mlir/lib/Transforms/LoopInvariantCodeMotion.cpp

   1 //===- LoopInvariantCodeMotion.cpp - Code to perform loop fusion-----------===//
   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 implements loop invariant code motion.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "mlir/Transforms/Passes.h"
  14
  15 #include "mlir/IR/PatternMatch.h"
  16 #include "mlir/Interfaces/LoopLikeInterface.h"
  17 #include "mlir/Interfaces/SideEffectInterfaces.h"
  18 #include "mlir/Transforms/LoopInvariantCodeMotionUtils.h"
  19
  20 namespace mlir {
  21 #define GEN_PASS_DEF_LOOPINVARIANTCODEMOTION
  22 #define GEN_PASS_DEF_LOOPINVARIANTSUBSETHOISTING
  23 #include "mlir/Transforms/Passes.h.inc"
  24 } // namespace mlir
  25
  26 using namespace mlir;
  27
  28 namespace {
  29 /// Loop invariant code motion (LICM) pass.
  30 struct LoopInvariantCodeMotion
  31     : public impl::LoopInvariantCodeMotionBase<LoopInvariantCodeMotion> {
  32   void runOnOperation() override;
  33 };
  34
  35 struct LoopInvariantSubsetHoisting
  36     : public impl::LoopInvariantSubsetHoistingBase<
  37           LoopInvariantSubsetHoisting> {
  38   void runOnOperation() override;
  39 };
  40 } // namespace
  41
  42 void LoopInvariantCodeMotion::runOnOperation() {
  43   // Walk through all loops in a function in innermost-loop-first order. This
  44   // way, we first LICM from the inner loop, and place the ops in
  45   // the outer loop, which in turn can be further LICM'ed.
  46   getOperation()->walk(
  47       [&](LoopLikeOpInterface loopLike) { moveLoopInvariantCode(loopLike); });
  48 }
  49
  50 void LoopInvariantSubsetHoisting::runOnOperation() {
  51   IRRewriter rewriter(getOperation()->getContext());
  52   // Walk through all loops in a function in innermost-loop-first order. This
  53   // way, we first hoist from the inner loop, and place the ops in the outer
  54   // loop, which in turn can be further hoisted from.
  55   getOperation()->walk([&](LoopLikeOpInterface loopLike) {
  56     (void)hoistLoopInvariantSubsets(rewriter, loopLike);
  57   });
  58 }
  59
  60 std::unique_ptr<Pass> mlir::createLoopInvariantCodeMotionPass() {
  61   return std::make_unique<LoopInvariantCodeMotion>();
  62 }
  63
  64 std::unique_ptr<Pass> mlir::createLoopInvariantSubsetHoistingPass() {
  65   return std::make_unique<LoopInvariantSubsetHoisting>();
  66 }