lib/Target/Sparc/DelaySlotFiller.cpp

   1 //===-- DelaySlotFiller.cpp - SPARC delay slot filler ---------------------===//
   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 is a simple local pass that fills delay slots with NOPs.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #define DEBUG_TYPE "delayslotfiller"
  15 #include "Sparc.h"
  16 #include "llvm/CodeGen/MachineFunctionPass.h"
  17 #include "llvm/CodeGen/MachineInstrBuilder.h"
  18 #include "llvm/Target/TargetMachine.h"
  19 #include "llvm/Target/TargetInstrInfo.h"
  20 #include "llvm/ADT/Statistic.h"
  21 using namespace llvm;
  22
  23 STATISTIC(FilledSlots, "Number of delay slots filled");
  24
  25 namespace {
  26   struct Filler : public MachineFunctionPass {
  27     /// Target machine description which we query for reg. names, data
  28     /// layout, etc.
  29     ///
  30     TargetMachine &TM;
  31     const TargetInstrInfo *TII;
  32
  33     static char ID;
  34     Filler(TargetMachine &tm)
  35       : MachineFunctionPass(&ID), TM(tm), TII(tm.getInstrInfo()) { }
  36
  37     virtual const char *getPassName() const {
  38       return "SPARC Delay Slot Filler";
  39     }
  40
  41     bool runOnMachineBasicBlock(MachineBasicBlock &MBB);
  42     bool runOnMachineFunction(MachineFunction &F) {
  43       bool Changed = false;
  44       for (MachineFunction::iterator FI = F.begin(), FE = F.end();
  45            FI != FE; ++FI)
  46         Changed |= runOnMachineBasicBlock(*FI);
  47       return Changed;
  48     }
  49
  50   };
  51   char Filler::ID = 0;
  52 } // end of anonymous namespace
  53
  54 /// createSparcDelaySlotFillerPass - Returns a pass that fills in delay
  55 /// slots in Sparc MachineFunctions
  56 ///
  57 FunctionPass *llvm::createSparcDelaySlotFillerPass(TargetMachine &tm) {
  58   return new Filler(tm);
  59 }
  60
  61 /// runOnMachineBasicBlock - Fill in delay slots for the given basic block.
  62 /// Currently, we fill delay slots with NOPs. We assume there is only one
  63 /// delay slot per delayed instruction.
  64 ///
  65 bool Filler::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
  66   bool Changed = false;
  67   for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I)
  68     if (I->getDesc().hasDelaySlot()) {
  69       MachineBasicBlock::iterator J = I;
  70       ++J;
  71       BuildMI(MBB, J, DebugLoc::getUnknownLoc(), TII->get(SP::NOP));
  72       ++FilledSlots;
  73       Changed = true;
  74     }
  75   return Changed;
  76 }