For PR418:

Add an example program that utilizes multiple threads in the JIT to process
work. This was used by Evan Jones as the original test case for ensuring
that the ExecutionEngine was thread safe.

Original source by Evan Jones (adapted from other LLVM JIT examples) and
made LLVM style compliant by Reid Spencer.

llvm-svn: 22411

examples/Makefile

@@ -11,6 +11,6 @@ LEVEL=..
 include $(LEVEL)/Makefile.config
 
 #PARALLEL_DIRS:= $(patsubst %/Makefile,%,$(wildcard $(SourceDir)/*/Makefile))
-PARALLEL_DIRS:= Fibonacci HowToUseJIT ModuleMaker BFtoLLVM
+PARALLEL_DIRS:= ParallelJIT Fibonacci HowToUseJIT ModuleMaker BFtoLLVM
 
 include $(LEVEL)/Makefile.common

examples/ParallelJIT/Makefile

@@ -0,0 +1,16 @@
+##===- examples/HowToUseJIT/Makefile -----------------------*- Makefile -*-===##
+# 
+#                     The LLVM Compiler Infrastructure
+#
+# This file was developed by Valery A. Khamenya and is distributed under
+# the University of Illinois Open Source License. See LICENSE.TXT for details.
+# 
+##===----------------------------------------------------------------------===##
+LEVEL = ../..
+TOOLNAME = ParallelJIT
+EXAMPLE_TOOL = 1
+
+# Enable JIT support
+LLVMLIBS := JIT
+
+include $(LEVEL)/Makefile.common

