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/Module.h"
  22 #include "llvm/Constants.h"
  23 #include "llvm/DerivedTypes.h"
  24 #include "llvm/Instructions.h"
  25 #include "llvm/ModuleProvider.h"
  26 #include "llvm/ExecutionEngine/JIT.h"
  27 #include "llvm/ExecutionEngine/Interpreter.h"
  28 #include "llvm/ExecutionEngine/GenericValue.h"
  29 #include <iostream>
  30 using namespace llvm;
  31
  32 static Function* createAdd1(Module *M) {
  33   // Create the add1 function entry and insert this entry into module M.  The
  34   // function will have a return type of "int" and take an argument of "int".
  35   // The '0' terminates the list of argument types.
  36   Function *Add1F =
  37     cast<Function>(M->getOrInsertFunction("add1", Type::Int32Ty, Type::Int32Ty,
  38                                           (Type *)0));
  39
  40   // Add a basic block to the function. As before, it automatically inserts
  41   // because of the last argument.
  42   BasicBlock *BB = BasicBlock::Create("EntryBlock", Add1F);
  43
  44   // Get pointers to the constant `1'.
  45   Value *One = ConstantInt::get(Type::Int32Ty, 1);
  46
  47   // Get pointers to the integer argument of the add1 function...
  48   assert(Add1F->arg_begin() != Add1F->arg_end()); // Make sure there's an arg
  49   Argument *ArgX = Add1F->arg_begin();  // Get the arg
  50   ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
  51
  52   // Create the add instruction, inserting it into the end of BB.
  53   Instruction *Add = BinaryOperator::CreateAdd(One, ArgX, "addresult", BB);
  54
  55   // Create the return instruction and add it to the basic block
  56   ReturnInst::Create(Add, BB);
  57
  58   // Now, function add1 is ready.
  59   return Add1F;
  60 }
  61
  62 static Function *CreateFibFunction(Module *M) {
  63   // Create the fib function and insert it into module M.  This function is said
  64   // to return an int and take an int parameter.
  65   Function *FibF =
  66     cast<Function>(M->getOrInsertFunction("fib", Type::Int32Ty, Type::Int32Ty,
  67                                           (Type *)0));
  68
  69   // Add a basic block to the function.
  70   BasicBlock *BB = BasicBlock::Create("EntryBlock", FibF);
  71
  72   // Get pointers to the constants.
  73   Value *One = ConstantInt::get(Type::Int32Ty, 1);
  74   Value *Two = ConstantInt::get(Type::Int32Ty, 2);
  75
  76   // Get pointer to the integer argument of the add1 function...
  77   Argument *ArgX = FibF->arg_begin();   // Get the arg.
  78   ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
  79
  80   // Create the true_block.
  81   BasicBlock *RetBB = BasicBlock::Create("return", FibF);
  82   // Create an exit block.
  83   BasicBlock* RecurseBB = BasicBlock::Create("recurse", FibF);
  84
  85   // Create the "if (arg < 2) goto exitbb"
  86   Value *CondInst = new ICmpInst(ICmpInst::ICMP_SLE, ArgX, Two, "cond", BB);
  87   BranchInst::Create(RetBB, RecurseBB, CondInst, BB);
  88
  89   // Create: ret int 1
  90   ReturnInst::Create(One, RetBB);
  91
  92   // create fib(x-1)
  93   Value *Sub = BinaryOperator::CreateSub(ArgX, One, "arg", RecurseBB);
  94   Value *CallFibX1 = CallInst::Create(FibF, Sub, "fibx1", RecurseBB);
  95
  96   // create fib(x-2)
  97   Sub = BinaryOperator::CreateSub(ArgX, Two, "arg", RecurseBB);
  98   Value *CallFibX2 = CallInst::Create(FibF, Sub, "fibx2", RecurseBB);
  99
 100   // fib(x-1)+fib(x-2)
 101   Value *Sum =
 102     BinaryOperator::CreateAdd(CallFibX1, CallFibX2, "addresult", RecurseBB);
 103
 104   // Create the return instruction and add it to the basic block
 105   ReturnInst::Create(Sum, RecurseBB);
 106
 107   return FibF;
 108 }
 109
 110 struct threadParams {
 111   ExecutionEngine* EE;
 112   Function* F;
 113   int value;
 114 };
 115
 116 // We block the subthreads just before they begin to execute:
 117 // we want all of them to call into the JIT at the same time,
 118 // to verify that the locking is working correctly.
