ExternalFunctions.cpp revision 4bf6c19e94e4c7eb888d94c1aa322d23dbcc93ba 
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->getName().str();
98
99  sys::ScopedLock Writer(*FunctionsLock);
100  ExFunc FnPtr = FuncNames[ExtName];
101  if (FnPtr == 0)
102    FnPtr = FuncNames["lle_X_" + F->getName().str()];
103  if (FnPtr == 0)  // Try calling a generic function... if it exists...
104    FnPtr = (ExFunc)(intptr_t)
105      sys::DynamicLibrary::SearchForAddressOfSymbol("lle_X_" +
106                                                    F->getName().str());
107  if (FnPtr != 0)
108    ExportedFunctions->insert(std::make_pair(F, FnPtr));  // Cache for later
109  return FnPtr;
110}
111
112#ifdef USE_LIBFFI
113static ffi_type *ffiTypeFor(Type *Ty) {
114  switch (Ty->getTypeID()) {
115    case Type::VoidTyID: return &ffi_type_void;
116    case Type::IntegerTyID:
117      switch (cast<IntegerType>(Ty)->getBitWidth()) {
118        case 8:  return &ffi_type_sint8;
119        case 16: return &ffi_type_sint16;
120        case 32: return &ffi_type_sint32;
121        case 64: return &ffi_type_sint64;
122      }
123    case Type::FloatTyID:   return &ffi_type_float;
124    case Type::DoubleTyID:  return &ffi_type_double;
125    case Type::PointerTyID: return &ffi_type_pointer;
126    default: break;
127  }
128  // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
129  report_fatal_error("Type could not be mapped for use with libffi.");
130  return NULL;
131}
132
133static void *ffiValueFor(Type *Ty, const GenericValue &AV,
134                         void *ArgDataPtr) {
135  switch (Ty->getTypeID()) {
136    case Type::IntegerTyID:
137      switch (cast<IntegerType>(Ty)->getBitWidth()) {
138        case 8: {
139          int8_t *I8Ptr = (int8_t *) ArgDataPtr;
140          *I8Ptr = (int8_t) AV.IntVal.getZExtValue();
141          return ArgDataPtr;
142        }
143        case 16: {
144          int16_t *I16Ptr = (int16_t *) ArgDataPtr;
145          *I16Ptr = (int16_t) AV.IntVal.getZExtValue();
146          return ArgDataPtr;
147        }
148        case 32: {
149          int32_t *I32Ptr = (int32_t *) ArgDataPtr;
150          *I32Ptr = (int32_t) AV.IntVal.getZExtValue();
151          return ArgDataPtr;
152        }
153        case 64: {
154          int64_t *I64Ptr = (int64_t *) ArgDataPtr;
155          *I64Ptr = (int64_t) AV.IntVal.getZExtValue();
156          return ArgDataPtr;
157        }
158      }
159    case Type::FloatTyID: {
160      float *FloatPtr = (float *) ArgDataPtr;
161      *FloatPtr = AV.FloatVal;
162      return ArgDataPtr;
163    }
164    case Type::DoubleTyID: {
165      double *DoublePtr = (double *) ArgDataPtr;
166      *DoublePtr = AV.DoubleVal;
167      return ArgDataPtr;
168    }
169    case Type::PointerTyID: {
170      void **PtrPtr = (void **) ArgDataPtr;
171      *PtrPtr = GVTOP(AV);
172      return ArgDataPtr;
173    }
174    default: break;
175  }
176  // TODO: Support other types such as StructTyID, ArrayTyID, OpaqueTyID, etc.
177  report_fatal_error("Type value could not be mapped for use with libffi.");
178  return NULL;
179}
180
181static bool ffiInvoke(RawFunc Fn, Function *F,
182                      const std::vector<GenericValue> &ArgVals,
183                      const TargetData *TD, GenericValue &Result) {
184  ffi_cif cif;
185  FunctionType *FTy = F->getFunctionType();
186  const unsigned NumArgs = F->arg_size();
187
188  // TODO: We don't have type information about the remaining arguments, because
189  // this information is never passed into ExecutionEngine::runFunction().
