#include "llvm/ADT/DepthFirstIterator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
using namespace llvm;
namespace {
struct VISIBILITY_HIDDEN StrongPHIElimination : public MachineFunctionPass {
static char ID; // Pass identification, replacement for typeid
- StrongPHIElimination() : MachineFunctionPass((intptr_t)&ID) {}
+ StrongPHIElimination() : MachineFunctionPass(&ID) {}
// Waiting stores, for each MBB, the set of copies that need to
// be inserted into that MBB
DenseMap<MachineBasicBlock*,
- std::map<unsigned, unsigned> > Waiting;
+ std::multimap<unsigned, unsigned> > Waiting;
// Stacks holds the renaming stack for each register
std::map<unsigned, std::vector<unsigned> > Stacks;
std::vector<StrongPHIElimination::DomForestNode*>& DF,
std::vector<std::pair<unsigned, unsigned> >& locals);
void ScheduleCopies(MachineBasicBlock* MBB, std::set<unsigned>& pushed);
- void InsertCopies(MachineBasicBlock* MBB,
+ void InsertCopies(MachineDomTreeNode* MBB,
SmallPtrSet<MachineBasicBlock*, 16>& v);
- void mergeLiveIntervals(unsigned primary, unsigned secondary,
- MachineBasicBlock* pred);
+ bool mergeLiveIntervals(unsigned primary, unsigned secondary);
};
}
LiveIntervals& LI) {
LiveInterval& I = LI.getOrCreateInterval(r);
unsigned idx = LI.getMBBStartIdx(MBB);
- return I.liveBeforeAndAt(idx);
+ return I.liveAt(idx);
}
/// isLiveOut - help method that determines, from a regno, if a register is
static bool isLiveOut(unsigned r, MachineBasicBlock* MBB,
LiveIntervals& LI) {
for (MachineBasicBlock::succ_iterator PI = MBB->succ_begin(),
- E = MBB->succ_end(); PI != E; ++PI) {
+ E = MBB->succ_end(); PI != E; ++PI)
if (isLiveIn(r, *PI, LI))
return true;
- }
return false;
}
MachineBasicBlock::iterator P = MBB->begin();
while (P != MBB->end() && P->getOpcode() == TargetInstrInfo::PHI) {
unsigned DestReg = P->getOperand(0).getReg();
-
// Don't both doing PHI elimination for dead PHI's.
if (P->registerDefIsDead(DestReg)) {
ProcessedNames.insert(SrcReg);
continue;
}
+
+ // We don't need to insert copies for implicit_defs.
+ MachineInstr* DefMI = MRI.getVRegDef(SrcReg);
+ if (DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
+ ProcessedNames.insert(SrcReg);
// Check for trivial interferences via liveness information, allowing us
// to avoid extra work later. Any registers that interfere cannot both
}
// Add the renaming set for this PHI node to our overall renaming information
+ for (std::map<unsigned, MachineBasicBlock*>::iterator QI = PHIUnion.begin(),
+ QE = PHIUnion.end(); QI != QE; ++QI) {
+ DOUT << "Adding Renaming: " << QI->first << " -> "
+ << P->getOperand(0).getReg() << "\n";
+ }
+
RenameSets.insert(std::make_pair(P->getOperand(0).getReg(), PHIUnion));
// Remember which registers are already renamed, so that we don't try to
void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB,
std::set<unsigned>& pushed) {
// FIXME: This function needs to update LiveIntervals
- std::map<unsigned, unsigned>& copy_set= Waiting[MBB];
+ std::multimap<unsigned, unsigned>& copy_set= Waiting[MBB];
- std::map<unsigned, unsigned> worklist;
+ std::multimap<unsigned, unsigned> worklist;
std::map<unsigned, unsigned> map;
// Setup worklist of initial copies
- for (std::map<unsigned, unsigned>::iterator I = copy_set.begin(),
+ for (std::multimap<unsigned, unsigned>::iterator I = copy_set.begin(),
E = copy_set.end(); I != E; ) {
