1 //===-- MipsEmitGPRestore.cpp - Emit GP restore instruction----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass emits instructions that restore $gp right
11 // after jalr instructions.
13 //===----------------------------------------------------------------------===//
15 #define DEBUG_TYPE "emit-gp-restore"
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"
28 struct Inserter : public MachineFunctionPass {
31 const TargetInstrInfo *TII;
34 Inserter(TargetMachine &tm)
35 : MachineFunctionPass(ID), TM(tm), TII(tm.getInstrInfo()) { }
37 virtual const char *getPassName() const {
38 return "Mips Emit GP Restore";
41 bool runOnMachineFunction(MachineFunction &F);
43 char Inserter::ID = 0;
44 } // end of anonymous namespace
46 bool Inserter::runOnMachineFunction(MachineFunction &F) {
47 if (TM.getRelocationModel() != Reloc::PIC_)
51 int FI = F.getInfo<MipsFunctionInfo>()->getGPFI();
53 for (MachineFunction::iterator MFI = F.begin(), MFE = F.end();
55 MachineBasicBlock& MBB = *MFI;
56 MachineBasicBlock::iterator I = MFI->begin();
58 // If MBB is a landing pad, insert instruction that restores $gp after
60 if (MBB.isLandingPad()) {
61 // Find EH_LABEL first.
62 for (; I->getOpcode() != TargetOpcode::EH_LABEL; ++I) ;
66 DebugLoc dl = I != MBB.end() ? I->getDebugLoc() : DebugLoc();
67 BuildMI(MBB, I, dl, TII->get(Mips::LW), Mips::GP).addFrameIndex(FI)
72 while (I != MFI->end()) {
73 if (I->getOpcode() != Mips::JALR) {
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)
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);