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 //===----------------------------------------------------------------------===// 21 22 #include "llvm/ADT/APInt.h" 23 #include "llvm/ADT/STLExtras.h" 24 #include "llvm/ExecutionEngine/ExecutionEngine.h" 25 #include "llvm/ExecutionEngine/GenericValue.h" 26 #include "llvm/IR/Argument.h" 27 #include "llvm/IR/BasicBlock.h" 28 #include "llvm/IR/Constants.h" 29 #include "llvm/IR/DerivedTypes.h" 30 #include "llvm/IR/Function.h" 31 #include "llvm/IR/InstrTypes.h" 32 #include "llvm/IR/Instruction.h" 33 #include "llvm/IR/Instructions.h" 34 #include "llvm/IR/LLVMContext.h" 35 #include "llvm/IR/Module.h" 36 #include "llvm/IR/Type.h" 37 #include "llvm/Support/Casting.h" 38 #include "llvm/Support/TargetSelect.h" 39 #include <algorithm> 40 #include <cassert> 41 #include <cstddef> 42 #include <cstdint> 43 #include <iostream> 44 #include <memory> 45 #include <vector> 46 #include <pthread.h> 47 48 using namespace llvm; 49 50 static Function* createAdd1(Module *M) { 51 // Create the add1 function entry and insert this entry into module M. The 52 // function will have a return type of "int" and take an argument of "int". 53 // The '0' terminates the list of argument types. 54 Function *Add1F = 55 cast<Function>(M->getOrInsertFunction("add1", 56 Type::getInt32Ty(M->getContext()), 57 Type::getInt32Ty(M->getContext()))); 58 59 // Add a basic block to the function. As before, it automatically inserts 60 // because of the last argument. 61 BasicBlock *BB = BasicBlock::Create(M->getContext(), "EntryBlock", Add1F); 62 63 // Get pointers to the constant `1'. 64 Value *One = ConstantInt::get(Type::getInt32Ty(M->getContext()), 1); 65 66 // Get pointers to the integer argument of the add1 function... 67 assert(Add1F->arg_begin() != Add1F->arg_end()); // Make sure there's an arg 68 Argument *ArgX = &*Add1F->arg_begin(); // Get the arg 69 ArgX->setName("AnArg"); // Give it a nice symbolic name for fun. 70 71 // Create the add instruction, inserting it into the end of BB. 72 Instruction *Add = BinaryOperator::CreateAdd(One, ArgX, "addresult", BB); 73 74 // Create the return instruction and add it to the basic block 75 ReturnInst::Create(M->getContext(), Add, BB); 76 77 // Now, function add1 is ready. 78 return Add1F; 79 } 80 81 static Function *CreateFibFunction(Module *M) { 82 // Create the fib function and insert it into module M. This function is said 83 // to return an int and take an int parameter. 84 Function *FibF = 85 cast<Function>(M->getOrInsertFunction("fib", 86 Type::getInt32Ty(M->getContext()), 87 Type::getInt32Ty(M->getContext()))); 88 89 // Add a basic block to the function. 90 BasicBlock *BB = BasicBlock::Create(M->getContext(), "EntryBlock", FibF); 91 92 // Get pointers to the constants. 93 Value *One = ConstantInt::get(Type::getInt32Ty(M->getContext()), 1); 94 Value *Two = ConstantInt::get(Type::getInt32Ty(M->getContext()), 2); 95 96 // Get pointer to the integer argument of the add1 function... 97 Argument *ArgX = &*FibF->arg_begin(); // Get the arg. 98 ArgX->setName("AnArg"); // Give it a nice symbolic name for fun. 99 100 // Create the true_block. 101 BasicBlock *RetBB = BasicBlock::Create(M->getContext(), "return", FibF); 102 // Create an exit block. 103 BasicBlock* RecurseBB = BasicBlock::Create(M->getContext(), "recurse", FibF); 104 105 // Create the "if (arg < 2) goto exitbb" 106 Value *CondInst = new ICmpInst(*BB, ICmpInst::ICMP_SLE, ArgX, Two, "cond"); 107 BranchInst::Create(RetBB, RecurseBB, CondInst, BB); 108 109 // Create: ret int 1 110 ReturnInst::Create(M->getContext(), One, RetBB); 111 112 // create fib(x-1) 113 Value *Sub = BinaryOperator::CreateSub(ArgX, One, "arg", RecurseBB); 114 Value *CallFibX1 = CallInst::Create(FibF, Sub, "fibx1", RecurseBB); 115 116 // create fib(x-2) 117 Sub = BinaryOperator::CreateSub(ArgX, Two, "arg", RecurseBB); 118 Value *CallFibX2 = CallInst::Create(FibF, Sub, "fibx2", RecurseBB); 119 120 // fib(x-1)+fib(x-2) 121 Value *Sum = 122 BinaryOperator::CreateAdd(CallFibX1, CallFibX2, "addresult", RecurseBB); 123 124 // Create the return instruction and add it to the basic block 125 ReturnInst::Create(M->getContext(), Sum, RecurseBB); 126 127 return FibF; 128 } 129 130 struct threadParams { 131 ExecutionEngine* EE; 132 Function* F; 133 int value; 134 }; 135 136 // We block the subthreads just before they begin to execute: 137 // we want all of them to call into the JIT at the same time, 138 // to verify that the locking is working correctly. 