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1 //===- LoopGeneratorsGOMP.h - IR helper to create loops ---------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains functions to create scalar and OpenMP parallel loops
10 // as LLVM-IR.
11 //
12 //===----------------------------------------------------------------------===//
13 #ifndef POLLY_LOOP_GENERATORS_GOMP_H
14 #define POLLY_LOOP_GENERATORS_GOMP_H
15 
16 #include "polly/CodeGen/IRBuilder.h"
17 #include "polly/CodeGen/LoopGenerators.h"
18 #include "polly/Support/ScopHelper.h"
19 #include "llvm/ADT/SetVector.h"
20 
21 namespace polly {
22 using namespace llvm;
23 
24 /// This ParallelLoopGenerator subclass handles the generation of parallelized
25 /// code, utilizing the GNU OpenMP library.
26 class ParallelLoopGeneratorGOMP : public ParallelLoopGenerator {
27 public:
28   /// Create a parallel loop generator for the current function.
ParallelLoopGeneratorGOMP(PollyIRBuilder & Builder,LoopInfo & LI,DominatorTree & DT,const DataLayout & DL)29   ParallelLoopGeneratorGOMP(PollyIRBuilder &Builder, LoopInfo &LI,
30                             DominatorTree &DT, const DataLayout &DL)
31       : ParallelLoopGenerator(Builder, LI, DT, DL) {}
32 
33   // The functions below may be used if one does not want to generate a
34   // specific OpenMP parallel loop, but generate individual parts of it
35   // (e.g. the subfunction definition).
36 
37   /// Create a runtime library call to spawn the worker threads.
38   ///
39   /// @param SubFn      The subfunction which holds the loop body.
40   /// @param SubFnParam The parameter for the subfunction (basically the struct
41   ///                   filled with the outside values).
42   /// @param LB         The lower bound for the loop we parallelize.
43   /// @param UB         The upper bound for the loop we parallelize.
44   /// @param Stride     The stride of the loop we parallelize.
45   void createCallSpawnThreads(Value *SubFn, Value *SubFnParam, Value *LB,
46                               Value *UB, Value *Stride);
47 
48   void deployParallelExecution(Function *SubFn, Value *SubFnParam, Value *LB,
49                                Value *UB, Value *Stride) override;
50 
51   virtual Function *prepareSubFnDefinition(Function *F) const override;
52 
53   std::tuple<Value *, Function *> createSubFn(Value *Stride, AllocaInst *Struct,
54                                               SetVector<Value *> UsedValues,
55                                               ValueMapT &VMap) override;
56 
57   /// Create a runtime library call to join the worker threads.
58   void createCallJoinThreads();
59 
60   /// Create a runtime library call to get the next work item.
61   ///
62   /// @param LBPtr A pointer value to store the work item begin in.
63   /// @param UBPtr A pointer value to store the work item end in.
64   ///
65   /// @returns A true value if the work item is not empty.
66   Value *createCallGetWorkItem(Value *LBPtr, Value *UBPtr);
67 
68   /// Create a runtime library call to allow cleanup of the thread.
69   ///
70   /// @note This function is called right before the thread will exit the
71   ///       subfunction and only if the runtime system depends on it.
72   void createCallCleanupThread();
73 };
74 } // end namespace polly
75 #endif
76