LoopGeneratorsGOMP.h

//===- LoopGeneratorsGOMP.h - IR helper to create loops ---------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file contains functions to create scalar and OpenMP parallel loops
// as LLVM-IR.
//
//===----------------------------------------------------------------------===//
#ifndef POLLY_LOOP_GENERATORS_GOMP_H
#define POLLY_LOOP_GENERATORS_GOMP_H

#include "polly/CodeGen/IRBuilder.h"
#include "polly/CodeGen/LoopGenerators.h"
#include "polly/Support/ScopHelper.h"
#include "llvm/ADT/SetVector.h"

namespace polly {

/// This ParallelLoopGenerator subclass handles the generation of parallelized
/// code, utilizing the GNU OpenMP library.
class ParallelLoopGeneratorGOMP : public ParallelLoopGenerator {
public:
  /// Create a parallel loop generator for the current function.
  ParallelLoopGeneratorGOMP(PollyIRBuilder &Builder, LoopInfo &LI,
                            DominatorTree &DT, const DataLayout &DL)
      : ParallelLoopGenerator(Builder, LI, DT, DL) {}

  // The functions below may be used if one does not want to generate a
  // specific OpenMP parallel loop, but generate individual parts of it
  // (e.g. the subfunction definition).

  /// Create a runtime library call to spawn the worker threads.
  ///
  /// @param SubFn      The subfunction which holds the loop body.
  /// @param SubFnParam The parameter for the subfunction (basically the struct
  ///                   filled with the outside values).
  /// @param LB         The lower bound for the loop we parallelize.
  /// @param UB         The upper bound for the loop we parallelize.
  /// @param Stride     The stride of the loop we parallelize.
  void createCallSpawnThreads(Value *SubFn, Value *SubFnParam, Value *LB,
                              Value *UB, Value *Stride);

  void deployParallelExecution(Function *SubFn, Value *SubFnParam, Value *LB,
                               Value *UB, Value *Stride) override;

  virtual Function *prepareSubFnDefinition(Function *F) const override;

  std::tuple<Value *, Function *> createSubFn(Value *Stride, AllocaInst *Struct,
                                              SetVector<Value *> UsedValues,
                                              ValueMapT &VMap) override;

  /// Create a runtime library call to join the worker threads.
  void createCallJoinThreads();

  /// Create a runtime library call to get the next work item.
  ///
  /// @param LBPtr A pointer value to store the work item begin in.
  /// @param UBPtr A pointer value to store the work item end in.
  ///
  /// @returns A true value if the work item is not empty.
  Value *createCallGetWorkItem(Value *LBPtr, Value *UBPtr);

  /// Create a runtime library call to allow cleanup of the thread.
  ///
  /// @note This function is called right before the thread will exit the
  ///       subfunction and only if the runtime system depends on it.
  void createCallCleanupThread();
};
} // end namespace polly
#endif