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llvm-project/llvm/lib/CodeGen/Splitter.cpp

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//===-- llvm/CodeGen/Splitter.cpp - Splitter -----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "loopsplitter"
#include "Splitter.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/CalcSpillWeights.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/SlotIndexes.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetInstrInfo.h"
using namespace llvm;
char LoopSplitter::ID = 0;
INITIALIZE_PASS_BEGIN(LoopSplitter, "loop-splitting",
"Split virtual regists across loop boundaries.", false, false)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
INITIALIZE_PASS_END(LoopSplitter, "loop-splitting",
"Split virtual regists across loop boundaries.", false, false)
namespace llvm {
class StartSlotComparator {
public:
StartSlotComparator(LiveIntervals &lis) : lis(lis) {}
bool operator()(const MachineBasicBlock *mbb1,
const MachineBasicBlock *mbb2) const {
return lis.getMBBStartIdx(mbb1) < lis.getMBBStartIdx(mbb2);
}
private:
LiveIntervals &lis;
};
class LoopSplit {
public:
LoopSplit(LoopSplitter &ls, LiveInterval &li, MachineLoop &loop)
: ls(ls), li(li), loop(loop), valid(true), inSplit(false), newLI(0) {
assert(TargetRegisterInfo::isVirtualRegister(li.reg) &&
"Cannot split physical registers.");
}
LiveInterval& getLI() const { return li; }
MachineLoop& getLoop() const { return loop; }
bool isValid() const { return valid; }
bool isWorthwhile() const { return valid && (inSplit || !outSplits.empty()); }
void invalidate() { valid = false; }
void splitIncoming() { inSplit = true; }
void splitOutgoing(MachineLoop::Edge &edge) { outSplits.insert(edge); }
void addLoopInstr(MachineInstr *i) { loopInstrs.push_back(i); }
void apply() {
assert(valid && "Attempt to apply invalid split.");
applyIncoming();
applyOutgoing();
copyRanges();
renameInside();
}
private:
LoopSplitter &ls;
LiveInterval &li;
MachineLoop &loop;
bool valid, inSplit;
std::set<MachineLoop::Edge> outSplits;
std::vector<MachineInstr*> loopInstrs;
LiveInterval *newLI;
std::map<VNInfo*, VNInfo*> vniMap;
LiveInterval* getNewLI() {
if (newLI == 0) {
const TargetRegisterClass *trc = ls.mri->getRegClass(li.reg);
unsigned vreg = ls.mri->createVirtualRegister(trc);
newLI = &ls.lis->getOrCreateInterval(vreg);
}
return newLI;
}
VNInfo* getNewVNI(VNInfo *oldVNI) {
VNInfo *newVNI = vniMap[oldVNI];
if (newVNI == 0) {
newVNI = getNewLI()->createValueCopy(oldVNI,
ls.lis->getVNInfoAllocator());
vniMap[oldVNI] = newVNI;
}
return newVNI;
}
void applyIncoming() {
if (!inSplit) {
return;
}
MachineBasicBlock *preHeader = loop.getLoopPreheader();
if (preHeader == 0) {
assert(ls.canInsertPreHeader(loop) &&
"Can't insert required preheader.");
preHeader = &ls.insertPreHeader(loop);
}
LiveRange *preHeaderRange =
ls.lis->findExitingRange(li, preHeader);
assert(preHeaderRange != 0 && "Range not live into preheader.");
// Insert the new copy.
