examples/ParallelJIT/ParallelJIT.cpp

   1 //===-- examples/ParallelJIT/ParallelJIT.cpp - Exercise threaded-safe JIT -===//
   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 // Parallel JIT
  11 //
  12 // This test program creates two LLVM functions then calls them from three
  13 // separate threads.  It requires the pthreads library.
  14 // The three threads are created and then block waiting on a condition variable.
  15 // Once all threads are blocked on the conditional variable, the main thread
  16 // wakes them up. This complicated work is performed so that all three threads
  17 // call into the JIT at the same time (or the best possible approximation of the
  18 // same time). This test had assertion errors until I got the locking right.
  19
  20 #include <pthread.h>
  21 #include "llvm/LLVMContext.h"
  22 #include "llvm/Module.h"
  23 #include "llvm/Constants.h"
  24 #include "llvm/DerivedTypes.h"
  25 #include "llvm/Instructions.h"
  26 #include "llvm/ModuleProvider.h"
  27 #include "llvm/ExecutionEngine/JIT.h"
  28 #include "llvm/ExecutionEngine/Interpreter.h"
  29 #include "llvm/ExecutionEngine/GenericValue.h"
  30 #include "llvm/Target/TargetSelect.h"
  31 #include <iostream>
  32 using namespace llvm;
  33
  34 static Function* createAdd1(Module *M) {
  35   // Create the add1 function entry and insert this entry into module M.  The
  36   // function will have a return type of "int" and take an argument of "int".
  37   // The '0' terminates the list of argument types.
  38   Function *Add1F =
  39     cast<Function>(M->getOrInsertFunction("add1",
  40                                           Type::getInt32Ty(M->getContext()),
  41                                           Type::getInt32Ty(M->getContext()),
  42                                           (Type *)0));
  43
  44   // Add a basic block to the function. As before, it automatically inserts
  45   // because of the last argument.
  46   BasicBlock *BB = BasicBlock::Create(M->getContext(), "EntryBlock", Add1F);
  47
  48   // Get pointers to the constant `1'.
  49   Value *One = ConstantInt::get(Type::getInt32Ty(M->getContext()), 1);
  50
  51   // Get pointers to the integer argument of the add1 function...
  52   assert(Add1F->arg_begin() != Add1F->arg_end()); // Make sure there's an arg
  53   Argument *ArgX = Add1F->arg_begin();  // Get the arg
  54   ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
  55
  56   // Create the add instruction, inserting it into the end of BB.
  57   Instruction *Add = BinaryOperator::CreateAdd(One, ArgX, "addresult", BB);
  58
  59   // Create the return instruction and add it to the basic block
  60   ReturnInst::Create(M->getContext(), Add, BB);
  61
  62   // Now, function add1 is ready.
  63   return Add1F;
  64 }
  65
  66 static Function *CreateFibFunction(Module *M) {
  67   // Create the fib function and insert it into module M.  This function is said
  68   // to return an int and take an int parameter.
  69   Function *FibF =
  70     cast<Function>(M->getOrInsertFunction("fib",
  71                                           Type::getInt32Ty(M->getContext()),
  72                                           Type::getInt32Ty(M->getContext()),
  73                                           (Type *)0));
  74
  75   // Add a basic block to the function.
  76   BasicBlock *BB = BasicBlock::Create(M->getContext(), "EntryBlock", FibF);
  77
  78   // Get pointers to the constants.
  79   Value *One = ConstantInt::get(Type::getInt32Ty(M->getContext()), 1);
  80   Value *Two = ConstantInt::get(Type::getInt32Ty(M->getContext()), 2);
  81
  82   // Get pointer to the integer argument of the add1 function...
  83   Argument *ArgX = FibF->arg_begin();   // Get the arg.
  84   ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
  85
  86   // Create the true_block.
  87   BasicBlock *RetBB = BasicBlock::Create(M->getContext(), "return", FibF);
  88   // Create an exit block.
