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      1 //===-- ExternalFunctions.cpp - Implement External Functions --------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 //  This file contains both code to deal with invoking "external" functions, but
     11 //  also contains code that implements "exported" external functions.
     12 //
     13 //  There are currently two mechanisms for handling external functions in the
     14 //  Interpreter.  The first is to implement lle_* wrapper functions that are
     15 //  specific to well-known library functions which manually translate the
     16 //  arguments from GenericValues and make the call.  If such a wrapper does
     17 //  not exist, and libffi is available, then the Interpreter will attempt to
     18 //  invoke the function using libffi, after finding its address.
     19 //
     20 //===----------------------------------------------------------------------===//
     21 
     22 #include "Interpreter.h"
     23 #include "llvm/DerivedTypes.h"
     24 #include "llvm/Module.h"
     25 #include "llvm/Config/config.h"     // Detect libffi
     26 #include "llvm/Support/ErrorHandling.h"
     27 #include "llvm/Support/DynamicLibrary.h"
     28 #include "llvm/Target/TargetData.h"
     29 #include "llvm/Support/ManagedStatic.h"
     30 #include "llvm/Support/Mutex.h"
     31 #include <csignal>
     32 #include <cstdio>
     33 #include <map>
     34 #include <cmath>
     35 #include <cstring>
     36 
     37 #ifdef HAVE_FFI_CALL
     38 #ifdef HAVE_FFI_H
     39 #include <ffi.h>
     40 #define USE_LIBFFI
     41 #elif HAVE_FFI_FFI_H
     42 #include <ffi/ffi.h>
     43 #define USE_LIBFFI
     44 #endif
     45 #endif
     46 
     47 using namespace llvm;
     48 
     49 static ManagedStatic<sys::Mutex> FunctionsLock;
     50 
     51 typedef GenericValue (*ExFunc)(FunctionType *,
     52                                const std::vector<GenericValue> &);
     53 static ManagedStatic<std::map<const Function *, ExFunc> > ExportedFunctions;
     54 static std::map<std::string, ExFunc> FuncNames;
     55 
     56 #ifdef USE_LIBFFI
     57 typedef void (*RawFunc)();
     58 static ManagedStatic<std::map<const Function *, RawFunc> > RawFunctions;
     59 #endif
     60 
     61 static Interpreter *TheInterpreter;
     62 
     63 static char getTypeID(Type *Ty) {
     64   switch (Ty->getTypeID()) {
     65   case Type::VoidTyID:    return 'V';
     66   case Type::IntegerTyID:
     67     switch (cast<IntegerType>(Ty)->getBitWidth()) {
     68       case 1:  return 'o';
     69       case 8:  return 'B';
     70       case 16: return 'S';
     71       case 32: return 'I';
     72       case 64: return 'L';
     73       default: return 'N';
     74     }
     75   case Type::FloatTyID:   return 'F';
     76   case Type::DoubleTyID:  return 'D';
     77   case Type::PointerTyID: return 'P';
     78   case Type::FunctionTyID:return 'M';
     79   case Type::StructTyID:  return 'T';
     80   case Type::ArrayTyID:   return 'A';
     81   default: return 'U';
     82   }
     83 }
     84 
     85 // Try to find address of external function given a Function object.
     86 // Please note, that interpreter doesn't know how to assemble a
     87 // real call in general case (this is JIT job), that's why it assumes,
     88 // that all external functions has the same (and pretty "general") signature.
     89 // The typical example of such functions are "lle_X_" ones.
     90 static ExFunc lookupFunction(const Function *F) {
     91   // Function not found, look it up... start by figuring out what the
     92   // composite function name should be.
     93   std::string ExtName = "lle_";
     94   FunctionType *FT = F->getFunctionType();
     95   for (unsigned i = 0, e = FT->getNumContainedTypes(); i != e; ++i)
     96     ExtName += getTypeID(FT->getContainedType(i));
     97   ExtName + "_" + F->getNameStr();
     98 
     99   sys::ScopedLock Writer(*FunctionsLock);
    100   ExFunc FnPtr = FuncNames[ExtName];
    101   if (FnPtr == 0)
    102     FnPtr = FuncNames["lle_X_" + F->getNameStr()];
    103   if (FnPtr == 0)  // Try calling a generic function... if it exists...