MachineInstr *copy = BuildMI(*preHeader,
preHeader->getFirstTerminator(),
DebugLoc(),
ls.tii->get(TargetOpcode::COPY))
.addReg(getNewLI()->reg, RegState::Define)
.addReg(li.reg, RegState::Kill);
ls.lis->InsertMachineInstrInMaps(copy);
SlotIndex copyDefIdx = ls.lis->getInstructionIndex(copy).getRegSlot();
VNInfo *newVal = getNewVNI(preHeaderRange->valno);
newVal->def = copyDefIdx;
newVal->setCopy(copy);
li.removeRange(copyDefIdx, ls.lis->getMBBEndIdx(preHeader), true);
getNewLI()->addRange(LiveRange(copyDefIdx,
ls.lis->getMBBEndIdx(preHeader),
newVal));
}
void applyOutgoing() {
for (std::set<MachineLoop::Edge>::iterator osItr = outSplits.begin(),
osEnd = outSplits.end();
osItr != osEnd; ++osItr) {
MachineLoop::Edge edge = *osItr;
MachineBasicBlock *outBlock = edge.second;
if (ls.isCriticalEdge(edge)) {
assert(ls.canSplitEdge(edge) && "Unsplitable critical edge.");
outBlock = &ls.splitEdge(edge, loop);
}
LiveRange *outRange = ls.lis->findEnteringRange(li, outBlock);
assert(outRange != 0 && "No exiting range?");
MachineInstr *copy = BuildMI(*outBlock, outBlock->begin(),
DebugLoc(),
ls.tii->get(TargetOpcode::COPY))
.addReg(li.reg, RegState::Define)
.addReg(getNewLI()->reg, RegState::Kill);
ls.lis->InsertMachineInstrInMaps(copy);
SlotIndex copyDefIdx = ls.lis->getInstructionIndex(copy).getRegSlot();
// Blow away output range definition.
outRange->valno->def = ls.lis->getInvalidIndex();
li.removeRange(ls.lis->getMBBStartIdx(outBlock), copyDefIdx);
SlotIndex newDefIdx = ls.lis->getMBBStartIdx(outBlock);
assert(ls.lis->getInstructionFromIndex(newDefIdx) == 0 &&
"PHI def index points at actual instruction.");
VNInfo *newVal =
getNewLI()->getNextValue(newDefIdx, 0, ls.lis->getVNInfoAllocator());
getNewLI()->addRange(LiveRange(ls.lis->getMBBStartIdx(outBlock),
copyDefIdx, newVal));
}
}
void copyRange(LiveRange &lr) {
std::pair<bool, LoopSplitter::SlotPair> lsr =
ls.getLoopSubRange(lr, loop);
if (!lsr.first)
return;
LiveRange loopRange(lsr.second.first, lsr.second.second,
getNewVNI(lr.valno));
li.removeRange(loopRange.start, loopRange.end, true);
getNewLI()->addRange(loopRange);
}
void copyRanges() {
for (std::vector<MachineInstr*>::iterator iItr = loopInstrs.begin(),
iEnd = loopInstrs.end();
iItr != iEnd; ++iItr) {
MachineInstr &instr = **iItr;
SlotIndex instrIdx = ls.lis->getInstructionIndex(&instr);
if (instr.modifiesRegister(li.reg, 0)) {
LiveRange *defRange =
li.getLiveRangeContaining(instrIdx.getRegSlot());
if (defRange != 0) // May have caught this already.
copyRange(*defRange);
}
if (instr.readsRegister(li.reg, 0)) {
LiveRange *useRange =
li.getLiveRangeContaining(instrIdx.getRegSlot(true));
if (useRange != 0) { // May have caught this already.
copyRange(*useRange);
}
}
}
for (MachineLoop::block_iterator bbItr = loop.block_begin(),
bbEnd = loop.block_end();
bbItr != bbEnd; ++bbItr) {
MachineBasicBlock &loopBlock = **bbItr;
LiveRange *enteringRange =
ls.lis->findEnteringRange(li, &loopBlock);
if (enteringRange != 0) {
copyRange(*enteringRange);
}
}
}
void renameInside() {
for (std::vector<MachineInstr*>::iterator iItr = loopInstrs.begin(),
iEnd = loopInstrs.end();
iItr != iEnd; ++iItr) {
MachineInstr &instr = **iItr;
for (unsigned i = 0; i < instr.getNumOperands(); ++i) {
MachineOperand &mop = instr.getOperand(i);
if (mop.isReg() && mop.getReg() == li.reg) {
mop.setReg(getNewLI()->reg);
}
}
}
}
};
void LoopSplitter::getAnalysisUsage(AnalysisUsage &au) const {
