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 "PassDetail.h" 14 #include "mlir/IR/Builders.h" 15 #include "mlir/Interfaces/LoopLikeInterface.h" 16 #include "mlir/Interfaces/SideEffectInterfaces.h" 17 #include "mlir/Transforms/Passes.h" 18 #include "llvm/ADT/SmallPtrSet.h" 19 #include "llvm/Support/CommandLine.h" 20 #include "llvm/Support/Debug.h" 21 22 #define DEBUG_TYPE "licm" 23 24 using namespace mlir; 25 26 namespace { 27 /// Loop invariant code motion (LICM) pass. 28 struct LoopInvariantCodeMotion 29 : public LoopInvariantCodeMotionBase<LoopInvariantCodeMotion> { 30 void runOnOperation() override; 31 }; 32 } // namespace 33 34 void LoopInvariantCodeMotion::runOnOperation() { 35 // Walk through all loops in a function in innermost-loop-first order. This 36 // way, we first LICM from the inner loop, and place the ops in 37 // the outer loop, which in turn can be further LICM'ed. 38 getOperation()->walk([&](LoopLikeOpInterface loopLike) { 39 LLVM_DEBUG(loopLike.print(llvm::dbgs() << "\nOriginal loop:\n")); 40 moveLoopInvariantCode(loopLike); 41 }); 42 } 43 44 std::unique_ptr<Pass> mlir::createLoopInvariantCodeMotionPass() { 45 return std::make_unique<LoopInvariantCodeMotion>(); 46 } 47