    104     FnPtr = (ExFunc)(intptr_t)
    105       sys::DynamicLibrary::SearchForAddressOfSymbol("lle_X_"+F->getNameStr());
    106   if (FnPtr != 0)
    107     ExportedFunctions->insert(std::make_pair(F, FnPtr));  // Cache for later
    108   return FnPtr;
    109 }
    110 
    111 #ifdef USE_LIBFFI
    112 static ffi_type *ffiTypeFor(Type *Ty) {
    113   switch (Ty->getTypeID()) {
    114     case Type::VoidTyID: return &ffi_type_void;
    115     case Type::IntegerTyID:
    116       switch (cast<IntegerType>(Ty)->getBitWidth()) {
    117         case 8:  return &ffi_type_sint8;
    118         case 16: return &ffi_type_sint16;
    119         case 32: return &ffi_type_sint32;
    120         case 64: return &ffi_type_sint64;
    121       }
    122     case Type::FloatTyID:   return &ffi_type_float;
    123     case Type::DoubleTyID:  return &ffi_type_double;
    124     case Type::PointerTyID: return &ffi_type_pointer;
    125     default: break;
    126   }
    127   // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
    128   report_fatal_error("Type could not be mapped for use with libffi.");
    129   return NULL;
    130 }
    131 
    132 static void *ffiValueFor(Type *Ty, const GenericValue &AV,
    133                          void *ArgDataPtr) {
    134   switch (Ty->getTypeID()) {
    135     case Type::IntegerTyID:
    136       switch (cast<IntegerType>(Ty)->getBitWidth()) {
    137         case 8: {
    138           int8_t *I8Ptr = (int8_t *) ArgDataPtr;
    139           *I8Ptr = (int8_t) AV.IntVal.getZExtValue();
    140           return ArgDataPtr;
    141         }
    142         case 16: {
    143           int16_t *I16Ptr = (int16_t *) ArgDataPtr;
    144           *I16Ptr = (int16_t) AV.IntVal.getZExtValue();
    145           return ArgDataPtr;
    146         }
    147         case 32: {
    148           int32_t *I32Ptr = (int32_t *) ArgDataPtr;
    149           *I32Ptr = (int32_t) AV.IntVal.getZExtValue();
    150           return ArgDataPtr;
    151         }
    152         case 64: {
    153           int64_t *I64Ptr = (int64_t *) ArgDataPtr;
    154           *I64Ptr = (int64_t) AV.IntVal.getZExtValue();
    155           return ArgDataPtr;
    156         }
    157       }
    158     case Type::FloatTyID: {
    159       float *FloatPtr = (float *) ArgDataPtr;
    160       *FloatPtr = AV.FloatVal;
    161       return ArgDataPtr;
    162     }
    163     case Type::DoubleTyID: {
    164       double *DoublePtr = (double *) ArgDataPtr;
    165       *DoublePtr = AV.DoubleVal;
    166       return ArgDataPtr;
    167     }
    168     case Type::PointerTyID: {
    169       void **PtrPtr = (void **) ArgDataPtr;
    170       *PtrPtr = GVTOP(AV);
    171       return ArgDataPtr;
    172     }
    173     default: break;
    174   }
    175   // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
    176   report_fatal_error("Type value could not be mapped for use with libffi.");
    177   return NULL;
    178 }
    179 
    180 static bool ffiInvoke(RawFunc Fn, Function *F,
    181                       const std::vector<GenericValue> &ArgVals,
    182                       const TargetData *TD, GenericValue &Result) {
    183   ffi_cif cif;
    184   FunctionType *FTy = F->getFunctionType();
    185   const unsigned NumArgs = F->arg_size();
    186 
    187   // TODO: We don't have type information about the remaining arguments, because
    188   // this information is never passed into ExecutionEngine::runFunction().