examples/ParallelJIT/ParallelJIT.cpp

@@ -0,0 +1,295 @@
+//===-- examples/ParallelJIT/ParallelJIT.cpp - Exercise threaded-safe JIT -===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Evan Jones and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Parallel JIT
+//
+// This test program creates two LLVM functions then calls them from three 
+// separate threads.  It requires the pthreads library.
+// The three threads are created and then block waiting on a condition variable.
+// Once all threads are blocked on the conditional variable, the main thread
+// wakes them up. This complicated work is performed so that all three threads
+// call into the JIT at the same time (or the best possible approximation of the
+// same time). This test had assertion errors until I got the locking right.
+
+#include <pthread.h>
+#include "llvm/Module.h"
+#include "llvm/Constants.h"
+#include "llvm/Type.h"
+#include "llvm/Instructions.h"
+#include "llvm/ModuleProvider.h"
+#include "llvm/ExecutionEngine/ExecutionEngine.h"
+#include "llvm/ExecutionEngine/GenericValue.h"
+#include <iostream>
+using namespace llvm;
+
+static Function* createAdd1( Module* M )
+{
+  // Create the add1 function entry and insert this entry into module M.  The
+  // function will have a return type of "int" and take an argument of "int".
+  // The '0' terminates the list of argument types.
+  Function *Add1F = M->getOrInsertFunction("add1", Type::IntTy, Type::IntTy, 0);
+  
+  // Add a basic block to the function. As before, it automatically inserts
+  // because of the last argument.
+  BasicBlock *BB = new BasicBlock("EntryBlock", Add1F);
+  
+  // Get pointers to the constant `1'.
+  Value *One = ConstantSInt::get(Type::IntTy, 1);
+  
+  // Get pointers to the integer argument of the add1 function...
+  assert(Add1F->arg_begin() != Add1F->arg_end()); // Make sure there's an arg
+  Argument *ArgX = Add1F->arg_begin();  // Get the arg
+  ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
+  
+  // Create the add instruction, inserting it into the end of BB.
+  Instruction *Add = BinaryOperator::createAdd(One, ArgX, "addresult", BB);
+  
+  // Create the return instruction and add it to the basic block
+  new ReturnInst(Add, BB);
+  
+  // Now, function add1 is ready.	
+  return Add1F;
+}
+
+static Function *CreateFibFunction(Module *M)
+{
+  // Create the fib function and insert it into module M.  This function is said
+  // to return an int and take an int parameter.
+  Function *FibF = M->getOrInsertFunction("fib", Type::IntTy, Type::IntTy, 0);
+  
+  // Add a basic block to the function.
+  BasicBlock *BB = new BasicBlock("EntryBlock", FibF);
+  
+  // Get pointers to the constants.
+  Value *One = ConstantSInt::get(Type::IntTy, 1);
+  Value *Two = ConstantSInt::get(Type::IntTy, 2);
+  
+  // Get pointer to the integer argument of the add1 function...
+  Argument *ArgX = FibF->arg_begin();   // Get the arg.
+  ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
+  
+  // Create the true_block.
+  BasicBlock *RetBB = new BasicBlock("return", FibF);
+  // Create an exit block.
+  BasicBlock* RecurseBB = new BasicBlock("recurse", FibF);
+  
+  // Create the "if (arg < 2) goto exitbb"
+  Value *CondInst = BinaryOperator::createSetLE(ArgX, Two, "cond", BB);
+  new BranchInst(RetBB, RecurseBB, CondInst, BB);
+  
+  // Create: ret int 1
+  new ReturnInst(One, RetBB);
+  
+  // create fib(x-1)
+  Value *Sub = BinaryOperator::createSub(ArgX, One, "arg", RecurseBB);
+  Value *CallFibX1 = new CallInst(FibF, Sub, "fibx1", RecurseBB);
+  
+  // create fib(x-2)
+  Sub = BinaryOperator::createSub(ArgX, Two, "arg", RecurseBB);
+  Value *CallFibX2 = new CallInst(FibF, Sub, "fibx2", RecurseBB);
+  
+  // fib(x-1)+fib(x-2)
+  Value *Sum = 
+    BinaryOperator::createAdd(CallFibX1, CallFibX2, "addresult", RecurseBB);
+  
+  // Create the return instruction and add it to the basic block
+  new ReturnInst(Sum, RecurseBB);
+  
+  return FibF;
+}
+
+struct threadParams {
+  ExecutionEngine* EE;
+  Function* F;
+  int value;
+};
+
+// We block the subthreads just before they begin to execute:
+// we want all of them to call into the JIT at the same time,
+// to verify that the locking is working correctly.
+class WaitForThreads
+{
+public:
+  WaitForThreads()
+  {
+    n = 0;
+    waitFor = 0;
+    
+    int result = pthread_cond_init( &condition, NULL );
+    assert( result == 0 );
+    
+    result = pthread_mutex_init( &mutex, NULL );
+    assert( result == 0 );
+  }
+  
+  ~WaitForThreads()
+  {
+    int result = pthread_cond_destroy( &condition );
+    assert( result == 0 );
+    
+    result = pthread_mutex_destroy( &mutex );
+    assert( result == 0 );