au.addRequired<MachineDominatorTree>();
au.addPreserved<MachineDominatorTree>();
au.addRequired<MachineLoopInfo>();
au.addPreserved<MachineLoopInfo>();
au.addPreservedID(RegisterCoalescerPassID);
au.addPreserved<CalculateSpillWeights>();
au.addPreserved<LiveStacks>();
au.addRequired<SlotIndexes>();
au.addPreserved<SlotIndexes>();
au.addRequired<LiveIntervals>();
au.addPreserved<LiveIntervals>();
MachineFunctionPass::getAnalysisUsage(au);
}
bool LoopSplitter::runOnMachineFunction(MachineFunction &fn) {
mf = &fn;
mri = &mf->getRegInfo();
tii = mf->getTarget().getInstrInfo();
tri = mf->getTarget().getRegisterInfo();
sis = &getAnalysis<SlotIndexes>();
lis = &getAnalysis<LiveIntervals>();
mli = &getAnalysis<MachineLoopInfo>();
mdt = &getAnalysis<MachineDominatorTree>();
fqn = mf->getFunction()->getParent()->getModuleIdentifier() + "." +
mf->getFunction()->getName().str();
dbgs() << "Splitting " << mf->getFunction()->getName() << ".";
dumpOddTerminators();
// dbgs() << "----------------------------------------\n";
// lis->dump();
// dbgs() << "----------------------------------------\n";
// std::deque<MachineLoop*> loops;
// std::copy(mli->begin(), mli->end(), std::back_inserter(loops));
// dbgs() << "Loops:\n";
// while (!loops.empty()) {
// MachineLoop &loop = *loops.front();
// loops.pop_front();
// std::copy(loop.begin(), loop.end(), std::back_inserter(loops));
// dumpLoopInfo(loop);
// }
//lis->dump();
//exit(0);
// Setup initial intervals.
for (LiveIntervals::iterator liItr = lis->begin(), liEnd = lis->end();
liItr != liEnd; ++liItr) {
LiveInterval *li = liItr->second;
if (TargetRegisterInfo::isVirtualRegister(li->reg) &&
!lis->intervalIsInOneMBB(*li)) {
intervals.push_back(li);
}
}
processIntervals();
intervals.clear();
// dbgs() << "----------------------------------------\n";
// lis->dump();
// dbgs() << "----------------------------------------\n";
dumpOddTerminators();
//exit(1);
return false;
}
void LoopSplitter::releaseMemory() {
fqn.clear();
intervals.clear();
loopRangeMap.clear();
}
void LoopSplitter::dumpOddTerminators() {
for (MachineFunction::iterator bbItr = mf->begin(), bbEnd = mf->end();
bbItr != bbEnd; ++bbItr) {
MachineBasicBlock *mbb = &*bbItr;
MachineBasicBlock *a = 0, *b = 0;
SmallVector<MachineOperand, 4> c;
if (tii->AnalyzeBranch(*mbb, a, b, c)) {
dbgs() << "MBB#" << mbb->getNumber() << " has multiway terminator.\n";
dbgs() << " Terminators:\n";
for (MachineBasicBlock::iterator iItr = mbb->begin(), iEnd = mbb->end();
iItr != iEnd; ++iItr) {
MachineInstr *instr= &*iItr;
dbgs() << " " << *instr << "";
}
dbgs() << "\n Listed successors: [ ";
for (MachineBasicBlock::succ_iterator sItr = mbb->succ_begin(), sEnd = mbb->succ_end();
sItr != sEnd; ++sItr) {
MachineBasicBlock *succMBB = *sItr;
dbgs() << succMBB->getNumber() << " ";
}
dbgs() << "]\n\n";
}
}
}
void LoopSplitter::dumpLoopInfo(MachineLoop &loop) {
MachineBasicBlock &headerBlock = *loop.getHeader();
typedef SmallVector<MachineLoop::Edge, 8> ExitEdgesList;
ExitEdgesList exitEdges;
loop.getExitEdges(exitEdges);
dbgs() << " Header: BB#" << headerBlock.getNumber() << ", Contains: [ ";
for (std::vector<MachineBasicBlock*>::const_iterator
subBlockItr = loop.getBlocks().begin(),
subBlockEnd = loop.getBlocks().end();
subBlockItr != subBlockEnd; ++subBlockItr) {
MachineBasicBlock &subBlock = **subBlockItr;
dbgs() << "BB#" << subBlock.getNumber() << " ";
}
