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llvm-6502/lib/CodeGen/SlotIndexes.cpp
Jakob Stoklund Olesen 1e8e72d72a Insert two blank SlotIndexes between basic blocks instead of just one.
This is the first small step towards using closed intervals for liveness instead
of the half-open intervals we're using now.

We want to be able to distinguish between a SlotIndex that represents a variable
being live-out of a basic block, and an index representing a variable live-in to
its successor.

That requires two separate indexes between blocks. One for live-outs and one for
live-ins.

With this change, getMBBEndIdx(MBB).getPrevSlot() becomes stable so it stays
greater than any instructions inserted at the end of MBB.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@118747 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-11 00:19:20 +00:00

215 lines
6.1 KiB
C++

//===-- SlotIndexes.cpp - Slot Indexes Pass ------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "slotindexes"
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Target/TargetInstrInfo.h"
using namespace llvm;
// Yep - these are thread safe. See the header for details.
namespace {
class EmptyIndexListEntry : public IndexListEntry {
public:
EmptyIndexListEntry() : IndexListEntry(EMPTY_KEY) {}
};
class TombstoneIndexListEntry : public IndexListEntry {
public:
TombstoneIndexListEntry() : IndexListEntry(TOMBSTONE_KEY) {}
};
// The following statics are thread safe. They're read only, and you
// can't step from them to any other list entries.
ManagedStatic<EmptyIndexListEntry> IndexListEntryEmptyKey;
ManagedStatic<TombstoneIndexListEntry> IndexListEntryTombstoneKey;
}
char SlotIndexes::ID = 0;
INITIALIZE_PASS(SlotIndexes, "slotindexes",
"Slot index numbering", false, false)
IndexListEntry* IndexListEntry::getEmptyKeyEntry() {
return &*IndexListEntryEmptyKey;
}
IndexListEntry* IndexListEntry::getTombstoneKeyEntry() {
return &*IndexListEntryTombstoneKey;
}
void SlotIndexes::getAnalysisUsage(AnalysisUsage &au) const {
au.setPreservesAll();
MachineFunctionPass::getAnalysisUsage(au);
}
void SlotIndexes::releaseMemory() {
mi2iMap.clear();
mbb2IdxMap.clear();
idx2MBBMap.clear();
clearList();
}
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;
initList();
// Check that the list contains only the sentinal.
assert(indexListHead->getNext() == 0 &&
"Index list non-empty at initial numbering?");
assert(idx2MBBMap.empty() &&
"Index -> MBB mapping non-empty at initial numbering?");
assert(mbb2IdxMap.empty() &&
"MBB -> Index mapping non-empty at initial numbering?");
assert(mi2iMap.empty() &&
"MachineInstr -> Index mapping non-empty at initial numbering?");
functionSize = 0;
unsigned index = 0;
push_back(createEntry(0, index));
// Iterate over the function.
for (MachineFunction::iterator mbbItr = mf->begin(), mbbEnd = mf->end();
mbbItr != mbbEnd; ++mbbItr) {
MachineBasicBlock *mbb = &*mbbItr;
// Insert an index for the MBB start.
SlotIndex blockStartIndex(back(), SlotIndex::LOAD);
index += SlotIndex::NUM;
for (MachineBasicBlock::iterator miItr = mbb->begin(), miEnd = mbb->end();
miItr != miEnd; ++miItr) {
MachineInstr *mi = miItr;
if (mi->isDebugValue())
continue;
// Insert a store index for the instr.
push_back(createEntry(mi, index));
// Save this base index in the maps.
mi2iMap.insert(
std::make_pair(mi, SlotIndex(back(), SlotIndex::LOAD)));
++functionSize;
unsigned Slots = mi->getDesc().getNumDefs();
if (Slots == 0)
Slots = 1;
index += (Slots + 1) * SlotIndex::NUM;
}
// We insert two blank instructions between basic blocks.
// One to represent live-out registers and one to represent live-ins.
push_back(createEntry(0, index));
index += SlotIndex::NUM;
push_back(createEntry(0, index));
SlotIndex blockEndIndex(back(), SlotIndex::LOAD);
mbb2IdxMap.insert(
std::make_pair(mbb, std::make_pair(blockStartIndex, blockEndIndex)));
idx2MBBMap.push_back(IdxMBBPair(blockStartIndex, mbb));
}
// Sort the Idx2MBBMap
std::sort(idx2MBBMap.begin(), idx2MBBMap.end(), Idx2MBBCompare());
DEBUG(dump());
// And we're done!
return false;
}
void SlotIndexes::renumberIndexes() {
// Renumber updates the index of every element of the index list.
// If all instrs in the function have been allocated an index (which has been
// placed in the index list in the order of instruction iteration) then the
// resulting numbering will match what would have been generated by the
// pass during the initial numbering of the function if the new instructions
// had been present.
functionSize = 0;
unsigned index = 0;
for (IndexListEntry *curEntry = front(); curEntry != getTail();
curEntry = curEntry->getNext()) {
curEntry->setIndex(index);
if (curEntry->getInstr() == 0) {
// MBB start entry. Just step index by 1.
index += SlotIndex::NUM;
}
else {
++functionSize;
unsigned Slots = curEntry->getInstr()->getDesc().getNumDefs();
if (Slots == 0)
Slots = 1;
index += (Slots + 1) * SlotIndex::NUM;
}
}
}
void SlotIndexes::dump() const {
for (const IndexListEntry *itr = front(); itr != getTail();
itr = itr->getNext()) {
dbgs() << itr->getIndex() << " ";
if (itr->getInstr() != 0) {
dbgs() << *itr->getInstr();
} else {
dbgs() << "\n";
}
}
for (MBB2IdxMap::const_iterator itr = mbb2IdxMap.begin();
itr != mbb2IdxMap.end(); ++itr) {
dbgs() << "MBB " << itr->first->getNumber() << " (" << itr->first << ") - ["
<< itr->second.first << ", " << itr->second.second << "]\n";
}
}
// Print a SlotIndex to a raw_ostream.
void SlotIndex::print(raw_ostream &os) const {
os << entry().getIndex() << "LudS"[getSlot()];
}
// Dump a SlotIndex to stderr.
void SlotIndex::dump() const {
print(dbgs());
dbgs() << "\n";
}