
 485                                  ArrayRef<GenericValue> Args) {
 486   memcpy(GVTOP(Args[0]), GVTOP(Args[1]),
 487          (size_t)(Args[2].IntVal.getLimitedValue()));
 488
 489   // llvm.memcpy* returns void, lle_X_* returns GenericValue,
 490   // so here we return GenericValue with IntVal set to zero
 491   GenericValue GV;
 492   GV.IntVal = 0;
 493   return GV;
 494 }
 495
 496 void Interpreter::initializeExternalFunctions() {
 497   sys::ScopedLock Writer(*FunctionsLock);
 498   (*FuncNames)["lle_X_atexit"]       = lle_X_atexit;
 499   (*FuncNames)["lle_X_exit"]         = lle_X_exit;
 500   (*FuncNames)["lle_X_abort"]        = lle_X_abort;
 501
 502   (*FuncNames)["lle_X_printf"]       = lle_X_printf;
 503   (*FuncNames)["lle_X_sprintf"]      = lle_X_sprintf;
 504   (*FuncNames)["lle_X_sscanf"]       = lle_X_sscanf;
 505   (*FuncNames)["lle_X_scanf"]        = lle_X_scanf;
 506   (*FuncNames)["lle_X_fprintf"]      = lle_X_fprintf;
 507   (*FuncNames)["lle_X_memset"]       = lle_X_memset;
 508   (*FuncNames)["lle_X_memcpy"]       = lle_X_memcpy;
 509 }