lib/CodeGen/SlotIndexes.cpp

   1 //===-- SlotIndexes.cpp - Slot Indexes Pass  ------------------------------===//
   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 #define DEBUG_TYPE "slotindexes"
  11
  12 #include "llvm/CodeGen/SlotIndexes.h"
  13 #include "llvm/ADT/Statistic.h"
  14 #include "llvm/CodeGen/MachineFunction.h"
  15 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 #include "llvm/Target/TargetInstrInfo.h"
  18
  19 using namespace llvm;
  20
  21 char SlotIndexes::ID = 0;
  22 INITIALIZE_PASS(SlotIndexes, "slotindexes",
  23                 "Slot index numbering", false, false)
  24
  25 STATISTIC(NumLocalRenum,  "Number of local renumberings");
  26 STATISTIC(NumGlobalRenum, "Number of global renumberings");
  27
  28 void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
  29   au.setPreservesAll();
  30   MachineFunctionPass::getAnalysisUsage(au);
  31 }
  32
  33 void SlotIndexes::releaseMemory() {
  34   mi2iMap.clear();
  35   MBBRanges.clear();
  36   idx2MBBMap.clear();
  37   clearList();
  38 }
  39
  40 bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
  41
  42   // Compute numbering as follows:
  43   // Grab an iterator to the start of the index list.
  44   // Iterate over all MBBs, and within each MBB all MIs, keeping the MI
  45   // iterator in lock-step (though skipping it over indexes which have
  46   // null pointers in the instruction field).
  47   // At each iteration assert that the instruction pointed to in the index
  48   // is the same one pointed to by the MI iterator. This
  49
  50   // FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
  51   // only need to be set up once after the first numbering is computed.
  52
  53   mf = &fn;
  54   initList();
  55
  56   // Check that the list contains only the sentinal.
  57   assert(indexListHead->getNext() == 0 &&
  58          "Index list non-empty at initial numbering?");
  59   assert(idx2MBBMap.empty() &&
  60          "Index -> MBB mapping non-empty at initial numbering?");
  61   assert(MBBRanges.empty() &&
  62          "MBB -> Index mapping non-empty at initial numbering?");
  63   assert(mi2iMap.empty() &&
  64          "MachineInstr -> Index mapping non-empty at initial numbering?");
  65
  66   functionSize = 0;
  67   unsigned index = 0;
  68   MBBRanges.resize(mf->getNumBlockIDs());
  69   idx2MBBMap.reserve(mf->size());
  70
  71   push_back(createEntry(0, index));
  72
  73   // Iterate over the function.
  74   for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
  75        mbbItr != mbbEnd; ++mbbItr) {
  76     MachineBasicBlock *mbb = &*mbbItr;
  77
  78     // Insert an index for the MBB start.
  79     SlotIndex blockStartIndex(back(), SlotIndex::LOAD);
  80
  81     for (MachineBasicBlock::iterator miItr = mbb->begin(), miEnd = mbb->end();
  82          miItr != miEnd; ++miItr) {
  83       MachineInstr *mi = miItr;
  84       if (mi->isDebugValue())
  85         continue;
  86
  87       // Insert a store index for the instr.
  88       push_back(createEntry(mi, index += SlotIndex::InstrDist));
  89
  90       // Save this base index in the maps.
  91       mi2iMap.insert(std::make_pair(mi, SlotIndex(back(), SlotIndex::LOAD)));
  92
  93       ++functionSize;
  94     }
  95
  96     // We insert one blank instructions between basic blocks.
  97     push_back(createEntry(0, index += SlotIndex::InstrDist));
  98
  99     MBBRanges[mbb->getNumber()].first = blockStartIndex;
 100     MBBRanges[mbb->getNumber()].second = SlotIndex(back(), SlotIndex::LOAD);
 101     idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
 102   }
 103
 104   // Sort the Idx2MBBMap
 105   std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
 106
 107   DEBUG(dump());
 108
 109   // And we're done!
 110   return false;
 111 }
 112
 113 void SlotIndexes::renumberIndexes() {
 114   // Renumber updates the index of every element of the index list.
 115   DEBUG(dbgs() << "\n*** Renumbering SlotIndexes ***\n");
 116   ++NumGlobalRenum;
 117
 118   unsigned index = 0;
 119
 120   for (IndexListEntry *curEntry = front(); curEntry != getTail();
 121        curEntry = curEntry->getNext()) {
 122     curEntry->setIndex(index);
 123     index += SlotIndex::InstrDist;
 124   }
 125 }
 126
 127 // Renumber indexes locally after curEntry was inserted, but failed to get a new
 128 // index.
 129 void SlotIndexes::renumberIndexes(IndexListEntry *curEntry) {
 130   // Number indexes with half the default spacing so we can catch up quickly.
 131   const unsigned Space = SlotIndex::InstrDist/2;
 132   assert((Space & 3) == 0 && "InstrDist must be a multiple of 2*NUM");
 133
 134   IndexListEntry *start = curEntry->getPrev();
 135   unsigned index = start->getIndex();
 136   IndexListEntry *tail = getTail();
 137   do {
 138     curEntry->setIndex(index += Space);
 139     curEntry = curEntry->getNext();
 140     // If the next index is bigger, we have caught up.
 141   } while (curEntry != tail && curEntry->getIndex() <= index);
 142
 143   DEBUG(dbgs() << "\n*** Renumbered SlotIndexes " << start->getIndex() << '-'
 144                << index << " ***\n");
 145   ++NumLocalRenum;
 146 }
 147
 148
 149 void SlotIndexes::dump() const {
 150   for (const IndexListEntry *itr = front(); itr != getTail();
 151        itr = itr->getNext()) {
 152     dbgs() << itr->getIndex() << " ";
 153
 154     if (itr->getInstr() != 0) {
 155       dbgs() << *itr->getInstr();
 156     } else {
 157       dbgs() << "\n";
 158     }
 159   }
 160
 161   for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
 162     dbgs() << "BB#" << i << "\t[" << MBBRanges[i].first << ';'
 163            << MBBRanges[i].second << ")\n";
 164 }
 165
 166 // Print a SlotIndex to a raw_ostream.
 167 void SlotIndex::print(raw_ostream &os) const {
 168   if (isValid())
 169     os << entry().getIndex() << "LudS"[getSlot()];
 170   else
 171     os << "invalid";
 172 }
 173
 174 // Dump a SlotIndex to stderr.
 175 void SlotIndex::dump() const {
 176   print(dbgs());
 177   dbgs() << "\n";
 178 }
 179