190  if (ArgVals.size() > NumArgs && F->isVarArg()) {
191    report_fatal_error("Calling external var arg function '" + F->getName()
192                      + "' is not supported by the Interpreter.");
193  }
194
195  unsigned ArgBytes = 0;
196
197  std::vector<ffi_type*> args(NumArgs);
198  for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
199       A != E; ++A) {
200    const unsigned ArgNo = A->getArgNo();
201    Type *ArgTy = FTy->getParamType(ArgNo);
202    args[ArgNo] = ffiTypeFor(ArgTy);
203    ArgBytes += TD->getTypeStoreSize(ArgTy);
204  }
205
206  SmallVector<uint8_t, 128> ArgData;
207  ArgData.resize(ArgBytes);
208  uint8_t *ArgDataPtr = ArgData.data();
209  SmallVector<void*, 16> values(NumArgs);
210  for (Function::const_arg_iterator A = F->arg_begin(), E = F->arg_end();
211       A != E; ++A) {
212    const unsigned ArgNo = A->getArgNo();
213    Type *ArgTy = FTy->getParamType(ArgNo);
214    values[ArgNo] = ffiValueFor(ArgTy, ArgVals[ArgNo], ArgDataPtr);
215    ArgDataPtr += TD->getTypeStoreSize(ArgTy);
216  }
217
218  Type *RetTy = FTy->getReturnType();
219  ffi_type *rtype = ffiTypeFor(RetTy);
220
221  if (ffi_prep_cif(&cif, FFI_DEFAULT_ABI, NumArgs, rtype, &args[0]) == FFI_OK) {
222    SmallVector<uint8_t, 128> ret;
223    if (RetTy->getTypeID() != Type::VoidTyID)
224      ret.resize(TD->getTypeStoreSize(RetTy));
225    ffi_call(&cif, Fn, ret.data(), values.data());
226    switch (RetTy->getTypeID()) {
227      case Type::IntegerTyID:
228        switch (cast<IntegerType>(RetTy)->getBitWidth()) {
229          case 8:  Result.IntVal = APInt(8 , *(int8_t *) ret.data()); break;
230          case 16: Result.IntVal = APInt(16, *(int16_t*) ret.data()); break;
231          case 32: Result.IntVal = APInt(32, *(int32_t*) ret.data()); break;
232          case 64: Result.IntVal = APInt(64, *(int64_t*) ret.data()); break;
233        }
234        break;
235      case Type::FloatTyID:   Result.FloatVal   = *(float *) ret.data(); break;
236      case Type::DoubleTyID:  Result.DoubleVal  = *(double*) ret.data(); break;
237      case Type::PointerTyID: Result.PointerVal = *(void **) ret.data(); break;
238      default: break;
239    }
240    return true;
241  }
242
243  return false;
244}
245#endif // USE_LIBFFI
246
247GenericValue Interpreter::callExternalFunction(Function *F,
248                                     const std::vector<GenericValue> &ArgVals) {
249  TheInterpreter = this;
250
251  FunctionsLock->acquire();
252
253  // Do a lookup to see if the function is in our cache... this should just be a
254  // deferred annotation!
255  std::map<const Function *, ExFunc>::iterator FI = ExportedFunctions->find(F);
256  if (ExFunc Fn = (FI == ExportedFunctions->end()) ? lookupFunction(F)
257                                                   : FI->second) {
258    FunctionsLock->release();
259    return Fn(F->getFunctionType(), ArgVals);
260  }
261
262#ifdef USE_LIBFFI
263  std::map<const Function *, RawFunc>::iterator RF = RawFunctions->find(F);
264  RawFunc RawFn;
265  if (RF == RawFunctions->end()) {
266    RawFn = (RawFunc)(intptr_t)
267      sys::DynamicLibrary::SearchForAddressOfSymbol(F->getName());
268    if (!RawFn)
269      RawFn = (RawFunc)(intptr_t)getPointerToGlobalIfAvailable(F);
270    if (RawFn != 0)
271      RawFunctions->insert(std::make_pair(F, RawFn));  // Cache for later
272  } else {
273    RawFn = RF->second;
274  }
275
276  FunctionsLock->release();
277
278  GenericValue Result;
279  if (RawFn != 0 && ffiInvoke(RawFn, F, ArgVals, getTargetData(), Result))
280    return Result;
281#endif // USE_LIBFFI
282
283  if (F->getName() == "__main")
284    errs() << "Tried to execute an unknown external function: "
285      << *F->getType() << " __main\n";
286  else
287    report_fatal_error("Tried to execute an unknown external function: " +
288                       F->getName());
289#ifndef USE_LIBFFI
290  errs() << "Recompiling LLVM with --enable-libffi might help.\n";
291#endif
292  return GenericValue();
293}
294
295
296//===----------------------------------------------------------------------===//
297//  Functions "exported" to the running application...
298//
299
300// void atexit(Function*)
301static
302GenericValue lle_X_atexit(FunctionType *FT,
303                          const std::vector<GenericValue> &Args) {
304  assert(Args.size() == 1);
305  TheInterpreter->addAtExitHandler((Function*)GVTOP(Args[0]));
306  GenericValue GV;
307  GV.IntVal = 0;
308  return GV;
309}
310
311// void exit(int)
312static
313GenericValue lle_X_exit(FunctionType *FT,
314                        const std::vector<GenericValue> &Args) {
315  TheInterpreter->exitCalled(Args[0]);
316  return GenericValue();
317}
318
319// void abort(void)
320static
321GenericValue lle_X_abort(FunctionType *FT,
322                         const std::vector<GenericValue> &Args) {
323  //FIXME: should we report or raise here?
324  //report_fatal_error("Interpreted program raised SIGABRT");
325  raise (SIGABRT);
326  return GenericValue();
327}
328
329// int sprintf(char *, const char *, ...) - a very rough implementation to make
330// output useful.
