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 "llvm/ADT/STLExtras.h" 21 #include "llvm/ExecutionEngine/GenericValue.h" 22 #include "llvm/ExecutionEngine/Interpreter.h" 23 #include "llvm/IR/Constants.h" 24 #include "llvm/IR/DerivedTypes.h" 25 #include "llvm/IR/Instructions.h" 26 #include "llvm/IR/LLVMContext.h" 27 #include "llvm/IR/Module.h" 28 #include "llvm/Support/TargetSelect.h" 29 #include <iostream> 30 #include <pthread.h> 31 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 nullptr)); 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 nullptr)); 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, nullptr ); 134 assert( result == 0 ); 135 136 result = pthread_mutex_init( &mutex, nullptr ); 137 assert( result == 0 ); 138 } 139 140 ~WaitForThreads() 141 { 142 int result = pthread_cond_destroy( &condition ); 143 (void)result; 144 assert( result == 0 ); 145 146 result = pthread_mutex_destroy( &mutex ); 147 assert( result == 0 ); 148 } 149 150 // All threads will stop here until another thread calls releaseThreads 151 void block() 152 { 153 int result = pthread_mutex_lock( &mutex ); 154 (void)result; 155 assert( result == 0 ); 156 n ++; 157 //~ std::cout << "block() n " << n << " waitFor " << waitFor << std::endl; 158 159 assert( waitFor == 0 || n <= waitFor ); 160 if ( waitFor > 0 && n == waitFor ) 161 { 162 // There are enough threads blocked that we can release all of them 163 std::cout << "Unblocking threads from block()" << std::endl; 164 unblockThreads(); 165 } 166 else 167 { 168 // We just need to wait until someone unblocks us 169 result = pthread_cond_wait( &condition, &mutex ); 170 assert( result == 0 ); 171 } 172 173 // unlock the mutex before returning 174 result = pthread_mutex_unlock( &mutex ); 175 assert( result == 0 ); 176 } 177 178 // If there are num or more threads blocked, it will signal them all 179 // Otherwise, this thread blocks until there are enough OTHER threads 180 // blocked 181 void releaseThreads( size_t num ) 182 { 183 int result = pthread_mutex_lock( &mutex ); 184 (void)result; 185 assert( result == 0 ); 186 187 if ( n >= num ) { 188 std::cout << "Unblocking threads from releaseThreads()" << std::endl; 189 unblockThreads(); 190 } 191 else 192 { 193 waitFor = num; 194 pthread_cond_wait( &condition, &mutex ); 195 } 196 197 // unlock the mutex before returning 198 result = pthread_mutex_unlock( &mutex ); 199 assert( result == 0 ); 200 } 201 202 private: 203 void unblockThreads() 204 { 205 // Reset the counters to zero: this way, if any new threads 206 // enter while threads are exiting, they will block instead 207 // of triggering a new release of threads 208 n = 0; 209 210 // Reset waitFor to zero: this way, if waitFor threads enter 211 // while threads are exiting, they will block instead of 212 // triggering a new release of threads 213 waitFor = 0; 214 215 int result = pthread_cond_broadcast( &condition ); 216 (void)result; 217 assert(result == 0); 218 } 219 220 size_t n; 221 size_t waitFor; 222 pthread_cond_t condition; 223 pthread_mutex_t mutex; 224 }; 225 226 static WaitForThreads synchronize; 227 228 void* callFunc( void* param ) 229 { 230 struct threadParams* p = (struct threadParams*) param; 231 232 // Call the `foo' function with no arguments: 233 std::vector<GenericValue> Args(1); 234 Args[0].IntVal = APInt(32, p->value); 235 236 synchronize.block(); // wait until other threads are at this point 237 GenericValue gv = p->EE->runFunction(p->F, Args); 238 239 return (void*)(intptr_t)gv.IntVal.getZExtValue(); 240 } 241 242 int main() { 243 InitializeNativeTarget(); 244 LLVMContext Context; 245 246 // Create some module to put our function into it. 247 std::unique_ptr<Module> Owner = make_unique<Module>("test", Context); 248 Module *M = Owner.get(); 249 250 Function* add1F = createAdd1( M ); 251 Function* fibF = CreateFibFunction( M ); 252 253 // Now we create the JIT. 254 ExecutionEngine* EE = EngineBuilder(std::move(Owner)).create(); 255 256 //~ std::cout << "We just constructed this LLVM module:\n\n" << *M; 257 //~ std::cout << "\n\nRunning foo: " << std::flush; 258 259 // Create one thread for add1 and two threads for fib 260 struct threadParams add1 = { EE, add1F, 1000 }; 261 struct threadParams fib1 = { EE, fibF, 39 }; 262 struct threadParams fib2 = { EE, fibF, 42 }; 263 264 pthread_t add1Thread; 265 int result = pthread_create( &add1Thread, nullptr, callFunc, &add1 ); 266 if ( result != 0 ) { 267 std::cerr << "Could not create thread" << std::endl; 268 return 1; 269 } 270 271 pthread_t fibThread1; 272 result = pthread_create( &fibThread1, nullptr, callFunc, &fib1 ); 273 if ( result != 0 ) { 274 std::cerr << "Could not create thread" << std::endl; 275 return 1; 276 } 277 278 pthread_t fibThread2; 279 result = pthread_create( &fibThread2, nullptr, callFunc, &fib2 ); 280 if ( result != 0 ) { 281 std::cerr << "Could not create thread" << std::endl; 282 return 1; 283 } 284 285 synchronize.releaseThreads(3); // wait until other threads are at this point 286 287 void* returnValue; 288 result = pthread_join( add1Thread, &returnValue ); 289 if ( result != 0 ) { 290 std::cerr << "Could not join thread" << std::endl; 291 return 1; 292 } 293 std::cout << "Add1 returned " << intptr_t(returnValue) << std::endl; 294 295 result = pthread_join( fibThread1, &returnValue ); 296 if ( result != 0 ) { 297 std::cerr << "Could not join thread" << std::endl; 298 return 1; 299 } 300 std::cout << "Fib1 returned " << intptr_t(returnValue) << std::endl; 301 302 result = pthread_join( fibThread2, &returnValue ); 303 if ( result != 0 ) { 304 std::cerr << "Could not join thread" << std::endl; 305 return 1; 306 } 307 std::cout << "Fib2 returned " << intptr_t(returnValue) << std::endl; 308 309 return 0; 310 } 311
