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//===-- SlotIndexes.cpp - Slot Indexes Pass ------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/InitializePasses.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "slotindexes"
char SlotIndexes::ID = 0;
SlotIndexes::SlotIndexes() : MachineFunctionPass(ID), mf(nullptr) {
initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
}
SlotIndexes::~SlotIndexes() {
// The indexList's nodes are all allocated in the BumpPtrAllocator.
indexList.clearAndLeakNodesUnsafely();
}
INITIALIZE_PASS(SlotIndexes, DEBUG_TYPE,
"Slot index numbering", false, false)
STATISTIC(NumLocalRenum, "Number of local renumberings");
void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
au.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(au);
}
void SlotIndexes::releaseMemory() {
mi2iMap.clear();
MBBRanges.clear();
idx2MBBMap.clear();
indexList.clear();
ileAllocator.Reset();
}
bool SlotIndexes::runOnMachineFunction(MachineFunction &fn) {
// Compute numbering as follows:
// Grab an iterator to the start of the index list.
// Iterate over all MBBs, and within each MBB all MIs, keeping the MI
// iterator in lock-step (though skipping it over indexes which have
// null pointers in the instruction field).
// At each iteration assert that the instruction pointed to in the index
// is the same one pointed to by the MI iterator. This
// FIXME: This can be simplified. The mi2iMap_, Idx2MBBMap, etc. should
// only need to be set up once after the first numbering is computed.
mf = &fn;
// Check that the list contains only the sentinal.
assert(indexList.empty() && "Index list non-empty at initial numbering?");
assert(idx2MBBMap.empty() &&
"Index -> MBB mapping non-empty at initial numbering?");
assert(MBBRanges.empty() &&
"MBB -> Index mapping non-empty at initial numbering?");
assert(mi2iMap.empty() &&
"MachineInstr -> Index mapping non-empty at initial numbering?");
unsigned index = 0;
MBBRanges.resize(mf->getNumBlockIDs());
idx2MBBMap.reserve(mf->size());
indexList.push_back(createEntry(nullptr, index));
// Iterate over the function.
for (MachineBasicBlock &MBB : *mf) {
// Insert an index for the MBB start.
SlotIndex blockStartIndex(&indexList.back(), SlotIndex::Slot_Block);
for (MachineInstr &MI : MBB) {
if (MI.isDebugOrPseudoInstr())
continue;
// Insert a store index for the instr.
indexList.push_back(createEntry(&MI, index += SlotIndex::InstrDist));
// Save this base index in the maps.
mi2iMap.insert(std::make_pair(
&MI, SlotIndex(&indexList.back(), SlotIndex::Slot_Block)));
}
// We insert one blank instructions between basic blocks.
indexList.push_back(createEntry(nullptr, index += SlotIndex::InstrDist));
MBBRanges[MBB.getNumber()].first = blockStartIndex;
MBBRanges[MBB.getNumber()].second = SlotIndex(&indexList.back(),
SlotIndex::Slot_Block);
idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, &MBB));
}
// Sort the Idx2MBBMap
llvm::sort(idx2MBBMap, less_first());
LLVM_DEBUG(mf->print(dbgs(), this));
// And we're done!
return false;
}
void SlotIndexes::removeMachineInstrFromMaps(MachineInstr &MI,
bool AllowBundled) {
assert((AllowBundled || !MI.isBundledWithPred()) &&
"Use removeSingleMachineInstrFromMaps() instead");
Mi2IndexMap::iterator mi2iItr = mi2iMap.find(&MI);
if (mi2iItr == mi2iMap.end())
return;
SlotIndex MIIndex = mi2iItr->second;
IndexListEntry &MIEntry = *MIIndex.listEntry();
assert(MIEntry.getInstr() == &MI && "Instruction indexes broken.");
mi2iMap.erase(mi2iItr);
// FIXME: Eventually we want to actually delete these indexes.
MIEntry.setInstr(nullptr);
}
void SlotIndexes::removeSingleMachineInstrFromMaps(MachineInstr &MI) {
Mi2IndexMap::iterator mi2iItr = mi2iMap.find(&MI);
if (mi2iItr == mi2iMap.end())
return;
SlotIndex MIIndex = mi2iItr->second;
IndexListEntry &MIEntry = *MIIndex.listEntry();
assert(MIEntry.getInstr() == &MI && "Instruction indexes broken.");
mi2iMap.erase(mi2iItr);
// When removing the first instruction of a bundle update mapping to next
// instruction.
if (MI.isBundledWithSucc()) {
// Only the first instruction of a bundle should have an index assigned.
assert(!MI.isBundledWithPred() && "Should be first bundle instruction");
MachineBasicBlock::instr_iterator Next = std::next(MI.getIterator());
MachineInstr &NextMI = *Next;
MIEntry.setInstr(&NextMI);
mi2iMap.insert(std::make_pair(&NextMI, MIIndex));
return;
} else {
// FIXME: Eventually we want to actually delete these indexes.
