LLVM API Documentation

JIT.cpp

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00001 //===-- JIT.cpp - LLVM Just in Time Compiler ------------------------------===//
00002 //
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by the LLVM research group and is distributed under
00006 // the University of Illinois Open Source License. See LICENSE.TXT for details.
00007 //
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This tool implements a just-in-time compiler for LLVM, allowing direct
00011 // execution of LLVM bytecode in an efficient manner.
00012 //
00013 //===----------------------------------------------------------------------===//
00014 
00015 #include "JIT.h"
00016 #include "llvm/Constants.h"
00017 #include "llvm/DerivedTypes.h"
00018 #include "llvm/Function.h"
00019 #include "llvm/GlobalVariable.h"
00020 #include "llvm/Instructions.h"
00021 #include "llvm/ModuleProvider.h"
00022 #include "llvm/CodeGen/MachineCodeEmitter.h"
00023 #include "llvm/CodeGen/MachineFunction.h"
00024 #include "llvm/ExecutionEngine/GenericValue.h"
00025 #include "llvm/Support/MutexGuard.h"
00026 #include "llvm/System/DynamicLibrary.h"
00027 #include "llvm/Target/TargetData.h"
00028 #include "llvm/Target/TargetMachine.h"
00029 #include "llvm/Target/TargetJITInfo.h"
00030 #include <iostream>
00031 using namespace llvm;
00032 
00033 #ifdef __APPLE__ 
00034 #include <AvailabilityMacros.h>
00035 #if MAC_OS_X_VERSION_MIN_REQUIRED > MAC_OS_X_VERSION_10_4
00036 // __dso_handle is resolved by Mac OS X dynamic linker.
00037 extern void *__dso_handle __attribute__ ((__visibility__ ("hidden")));
00038 #endif
00039 #endif
00040 
00041 static struct RegisterJIT {
00042   RegisterJIT() { JIT::Register(); }
00043 } JITRegistrator;
00044 
00045 namespace llvm {
00046   void LinkInJIT() {
00047   }
00048 }
00049 
00050 JIT::JIT(ModuleProvider *MP, TargetMachine &tm, TargetJITInfo &tji)
00051   : ExecutionEngine(MP), TM(tm), TJI(tji), state(MP) {
00052   setTargetData(TM.getTargetData());
00053 
00054   // Initialize MCE
00055   MCE = createEmitter(*this);
00056 
00057   // Add target data
00058   MutexGuard locked(lock);
00059   FunctionPassManager& PM = state.getPM(locked);
00060   PM.add(new TargetData(*TM.getTargetData()));
00061 
00062   // Compile LLVM Code down to machine code in the intermediate representation
00063   TJI.addPassesToJITCompile(PM);
00064 
00065   // Turn the machine code intermediate representation into bytes in memory that
00066   // may be executed.
00067   if (TM.addPassesToEmitMachineCode(PM, *MCE)) {
00068     std::cerr << "Target '" << TM.getName()
00069               << "' doesn't support machine code emission!\n";
00070     abort();
00071   }
00072 }
00073 
00074 JIT::~JIT() {
00075   delete MCE;
00076   delete &TM;
00077 }
00078 
00079 /// run - Start execution with the specified function and arguments.
00080 ///
00081 GenericValue JIT::runFunction(Function *F,
00082                               const std::vector<GenericValue> &ArgValues) {
00083   assert(F && "Function *F was null at entry to run()");
00084 
00085   void *FPtr = getPointerToFunction(F);
00086   assert(FPtr && "Pointer to fn's code was null after getPointerToFunction");
00087   const FunctionType *FTy = F->getFunctionType();
00088   const Type *RetTy = FTy->getReturnType();
00089 
00090   assert((FTy->getNumParams() <= ArgValues.size() || FTy->isVarArg()) &&
00091          "Too many arguments passed into function!");
00092   assert(FTy->getNumParams() == ArgValues.size() &&
00093          "This doesn't support passing arguments through varargs (yet)!");
00094 
00095   // Handle some common cases first.  These cases correspond to common `main'
00096   // prototypes.
