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/Support/TargetSelect.h"
30#include <iostream>
31using namespace llvm;
32
33static 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
65static 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
115struct 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.
124class WaitForThreads
125{
126public:
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
198private:
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    (void)result;
213    assert(result == 0);
214  }
215
216  size_t n;
217  size_t waitFor;
218  pthread_cond_t condition;
219  pthread_mutex_t mutex;
220};
221
222static WaitForThreads synchronize;
223
224void* 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
238int 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}
306