llvm/mlir/lib/Dialect/Vector/Transforms/LowerVectorBitCast.cpp

//===- LowerVectorBitCast.cpp - Lower 'vector.bitcast' operation ----------===//
//
// 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 implements target-independent rewrites and utilities to lower the
// 'vector.bitcast' operation.
//
//===----------------------------------------------------------------------===//

#include "mlir/Dialect/Vector/IR/VectorOps.h"
#include "mlir/Dialect/Vector/Transforms/LoweringPatterns.h"
#include "mlir/Dialect/Vector/Utils/VectorUtils.h"
#include "mlir/IR/BuiltinTypes.h"
#include "mlir/IR/PatternMatch.h"

#define DEBUG_TYPE …

usingnamespacemlir;
usingnamespacemlir::vector;

namespace {

/// A one-shot unrolling of vector.bitcast to the `targetRank`.
///
/// Example:
///
///   vector.bitcast %a, %b : vector<1x2x3x4xi64> to vector<1x2x3x8xi32>
///
/// Would be unrolled to:
///
/// %result = arith.constant dense<0> : vector<1x2x3x8xi32>
/// %0 = vector.extract %a[0, 0, 0]                 ─┐
///        : vector<4xi64> from vector<1x2x3x4xi64>  |
/// %1 = vector.bitcast %0                           | - Repeated 6x for
///        : vector<4xi64> to vector<8xi32>          |   all leading positions
/// %2 = vector.insert %1, %result [0, 0, 0]         |
///        : vector<8xi64> into vector<1x2x3x8xi32> ─┘
///
/// Note: If any leading dimension before the `targetRank` is scalable the
/// unrolling will stop before the scalable dimension.
class UnrollBitCastOp final : public OpRewritePattern<vector::BitCastOp> { … };

} // namespace

void mlir::vector::populateVectorBitCastLoweringPatterns(
    RewritePatternSet &patterns, int64_t targetRank, PatternBenefit benefit) { … }