1 //===-- llvm/CodeGen/FinalizeISel.cpp ---------------------------*- C++ -*-===// 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 pass expands Pseudo-instructions produced by ISel, fixes register 10 /// reservations and may do machine frame information adjustments. 11 /// The pseudo instructions are used to allow the expansion to contain control 12 /// flow, such as a conditional move implemented with a conditional branch and a 13 /// phi, or an atomic operation implemented with a loop. 14 // 15 //===----------------------------------------------------------------------===// 16 17 #include "llvm/CodeGen/MachineFunction.h" 18 #include "llvm/CodeGen/MachineFunctionPass.h" 19 #include "llvm/CodeGen/TargetLowering.h" 20 #include "llvm/CodeGen/TargetSubtargetInfo.h" 21 #include "llvm/InitializePasses.h" 22 using namespace llvm; 23 24 #define DEBUG_TYPE "finalize-isel" 25 26 namespace { 27 class FinalizeISel : public MachineFunctionPass { 28 public: 29 static char ID; // Pass identification, replacement for typeid 30 FinalizeISel() : MachineFunctionPass(ID) {} 31 32 private: 33 bool runOnMachineFunction(MachineFunction &MF) override; 34 35 void getAnalysisUsage(AnalysisUsage &AU) const override { 36 MachineFunctionPass::getAnalysisUsage(AU); 37 } 38 }; 39 } // end anonymous namespace 40 41 char FinalizeISel::ID = 0; 42 char &llvm::FinalizeISelID = FinalizeISel::ID; 43 INITIALIZE_PASS(FinalizeISel, DEBUG_TYPE, 44 "Finalize ISel and expand pseudo-instructions", false, false) 45 46 bool FinalizeISel::runOnMachineFunction(MachineFunction &MF) { 47 bool Changed = false; 48 const TargetLowering *TLI = MF.getSubtarget().getTargetLowering(); 49 50 // Iterate through each instruction in the function, looking for pseudos. 51 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) { 52 MachineBasicBlock *MBB = &*I; 53 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end(); 54 MBBI != MBBE; ) { 55 MachineInstr &MI = *MBBI++; 56 57 // If MI is a pseudo, expand it. 58 if (MI.usesCustomInsertionHook()) { 59 Changed = true; 60 MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB); 61 // The expansion may involve new basic blocks. 62 if (NewMBB != MBB) { 63 MBB = NewMBB; 64 I = NewMBB->getIterator(); 65 MBBI = NewMBB->begin(); 66 MBBE = NewMBB->end(); 67 } 68 } 69 } 70 } 71 72 TLI->finalizeLowering(MF); 73 74 return Changed; 75 } 76