00097   if (RetTy == Type::IntTy || RetTy == Type::UIntTy || RetTy == Type::VoidTy) {
00098     switch (ArgValues.size()) {
00099     case 3:
00100       if ((FTy->getParamType(0) == Type::IntTy ||
00101            FTy->getParamType(0) == Type::UIntTy) &&
00102           isa<PointerType>(FTy->getParamType(1)) &&
00103           isa<PointerType>(FTy->getParamType(2))) {
00104         int (*PF)(int, char **, const char **) =
00105           (int(*)(int, char **, const char **))(intptr_t)FPtr;
00106 
00107         // Call the function.
00108         GenericValue rv;
00109         rv.IntVal = PF(ArgValues[0].IntVal, (char **)GVTOP(ArgValues[1]),
00110                        (const char **)GVTOP(ArgValues[2]));
00111         return rv;
00112       }
00113       break;
00114     case 2:
00115       if ((FTy->getParamType(0) == Type::IntTy ||
00116            FTy->getParamType(0) == Type::UIntTy) &&
00117           isa<PointerType>(FTy->getParamType(1))) {
00118         int (*PF)(int, char **) = (int(*)(int, char **))(intptr_t)FPtr;
00119 
00120         // Call the function.
00121         GenericValue rv;
00122         rv.IntVal = PF(ArgValues[0].IntVal, (char **)GVTOP(ArgValues[1]));
00123         return rv;
00124       }
00125       break;
00126     case 1:
00127       if (FTy->getNumParams() == 1 &&
00128           (FTy->getParamType(0) == Type::IntTy ||
00129            FTy->getParamType(0) == Type::UIntTy)) {
00130         GenericValue rv;
00131         int (*PF)(int) = (int(*)(int))(intptr_t)FPtr;
00132         rv.IntVal = PF(ArgValues[0].IntVal);
00133         return rv;
00134       }
00135       break;
00136     }
00137   }
00138 
00139   // Handle cases where no arguments are passed first.
00140   if (ArgValues.empty()) {
00141     GenericValue rv;
00142     switch (RetTy->getTypeID()) {
00143     default: assert(0 && "Unknown return type for function call!");
00144     case Type::BoolTyID:
00145       rv.BoolVal = ((bool(*)())(intptr_t)FPtr)();
00146       return rv;
00147     case Type::SByteTyID:
00148     case Type::UByteTyID:
00149       rv.SByteVal = ((char(*)())(intptr_t)FPtr)();
00150       return rv;
00151     case Type::ShortTyID:
00152     case Type::UShortTyID:
00153       rv.ShortVal = ((short(*)())(intptr_t)FPtr)();
00154       return rv;
00155     case Type::VoidTyID:
00156     case Type::IntTyID:
00157     case Type::UIntTyID:
00158       rv.IntVal = ((int(*)())(intptr_t)FPtr)();
00159       return rv;
00160     case Type::LongTyID:
00161     case Type::ULongTyID:
00162       rv.LongVal = ((int64_t(*)())(intptr_t)FPtr)();
00163       return rv;
00164     case Type::FloatTyID:
00165       rv.FloatVal = ((float(*)())(intptr_t)FPtr)();
00166       return rv;
00167     case Type::DoubleTyID:
00168       rv.DoubleVal = ((double(*)())(intptr_t)FPtr)();
00169       return rv;
00170     case Type::PointerTyID:
00171       return PTOGV(((void*(*)())(intptr_t)FPtr)());
00172     }
00173   }
00174 
00175   // Okay, this is not one of our quick and easy cases.  Because we don't have a
00176   // full FFI, we have to codegen a nullary stub function that just calls the
00177   // function we are interested in, passing in constants for all of the
00178   // arguments.  Make this function and return.
00179 
00180   // First, create the function.
00181   FunctionType *STy=FunctionType::get(RetTy, std::vector<const Type*>(), false);
00182   Function *Stub = new Function(STy, Function::InternalLinkage, "",
00183                                 F->getParent());
00184 
00185   // Insert a basic block.
00186   BasicBlock *StubBB = new BasicBlock("", Stub);
00187 
00188   // Convert all of the GenericValue arguments over to constants.  Note that we
00189   // currently don't support varargs.
