//===-- examples/ParallelJIT/ParallelJIT.cpp - Exercise threaded-safe JIT -===//
//
// The LLVM Compiler Infrastructure
//
// This file 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/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/ExecutionEngine/JIT.h"
#include "llvm/ExecutionEngine/Interpreter.h"
#include "llvm/ExecutionEngine/GenericValue.h"
#include "llvm/Support/TargetSelect.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 =
cast<Function>(M->getOrInsertFunction("add1",
Type::getInt32Ty(M->getContext()),
Type::getInt32Ty(M->getContext()),
(Type *)0));
// Add a basic block to the function. As before, it automatically inserts
// because of the last argument.
BasicBlock *BB = BasicBlock::Create(M->getContext(), "EntryBlock", Add1F);
// Get pointers to the constant `1'.
Value *One = ConstantInt::get(Type::getInt32Ty(M->getContext()), 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
ReturnInst::Create(M->getContext(), 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 =
cast<Function>(M->getOrInsertFunction("fib",
Type::getInt32Ty(M->getContext()),
Type::getInt32Ty(M->getContext()),
(Type *)0));
// Add a basic block to the function.
BasicBlock *BB = BasicBlock::Create(M->getContext(), "EntryBlock", FibF);
// Get pointers to the constants.
Value *One = ConstantInt::get(Type::getInt32Ty(M->getContext()), 1);
Value *Two = ConstantInt::get(Type::getInt32Ty(M->getContext()), 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 = BasicBlock::Create(M->getContext(), "return", FibF);
// Create an exit block.
BasicBlock* RecurseBB = BasicBlock::Create(M->getContext(), "recurse", FibF);
// Create the "if (arg < 2) goto exitbb"
Value *CondInst = new ICmpInst(*BB, ICmpInst::ICMP_SLE, ArgX, Two, "cond");
BranchInst::Create(RetBB, RecurseBB, CondInst, BB);
// Create: ret int 1
ReturnInst::Create(M->getContext(), One, RetBB);
// create fib(x-1)
Value *Sub = BinaryOperator::CreateSub(ArgX, One, "arg", RecurseBB);
Value *CallFibX1 = CallInst::Create(FibF, Sub, "fibx1", RecurseBB);
// create fib(x-2)
Sub = BinaryOperator::CreateSub(ArgX, Two, "arg", RecurseBB);
Value *CallFibX2 = CallInst::Create(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
ReturnInst::Create(M->getContext(), 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 );
(void)result;
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 = APInt(32, p->value);
synchronize.block(); // wait until other threads are at this point
GenericValue gv = p->EE->runFunction(p->F, Args);
return (void*)(intptr_t)gv.IntVal.getZExtValue();
}
int main() {
InitializeNativeTarget();
LLVMContext Context;
// Create some module to put our function into it.
Module *M = new Module("test", Context);
Function* add1F = createAdd1( M );
Function* fibF = CreateFibFunction( M );
// Now we create the JIT.
ExecutionEngine* EE = EngineBuilder(M).create();
//~ 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 " << intptr_t(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 " << intptr_t(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 " << intptr_t(returnValue) << std::endl;
return 0;
}