DelaySlotFiller.cpp revision ae73dc1448d25b02cabc7c64c86c64371453dda8 
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"
21using namespace llvm;
22
23STATISTIC(FilledSlots, "Number of delay slots filled");
24
25namespace {
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///
57FunctionPass *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///
65bool 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, TII->get(SP::NOP));
72      ++FilledSlots;
73      Changed = true;
74    }
75  return Changed;
76}
77