dbgs() << "], Exit edges: [ ";
for (ExitEdgesList::iterator exitEdgeItr = exitEdges.begin(),
exitEdgeEnd = exitEdges.end();
exitEdgeItr != exitEdgeEnd; ++exitEdgeItr) {
MachineLoop::Edge &exitEdge = *exitEdgeItr;
dbgs() << "(MBB#" << exitEdge.first->getNumber()
<< ", MBB#" << exitEdge.second->getNumber() << ") ";
}
dbgs() << "], Sub-Loop Headers: [ ";
for (MachineLoop::iterator subLoopItr = loop.begin(),
subLoopEnd = loop.end();
subLoopItr != subLoopEnd; ++subLoopItr) {
MachineLoop &subLoop = **subLoopItr;
MachineBasicBlock &subLoopBlock = *subLoop.getHeader();
dbgs() << "BB#" << subLoopBlock.getNumber() << " ";
}
dbgs() << "]\n";
}
void LoopSplitter::updateTerminators(MachineBasicBlock &mbb) {
mbb.updateTerminator();
for (MachineBasicBlock::iterator miItr = mbb.begin(), miEnd = mbb.end();
miItr != miEnd; ++miItr) {
if (lis->isNotInMIMap(miItr)) {
lis->InsertMachineInstrInMaps(miItr);
}
}
}
bool LoopSplitter::canInsertPreHeader(MachineLoop &loop) {
MachineBasicBlock *header = loop.getHeader();
MachineBasicBlock *a = 0, *b = 0;
SmallVector<MachineOperand, 4> c;
for (MachineBasicBlock::pred_iterator pbItr = header->pred_begin(),
pbEnd = header->pred_end();
pbItr != pbEnd; ++pbItr) {
MachineBasicBlock *predBlock = *pbItr;
if (!!tii->AnalyzeBranch(*predBlock, a, b, c)) {
return false;
}
}
MachineFunction::iterator headerItr(header);
if (headerItr == mf->begin())
return true;
MachineBasicBlock *headerLayoutPred = llvm::prior(headerItr);
assert(headerLayoutPred != 0 && "Header should have layout pred.");
return (!tii->AnalyzeBranch(*headerLayoutPred, a, b, c));
}
MachineBasicBlock& LoopSplitter::insertPreHeader(MachineLoop &loop) {
assert(loop.getLoopPreheader() == 0 && "Loop already has preheader.");
MachineBasicBlock &header = *loop.getHeader();
// Save the preds - we'll need to update them once we insert the preheader.
typedef std::set<MachineBasicBlock*> HeaderPreds;
HeaderPreds headerPreds;
for (MachineBasicBlock::pred_iterator predItr = header.pred_begin(),
predEnd = header.pred_end();
predItr != predEnd; ++predItr) {
if (!loop.contains(*predItr))
headerPreds.insert(*predItr);
}
assert(!headerPreds.empty() && "No predecessors for header?");
//dbgs() << fqn << " MBB#" << header.getNumber() << " inserting preheader...";
MachineBasicBlock *preHeader =
mf->CreateMachineBasicBlock(header.getBasicBlock());
assert(preHeader != 0 && "Failed to create pre-header.");
mf->insert(header, preHeader);
for (HeaderPreds::iterator hpItr = headerPreds.begin(),
hpEnd = headerPreds.end();
hpItr != hpEnd; ++hpItr) {
assert(*hpItr != 0 && "How'd a null predecessor get into this set?");
MachineBasicBlock &hp = **hpItr;
hp.ReplaceUsesOfBlockWith(&header, preHeader);
}
preHeader->addSuccessor(&header);
MachineBasicBlock *oldLayoutPred =
llvm::prior(MachineFunction::iterator(preHeader));
if (oldLayoutPred != 0) {
updateTerminators(*oldLayoutPred);
}
lis->InsertMBBInMaps(preHeader);
if (MachineLoop *parentLoop = loop.getParentLoop()) {
assert(parentLoop->getHeader() != loop.getHeader() &&
"Parent loop has same header?");
parentLoop->addBasicBlockToLoop(preHeader, mli->getBase());
// Invalidate all parent loop ranges.
while (parentLoop != 0) {
loopRangeMap.erase(parentLoop);
parentLoop = parentLoop->getParentLoop();
}
}
for (LiveIntervals::iterator liItr = lis->begin(),
liEnd = lis->end();
liItr != liEnd; ++liItr) {
LiveInterval &li = *liItr->second;
// Is this safe for physregs?
