lib/Target/Mips/MipsExpandPseudo.cpp

   1 //===--  MipsExpandPseudo.cpp - Expand pseudo instructions ----------------===//
   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 expands pseudo instructions into target instructions after register
  11 // allocation but before post-RA scheduling.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #define DEBUG_TYPE "mips-expand-pseudo"
  16
  17 #include "Mips.h"
  18 #include "MipsTargetMachine.h"
  19 #include "llvm/CodeGen/MachineFunctionPass.h"
  20 #include "llvm/CodeGen/MachineInstrBuilder.h"
  21 #include "llvm/Target/TargetInstrInfo.h"
  22 #include "llvm/ADT/Statistic.h"
  23
  24 using namespace llvm;
  25
  26 namespace {
  27   struct MipsExpandPseudo : public MachineFunctionPass {
  28
  29     TargetMachine &TM;
  30     const TargetInstrInfo *TII;
  31
  32     static char ID;
  33     MipsExpandPseudo(TargetMachine &tm)
  34       : MachineFunctionPass(ID), TM(tm), TII(tm.getInstrInfo()) { }
  35
  36     virtual const char *getPassName() const {
  37       return "Mips PseudoInstrs Expansion";
  38     }
  39
  40     bool runOnMachineFunction(MachineFunction &F);
  41     bool runOnMachineBasicBlock(MachineBasicBlock &MBB);
  42
  43   private:
  44     void ExpandBuildPairF64(MachineBasicBlock&, MachineBasicBlock::iterator);
  45     void ExpandExtractElementF64(MachineBasicBlock&,
  46                                  MachineBasicBlock::iterator);
  47   };
  48   char MipsExpandPseudo::ID = 0;
  49 } // end of anonymous namespace
  50
  51 bool MipsExpandPseudo::runOnMachineFunction(MachineFunction& F) {
  52   bool Changed = false;
  53
  54   for (MachineFunction::iterator I = F.begin(); I != F.end(); ++I)
  55     Changed |= runOnMachineBasicBlock(*I);
  56
  57   return Changed;
  58 }
  59
  60 bool MipsExpandPseudo::runOnMachineBasicBlock(MachineBasicBlock& MBB) {
  61
  62   bool Changed = false;
  63   for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end();) {
  64     const MCInstrDesc& MCid = I->getDesc();
  65
  66     switch(MCid.getOpcode()) {
  67     default:
  68       ++I;
  69       continue;
  70     case Mips::BuildPairF64:
  71       ExpandBuildPairF64(MBB, I);
  72       break;
  73     case Mips::ExtractElementF64:
  74       ExpandExtractElementF64(MBB, I);
  75       break;
  76     }
  77
  78     // delete original instr
  79     MBB.erase(I++);
  80     Changed = true;
  81   }
  82
  83   return Changed;
  84 }
  85
  86 void MipsExpandPseudo::ExpandBuildPairF64(MachineBasicBlock& MBB,
  87                                             MachineBasicBlock::iterator I) {
  88   unsigned DstReg = I->getOperand(0).getReg();
  89   unsigned LoReg = I->getOperand(1).getReg(), HiReg = I->getOperand(2).getReg();
  90   const MCInstrDesc& Mtc1Tdd = TII->get(Mips::MTC1);
  91   DebugLoc dl = I->getDebugLoc();
  92   const unsigned* SubReg =
  93     TM.getRegisterInfo()->getSubRegisters(DstReg);
  94
  95   // mtc1 Lo, $fp
  96   // mtc1 Hi, $fp + 1
  97   BuildMI(MBB, I, dl, Mtc1Tdd, *SubReg).addReg(LoReg);
  98   BuildMI(MBB, I, dl, Mtc1Tdd, *(SubReg + 1)).addReg(HiReg);
  99 }
 100
 101 void MipsExpandPseudo::ExpandExtractElementF64(MachineBasicBlock& MBB,
 102                                                MachineBasicBlock::iterator I) {
 103   unsigned DstReg = I->getOperand(0).getReg();
 104   unsigned SrcReg = I->getOperand(1).getReg();
 105   unsigned N = I->getOperand(2).getImm();
 106   const MCInstrDesc& Mfc1Tdd = TII->get(Mips::MFC1);
 107   DebugLoc dl = I->getDebugLoc();
 108   const unsigned* SubReg = TM.getRegisterInfo()->getSubRegisters(SrcReg);
 109
 110   BuildMI(MBB, I, dl, Mfc1Tdd, DstReg).addReg(*(SubReg + N));
 111 }
 112
 113 /// createMipsMipsExpandPseudoPass - Returns a pass that expands pseudo
 114 /// instrs into real instrs
 115 FunctionPass *llvm::createMipsExpandPseudoPass(MipsTargetMachine &tm) {
 116   return new MipsExpandPseudo(tm);
 117 }