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->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
113 static 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 
133 static 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 
181 static 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 
247 GenericValue 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 // Visual Studio and Clang warn about returning GenericValue in extern "C" linkage
301 #ifdef _MSC_VER
302     #pragma warning(disable : 4190)
303 #endif
304 #ifdef __clang__
305     #pragma clang diagnostic push
306     #pragma clang diagnostic ignored "-Wreturn-type-c-linkage"
307 #endif
308 
309 extern "C" {  // Don't add C++ manglings to llvm mangling :)
310 
311 // void atexit(Function*)
312 GenericValue lle_X_atexit(FunctionType *FT,
313                           const std::vector<GenericValue> &Args) {
314   assert(Args.size() == 1);
315   TheInterpreter->addAtExitHandler((Function*)GVTOP(Args[0]));
316   GenericValue GV;
317   GV.IntVal = 0;
318   return GV;
319 }
320 
321 // void exit(int)
322 GenericValue lle_X_exit(FunctionType *FT,
323                         const std::vector<GenericValue> &Args) {
324   TheInterpreter->exitCalled(Args[0]);
325   return GenericValue();
326 }
327 
328 // void abort(void)
329 GenericValue lle_X_abort(FunctionType *FT,
330                          const std::vector<GenericValue> &Args) {
331   //FIXME: should we report or raise here?
332   //report_fatal_error("Interpreted program raised SIGABRT");
333   raise (SIGABRT);
334   return GenericValue();
335 }
336 
337 // int sprintf(char *, const char *, ...) - a very rough implementation to make
338 // output useful.
339 GenericValue lle_X_sprintf(FunctionType *FT,
340                            const std::vector<GenericValue> &Args) {
341   char *OutputBuffer = (char *)GVTOP(Args[0]);
342   const char *FmtStr = (const char *)GVTOP(Args[1]);
343   unsigned ArgNo = 2;
344 
345   // printf should return # chars printed.  This is completely incorrect, but
346   // close enough for now.
347   GenericValue GV;
348   GV.IntVal = APInt(32, strlen(FmtStr));
349   while (1) {
350     switch (*FmtStr) {
351     case 0: return GV;             // Null terminator...
352     default:                       // Normal nonspecial character
353       sprintf(OutputBuffer++, "%c", *FmtStr++);
354       break;
355     case '\\': {                   // Handle escape codes
356       sprintf(OutputBuffer, "%c%c", *FmtStr, *(FmtStr+1));
357       FmtStr += 2; OutputBuffer += 2;
358       break;
359     }
360     case '%': {                    // Handle format specifiers
361       char FmtBuf[100] = "", Buffer[1000] = "";
362       char *FB = FmtBuf;
363       *FB++ = *FmtStr++;
364       char Last = *FB++ = *FmtStr++;
365       unsigned HowLong = 0;
366       while (Last != 'c' && Last != 'd' && Last != 'i' && Last != 'u' &&
367              Last != 'o' && Last != 'x' && Last != 'X' && Last != 'e' &&
368              Last != 'E' && Last != 'g' && Last != 'G' && Last != 'f' &&
369              Last != 'p' && Last != 's' && Last != '%') {
370         if (Last == 'l' || Last == 'L') HowLong++;  // Keep track of l's
371         Last = *FB++ = *FmtStr++;
372       }
373       *FB = 0;
374 
375       switch (Last) {
376       case '%':
377         memcpy(Buffer, "%", 2); break;
378       case 'c':
379         sprintf(Buffer, FmtBuf, uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
380         break;
381       case 'd': case 'i':
382       case 'u': case 'o':
383       case 'x': case 'X':
384         if (HowLong >= 1) {
385           if (HowLong == 1 &&
386               TheInterpreter->getTargetData()->getPointerSizeInBits() == 64 &&
387               sizeof(long) < sizeof(int64_t)) {
388             // Make sure we use %lld with a 64 bit argument because we might be
389             // compiling LLI on a 32 bit compiler.
