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| 14 | pmbaty | 1 | //===- MatmulOptimizer.h -------------------------------------------------===// |
| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |||
| 9 | #ifndef POLLY_MATMULOPTIMIZER_H |
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| 10 | #define POLLY_MATMULOPTIMIZER_H |
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| 11 | |||
| 12 | #include "isl/isl-noexceptions.h" |
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| 13 | |||
| 14 | namespace llvm { |
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| 15 | class TargetTransformInfo; |
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| 16 | } |
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| 17 | |||
| 18 | namespace polly { |
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| 19 | class Dependences; |
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| 20 | |||
| 21 | /// Apply the BLIS matmul optimization pattern if possible. |
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| 22 | /// |
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| 23 | /// Make the loops containing the matrix multiplication be the innermost |
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| 24 | /// loops and apply the BLIS matmul optimization pattern. BLIS implements |
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| 25 | /// gemm as three nested loops around a macro-kernel, plus two packing |
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| 26 | /// routines. The macro-kernel is implemented in terms of two additional |
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| 27 | /// loops around a micro-kernel. The micro-kernel is a loop around a rank-1 |
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| 28 | /// (i.e., outer product) update. |
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| 29 | /// |
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| 30 | /// For a detailed description please see [1]. |
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| 31 | /// |
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| 32 | /// The order of the loops defines the data reused in the BLIS implementation |
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| 33 | /// of gemm ([1]). In particular, elements of the matrix B, the second |
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| 34 | /// operand of matrix multiplication, are reused between iterations of the |
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| 35 | /// innermost loop. To keep the reused data in cache, only elements of matrix |
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| 36 | /// A, the first operand of matrix multiplication, should be evicted during |
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| 37 | /// an iteration of the innermost loop. To provide such a cache replacement |
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| 38 | /// policy, elements of the matrix A can, in particular, be loaded first and, |
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| 39 | /// consequently, be least-recently-used. |
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| 40 | /// |
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| 41 | /// In our case matrices are stored in row-major order instead of |
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| 42 | /// column-major order used in the BLIS implementation ([1]). It affects only |
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| 43 | /// on the form of the BLIS micro kernel and the computation of its |
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| 44 | /// parameters. In particular, reused elements of the matrix B are |
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| 45 | /// successively multiplied by specific elements of the matrix A. |
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| 46 | /// |
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| 47 | /// Refs.: |
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| 48 | /// [1] - Analytical Modeling is Enough for High Performance BLIS |
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| 49 | /// Tze Meng Low, Francisco D Igual, Tyler M Smith, Enrique S Quintana-Orti |
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| 50 | /// Technical Report, 2014 |
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| 51 | /// http://www.cs.utexas.edu/users/flame/pubs/TOMS-BLIS-Analytical.pdf |
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| 52 | /// |
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| 53 | /// @see ScheduleTreeOptimizer::createMicroKernel |
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| 54 | /// @see ScheduleTreeOptimizer::createMacroKernel |
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| 55 | /// @see getMicroKernelParams |
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| 56 | /// @see getMacroKernelParams |
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| 57 | /// |
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| 58 | /// TODO: Implement the packing transformation. |
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| 59 | /// |
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| 60 | /// @param Node The node that contains a band to be optimized. The node |
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| 61 | /// is required to successfully pass |
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| 62 | /// ScheduleTreeOptimizer::isMatrMultPattern. |
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| 63 | /// @param TTI Target Transform Info. |
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| 64 | /// @param D The dependencies. |
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| 65 | /// |
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| 66 | /// @returns The transformed schedule or nullptr if the optimization |
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| 67 | /// cannot be applied. |
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| 68 | isl::schedule_node |
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| 69 | tryOptimizeMatMulPattern(isl::schedule_node Node, |
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| 70 | const llvm::TargetTransformInfo *TTI, |
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| 71 | const Dependences *D); |
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| 72 | |||
| 73 | } // namespace polly |
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| 74 | #endif // POLLY_MATMULOPTIMIZER_H |