  89   BasicBlock* RecurseBB = BasicBlock::Create(M->getContext(), "recurse", FibF);
  90
  91   // Create the "if (arg < 2) goto exitbb"
  92   Value *CondInst = new ICmpInst(*BB, ICmpInst::ICMP_SLE, ArgX, Two, "cond");
  93   BranchInst::Create(RetBB, RecurseBB, CondInst, BB);
  94
  95   // Create: ret int 1
  96   ReturnInst::Create(M->getContext(), One, RetBB);
  97
  98   // create fib(x-1)
  99   Value *Sub = BinaryOperator::CreateSub(ArgX, One, "arg", RecurseBB);
 100   Value *CallFibX1 = CallInst::Create(FibF, Sub, "fibx1", RecurseBB);
 101
 102   // create fib(x-2)
 103   Sub = BinaryOperator::CreateSub(ArgX, Two, "arg", RecurseBB);
 104   Value *CallFibX2 = CallInst::Create(FibF, Sub, "fibx2", RecurseBB);
 105
 106   // fib(x-1)+fib(x-2)
 107   Value *Sum =
 108     BinaryOperator::CreateAdd(CallFibX1, CallFibX2, "addresult", RecurseBB);
 109
 110   // Create the return instruction and add it to the basic block
 111   ReturnInst::Create(M->getContext(), Sum, RecurseBB);
 112
 113   return FibF;
 114 }
 115
 116 struct threadParams {
 117   ExecutionEngine* EE;
 118   Function* F;
 119   int value;
 120 };
 121
 122 // We block the subthreads just before they begin to execute:
 123 // we want all of them to call into the JIT at the same time,
 124 // to verify that the locking is working correctly.
 125 class WaitForThreads
 126 {
 127 public:
 128   WaitForThreads()
 129   {
 130     n = 0;
 131     waitFor = 0;
 132
 133     int result = pthread_cond_init( &condition, NULL );
 134     assert( result == 0 );
 135
 136     result = pthread_mutex_init( &mutex, NULL );
 137     assert( result == 0 );
 138   }
 139
 140   ~WaitForThreads()
 141   {
 142     int result = pthread_cond_destroy( &condition );
 143     assert( result == 0 );
 144
 145     result = pthread_mutex_destroy( &mutex );
 146     assert( result == 0 );
 147   }
 148
 149   // All threads will stop here until another thread calls releaseThreads
 150   void block()
 151   {
 152     int result = pthread_mutex_lock( &mutex );
 153     assert( result == 0 );
 154     n ++;
 155     //~ std::cout << "block() n " << n << " waitFor " << waitFor << std::endl;
 156
 157     assert( waitFor == 0 || n <= waitFor );
 158     if ( waitFor > 0 && n == waitFor )
 159     {
 160       // There are enough threads blocked that we can release all of them
 161       std::cout << "Unblocking threads from block()" << std::endl;
 162       unblockThreads();
 163     }
 164     else
 165     {
 166       // We just need to wait until someone unblocks us
 167       result = pthread_cond_wait( &condition, &mutex );
 168       assert( result == 0 );
 169     }
 170
 171     // unlock the mutex before returning
 172     result = pthread_mutex_unlock( &mutex );
 173     assert( result == 0 );
 174   }
 175
 176   // If there are num or more threads blocked, it will signal them all
 177   // Otherwise, this thread blocks until there are enough OTHER threads
 178   // blocked
 179   void releaseThreads( size_t num )
 180   {
 181     int result = pthread_mutex_lock( &mutex );
 182     assert( result == 0 );
 183
 184     if ( n >= num ) {
 185       std::cout << "Unblocking threads from releaseThreads()" << std::endl;
 186       unblockThreads();
 187     }
 188     else
 189     {
 190       waitFor = num;
 191       pthread_cond_wait( &condition, &mutex );
 192     }
 193
 194     // unlock the mutex before returning
 195     result = pthread_mutex_unlock( &mutex );
 196     assert( result == 0 );
 197   }
 198
 199 private:
 200   void unblockThreads()