    189   if (ArgVals.size() > NumArgs && F->isVarArg()) {
    190     report_fatal_error("Calling external var arg function '" + F->getName()
    191                       + "' is not supported by the Interpreter.");
    192   }
    193 
    194   unsigned ArgBytes = 0;
    195 
    196   std::vector<ffi_type*> args(NumArgs);
    197   for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
    198        A != E; ++A) {
    199     const unsigned ArgNo = A->getArgNo();
    200     Type *ArgTy = FTy->getParamType(ArgNo);
    201     args[ArgNo] = ffiTypeFor(ArgTy);
    202     ArgBytes += TD->getTypeStoreSize(ArgTy);
    203   }
    204 
    205   SmallVector<uint8_t, 128> ArgData;
    206   ArgData.resize(ArgBytes);
    207   uint8_t *ArgDataPtr = ArgData.data();
    208   SmallVector<void*, 16> values(NumArgs);
    209   for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
    210        A != E; ++A) {
    211     const unsigned ArgNo = A->getArgNo();
    212     Type *ArgTy = FTy->getParamType(ArgNo);
    213     values[ArgNo] = ffiValueFor(ArgTy, ArgVals[ArgNo], ArgDataPtr);
    214     ArgDataPtr += TD->getTypeStoreSize(ArgTy);
    215   }
    216 
    217   Type *RetTy = FTy->getReturnType();
    218   ffi_type *rtype = ffiTypeFor(RetTy);
    219 
    220   if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, NumArgs, rtype, &args[0]) == FFI_OK) {
    221     SmallVector<uint8_t, 128> ret;
    222     if (RetTy->getTypeID() != Type::VoidTyID)
    223       ret.resize(TD->getTypeStoreSize(RetTy));
    224     ffi_call(&cif, Fn, ret.data(), values.data());
    225     switch (RetTy->getTypeID()) {
    226       case Type::IntegerTyID:
    227         switch (cast<IntegerType>(RetTy)->getBitWidth()) {
    228           case 8:  Result.IntVal = APInt(8 , *(int8_t *) ret.data()); break;
    229           case 16: Result.IntVal = APInt(16, *(int16_t*) ret.data()); break;
    230           case 32: Result.IntVal = APInt(32, *(int32_t*) ret.data()); break;
    231           case 64: Result.IntVal = APInt(64, *(int64_t*) ret.data()); break;
    232         }
    233         break;
    234       case Type::FloatTyID:   Result.FloatVal   = *(float *) ret.data(); break;
    235       case Type::DoubleTyID:  Result.DoubleVal  = *(double*) ret.data(); break;
    236       case Type::PointerTyID: Result.PointerVal = *(void **) ret.data(); break;
    237       default: break;
    238     }
    239     return true;
    240   }
    241 
    242   return false;
    243 }
    244 #endif // USE_LIBFFI
    245 
    246 GenericValue Interpreter::callExternalFunction(Function *F,
    247                                      const std::vector<GenericValue> &ArgVals) {
    248   TheInterpreter = this;
    249 
    250   FunctionsLock->acquire();
    251 
    252   // Do a lookup to see if the function is in our cache... this should just be a
    253   // deferred annotation!
