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/FinalizeISel.h" 18 #include "llvm/CodeGen/MachineFrameInfo.h" 19 #include "llvm/CodeGen/MachineFunction.h" 20 #include "llvm/CodeGen/MachineFunctionPass.h" 21 #include "llvm/CodeGen/TargetInstrInfo.h" 22 #include "llvm/CodeGen/TargetLowering.h" 23 #include "llvm/CodeGen/TargetSubtargetInfo.h" 24 #include "llvm/InitializePasses.h" 25 using namespace llvm; 26 27 #define DEBUG_TYPE "finalize-isel" 28 29 namespace { 30 class FinalizeISel : public MachineFunctionPass { 31 public: 32 static char ID; // Pass identification, replacement for typeid 33 FinalizeISel() : MachineFunctionPass(ID) {} 34 35 private: 36 bool runOnMachineFunction(MachineFunction &MF) override; 37 38 void getAnalysisUsage(AnalysisUsage &AU) const override { 39 MachineFunctionPass::getAnalysisUsage(AU); 40 } 41 }; 42 } // end anonymous namespace 43 44 static std::pair<bool, bool> runImpl(MachineFunction &MF) { 45 bool Changed = false; 46 bool PreserveCFG = true; 47 const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo(); 48 const TargetLowering *TLI = MF.getSubtarget().getTargetLowering(); 49 50 TLI->finalizeLowering(MF); 51 52 // Iterate through each instruction in the function, looking for pseudos. 53 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) { 54 MachineBasicBlock *MBB = &*I; 55 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end(); 56 MBBI != MBBE; ) { 57 MachineInstr &MI = *MBBI++; 58 59 // Set AdjustsStack to true if the instruction selector emits a stack 60 // frame setup instruction or a stack aligning inlineasm. 61 if (TII->isFrameInstr(MI) || MI.isStackAligningInlineAsm()) 62 MF.getFrameInfo().setAdjustsStack(true); 63 64 // If MI is a pseudo, expand it. 65 if (MI.usesCustomInsertionHook()) { 66 Changed = true; 67 MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB); 68 // The expansion may involve new basic blocks. 69 if (NewMBB != MBB) { 70 PreserveCFG = false; 71 MBB = NewMBB; 72 I = NewMBB->getIterator(); 73 MBBI = NewMBB->begin(); 74 MBBE = NewMBB->end(); 75 } 76 } 77 } 78 } 79 return {Changed, PreserveCFG}; 80 } 81 82 char FinalizeISel::ID = 0; 83 char &llvm::FinalizeISelID = FinalizeISel::ID; 84 INITIALIZE_PASS(FinalizeISel, DEBUG_TYPE, 85 "Finalize ISel and expand pseudo-instructions", false, false) 86 87 bool FinalizeISel::runOnMachineFunction(MachineFunction &MF) { 88 return runImpl(MF).first; 89 } 90 91 PreservedAnalyses FinalizeISelPass::run(MachineFunction &MF, 92 MachineFunctionAnalysisManager &) { 93 auto [Changed, PreserveCFG] = runImpl(MF); 94 if (!Changed) 95 return PreservedAnalyses::all(); 96 auto PA = getMachineFunctionPassPreservedAnalyses(); 97 if (PreserveCFG) 98 PA.preserveSet<CFGAnalyses>(); 99 return PA; 100 } 101