//===-- MipsEmitGPRestore.cpp - Emit GP restore instruction----------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This pass emits instructions that restore $gp right // after jalr instructions. // //===----------------------------------------------------------------------===// #define DEBUG_TYPE "emit-gp-restore" #include "Mips.h" #include "MipsTargetMachine.h" #include "MipsMachineFunction.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineInstrBuilder.h" #include "llvm/Target/TargetInstrInfo.h" #include "llvm/ADT/Statistic.h" using namespace llvm; namespace { struct Inserter : public MachineFunctionPass { TargetMachine &TM; const TargetInstrInfo *TII; static char ID; Inserter(TargetMachine &tm) : MachineFunctionPass(ID), TM(tm), TII(tm.getInstrInfo()) { } virtual const char *getPassName() const { return "Mips Emit GP Restore"; } bool runOnMachineFunction(MachineFunction &F); }; char Inserter::ID = 0; } // end of anonymous namespace bool Inserter::runOnMachineFunction(MachineFunction &F) { if (TM.getRelocationModel() != Reloc::PIC_) return false; bool Changed = false; int FI = F.getInfo<MipsFunctionInfo>()->getGPFI(); for (MachineFunction::iterator MFI = F.begin(), MFE = F.end(); MFI != MFE; ++MFI) { MachineBasicBlock& MBB = *MFI; MachineBasicBlock::iterator I = MFI->begin(); // If MBB is a landing pad, insert instruction that restores $gp after // EH_LABEL. if (MBB.isLandingPad()) { // Find EH_LABEL first. for (; I->getOpcode() != TargetOpcode::EH_LABEL; ++I) ; // Insert lw. ++I; DebugLoc dl = I != MBB.end() ? I->getDebugLoc() : DebugLoc(); BuildMI(MBB, I, dl, TII->get(Mips::LW), Mips::GP).addFrameIndex(FI) .addImm(0); Changed = true; } while (I != MFI->end()) { if (I->getOpcode() != Mips::JALR) { ++I; continue; } DebugLoc dl = I->getDebugLoc(); // emit lw $gp, ($gp save slot on stack) after jalr BuildMI(MBB, ++I, dl, TII->get(Mips::LW), Mips::GP).addFrameIndex(FI) .addImm(0); Changed = true; } } return Changed; } /// createMipsEmitGPRestorePass - Returns a pass that emits instructions that /// restores $gp clobbered by jalr instructions. FunctionPass *llvm::createMipsEmitGPRestorePass(MipsTargetMachine &tm) { return new Inserter(tm); }