ExternalFunctions.cpp revision 226633 
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
47using namespace llvm;
48
49static ManagedStatic<sys::Mutex> FunctionsLock;
50
51typedef GenericValue (*ExFunc)(FunctionType *,
52                               const std::vector<GenericValue> &);
53static ManagedStatic<std::map<const Function *, ExFunc> > ExportedFunctions;
54static std::map<std::string, ExFunc> FuncNames;
55
56#ifdef USE_LIBFFI
57typedef void (*RawFunc)();
58static ManagedStatic<std::map<const Function *, RawFunc> > RawFunctions;
59#endif
60
61static Interpreter *TheInterpreter;
62
63static 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.
90static 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
112static 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
132static 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
180static 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
246GenericValue 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
304extern "C" {  // Don't add C++ manglings to llvm mangling :)
305
306// void atexit(Function*)
307GenericValue 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)
317GenericValue 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)
324GenericValue 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.
334GenericValue 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.
416GenericValue 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, ...);
428GenericValue 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, ...);
443GenericValue 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.
459GenericValue 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
480void 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