map.insert(std::make_pair(I->first, I->first));
map.insert(std::make_pair(I->second, I->second));
worklist.insert(*I);
// Avoid iterator invalidation
- unsigned first = I->first;
+ std::multimap<unsigned, unsigned>::iterator OI = I;
++I;
- copy_set.erase(first);
+ copy_set.erase(OI);
} else {
++I;
}
// Iterate over the worklist, inserting copies
while (!worklist.empty() || !copy_set.empty()) {
while (!worklist.empty()) {
- std::pair<unsigned, unsigned> curr = *worklist.begin();
- worklist.erase(curr.first);
+ std::multimap<unsigned, unsigned>::iterator WI = worklist.begin();
+ std::pair<unsigned, unsigned> curr = *WI;
+ worklist.erase(WI);
const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(curr.first);
TII->copyRegToReg(*PI->getParent(), PI, t,
curr.second, RC, RC);
+ DOUT << "Inserted copy from " << curr.second << " to " << t << "\n";
+
// Push temporary on Stacks
Stacks[curr.second].push_back(t);
// Insert curr.second in pushed
pushed.insert(curr.second);
+
+ // Create a live interval for this temporary
+ InsertedPHIDests.push_back(std::make_pair(t, --PI));
}
// Insert copy from map[curr.first] to curr.second
TII->copyRegToReg(*MBB, MBB->getFirstTerminator(), curr.second,
map[curr.first], RC, RC);
map[curr.first] = curr.second;
+ DOUT << "Inserted copy from " << curr.first << " to "
+ << curr.second << "\n";
// Push this copy onto InsertedPHICopies so we can
// update LiveIntervals with it.
InsertedPHIDests.push_back(std::make_pair(curr.second, --MI));
// If curr.first is a destination in copy_set...
- for (std::map<unsigned, unsigned>::iterator I = copy_set.begin(),
+ for (std::multimap<unsigned, unsigned>::iterator I = copy_set.begin(),
E = copy_set.end(); I != E; )
if (curr.first == I->second) {
std::pair<unsigned, unsigned> temp = *I;
+ worklist.insert(temp);
// Avoid iterator invalidation
+ std::multimap<unsigned, unsigned>::iterator OI = I;
++I;
- copy_set.erase(temp.first);
- worklist.insert(temp);
+ copy_set.erase(OI);
break;
} else {
}
if (!copy_set.empty()) {
- std::pair<unsigned, unsigned> curr = *copy_set.begin();
- copy_set.erase(curr.first);
-
- const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(curr.first);
+ std::multimap<unsigned, unsigned>::iterator CI = copy_set.begin();
+ std::pair<unsigned, unsigned> curr = *CI;
+ worklist.insert(curr);
+ copy_set.erase(CI);
- // Insert a copy from dest to a new temporary t at the end of b
- unsigned t = MF->getRegInfo().createVirtualRegister(RC);
- TII->copyRegToReg(*MBB, MBB->getFirstTerminator(), t,
- curr.second, RC, RC);
- map[curr.second] = t;
+ LiveInterval& I = LI.getInterval(curr.second);
+ MachineBasicBlock::iterator term = MBB->getFirstTerminator();
+ unsigned endIdx = 0;
+ if (term != MBB->end())
+ endIdx = LI.getInstructionIndex(term);
+ else
+ endIdx = LI.getMBBEndIdx(MBB);
- worklist.insert(curr);
+ if (I.liveAt(endIdx)) {
+ const TargetRegisterClass *RC =
+ MF->getRegInfo().getRegClass(curr.first);
+
+ // Insert a copy from dest to a new temporary t at the end of b
+ unsigned t = MF->getRegInfo().createVirtualRegister(RC);
+ TII->copyRegToReg(*MBB, MBB->getFirstTerminator(), t,
+ curr.second, RC, RC);
+ map[curr.second] = t;
+
+ MachineBasicBlock::iterator TI = MBB->getFirstTerminator();
+ InsertedPHIDests.push_back(std::make_pair(t, --TI));
+ }
}
}
// PHI, we don't create multiple overlapping live intervals.