MIEntry.setInstr(nullptr);
}
}
// Renumber indexes locally after curItr was inserted, but failed to get a new
// index.
void SlotIndexes::renumberIndexes(IndexList::iterator curItr) {
// Number indexes with half the default spacing so we can catch up quickly.
const unsigned Space = SlotIndex::InstrDist/2;
static_assert((Space & 3) == 0, "InstrDist must be a multiple of 2*NUM");
IndexList::iterator startItr = std::prev(curItr);
unsigned index = startItr->getIndex();
do {
curItr->setIndex(index += Space);
++curItr;
// If the next index is bigger, we have caught up.
} while (curItr != indexList.end() && curItr->getIndex() <= index);
LLVM_DEBUG(dbgs() << "\n*** Renumbered SlotIndexes " << startItr->getIndex()
<< '-' << index << " ***\n");
++NumLocalRenum;
}
// Repair indexes after adding and removing instructions.
void SlotIndexes::repairIndexesInRange(MachineBasicBlock *MBB,
MachineBasicBlock::iterator Begin,
MachineBasicBlock::iterator End) {
// FIXME: Is this really necessary? The only caller repairIntervalsForRange()
// does the same thing.
// Find anchor points, which are at the beginning/end of blocks or at
// instructions that already have indexes.
while (Begin != MBB->begin() && !hasIndex(*Begin))
--Begin;
while (End != MBB->end() && !hasIndex(*End))
++End;
bool includeStart = (Begin == MBB->begin());
SlotIndex startIdx;
if (includeStart)
startIdx = getMBBStartIdx(MBB);
else
startIdx = getInstructionIndex(*Begin);
SlotIndex endIdx;
if (End == MBB->end())
endIdx = getMBBEndIdx(MBB);
else
endIdx = getInstructionIndex(*End);
// FIXME: Conceptually, this code is implementing an iterator on MBB that
// optionally includes an additional position prior to MBB->begin(), indicated
// by the includeStart flag. This is done so that we can iterate MIs in a MBB
// in parallel with SlotIndexes, but there should be a better way to do this.
IndexList::iterator ListB = startIdx.listEntry()->getIterator();
IndexList::iterator ListI = endIdx.listEntry()->getIterator();
MachineBasicBlock::iterator MBBI = End;
bool pastStart = false;
while (ListI != ListB || MBBI != Begin || (includeStart && !pastStart)) {
assert(ListI->getIndex() >= startIdx.getIndex() &&
(includeStart || !pastStart) &&
"Decremented past the beginning of region to repair.");
MachineInstr *SlotMI = ListI->getInstr();
MachineInstr *MI = (MBBI != MBB->end() && !pastStart) ? &*MBBI : nullptr;
bool MBBIAtBegin = MBBI == Begin && (!includeStart || pastStart);
if (SlotMI == MI && !MBBIAtBegin) {
--ListI;
if (MBBI != Begin)
--MBBI;
else
pastStart = true;
} else if (MI && mi2iMap.find(MI) == mi2iMap.end()) {
if (MBBI != Begin)
--MBBI;
else
pastStart = true;
} else {
--ListI;
if (SlotMI)
removeMachineInstrFromMaps(*SlotMI);
}
}
// In theory this could be combined with the previous loop, but it is tricky
// to update the IndexList while we are iterating it.
for (MachineBasicBlock::iterator I = End; I != Begin;) {
--I;
MachineInstr &MI = *I;
if (!MI.isDebugOrPseudoInstr() && mi2iMap.find(&MI) == mi2iMap.end())
insertMachineInstrInMaps(MI);
}
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void SlotIndexes::dump() const {
for (const IndexListEntry &ILE : indexList) {
dbgs() << ILE.getIndex() << " ";
if (ILE.getInstr()) {
dbgs() << *ILE.getInstr();
} else {
dbgs() << "\n";
}
}
for (unsigned i = 0, e = MBBRanges.size(); i != e; ++i)
dbgs() << "%bb." << i << "\t[" << MBBRanges[i].first << ';'
<< MBBRanges[i].second << ")\n";
}
#endif
// Print a SlotIndex to a raw_ostream.
void SlotIndex::print(raw_ostream &os) const {
if (isValid())
os << listEntry()->getIndex() << "Berd"[getSlot()];
else
os << "invalid";
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
// Dump a SlotIndex to stderr.
LLVM_DUMP_METHOD void SlotIndex::dump() const {
print(dbgs());
dbgs() << "\n";
}
#endif