// TargetRegisterInfo::isPhysicalRegister(li.reg) ||
if (!lis->isLiveInToMBB(li, &header))
continue;
if (lis->isLiveInToMBB(li, preHeader)) {
assert(lis->isLiveOutOfMBB(li, preHeader) &&
"Range terminates in newly added preheader?");
continue;
}
bool insertRange = false;
for (MachineBasicBlock::pred_iterator predItr = preHeader->pred_begin(),
predEnd = preHeader->pred_end();
predItr != predEnd; ++predItr) {
MachineBasicBlock *predMBB = *predItr;
if (lis->isLiveOutOfMBB(li, predMBB)) {
insertRange = true;
break;
}
}
if (!insertRange)
continue;
SlotIndex newDefIdx = lis->getMBBStartIdx(preHeader);
assert(lis->getInstructionFromIndex(newDefIdx) == 0 &&
"PHI def index points at actual instruction.");
VNInfo *newVal = li.getNextValue(newDefIdx, 0, lis->getVNInfoAllocator());
li.addRange(LiveRange(lis->getMBBStartIdx(preHeader),
lis->getMBBEndIdx(preHeader),
newVal));
}
//dbgs() << "Dumping SlotIndexes:\n";
//sis->dump();
//dbgs() << "done. (Added MBB#" << preHeader->getNumber() << ")\n";
return *preHeader;
}
bool LoopSplitter::isCriticalEdge(MachineLoop::Edge &edge) {
assert(edge.first->succ_size() > 1 && "Non-sensical edge.");
if (edge.second->pred_size() > 1)
return true;
return false;
}
bool LoopSplitter::canSplitEdge(MachineLoop::Edge &edge) {
MachineFunction::iterator outBlockItr(edge.second);
if (outBlockItr == mf->begin())
return true;
MachineBasicBlock *outBlockLayoutPred = llvm::prior(outBlockItr);
assert(outBlockLayoutPred != 0 && "Should have a layout pred if out!=begin.");
MachineBasicBlock *a = 0, *b = 0;
SmallVector<MachineOperand, 4> c;
return (!tii->AnalyzeBranch(*outBlockLayoutPred, a, b, c) &&
!tii->AnalyzeBranch(*edge.first, a, b, c));
}
MachineBasicBlock& LoopSplitter::splitEdge(MachineLoop::Edge &edge,
MachineLoop &loop) {
MachineBasicBlock &inBlock = *edge.first;
MachineBasicBlock &outBlock = *edge.second;
assert((inBlock.succ_size() > 1) && (outBlock.pred_size() > 1) &&
"Splitting non-critical edge?");
//dbgs() << fqn << " Splitting edge (MBB#" << inBlock.getNumber()
// << " -> MBB#" << outBlock.getNumber() << ")...";
MachineBasicBlock *splitBlock =
mf->CreateMachineBasicBlock();
assert(splitBlock != 0 && "Failed to create split block.");
mf->insert(&outBlock, splitBlock);
inBlock.ReplaceUsesOfBlockWith(&outBlock, splitBlock);
splitBlock->addSuccessor(&outBlock);
MachineBasicBlock *oldLayoutPred =
llvm::prior(MachineFunction::iterator(splitBlock));
if (oldLayoutPred != 0) {
updateTerminators(*oldLayoutPred);
}
lis->InsertMBBInMaps(splitBlock);
loopRangeMap.erase(&loop);
MachineLoop *splitParentLoop = loop.getParentLoop();
while (splitParentLoop != 0 &&
!splitParentLoop->contains(&outBlock)) {
splitParentLoop = splitParentLoop->getParentLoop();
}
if (splitParentLoop != 0) {
assert(splitParentLoop->contains(&loop) &&
"Split-block parent doesn't contain original loop?");
splitParentLoop->addBasicBlockToLoop(splitBlock, mli->getBase());
// Invalidate all parent loop ranges.