331static
332GenericValue lle_X_sprintf(FunctionType *FT,
333                           const std::vector<GenericValue> &Args) {
334  char *OutputBuffer = (char *)GVTOP(Args[0]);
335  const char *FmtStr = (const char *)GVTOP(Args[1]);
336  unsigned ArgNo = 2;
337
338  // printf should return # chars printed.  This is completely incorrect, but
339  // close enough for now.
340  GenericValue GV;
341  GV.IntVal = APInt(32, strlen(FmtStr));
342  while (1) {
343    switch (*FmtStr) {
344    case 0: return GV;             // Null terminator...
345    default:                       // Normal nonspecial character
346      sprintf(OutputBuffer++, "%c", *FmtStr++);
347      break;
348    case '\\': {                   // Handle escape codes
349      sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1));
350      FmtStr += 2; OutputBuffer += 2;
351      break;
352    }
353    case '%': {                    // Handle format specifiers
354      char FmtBuf[100] = "", Buffer[1000] = "";
355      char *FB = FmtBuf;
356      *FB++ = *FmtStr++;
357      char Last = *FB++ = *FmtStr++;
358      unsigned HowLong = 0;
359      while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' &&
360             Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' &&
361             Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' &&
362             Last != 'p' && Last != 's' && Last != '%') {
363        if (Last == 'l' || Last == 'L') HowLong++;  // Keep track of l's
364        Last = *FB++ = *FmtStr++;
365      }
366      *FB = 0;
367
368      switch (Last) {
369      case '%':
370        memcpy(Buffer, "%", 2); break;
371      case 'c':
372        sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
373        break;
374      case 'd': case 'i':
375      case 'u': case 'o':
376      case 'x': case 'X':
377        if (HowLong >= 1) {
378          if (HowLong == 1 &&
379              TheInterpreter->getTargetData()->getPointerSizeInBits() == 64 &&
380              sizeof(long) < sizeof(int64_t)) {
381            // Make sure we use %lld with a 64 bit argument because we might be
382            // compiling LLI on a 32 bit compiler.
383            unsigned Size = strlen(FmtBuf);
384            FmtBuf[Size] = FmtBuf[Size-1];
385            FmtBuf[Size+1] = 0;
386            FmtBuf[Size-1] = 'l';
387          }
388          sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
389        } else
390          sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
391        break;
392      case 'e': case 'E': case 'g': case 'G': case 'f':
393        sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break;
394      case 'p':
395        sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break;
396      case 's':
397        sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break;
398      default:
399        errs() << "<unknown printf code '" << *FmtStr << "'!>";
400        ArgNo++; break;
401      }
402      size_t Len = strlen(Buffer);
403      memcpy(OutputBuffer, Buffer, Len + 1);
404      OutputBuffer += Len;
405      }
406      break;
407    }
408  }
409}
410
411// int printf(const char *, ...) - a very rough implementation to make output
412// useful.
413static
414GenericValue lle_X_printf(FunctionType *FT,
415                          const std::vector<GenericValue> &Args) {
416  char Buffer[10000];
417  std::vector<GenericValue> NewArgs;
418  NewArgs.push_back(PTOGV((void*)&Buffer[0]));
419  NewArgs.insert(NewArgs.end(), Args.begin(), Args.end());
420  GenericValue GV = lle_X_sprintf(FT, NewArgs);
421  outs() << Buffer;
422  return GV;
423}
424
425// int sscanf(const char *format, ...);
426static
427GenericValue lle_X_sscanf(FunctionType *FT,
428                          const std::vector<GenericValue> &args) {
429  assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!");
430
431  char *Args[10];
432  for (unsigned i = 0; i < args.size(); ++i)
433    Args[i] = (char*)GVTOP(args[i]);
434
435  GenericValue GV;
436  GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4],
437                        Args[5], Args[6], Args[7], Args[8], Args[9]));
438  return GV;
439}
440
441// int scanf(const char *format, ...);
442static
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.
459static
460GenericValue lle_X_fprintf(FunctionType *FT,
461                           const std::vector<GenericValue> &Args) {
462  assert(Args.size() >= 2);
463  char Buffer[10000];
464  std::vector<GenericValue> NewArgs;
465  NewArgs.push_back(PTOGV(Buffer));
466  NewArgs.insert(NewArgs.end(), Args.begin()+1, Args.end());
467  GenericValue GV = lle_X_sprintf(FT, NewArgs);
468
469  fputs(Buffer, (FILE *) GVTOP(Args[0]));
470  return GV;
471}
472
473void Interpreter::initializeExternalFunctions() {
474  sys::ScopedLock Writer(*FunctionsLock);
475  FuncNames["lle_X_atexit"]       = lle_X_atexit;
476  FuncNames["lle_X_exit"]         = lle_X_exit;
477  FuncNames["lle_X_abort"]        = lle_X_abort;
478
479  FuncNames["lle_X_printf"]       = lle_X_printf;
480  FuncNames["lle_X_sprintf"]      = lle_X_sprintf;
481  FuncNames["lle_X_sscanf"]       = lle_X_sscanf;
482  FuncNames["lle_X_scanf"]        = lle_X_scanf;
483  FuncNames["lle_X_fprintf"]      = lle_X_fprintf;
484}
485