std::set<unsigned> RegHandled;
for (SmallVector<std::pair<unsigned, MachineInstr*>, 4>::iterator I =
- InsertedPHIDests.begin(), E = InsertedPHIDests.end(); I != E; ++I)
- if (RegHandled.insert(I->first).second)
- LI.addLiveRangeToEndOfBlock(I->first, I->second);
+ InsertedPHIDests.begin(), E = InsertedPHIDests.end(); I != E; ++I) {
+ if (RegHandled.insert(I->first).second) {
+ LiveInterval& Int = LI.getOrCreateInterval(I->first);
+ unsigned instrIdx = LI.getInstructionIndex(I->second);
+ if (Int.liveAt(LiveIntervals::getDefIndex(instrIdx)))
+ Int.removeRange(LiveIntervals::getDefIndex(instrIdx),
+ LI.getMBBEndIdx(I->second->getParent())+1,
+ true);
+
+ LiveRange R = LI.addLiveRangeToEndOfBlock(I->first, I->second);
+ R.valno->copy = I->second;
+ R.valno->def =
+ LiveIntervals::getDefIndex(LI.getInstructionIndex(I->second));
+ }
+ }
}
/// InsertCopies - insert copies into MBB and all of its successors
-void StrongPHIElimination::InsertCopies(MachineBasicBlock* MBB,
+void StrongPHIElimination::InsertCopies(MachineDomTreeNode* MDTN,
SmallPtrSet<MachineBasicBlock*, 16>& visited) {
+ MachineBasicBlock* MBB = MDTN->getBlock();
visited.insert(MBB);
std::set<unsigned> pushed;
+ LiveIntervals& LI = getAnalysis<LiveIntervals>();
// Rewrite register uses from Stacks
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
- I != E; ++I)
+ I != E; ++I) {
+ if (I->getOpcode() == TargetInstrInfo::PHI)
+ continue;
+
for (unsigned i = 0; i < I->getNumOperands(); ++i)
- if (I->getOperand(i).isRegister() &&
+ if (I->getOperand(i).isReg() &&
Stacks[I->getOperand(i).getReg()].size()) {
+ // Remove the live range for the old vreg.
+ LiveInterval& OldInt = LI.getInterval(I->getOperand(i).getReg());
+ LiveInterval::iterator OldLR = OldInt.FindLiveRangeContaining(
+ LiveIntervals::getUseIndex(LI.getInstructionIndex(I)));
+ if (OldLR != OldInt.end())
+ OldInt.removeRange(*OldLR, true);
+
+ // Change the register
I->getOperand(i).setReg(Stacks[I->getOperand(i).getReg()].back());
+
+ // Add a live range for the new vreg
+ LiveInterval& Int = LI.getInterval(I->getOperand(i).getReg());
+ VNInfo* FirstVN = *Int.vni_begin();
+ FirstVN->hasPHIKill = false;
+ if (I->getOperand(i).isKill())
+ FirstVN->kills.push_back(
+ LiveIntervals::getUseIndex(LI.getInstructionIndex(I)));
+
+ LiveRange LR (LI.getMBBStartIdx(I->getParent()),
+ LiveIntervals::getUseIndex(LI.getInstructionIndex(I))+1,
+ FirstVN);
+
+ Int.addRange(LR);
}
+ }
// Schedule the copies for this block
ScheduleCopies(MBB, pushed);
- // Recur to our successors
- for (GraphTraits<MachineBasicBlock*>::ChildIteratorType I =
- GraphTraits<MachineBasicBlock*>::child_begin(MBB), E =
- GraphTraits<MachineBasicBlock*>::child_end(MBB); I != E; ++I)
- if (!visited.count(*I))
+ // Recur down the dominator tree.