390             unsigned Size = strlen(FmtBuf);
391             FmtBuf[Size] = FmtBuf[Size-1];
392             FmtBuf[Size+1] = 0;
393             FmtBuf[Size-1] = 'l';
394           }
395           sprintf(Buffer, FmtBuf, Args[ArgNo++].IntVal.getZExtValue());
396         } else
397           sprintf(Buffer, FmtBuf,uint32_t(Args[ArgNo++].IntVal.getZExtValue()));
398         break;
399       case 'e': case 'E': case 'g': case 'G': case 'f':
400         sprintf(Buffer, FmtBuf, Args[ArgNo++].DoubleVal); break;
401       case 'p':
402         sprintf(Buffer, FmtBuf, (void*)GVTOP(Args[ArgNo++])); break;
403       case 's':
404         sprintf(Buffer, FmtBuf, (char*)GVTOP(Args[ArgNo++])); break;
405       default:
406         errs() << "<unknown printf code '" << *FmtStr << "'!>";
407         ArgNo++; break;
408       }
409       size_t Len = strlen(Buffer);
410       memcpy(OutputBuffer, Buffer, Len + 1);
411       OutputBuffer += Len;
412       }
413       break;
414     }
415   }
416 }
417 
418 // int printf(const char *, ...) - a very rough implementation to make output
419 // useful.
420 GenericValue lle_X_printf(FunctionType *FT,
421                           const std::vector<GenericValue> &Args) {
422   char Buffer[10000];
423   std::vector<GenericValue> NewArgs;
424   NewArgs.push_back(PTOGV((void*)&Buffer[0]));
425   NewArgs.insert(NewArgs.end(), Args.begin(), Args.end());
426   GenericValue GV = lle_X_sprintf(FT, NewArgs);
427   outs() << Buffer;
428   return GV;
429 }
430 
431 // int sscanf(const char *format, ...);
432 GenericValue lle_X_sscanf(FunctionType *FT,
433                           const std::vector<GenericValue> &args) {
434   assert(args.size() < 10 && "Only handle up to 10 args to sscanf right now!");
435 
436   char *Args[10];
437   for (unsigned i = 0; i < args.size(); ++i)
438     Args[i] = (char*)GVTOP(args[i]);
439 
440   GenericValue GV;
441   GV.IntVal = APInt(32, sscanf(Args[0], Args[1], Args[2], Args[3], Args[4],
442                         Args[5], Args[6], Args[7], Args[8], Args[9]));
443   return GV;
444 }
445 
446 // int scanf(const char *format, ...);
447 GenericValue lle_X_scanf(FunctionType *FT,
448                          const std::vector<GenericValue> &args) {
449   assert(args.size() < 10 && "Only handle up to 10 args to scanf right now!");
450 
451   char *Args[10];
452   for (unsigned i = 0; i < args.size(); ++i)
453     Args[i] = (char*)GVTOP(args[i]);
454 
455   GenericValue GV;
456   GV.IntVal = APInt(32, scanf( Args[0], Args[1], Args[2], Args[3], Args[4],
457                         Args[5], Args[6], Args[7], Args[8], Args[9]));
458   return GV;
459 }
460 
461 // int fprintf(FILE *, const char *, ...) - a very rough implementation to make
462 // output useful.
463 GenericValue lle_X_fprintf(FunctionType *FT,
464                            const std::vector<GenericValue> &Args) {
465   assert(Args.size() >= 2);
466   char Buffer[10000];
467   std::vector<GenericValue> NewArgs;
468   NewArgs.push_back(PTOGV(Buffer));
469   NewArgs.insert(NewArgs.end(), Args.begin()+1, Args.end());
470   GenericValue GV = lle_X_sprintf(FT, NewArgs);
471 
472   fputs(Buffer, (FILE *) GVTOP(Args[0]));
473   return GV;
474 }
475 
476 } // End extern "C"
477 
478 // Done with externals; turn the warning back on for Clang and Visual Studio
479 #ifdef __clang__
480     #pragma clang diagnostic pop
481 #endif
482 #ifdef _MSC_VER
483     #pragma warning(default: 4190)
484 #endif
485 
486 
487 void Interpreter::initializeExternalFunctions() {
488   sys::ScopedLock Writer(*FunctionsLock);
489   FuncNames["lle_X_atexit"]       = lle_X_atexit;
490   FuncNames["lle_X_exit"]         = lle_X_exit;
491   FuncNames["lle_X_abort"]        = lle_X_abort;
492 
493   FuncNames["lle_X_printf"]       = lle_X_printf;
494   FuncNames["lle_X_sprintf"]      = lle_X_sprintf;
495   FuncNames["lle_X_sscanf"]       = lle_X_sscanf;
496   FuncNames["lle_X_scanf"]        = lle_X_scanf;
497   FuncNames["lle_X_fprintf"]      = lle_X_fprintf;
498 }
499