MNN/source/backend/cpu/compute/StrassenMatmulComputor.hpp

//
//  StrassenMatmulComputor.hpp
//  MNN
//
//  Created by MNN on 2019/02/11.
//  Copyright © 2018, Alibaba Group Holding Limited
//

#ifndef StrassenMatmulComputor_hpp
#define StrassenMatmulComputor_hpp

#include <functional>
#include "core/Backend.hpp"
namespace MNN {
/**
 Based on
 Boyer, B., Dumas, J.-G., Pernet, C., & Zhou, W. (2007). Memory efficient scheduling of Strassen-Winogradʼs matrix multiplication algorithm. Proceedings of the 2009 international symposium on Symbolic and algebraic computation ISSAC 09, 55. ACM Press. Retrieved from http://arxiv.org/abs/0707.2347
 
 Use Table 2
 */
class StrassenMatrixComputor {
public:
    StrassenMatrixComputor(Backend* bn, bool multithread, int maxDepth);
    virtual ~StrassenMatrixComputor();

    /*
     It's assume that:
     A is a matrix where each element is a (4,1) vector : lC4, e, 4
     B is a matrix where each element is a (hP,1) vector : h, l, hP
     inputs[0] is the transpose of A: AT, inputs[1] is the transpose of B: BT
     outputs[0] is the transpose of C: CT
     C is a matrix where each element is a (4,1) vector, the same as A : hC4, e, 4

     if (inputs.size() > 2) {
        inputs[2] is origin CO: CT
        CO can be the same same as C or broadcast in lenght(1): hC4, e, 4 or hC4, 1, 4
     }
     Compute: C = alpha * AB + beta * CO , alpha must be 1.0f
     
     postParameters:
     0: alpha
     1: beta
     2: min
     3: max
     
     if (postParameters.empty()) {
        alpha = 1.0f
        beta = 0.0f;
        min = -FLT_MAX
        max = FLT_MAX
     }
     */
    ErrorCode onEncode(const std::vector<Tensor*>& inputs, const std::vector<Tensor*>& outputs, const std::vector<float>& postParameters = {}, int l = 0, int h = 0);

    void onExecute(const uint8_t* AT = nullptr, const uint8_t* BT = nullptr, const uint8_t* COT = nullptr, uint8_t* CT = nullptr);

    void onReset();
protected:
    Backend* backend() const {
        return mBackend;
    }

private:
    struct MatrixInfo {
        int stackIndex;
        int offsetBytes;
        int lineStrideBytes;
    };
    ErrorCode _generateMatMul(int e, int l, int h, const MatrixInfo& AT, const MatrixInfo& BT, const MatrixInfo& CT, const MatrixInfo& COT, int currentDepth, const std::vector<float>& postParameters);
    ErrorCode _generateTrivalMatMul(int e, int l, int h, const MatrixInfo& AT, const MatrixInfo& BT, const MatrixInfo& CT, const MatrixInfo& COT, const std::vector<float>& postParameters);
    ErrorCode _generateBasicMatMul(int e, int l, int h, const MatrixInfo& AT, const MatrixInfo& BT, const MatrixInfo& CT, const MatrixInfo& COT, const std::vector<float>& postParameters);

    std::vector<std::pair<std::function<void(int tId)>, int>> mFunctions;
    int mMaxDepth;
    bool mSupportMultiThread;

    Backend* mBackend;
    
    std::vector<uint8_t*> mStack;
};
} // namespace MNN

#endif /* StrassenMatmulComputor_hpp */