    254   std::map<const Function *, ExFunc>::iterator FI = ExportedFunctions->find(F);
    255   if (ExFunc Fn = (FI == ExportedFunctions->end()) ? lookupFunction(F)
    256                                                    : FI->second) {
    257     FunctionsLock->release();
    258     return Fn(F->getFunctionType(), ArgVals);
    259   }
    260 
    261 #ifdef USE_LIBFFI
    262   std::map<const Function *, RawFunc>::iterator RF = RawFunctions->find(F);
    263   RawFunc RawFn;
    264   if (RF == RawFunctions->end()) {
    265     RawFn = (RawFunc)(intptr_t)
    266       sys::DynamicLibrary::SearchForAddressOfSymbol(F->getName());
    267     if (!RawFn)
    268       RawFn = (RawFunc)(intptr_t)getPointerToGlobalIfAvailable(F);
    269     if (RawFn != 0)
    270       RawFunctions->insert(std::make_pair(F, RawFn));  // Cache for later
    271   } else {
    272     RawFn = RF->second;
    273   }
    274 
    275   FunctionsLock->release();
    276 
    277   GenericValue Result;
    278   if (RawFn != 0 && ffiInvoke(RawFn, F, ArgVals, getTargetData(), Result))
    279     return Result;
    280 #endif // USE_LIBFFI
    281 
    282   if (F->getName() == "__main")
    283     errs() << "Tried to execute an unknown external function: "
    284       << *F->getType() << " __main\n";
    285   else
    286     report_fatal_error("Tried to execute an unknown external function: " +
    287                        F->getName());
    288 #ifndef USE_LIBFFI
    289   errs() << "Recompiling LLVM with --enable-libffi might help.\n";
    290 #endif
    291   return GenericValue();
    292 }
    293 
    294 
    295 //===----------------------------------------------------------------------===//
    296 //  Functions "exported" to the running application...
    297 //
    298 
    299 // Visual Studio warns about returning GenericValue in extern "C" linkage
    300 #ifdef _MSC_VER
    301     #pragma warning(disable : 4190)
    302 #endif
    303 
    304 extern "C" {  // Don't add C++ manglings to llvm mangling :)
    305 
    306 // void atexit(Function*)
    307 GenericValue lle_X_atexit(FunctionType *FT,
    308                           const std::vector<GenericValue> &Args) {
    309   assert(Args.size() == 1);
    310   TheInterpreter->addAtExitHandler((Function*)GVTOP(Args[0]));
    311   GenericValue GV;
    312   GV.IntVal = 0;
    313   return GV;
    314 }
    315 
    316 // void exit(int)
    317 GenericValue lle_X_exit(FunctionType *FT,
    318                         const std::vector<GenericValue> &Args) {
    319   TheInterpreter->exitCalled(Args[0]);
    320   return GenericValue();
    321 }
    322 
    323 // void abort(void)
    324 GenericValue lle_X_abort(FunctionType *FT,
    325                          const std::vector<GenericValue> &Args) {
    326   //FIXME: should we report or raise here?
    327   //report_fatal_error("Interpreted program raised SIGABRT");
    328   raise (SIGABRT);
    329   return GenericValue();
    330 }
    331 
    332 // int sprintf(char *, const char *, ...) - a very rough implementation to make
    333 // output useful.
    334 GenericValue lle_X_sprintf(FunctionType *FT,
    335                            const std::vector<GenericValue> &Args) {
    336   char *OutputBuffer = (char *)GVTOP(Args[0]);
    337   const char *FmtStr = (const char *)GVTOP(Args[1]);
    338   unsigned ArgNo = 2;
    339 
    340   // printf should return # chars printed.  This is completely incorrect, but
    341   // close enough for now.
    342   GenericValue GV;
    343   GV.IntVal = APInt(32, strlen(FmtStr));
    344   while (1) {
    345     switch (*FmtStr) {
    346     case 0: return GV;             // Null terminator...
    347     default:                       // Normal nonspecial character
    348       sprintf(OutputBuffer++, "%c", *FmtStr++);
    349       break;
    350     case '\\': {                   // Handle escape codes
    351       sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1));
    352       FmtStr += 2; OutputBuffer += 2;
    353       break;
    354     }
    355     case '%': {                    // Handle format specifiers
    356       char FmtBuf[100] = "", Buffer[1000] = "";
    357       char *FB = FmtBuf;
    358       *FB++ = *FmtStr++;
    359       char Last = *FB++ = *FmtStr++;
    360       unsigned HowLong = 0;
    361       while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' &&
    362              Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' &&
    363              Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' &&
    364              Last != 'p' && Last != 's' && Last != '%') {
    365         if (Last == 'l' || Last == 'L') HowLong++;  // Keep track of l's
    366         Last = *FB++ = *FmtStr++;
    367       }
    368       *FB = 0;
    369 
    370       switch (Last) {
    371       case '%':
    372         memcpy(Buffer, "%", 2); break;
    373       case 'c':
    374         sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
    375         break;
    376       case 'd': case 'i':
    377       case 'u': case 'o':
    378       case 'x': case 'X':
    379         if (HowLong >= 1) {
    380           if (HowLong == 1 &&
    381               TheInterpreter->getTargetData()->getPointerSizeInBits() == 64 &&
    382               sizeof(long) < sizeof(int64_t)) {
    383             // Make sure we use %lld with a 64 bit argument because we might be
    384             // compiling LLI on a 32 bit compiler.
