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