while (splitParentLoop != 0) {
loopRangeMap.erase(splitParentLoop);
splitParentLoop = splitParentLoop->getParentLoop();
}
}
for (LiveIntervals::iterator liItr = lis->begin(),
liEnd = lis->end();
liItr != liEnd; ++liItr) {
LiveInterval &li = *liItr->second;
bool intersects = lis->isLiveOutOfMBB(li, &inBlock) &&
lis->isLiveInToMBB(li, &outBlock);
if (lis->isLiveInToMBB(li, splitBlock)) {
if (!intersects) {
li.removeRange(lis->getMBBStartIdx(splitBlock),
lis->getMBBEndIdx(splitBlock), true);
}
} else if (intersects) {
SlotIndex newDefIdx = lis->getMBBStartIdx(splitBlock);
assert(lis->getInstructionFromIndex(newDefIdx) == 0 &&
"PHI def index points at actual instruction.");
VNInfo *newVal = li.getNextValue(newDefIdx, 0,
lis->getVNInfoAllocator());
li.addRange(LiveRange(lis->getMBBStartIdx(splitBlock),
lis->getMBBEndIdx(splitBlock),
newVal));
}
}
//dbgs() << "done. (Added MBB#" << splitBlock->getNumber() << ")\n";
return *splitBlock;
}
LoopSplitter::LoopRanges& LoopSplitter::getLoopRanges(MachineLoop &loop) {
typedef std::set<MachineBasicBlock*, StartSlotComparator> LoopMBBSet;
LoopRangeMap::iterator lrItr = loopRangeMap.find(&loop);
if (lrItr == loopRangeMap.end()) {
LoopMBBSet loopMBBs((StartSlotComparator(*lis)));
std::copy(loop.block_begin(), loop.block_end(),
std::inserter(loopMBBs, loopMBBs.begin()));
assert(!loopMBBs.empty() && "No blocks in loop?");
LoopRanges &loopRanges = loopRangeMap[&loop];
assert(loopRanges.empty() && "Loop encountered but not processed?");
SlotIndex oldEnd = lis->getMBBEndIdx(*loopMBBs.begin());
loopRanges.push_back(
std::make_pair(lis->getMBBStartIdx(*loopMBBs.begin()),
lis->getInvalidIndex()));
for (LoopMBBSet::iterator curBlockItr = llvm::next(loopMBBs.begin()),
curBlockEnd = loopMBBs.end();
curBlockItr != curBlockEnd; ++curBlockItr) {
SlotIndex newStart = lis->getMBBStartIdx(*curBlockItr);
if (newStart != oldEnd) {
loopRanges.back().second = oldEnd;
loopRanges.push_back(std::make_pair(newStart,
lis->getInvalidIndex()));
}
oldEnd = lis->getMBBEndIdx(*curBlockItr);
}
loopRanges.back().second =
lis->getMBBEndIdx(*llvm::prior(loopMBBs.end()));
return loopRanges;
}
return lrItr->second;
}
std::pair<bool, LoopSplitter::SlotPair> LoopSplitter::getLoopSubRange(
const LiveRange &lr,
MachineLoop &loop) {
LoopRanges &loopRanges = getLoopRanges(loop);
LoopRanges::iterator lrItr = loopRanges.begin(),
lrEnd = loopRanges.end();
while (lrItr != lrEnd && lr.start >= lrItr->second) {
++lrItr;
}
if (lrItr == lrEnd) {
SlotIndex invalid = lis->getInvalidIndex();
return std::make_pair(false, SlotPair(invalid, invalid));
}
SlotIndex srStart(lr.start < lrItr->first ? lrItr->first : lr.start);
SlotIndex srEnd(lr.end > lrItr->second ? lrItr->second : lr.end);
return std::make_pair(true, SlotPair(srStart, srEnd));
}
void LoopSplitter::dumpLoopRanges(MachineLoop &loop) {
LoopRanges &loopRanges = getLoopRanges(loop);
dbgs() << "For loop MBB#" << loop.getHeader()->getNumber() << ", subranges are: [ ";
for (LoopRanges::iterator lrItr = loopRanges.begin(), lrEnd = loopRanges.end();
lrItr != lrEnd; ++lrItr) {
dbgs() << "[" << lrItr->first << ", " << lrItr->second << ") ";
}
dbgs() << "]\n";
}
void LoopSplitter::processHeader(LoopSplit &split) {
MachineBasicBlock &header = *split.getLoop().getHeader();
//dbgs() << " Processing loop header BB#" << header.getNumber() << "\n";
if (!lis->isLiveInToMBB(split.getLI(), &header))
return; // Not live in, but nothing wrong so far.