    385             unsigned Size = strlen(FmtBuf);
    386             FmtBuf[Size] = FmtBuf[Size-1];
    387             FmtBuf[Size+1] = 0;
    388             FmtBuf[Size-1] = 'l';
    389           }
    390           sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
    391         } else
    392           sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
    393         break;
    394       case 'e': case 'E': case 'g': case 'G': case 'f':
    395         sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break;
    396       case 'p':
    397         sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break;
    398       case 's':
    399         sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break;
    400       default:
    401         errs() << "<unknown printf code '" << *FmtStr << "'!>";
    402         ArgNo++; break;
    403       }
    404       size_t Len = strlen(Buffer);
    405       memcpy(OutputBuffer, Buffer, Len + 1);
    406       OutputBuffer += Len;
    407       }
    408       break;
    409     }
    410   }
    411   return GV;
    412 }
    413 
    414 // int printf(const char *, ...) - a very rough implementation to make output
    415 // useful.
    416 GenericValue lle_X_printf(FunctionType *FT,
    417                           const std::vector<GenericValue> &Args) {
    418   char Buffer[10000];
    419   std::vector<GenericValue> NewArgs;
    420   NewArgs.push_back(PTOGV((void*)&Buffer[0]));
    421   NewArgs.insert(NewArgs.end(), Args.begin(), Args.end());
    422   GenericValue GV = lle_X_sprintf(FT, NewArgs);
    423   outs() << Buffer;
    424   return GV;
    425 }
    426 
    427 // int sscanf(const char *format, ...);
    428 GenericValue lle_X_sscanf(FunctionType *FT,
    429                           const std::vector<GenericValue> &args) {
    430   assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!");
    431 
    432   char *Args[10];
    433   for (unsigned i = 0; i < args.size(); ++i)
    434     Args[i] = (char*)GVTOP(args[i]);
    435 
    436   GenericValue GV;
    437   GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4],
    438                         Args[5], Args[6], Args[7], Args[8], Args[9]));
    439   return GV;
    440 }
    441 
    442 // int scanf(const char *format, ...);
    443 GenericValue lle_X_scanf(FunctionType *FT,
    444                          const std::vector<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 GenericValue lle_X_fprintf(FunctionType *FT,
    460                            const std::vector<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 } // End extern "C"
    473 
    474 // Done with externals; turn the warning back on
    475 #ifdef _MSC_VER
    476     #pragma warning(default: 4190)
    477 #endif
    478 
    479 
    480 void Interpreter::initializeExternalFunctions() {
    481   sys::ScopedLock Writer(*FunctionsLock);
    482   FuncNames["lle_X_atexit"]       = lle_X_atexit;
    483   FuncNames["lle_X_exit"]         = lle_X_exit;
    484   FuncNames["lle_X_abort"]        = lle_X_abort;
    485 
    486   FuncNames["lle_X_printf"]       = lle_X_printf;
    487   FuncNames["lle_X_sprintf"]      = lle_X_sprintf;
    488   FuncNames["lle_X_sscanf"]       = lle_X_sscanf;
    489   FuncNames["lle_X_scanf"]        = lle_X_scanf;
    490   FuncNames["lle_X_fprintf"]      = lle_X_fprintf;
    491 }
    492