 201   {
 202     // Reset the counters to zero: this way, if any new threads
 203     // enter while threads are exiting, they will block instead
 204     // of triggering a new release of threads
 205     n = 0;
 206
 207     // Reset waitFor to zero: this way, if waitFor threads enter
 208     // while threads are exiting, they will block instead of
 209     // triggering a new release of threads
 210     waitFor = 0;
 211
 212     int result = pthread_cond_broadcast( &condition );
 213     assert(result == 0); result=result;
 214   }
 215
 216   size_t n;
 217   size_t waitFor;
 218   pthread_cond_t condition;
 219   pthread_mutex_t mutex;
 220 };
 221
 222 static WaitForThreads synchronize;
 223
 224 void* callFunc( void* param )
 225 {
 226   struct threadParams* p = (struct threadParams*) param;
 227
 228   // Call the `foo' function with no arguments:
 229   std::vector<GenericValue> Args(1);
 230   Args[0].IntVal = APInt(32, p->value);
 231
 232   synchronize.block(); // wait until other threads are at this point
 233   GenericValue gv = p->EE->runFunction(p->F, Args);
 234
 235   return (void*)(intptr_t)gv.IntVal.getZExtValue();
 236 }
 237
 238 int main() {
 239   InitializeNativeTarget();
 240   LLVMContext Context;
 241
 242   // Create some module to put our function into it.
 243   Module *M = new Module("test", Context);
 244
 245   Function* add1F = createAdd1( M );
 246   Function* fibF = CreateFibFunction( M );
 247
 248   // Now we create the JIT.
 249   ExecutionEngine* EE = EngineBuilder(M).create();
 250
 251   //~ std::cout << "We just constructed this LLVM module:\n\n" << *M;
 252   //~ std::cout << "\n\nRunning foo: " << std::flush;
 253
 254   // Create one thread for add1 and two threads for fib
 255   struct threadParams add1 = { EE, add1F, 1000 };
 256   struct threadParams fib1 = { EE, fibF, 39 };
 257   struct threadParams fib2 = { EE, fibF, 42 };
 258
 259   pthread_t add1Thread;
 260   int result = pthread_create( &add1Thread, NULL, callFunc, &add1 );
 261   if ( result != 0 ) {
 262           std::cerr << "Could not create thread" << std::endl;
 263           return 1;
 264   }
 265
 266   pthread_t fibThread1;
 267   result = pthread_create( &fibThread1, NULL, callFunc, &fib1 );
 268   if ( result != 0 ) {
 269           std::cerr << "Could not create thread" << std::endl;
 270           return 1;
 271   }
 272
 273   pthread_t fibThread2;
 274   result = pthread_create( &fibThread2, NULL, callFunc, &fib2 );
 275   if ( result != 0 ) {
 276           std::cerr << "Could not create thread" << std::endl;
 277           return 1;
 278   }
 279
 280   synchronize.releaseThreads(3); // wait until other threads are at this point
 281
 282   void* returnValue;
 283   result = pthread_join( add1Thread, &returnValue );
 284   if ( result != 0 ) {
 285           std::cerr << "Could not join thread" << std::endl;
 286           return 1;
 287   }
 288   std::cout << "Add1 returned " << intptr_t(returnValue) << std::endl;
 289
 290   result = pthread_join( fibThread1, &returnValue );
 291   if ( result != 0 ) {
 292           std::cerr << "Could not join thread" << std::endl;
 293           return 1;
 294   }
 295   std::cout << "Fib1 returned " << intptr_t(returnValue) << std::endl;
 296
 297   result = pthread_join( fibThread2, &returnValue );
 298   if ( result != 0 ) {
 299           std::cerr << "Could not join thread" << std::endl;
 300           return 1;
 301   }
 302   std::cout << "Fib2 returned " << intptr_t(returnValue) << std::endl;
 303
 304   return 0;
 305 }