| //== llvm/CodeGen/GlobalISel/Localizer.h - Localizer -------------*- C++ -*-==// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| /// \file This file describes the interface of the Localizer pass. |
| /// This pass moves/duplicates constant-like instructions close to their uses. |
| /// Its primarily goal is to workaround the deficiencies of the fast register |
| /// allocator. |
| /// With GlobalISel constants are all materialized in the entry block of |
| /// a function. However, the fast allocator cannot rematerialize constants and |
| /// has a lot more live-ranges to deal with and will most likely end up |
| /// spilling a lot. |
| /// By pushing the constants close to their use, we only create small |
| /// live-ranges. |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CODEGEN_GLOBALISEL_LOCALIZER_H |
| #define LLVM_CODEGEN_GLOBALISEL_LOCALIZER_H |
| |
| #include "llvm/ADT/SetVector.h" |
| #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| |
| namespace llvm { |
| // Forward declarations. |
| class MachineRegisterInfo; |
| class TargetTransformInfo; |
| |
| /// This pass implements the localization mechanism described at the |
| /// top of this file. One specificity of the implementation is that |
| /// it will materialize one and only one instance of a constant per |
| /// basic block, thus enabling reuse of that constant within that block. |
| /// Moreover, it only materializes constants in blocks where they |
| /// are used. PHI uses are considered happening at the end of the |
| /// related predecessor. |
| class Localizer : public MachineFunctionPass { |
| public: |
| static char ID; |
| |
| private: |
| /// MRI contains all the register class/bank information that this |
| /// pass uses and updates. |
| MachineRegisterInfo *MRI; |
| /// TTI used for getting remat costs for instructions. |
| TargetTransformInfo *TTI; |
| |
| /// Check whether or not \p MI needs to be moved close to its uses. |
| bool shouldLocalize(const MachineInstr &MI); |
| |
| /// Check if \p MOUse is used in the same basic block as \p Def. |
| /// If the use is in the same block, we say it is local. |
| /// When the use is not local, \p InsertMBB will contain the basic |
| /// block when to insert \p Def to have a local use. |
| static bool isLocalUse(MachineOperand &MOUse, const MachineInstr &Def, |
| MachineBasicBlock *&InsertMBB); |
| |
| /// Initialize the field members using \p MF. |
| void init(MachineFunction &MF); |
| |
| typedef SmallSetVector<MachineInstr *, 32> LocalizedSetVecT; |
| |
| /// Do inter-block localization from the entry block. |
| bool localizeInterBlock(MachineFunction &MF, |
| LocalizedSetVecT &LocalizedInstrs); |
| |
| /// Do intra-block localization of already localized instructions. |
| bool localizeIntraBlock(LocalizedSetVecT &LocalizedInstrs); |
| |
| public: |
| Localizer(); |
| |
| StringRef getPassName() const override { return "Localizer"; } |
| |
| MachineFunctionProperties getRequiredProperties() const override { |
| return MachineFunctionProperties() |
| .set(MachineFunctionProperties::Property::IsSSA) |
| .set(MachineFunctionProperties::Property::Legalized) |
| .set(MachineFunctionProperties::Property::RegBankSelected); |
| } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| bool runOnMachineFunction(MachineFunction &MF) override; |
| }; |
| |
| } // End namespace llvm. |
| |
| #endif |