+  }
+  
+  // All threads will stop here until another thread calls releaseThreads
+  void block()
+  {
+    int result = pthread_mutex_lock( &mutex );
+    assert( result == 0 );
+    n ++;
+    //~ std::cout << "block() n " << n << " waitFor " << waitFor << std::endl;
+    
+    assert( waitFor == 0 || n <= waitFor );
+    if ( waitFor > 0 && n == waitFor ) 
+    {
+      // There are enough threads blocked that we can release all of them
+      std::cout << "Unblocking threads from block()" << std::endl;
+      unblockThreads();
+    } 
+    else 
+    {
+      // We just need to wait until someone unblocks us
+      result = pthread_cond_wait( &condition, &mutex );
+      assert( result == 0 );
+    }
+    
+    // unlock the mutex before returning
+    result = pthread_mutex_unlock( &mutex );
+    assert( result == 0 );
+  }
+  
+  // If there are num or more threads blocked, it will signal them all
+  // Otherwise, this thread blocks until there are enough OTHER threads
+  // blocked
+  void releaseThreads( size_t num )
+  {
+    int result = pthread_mutex_lock( &mutex );
+    assert( result == 0 );
+    
+    if ( n >= num ) {
+      std::cout << "Unblocking threads from releaseThreads()" << std::endl;
+      unblockThreads();
+    } 
+    else 
+    {
+      waitFor = num;
+      pthread_cond_wait( &condition, &mutex );
+    }
+    
+    // unlock the mutex before returning
+    result = pthread_mutex_unlock( &mutex );
+    assert( result == 0 );
+  }
+  
+private:
+  void unblockThreads()
+  {
+    // Reset the counters to zero: this way, if any new threads
+    // enter while threads are exiting, they will block instead
+    // of triggering a new release of threads
+    n = 0;
+    
+    // Reset waitFor to zero: this way, if waitFor threads enter
+    // while threads are exiting, they will block instead of
+    // triggering a new release of threads
+    waitFor = 0;
+
+    int result = pthread_cond_broadcast( &condition );
+    assert( result == 0 );
+  }
+  
+  size_t n;
+  size_t waitFor;
+  pthread_cond_t condition;
+  pthread_mutex_t mutex;
+};
+
+static WaitForThreads synchronize;
+
+void* callFunc( void* param )
+{
+  struct threadParams* p = (struct threadParams*) param;
+  
+  // Call the `foo' function with no arguments:
+  std::vector<GenericValue> Args(1);
+  Args[0].IntVal = p->value;
+  
+  synchronize.block(); // wait until other threads are at this point
+  GenericValue gv = p->EE->runFunction(p->F, Args);
+          
+  return (void*) gv.IntVal;
+}
+
+int main() 
+{
+  // Create some module to put our function into it.
+  Module *M = new Module("test");
+  
+  Function* add1F = createAdd1( M );
+  Function* fibF = CreateFibFunction( M );
+  
+  // Now we create the JIT.
+  ExistingModuleProvider* MP = new ExistingModuleProvider(M);
+  ExecutionEngine* EE = ExecutionEngine::create(MP, false);
+  
+  //~ std::cout << "We just constructed this LLVM module:\n\n" << *M;
+  //~ std::cout << "\n\nRunning foo: " << std::flush;
+  
+  // Create one thread for add1 and two threads for fib
+  struct threadParams add1 = { EE, add1F, 1000 };
+  struct threadParams fib1 = { EE, fibF, 39 };
+  struct threadParams fib2 = { EE, fibF, 42 };
+  
+  pthread_t add1Thread;
+  int result = pthread_create( &add1Thread, NULL, callFunc, &add1 );
+  if ( result != 0 ) {
+          std::cerr << "Could not create thread" << std::endl;
+          return 1;
+  }
+  
+  pthread_t fibThread1;
+  result = pthread_create( &fibThread1, NULL, callFunc, &fib1 );
+  if ( result != 0 ) {
+          std::cerr << "Could not create thread" << std::endl;
+          return 1;
+  }
+  
+  pthread_t fibThread2;
+  result = pthread_create( &fibThread2, NULL, callFunc, &fib2 );
+  if ( result != 0 ) {
+          std::cerr << "Could not create thread" << std::endl;
+          return 1;
+  }
+  
+  synchronize.releaseThreads(3); // wait until other threads are at this point
+  
+  void* returnValue;
+  result = pthread_join( add1Thread, &returnValue );
+  if ( result != 0 ) {
+          std::cerr << "Could not join thread" << std::endl;
+          return 1;
+  }
+  std::cout << "Add1 returned " << (int) returnValue << std::endl;
+  
+  result = pthread_join( fibThread1, &returnValue );
+  if ( result != 0 ) {
+          std::cerr << "Could not join thread" << std::endl;
+          return 1;
+  }
+  std::cout << "Fib1 returned " << (int) returnValue << std::endl;
+  
+  result = pthread_join( fibThread2, &returnValue );
+  if ( result != 0 ) {
+          std::cerr << "Could not join thread" << std::endl;
+          return 1;
+  }
+  std::cout << "Fib2 returned " << (int) returnValue << std::endl;
+  
+  return 0;
+}