139 class WaitForThreads 140 { 141 public: 142 WaitForThreads() 143 { 144 n = 0; 145 waitFor = 0; 146 147 int result = pthread_cond_init( &condition, nullptr ); 148 (void)result; 149 assert( result == 0 ); 150 151 result = pthread_mutex_init( &mutex, nullptr ); 152 assert( result == 0 ); 153 } 154 155 ~WaitForThreads() 156 { 157 int result = pthread_cond_destroy( &condition ); 158 (void)result; 159 assert( result == 0 ); 160 161 result = pthread_mutex_destroy( &mutex ); 162 assert( result == 0 ); 163 } 164 165 // All threads will stop here until another thread calls releaseThreads 166 void block() 167 { 168 int result = pthread_mutex_lock( &mutex ); 169 (void)result; 170 assert( result == 0 ); 171 n ++; 172 //~ std::cout << "block() n " << n << " waitFor " << waitFor << std::endl; 173 174 assert( waitFor == 0 || n <= waitFor ); 175 if ( waitFor > 0 && n == waitFor ) 176 { 177 // There are enough threads blocked that we can release all of them 178 std::cout << "Unblocking threads from block()" << std::endl; 179 unblockThreads(); 180 } 181 else 182 { 183 // We just need to wait until someone unblocks us 184 result = pthread_cond_wait( &condition, &mutex ); 185 assert( result == 0 ); 186 } 187 188 // unlock the mutex before returning 189 result = pthread_mutex_unlock( &mutex ); 190 assert( result == 0 ); 191 } 192 193 // If there are num or more threads blocked, it will signal them all 194 // Otherwise, this thread blocks until there are enough OTHER threads 195 // blocked 196 void releaseThreads( size_t num ) 197 { 198 int result = pthread_mutex_lock( &mutex ); 199 (void)result; 200 assert( result == 0 ); 201 202 if ( n >= num ) { 203 std::cout << "Unblocking threads from releaseThreads()" << std::endl; 204 unblockThreads(); 205 } 206 else 207 { 208 waitFor = num; 209 pthread_cond_wait( &condition, &mutex ); 210 } 211 212 // unlock the mutex before returning 213 result = pthread_mutex_unlock( &mutex ); 214 assert( result == 0 ); 215 } 216 217 private: 218 void unblockThreads() 219 { 220 // Reset the counters to zero: this way, if any new threads 221 // enter while threads are exiting, they will block instead 222 // of triggering a new release of threads 223 n = 0; 224 225 // Reset waitFor to zero: this way, if waitFor threads enter 226 // while threads are exiting, they will block instead of 227 // triggering a new release of threads 228 waitFor = 0; 229 230 int result = pthread_cond_broadcast( &condition ); 231 (void)result; 232 assert(result == 0); 233 } 234 235 size_t n; 236 size_t waitFor; 237 pthread_cond_t condition; 238 pthread_mutex_t mutex; 239 }; 240 241 static WaitForThreads synchronize; 242 243 void* callFunc( void* param ) 244 { 245 struct threadParams* p = (struct threadParams*) param; 246 247 // Call the `foo' function with no arguments: 248 std::vector<GenericValue> Args(1); 249 Args[0].IntVal = APInt(32, p->value); 250 251 synchronize.block(); // wait until other threads are at this point 252 GenericValue gv = p->EE->runFunction(p->F, Args); 253 254 return (void*)(intptr_t)gv.IntVal.getZExtValue(); 255 } 256 257 int main() { 258 InitializeNativeTarget(); 259 LLVMContext Context; 260 261 // Create some module to put our function into it. 262 std::unique_ptr<Module> Owner = make_unique<Module>("test", Context); 263 Module *M = Owner.get(); 264 265 Function* add1F = createAdd1( M ); 266 Function* fibF = CreateFibFunction( M ); 267 268 // Now we create the JIT. 269 ExecutionEngine* EE = EngineBuilder(std::move(Owner)).create(); 270 271 //~ std::cout << "We just constructed this LLVM module:\n\n" << *M; 272 //~ std::cout << "\n\nRunning foo: " << std::flush; 273 274 // Create one thread for add1 and two threads for fib 275 struct threadParams add1 = { EE, add1F, 1000 }; 276 struct threadParams fib1 = { EE, fibF, 39 }; 277 struct threadParams fib2 = { EE, fibF, 42 }; 278 279 pthread_t add1Thread; 280 int result = pthread_create( &add1Thread, nullptr, callFunc, &add1 ); 281 if ( result != 0 ) { 282 std::cerr << "Could not create thread" << std::endl; 283 return 1; 284 } 285 286 pthread_t fibThread1; 287 result = pthread_create( &fibThread1, nullptr, callFunc, &fib1 ); 288 if ( result != 0 ) { 289 std::cerr << "Could not create thread" << std::endl; 290 return 1; 291 } 292 293 pthread_t fibThread2; 294 result = pthread_create( &fibThread2, nullptr, callFunc, &fib2 ); 295 if ( result != 0 ) { 296 std::cerr << "Could not create thread" << std::endl; 297 return 1; 298 } 299 300 synchronize.releaseThreads(3); // wait until other threads are at this point 301 302 void* returnValue; 303 result = pthread_join( add1Thread, &returnValue ); 304 if ( result != 0 ) { 305 std::cerr << "Could not join thread" << std::endl; 306 return 1; 307 } 308 std::cout << "Add1 returned " << intptr_t(returnValue) << std::endl; 309 310 result = pthread_join( fibThread1, &returnValue ); 311 if ( result != 0 ) { 312 std::cerr << "Could not join thread" << std::endl; 313 return 1; 314 } 315 std::cout << "Fib1 returned " << intptr_t(returnValue) << std::endl; 316 317 result = pthread_join( fibThread2, &returnValue ); 318 if ( result != 0 ) { 319 std::cerr << "Could not join thread" << std::endl; 320 return 1; 321 } 322 std::cout << "Fib2 returned " << intptr_t(returnValue) << std::endl; 323 324 return 0; 325 } 326