MachineBasicBlock *preHeader = split.getLoop().getLoopPreheader();
if (!preHeader) {
if (!canInsertPreHeader(split.getLoop())) {
split.invalidate();
return; // Couldn't insert a pre-header. Bail on this interval.
}
for (MachineBasicBlock::pred_iterator predItr = header.pred_begin(),
predEnd = header.pred_end();
predItr != predEnd; ++predItr) {
if (lis->isLiveOutOfMBB(split.getLI(), *predItr)) {
split.splitIncoming();
break;
}
}
} else if (lis->isLiveOutOfMBB(split.getLI(), preHeader)) {
split.splitIncoming();
}
}
void LoopSplitter::processLoopExits(LoopSplit &split) {
typedef SmallVector<MachineLoop::Edge, 8> ExitEdgesList;
ExitEdgesList exitEdges;
split.getLoop().getExitEdges(exitEdges);
//dbgs() << " Processing loop exits:\n";
for (ExitEdgesList::iterator exitEdgeItr = exitEdges.begin(),
exitEdgeEnd = exitEdges.end();
exitEdgeItr != exitEdgeEnd; ++exitEdgeItr) {
MachineLoop::Edge exitEdge = *exitEdgeItr;
LiveRange *outRange =
split.getLI().getLiveRangeContaining(lis->getMBBStartIdx(exitEdge.second));
if (outRange != 0) {
if (isCriticalEdge(exitEdge) && !canSplitEdge(exitEdge)) {
split.invalidate();
return;
}
split.splitOutgoing(exitEdge);
}
}
}
void LoopSplitter::processLoopUses(LoopSplit &split) {
std::set<MachineInstr*> processed;
for (MachineRegisterInfo::reg_iterator
rItr = mri->reg_begin(split.getLI().reg),
rEnd = mri->reg_end();
rItr != rEnd; ++rItr) {
MachineInstr &instr = *rItr;
if (split.getLoop().contains(&instr) && processed.count(&instr) == 0) {
split.addLoopInstr(&instr);
processed.insert(&instr);
}
}
//dbgs() << " Rewriting reg" << li.reg << " to reg" << newLI->reg
// << " in blocks [ ";
//dbgs() << "]\n";
}
bool LoopSplitter::splitOverLoop(LiveInterval &li, MachineLoop &loop) {
assert(TargetRegisterInfo::isVirtualRegister(li.reg) &&
"Attempt to split physical register.");
LoopSplit split(*this, li, loop);
processHeader(split);
if (split.isValid())
processLoopExits(split);
if (split.isValid())
processLoopUses(split);
if (split.isValid() /* && split.isWorthwhile() */) {
split.apply();
DEBUG(dbgs() << "Success.\n");
return true;
}
DEBUG(dbgs() << "Failed.\n");
return false;
}
void LoopSplitter::processInterval(LiveInterval &li) {
std::deque<MachineLoop*> loops;
std::copy(mli->begin(), mli->end(), std::back_inserter(loops));
while (!loops.empty()) {
MachineLoop &loop = *loops.front();
loops.pop_front();
DEBUG(
dbgs() << fqn << " reg" << li.reg << " " << li.weight << " BB#"
<< loop.getHeader()->getNumber() << " ";
);
if (!splitOverLoop(li, loop)) {
// Couldn't split over outer loop, schedule sub-loops to be checked.
std::copy(loop.begin(), loop.end(), std::back_inserter(loops));
}
}
}
void LoopSplitter::processIntervals() {
while (!intervals.empty()) {
LiveInterval &li = *intervals.front();
intervals.pop_front();
assert(!lis->intervalIsInOneMBB(li) &&
"Single interval in process worklist.");
processInterval(li);
}
}
}
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