 119 class WaitForThreads
 120 {
 121 public:
 122   WaitForThreads()
 123   {
 124     n = 0;
 125     waitFor = 0;
 126
 127     int result = pthread_cond_init( &condition, NULL );
 128     assert( result == 0 );
 129
 130     result = pthread_mutex_init( &mutex, NULL );
 131     assert( result == 0 );
 132   }
 133
 134   ~WaitForThreads()
 135   {
 136     int result = pthread_cond_destroy( &condition );
 137     assert( result == 0 );
 138
 139     result = pthread_mutex_destroy( &mutex );
 140     assert( result == 0 );
 141   }
 142
 143   // All threads will stop here until another thread calls releaseThreads
 144   void block()
 145   {
 146     int result = pthread_mutex_lock( &mutex );
 147     assert( result == 0 );
 148     n ++;
 149     //~ std::cout << "block() n " << n << " waitFor " << waitFor << std::endl;
 150
 151     assert( waitFor == 0 || n <= waitFor );
 152     if ( waitFor > 0 && n == waitFor )
 153     {
 154       // There are enough threads blocked that we can release all of them
 155       std::cout << "Unblocking threads from block()" << std::endl;
 156       unblockThreads();
 157     }
 158     else
 159     {
 160       // We just need to wait until someone unblocks us
 161       result = pthread_cond_wait( &condition, &mutex );
 162       assert( result == 0 );
 163     }
 164
 165     // unlock the mutex before returning
 166     result = pthread_mutex_unlock( &mutex );
 167     assert( result == 0 );
 168   }
 169
 170   // If there are num or more threads blocked, it will signal them all
 171   // Otherwise, this thread blocks until there are enough OTHER threads
 172   // blocked
 173   void releaseThreads( size_t num )
 174   {
 175     int result = pthread_mutex_lock( &mutex );
 176     assert( result == 0 );
 177
 178     if ( n >= num ) {
 179       std::cout << "Unblocking threads from releaseThreads()" << std::endl;
 180       unblockThreads();
 181     }
 182     else
 183     {
 184       waitFor = num;
 185       pthread_cond_wait( &condition, &mutex );
 186     }
 187
 188     // unlock the mutex before returning
 189     result = pthread_mutex_unlock( &mutex );
 190     assert( result == 0 );
 191   }
 192
 193 private:
 194   void unblockThreads()
 195   {
 196     // Reset the counters to zero: this way, if any new threads
 197     // enter while threads are exiting, they will block instead
 198     // of triggering a new release of threads
 199     n = 0;
 200
 201     // Reset waitFor to zero: this way, if waitFor threads enter
 202     // while threads are exiting, they will block instead of
 203     // triggering a new release of threads
 204     waitFor = 0;
 205
 206     int result = pthread_cond_broadcast( &condition );
 207     assert(result == 0); result=result;
 208   }
 209
 210   size_t n;
 211   size_t waitFor;
 212   pthread_cond_t condition;
 213   pthread_mutex_t mutex;
 214 };
 215
 216 static WaitForThreads synchronize;
 217
 218 void* callFunc( void* param )
 219 {
 220   struct threadParams* p = (struct threadParams*) param;
 221
 222   // Call the `foo' function with no arguments:
 223   std::vector<GenericValue> Args(1);
 224   Args[0].IntVal = APInt(32, p->value);
 225
 226   synchronize.block(); // wait until other threads are at this point
 227   GenericValue gv = p->EE->runFunction(p->F, Args);
 228
 229   return (void*)(intptr_t)gv.IntVal.getZExtValue();
 230 }
 231
 232 int main()
 233 {
 234   // Create some module to put our function into it.
 235   Module *M = new Module("test");
 236
 237   Function* add1F = createAdd1( M );
 238   Function* fibF = CreateFibFunction( M );
 239
 240   // Now we create the JIT.
 241   ExistingModuleProvider* MP = new ExistingModuleProvider(M);
 242   ExecutionEngine* EE = ExecutionEngine::create(MP, false);
 243
 244   //~ std::cout << "We just constructed this LLVM module:\n\n" << *M;
 245   //~ std::cout << "\n\nRunning foo: " << std::flush;
 246
 247   // Create one thread for add1 and two threads for fib
 248   struct threadParams add1 = { EE, add1F, 1000 };
 249   struct threadParams fib1 = { EE, fibF, 39 };
 250   struct threadParams fib2 = { EE, fibF, 42 };
 251
 252   pthread_t add1Thread;
 253   int result = pthread_create( &add1Thread, NULL, callFunc, &add1 );
 254   if ( result != 0 ) {
 255           std::cerr << "Could not create thread" << std::endl;
 256           return 1;
 257   }
 258
 259   pthread_t fibThread1;
 260   result = pthread_create( &fibThread1, NULL, callFunc, &fib1 );
 261   if ( result != 0 ) {
 262           std::cerr << "Could not create thread" << std::endl;
 263           return 1;
 264   }
 265
 266   pthread_t fibThread2;
 267   result = pthread_create( &fibThread2, NULL, callFunc, &fib2 );
 268   if ( result != 0 ) {
 269           std::cerr << "Could not create thread" << std::endl;
 270           return 1;
 271   }
 272
 273   synchronize.releaseThreads(3); // wait until other threads are at this point
 274
 275   void* returnValue;
 276   result = pthread_join( add1Thread, &returnValue );
 277   if ( result != 0 ) {
 278           std::cerr << "Could not join thread" << std::endl;
 279           return 1;
 280   }
 281   std::cout << "Add1 returned " << intptr_t(returnValue) << std::endl;
 282
 283   result = pthread_join( fibThread1, &returnValue );
 284   if ( result != 0 ) {
 285           std::cerr << "Could not join thread" << std::endl;
 286           return 1;
 287   }
 288   std::cout << "Fib1 returned " << intptr_t(returnValue) << std::endl;
 289
 290   result = pthread_join( fibThread2, &returnValue );
 291   if ( result != 0 ) {
 292           std::cerr << "Could not join thread" << std::endl;
 293           return 1;
 294   }
 295   std::cout << "Fib2 returned " << intptr_t(returnValue) << std::endl;
 296
 297   return 0;
 298 }