| //==---- SystemZPostRewrite.cpp - Select pseudos after RegAlloc ---*- 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains a pass that is run immediately after VirtRegRewriter |
| // but before MachineCopyPropagation. The purpose is to lower pseudos to |
| // target instructions before any later pass might substitute a register for |
| // another. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "SystemZ.h" |
| #include "SystemZInstrInfo.h" |
| #include "SystemZSubtarget.h" |
| #include "llvm/ADT/Statistic.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineInstrBuilder.h" |
| using namespace llvm; |
| |
| #define SYSTEMZ_POSTREWRITE_NAME "SystemZ Post Rewrite pass" |
| |
| #define DEBUG_TYPE "systemz-postrewrite" |
| STATISTIC(MemFoldCopies, "Number of copies inserted before folded mem ops."); |
| |
| namespace llvm { |
| void initializeSystemZPostRewritePass(PassRegistry&); |
| } |
| |
| namespace { |
| |
| class SystemZPostRewrite : public MachineFunctionPass { |
| public: |
| static char ID; |
| SystemZPostRewrite() : MachineFunctionPass(ID) { |
| initializeSystemZPostRewritePass(*PassRegistry::getPassRegistry()); |
| } |
| |
| const SystemZInstrInfo *TII; |
| |
| bool runOnMachineFunction(MachineFunction &Fn) override; |
| |
| StringRef getPassName() const override { return SYSTEMZ_POSTREWRITE_NAME; } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override { |
| AU.setPreservesAll(); |
| MachineFunctionPass::getAnalysisUsage(AU); |
| } |
| |
| private: |
| bool selectMI(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, |
| MachineBasicBlock::iterator &NextMBBI); |
| bool selectMBB(MachineBasicBlock &MBB); |
| }; |
| |
| char SystemZPostRewrite::ID = 0; |
| |
| } // end anonymous namespace |
| |
| INITIALIZE_PASS(SystemZPostRewrite, "systemz-post-rewrite", |
| SYSTEMZ_POSTREWRITE_NAME, false, false) |
| |
| /// Returns an instance of the Post Rewrite pass. |
| FunctionPass *llvm::createSystemZPostRewritePass(SystemZTargetMachine &TM) { |
| return new SystemZPostRewrite(); |
| } |
| |
| /// If MBBI references a pseudo instruction that should be selected here, |
| /// do it and return true. Otherwise return false. |
| bool SystemZPostRewrite::selectMI(MachineBasicBlock &MBB, |
| MachineBasicBlock::iterator MBBI, |
| MachineBasicBlock::iterator &NextMBBI) { |
| MachineInstr &MI = *MBBI; |
| unsigned Opcode = MI.getOpcode(); |
| |
| // Note: If this could be done during regalloc in foldMemoryOperandImpl() |
| // while also updating the LiveIntervals, there would be no need for the |
| // MemFoldPseudo to begin with. |
| int TargetMemOpcode = SystemZ::getTargetMemOpcode(Opcode); |
| if (TargetMemOpcode != -1) { |
| MI.setDesc(TII->get(TargetMemOpcode)); |
| MI.tieOperands(0, 1); |
| Register DstReg = MI.getOperand(0).getReg(); |
| MachineOperand &SrcMO = MI.getOperand(1); |
| if (DstReg != SrcMO.getReg()) { |
| BuildMI(MBB, &MI, MI.getDebugLoc(), TII->get(SystemZ::COPY), DstReg) |
| .addReg(SrcMO.getReg()); |
| SrcMO.setReg(DstReg); |
| MemFoldCopies++; |
| } |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /// Iterate over the instructions in basic block MBB and select any |
| /// pseudo instructions. Return true if anything was modified. |
| bool SystemZPostRewrite::selectMBB(MachineBasicBlock &MBB) { |
| bool Modified = false; |
| |
| MachineBasicBlock::iterator MBBI = MBB.begin(), E = MBB.end(); |
| while (MBBI != E) { |
| MachineBasicBlock::iterator NMBBI = std::next(MBBI); |
| Modified |= selectMI(MBB, MBBI, NMBBI); |
| MBBI = NMBBI; |
| } |
| |
| return Modified; |
| } |
| |
| bool SystemZPostRewrite::runOnMachineFunction(MachineFunction &MF) { |
| TII = static_cast<const SystemZInstrInfo *>(MF.getSubtarget().getInstrInfo()); |
| |
| bool Modified = false; |
| for (auto &MBB : MF) |
| Modified |= selectMBB(MBB); |
| |
| return Modified; |
| } |
| |