00190   std::vector<Value*> Args;
00191   for (unsigned i = 0, e = ArgValues.size(); i != e; ++i) {
00192     Constant *C = 0;
00193     const Type *ArgTy = FTy->getParamType(i);
00194     const GenericValue &AV = ArgValues[i];
00195     switch (ArgTy->getTypeID()) {
00196     default: assert(0 && "Unknown argument type for function call!");
00197     case Type::BoolTyID:   C = ConstantBool::get(AV.BoolVal); break;
00198     case Type::SByteTyID:  C = ConstantSInt::get(ArgTy, AV.SByteVal);  break;
00199     case Type::UByteTyID:  C = ConstantUInt::get(ArgTy, AV.UByteVal);  break;
00200     case Type::ShortTyID:  C = ConstantSInt::get(ArgTy, AV.ShortVal);  break;
00201     case Type::UShortTyID: C = ConstantUInt::get(ArgTy, AV.UShortVal); break;
00202     case Type::IntTyID:    C = ConstantSInt::get(ArgTy, AV.IntVal);    break;
00203     case Type::UIntTyID:   C = ConstantUInt::get(ArgTy, AV.UIntVal);   break;
00204     case Type::LongTyID:   C = ConstantSInt::get(ArgTy, AV.LongVal);   break;
00205     case Type::ULongTyID:  C = ConstantUInt::get(ArgTy, AV.ULongVal);  break;
00206     case Type::FloatTyID:  C = ConstantFP  ::get(ArgTy, AV.FloatVal);  break;
00207     case Type::DoubleTyID: C = ConstantFP  ::get(ArgTy, AV.DoubleVal); break;
00208     case Type::PointerTyID:
00209       void *ArgPtr = GVTOP(AV);
00210       if (sizeof(void*) == 4) {
00211         C = ConstantSInt::get(Type::IntTy, (int)(intptr_t)ArgPtr);
00212       } else {
00213         C = ConstantSInt::get(Type::LongTy, (intptr_t)ArgPtr);
00214       }
00215       C = ConstantExpr::getCast(C, ArgTy);  // Cast the integer to pointer
00216       break;
00217     }
00218     Args.push_back(C);
00219   }
00220 
00221   CallInst *TheCall = new CallInst(F, Args, "", StubBB);
00222   TheCall->setTailCall();
00223   if (TheCall->getType() != Type::VoidTy)
00224     new ReturnInst(TheCall, StubBB);             // Return result of the call.
00225   else
00226     new ReturnInst(StubBB);                      // Just return void.
00227 
00228   // Finally, return the value returned by our nullary stub function.
00229   return runFunction(Stub, std::vector<GenericValue>());
00230 }
00231 
00232 /// runJITOnFunction - Run the FunctionPassManager full of
00233 /// just-in-time compilation passes on F, hopefully filling in
00234 /// GlobalAddress[F] with the address of F's machine code.
00235 ///
00236 void JIT::runJITOnFunction(Function *F) {
00237   static bool isAlreadyCodeGenerating = false;
00238   assert(!isAlreadyCodeGenerating && "Error: Recursive compilation detected!");
00239 
00240   MutexGuard locked(lock);
00241 
00242   // JIT the function
00243   isAlreadyCodeGenerating = true;
00244   state.getPM(locked).run(*F);
00245   isAlreadyCodeGenerating = false;
00246 
00247   // If the function referred to a global variable that had not yet been
00248   // emitted, it allocates memory for the global, but doesn't emit it yet.  Emit
00249   // all of these globals now.
00250   while (!state.getPendingGlobals(locked).empty()) {
00251     const GlobalVariable *GV = state.getPendingGlobals(locked).back();
00252     state.getPendingGlobals(locked).pop_back();
00253     EmitGlobalVariable(GV);
00254   }
00255 }
00256 
00257 /// getPointerToFunction - This method is used to get the address of the
00258 /// specified function, compiling it if neccesary.
