1 //===-- MipsEmitGPRestore.cpp - Emit GP restore instruction----------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This pass emits instructions that restore $gp right 11 // after jalr instructions. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #define DEBUG_TYPE "emit-gp-restore" 16 17 #include "Mips.h" 18 #include "MipsTargetMachine.h" 19 #include "MipsMachineFunction.h" 20 #include "llvm/CodeGen/MachineFunctionPass.h" 21 #include "llvm/CodeGen/MachineInstrBuilder.h" 22 #include "llvm/Target/TargetInstrInfo.h" 23 #include "llvm/ADT/Statistic.h" 24 25 using namespace llvm; 26 27 namespace { 28 struct Inserter : public MachineFunctionPass { 29 30 TargetMachine &TM; 31 const TargetInstrInfo *TII; 32 33 static char ID; 34 Inserter(TargetMachine &tm) 35 : MachineFunctionPass(ID), TM(tm), TII(tm.getInstrInfo()) { } 36 37 virtual const char *getPassName() const { 38 return "Mips Emit GP Restore"; 39 } 40 41 bool runOnMachineFunction(MachineFunction &F); 42 }; 43 char Inserter::ID = 0; 44 } // end of anonymous namespace 45 46 bool Inserter::runOnMachineFunction(MachineFunction &F) { 47 if (TM.getRelocationModel() != Reloc::PIC_) 48 return false; 49 50 bool Changed = false; 51 int FI = F.getInfo<MipsFunctionInfo>()->getGPFI(); 52 53 for (MachineFunction::iterator MFI = F.begin(), MFE = F.end(); 54 MFI != MFE; ++MFI) { 55 MachineBasicBlock& MBB = *MFI; 56 MachineBasicBlock::iterator I = MFI->begin(); 57 58 // If MBB is a landing pad, insert instruction that restores $gp after 59 // EH_LABEL. 60 if (MBB.isLandingPad()) { 61 // Find EH_LABEL first. 62 for (; I->getOpcode() != TargetOpcode::EH_LABEL; ++I) ; 63 64 // Insert lw. 65 ++I; 66 DebugLoc dl = I != MBB.end() ? I->getDebugLoc() : DebugLoc(); 67 BuildMI(MBB, I, dl, TII->get(Mips::LW), Mips::GP).addFrameIndex(FI) 68 .addImm(0); 69 Changed = true; 70 } 71 72 while (I != MFI->end()) { 73 if (I->getOpcode() != Mips::JALR) { 74 ++I; 75 continue; 76 } 77 78 DebugLoc dl = I->getDebugLoc(); 79 // emit lw $gp, ($gp save slot on stack) after jalr 80 BuildMI(MBB, ++I, dl, TII->get(Mips::LW), Mips::GP).addFrameIndex(FI) 81 .addImm(0); 82 Changed = true; 83 } 84 } 85 86 return Changed; 87 } 88 89 /// createMipsEmitGPRestorePass - Returns a pass that emits instructions that 90 /// restores $gp clobbered by jalr instructions. 91 FunctionPass *llvm::createMipsEmitGPRestorePass(MipsTargetMachine &tm) { 92 return new Inserter(tm); 93 } 94 95
