| //===- ControlFlowSink.cpp - Code to perform control-flow sinking ---------===// |
| // |
| // 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 a basic control-flow sink pass. Control-flow sinking |
| // moves operations whose only uses are in conditionally-executed blocks in to |
| // those blocks so that they aren't executed on paths where their results are |
| // not needed. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "mlir/Transforms/Passes.h" |
| |
| #include "mlir/IR/Dominance.h" |
| #include "mlir/Interfaces/ControlFlowInterfaces.h" |
| #include "mlir/Interfaces/SideEffectInterfaces.h" |
| #include "mlir/Transforms/ControlFlowSinkUtils.h" |
| |
| namespace mlir { |
| #define GEN_PASS_DEF_CONTROLFLOWSINK |
| #include "mlir/Transforms/Passes.h.inc" |
| } // namespace mlir |
| |
| using namespace mlir; |
| |
| namespace { |
| /// A control-flow sink pass. |
| struct ControlFlowSink : public impl::ControlFlowSinkBase<ControlFlowSink> { |
| void runOnOperation() override; |
| }; |
| } // end anonymous namespace |
| |
| void ControlFlowSink::runOnOperation() { |
| auto &domInfo = getAnalysis<DominanceInfo>(); |
| getOperation()->walk([&](RegionBranchOpInterface branch) { |
| SmallVector<Region *> regionsToSink; |
| // Get the regions are that known to be executed at most once. |
| getSinglyExecutedRegionsToSink(branch, regionsToSink); |
| // Sink side-effect free operations. |
| numSunk = controlFlowSink( |
| regionsToSink, domInfo, |
| [](Operation *op, Region *) { return isMemoryEffectFree(op); }, |
| [](Operation *op, Region *region) { |
| // Move the operation to the beginning of the region's entry block. |
| // This guarantees the preservation of SSA dominance of all of the |
| // operation's uses are in the region. |
| op->moveBefore(®ion->front(), region->front().begin()); |
| }); |
| }); |
| } |
| |
| std::unique_ptr<Pass> mlir::createControlFlowSinkPass() { |
| return std::make_unique<ControlFlowSink>(); |
| } |