00259 ///
00260 void *JIT::getPointerToFunction(Function *F) {
00261   MutexGuard locked(lock);
00262 
00263   if (void *Addr = getPointerToGlobalIfAvailable(F))
00264     return Addr;   // Check if function already code gen'd
00265 
00266   // Make sure we read in the function if it exists in this Module
00267   if (F->hasNotBeenReadFromBytecode()) {
00268     std::string ErrorMsg;
00269     if (MP->materializeFunction(F, &ErrorMsg)) {
00270       std::cerr << "Error reading function '" << F->getName()
00271                 << "' from bytecode file: " << ErrorMsg << "\n";
00272       abort();
00273     }
00274   }
00275 
00276   if (F->isExternal()) {
00277     void *Addr = getPointerToNamedFunction(F->getName());
00278     addGlobalMapping(F, Addr);
00279     return Addr;
00280   }
00281 
00282   runJITOnFunction(F);
00283 
00284   void *Addr = getPointerToGlobalIfAvailable(F);
00285   assert(Addr && "Code generation didn't add function to GlobalAddress table!");
00286   return Addr;
00287 }
00288 
00289 /// getOrEmitGlobalVariable - Return the address of the specified global
00290 /// variable, possibly emitting it to memory if needed.  This is used by the
00291 /// Emitter.
00292 void *JIT::getOrEmitGlobalVariable(const GlobalVariable *GV) {
00293   MutexGuard locked(lock);
00294 
00295   void *Ptr = getPointerToGlobalIfAvailable(GV);
00296   if (Ptr) return Ptr;
00297 
00298   // If the global is external, just remember the address.
00299   if (GV->isExternal()) {
00300 #ifdef __APPLE__
00301 #if MAC_OS_X_VERSION_MIN_REQUIRED > MAC_OS_X_VERSION_10_4
00302     // __dso_handle is resolved by the Mac OS X dynamic linker.
00303     if (GV->getName() == "__dso_handle")
00304       return (void*)&__dso_handle;
00305 #endif
00306 #endif
00307     Ptr = sys::DynamicLibrary::SearchForAddressOfSymbol(GV->getName().c_str());
00308     if (Ptr == 0) {
00309       std::cerr << "Could not resolve external global address: "
00310                 << GV->getName() << "\n";
00311       abort();
00312     }
00313   } else {
00314     // If the global hasn't been emitted to memory yet, allocate space.  We will
00315     // actually initialize the global after current function has finished
00316     // compilation.
00317     const Type *GlobalType = GV->getType()->getElementType();
00318     size_t S = getTargetData()->getTypeSize(GlobalType);
00319     size_t A = getTargetData()->getTypeAlignment(GlobalType);
00320     if (A <= 8) {
00321       Ptr = malloc(S);
00322     } else {
00323       // Allocate S+A bytes of memory, then use an aligned pointer within that
00324       // space.
00325       Ptr = malloc(S+A);
00326       unsigned MisAligned = ((intptr_t)Ptr & (A-1));
00327       Ptr = (char*)Ptr + (MisAligned ? (A-MisAligned) : 0);
00328     }
00329     state.getPendingGlobals(locked).push_back(GV);
00330   }
00331   addGlobalMapping(GV, Ptr);
00332   return Ptr;
00333 }
00334 
00335 
00336 /// recompileAndRelinkFunction - This method is used to force a function
00337 /// which has already been compiled, to be compiled again, possibly
00338 /// after it has been modified. Then the entry to the old copy is overwritten
00339 /// with a branch to the new copy. If there was no old copy, this acts
00340 /// just like JIT::getPointerToFunction().
00341 ///
00342 void *JIT::recompileAndRelinkFunction(Function *F) {
00343   void *OldAddr = getPointerToGlobalIfAvailable(F);
00344 
00345   // If it's not already compiled there is no reason to patch it up.
00346   if (OldAddr == 0) { return getPointerToFunction(F); }
00347 
00348   // Delete the old function mapping.
00349   addGlobalMapping(F, 0);
00350 
00351   // Recodegen the function
00352   runJITOnFunction(F);
00353 
00354   // Update state, forward the old function to the new function.
00355   void *Addr = getPointerToGlobalIfAvailable(F);
00356   assert(Addr && "Code generation didn't add function to GlobalAddress table!");
00357   TJI.replaceMachineCodeForFunction(OldAddr, Addr);
00358   return Addr;
00359 }
00360