+ for (MachineDomTreeNode::iterator I = MDTN->begin(),
+ E = MDTN->end(); I != E; ++I)
+ if (!visited.count((*I)->getBlock()))
InsertCopies(*I, visited);
// As we exit this block, pop the names we pushed while processing it
Stacks[*I].pop_back();
}
-void StrongPHIElimination::mergeLiveIntervals(unsigned primary,
- unsigned secondary,
- MachineBasicBlock* pred) {
+bool StrongPHIElimination::mergeLiveIntervals(unsigned primary,
+ unsigned secondary) {
LiveIntervals& LI = getAnalysis<LiveIntervals>();
LiveInterval& LHS = LI.getOrCreateInterval(primary);
LiveInterval& RHS = LI.getOrCreateInterval(secondary);
LI.computeNumbering();
- const LiveRange* RangeMergingIn =
- RHS.getLiveRangeContaining(LI.getMBBEndIdx(pred));
- VNInfo* RHSVN = RangeMergingIn->valno;
- VNInfo* NewVN = LHS.getNextValue(RangeMergingIn->valno->def,
- RangeMergingIn->valno->copy,
- LI.getVNInfoAllocator());
-
- // If we discover that a live range was defined by a two-addr
- // instruction, we need to merge over the input as well, even if
- // it has a different VNInfo.
- SmallPtrSet<VNInfo*, 4> MergedVNs;
- MergedVNs.insert(RHSVN);
DenseMap<VNInfo*, VNInfo*> VNMap;
- VNMap.insert(std::make_pair(RangeMergingIn->valno, NewVN));
-
- // Find all VNs that are the inputs to two-address instructiosn
- // chaining upwards from the VN we're trying to merge.
- bool addedVN = true;
- while (addedVN) {
- addedVN = false;
- unsigned defIndex = RHSVN->def;
-
- if (defIndex != ~0U) {
- MachineInstr* instr = LI.getInstructionFromIndex(defIndex);
-
- for (unsigned i = 0; i < instr->getNumOperands(); ++i) {
- if (instr->getOperand(i).isReg() &&
- instr->getOperand(i).getReg() == secondary)
- if (instr->isRegReDefinedByTwoAddr(secondary, i)) {
- RHSVN = RHS.getLiveRangeContaining(defIndex-1)->valno;
- addedVN = true;
-
- VNInfo* NextVN = LHS.getNextValue(RHSVN->def,
- RHSVN->copy,
- LI.getVNInfoAllocator());
- VNMap.insert(std::make_pair(RHSVN, NextVN));
-
- break;
- }
- }
- }
+ for (LiveInterval::iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) {
+ LiveRange R = *I;
+
+ unsigned Start = R.start;
+ unsigned End = R.end;
+ if (LHS.getLiveRangeContaining(Start))
+ return false;
+
+ if (LHS.getLiveRangeContaining(End))
+ return false;
+
+ LiveInterval::iterator RI = std::upper_bound(LHS.begin(), LHS.end(), R);
+ if (RI != LHS.end() && RI->start < End)
+ return false;
}
- // Merge VNs from RHS into LHS using the mapping we computed above.
- for (DenseMap<VNInfo*, VNInfo*>::iterator VI = VNMap.begin(),
- VE = VNMap.end(); VI != VE; ++VI) {
- LHS.MergeValueInAsValue(RHS, VI->first, VI->second);
- RHS.removeValNo(VI->first);
+ for (LiveInterval::iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) {
+ LiveRange R = *I;
+ VNInfo* OldVN = R.valno;
+ VNInfo*& NewVN = VNMap[OldVN];
+ if (!NewVN) {
+ NewVN = LHS.getNextValue(OldVN->def,
+ OldVN->copy,
+ LI.getVNInfoAllocator());
+ NewVN->kills = OldVN->kills;
+ }
+
+ LiveRange LR (R.start, R.end, NewVN);
+ LHS.addRange(LR);
}
- if (RHS.begin() == RHS.end())
- LI.removeInterval(RHS.reg);
+ LI.removeInterval(RHS.reg);
+
+ return true;
}
bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
unsigned reg = OI->first;
++OI;
I->second.erase(reg);
+ DOUT << "Removing Renaming: " << reg << " -> " << I->first << "\n";
}
}
}
// Insert copies
// FIXME: This process should probably preserve LiveIntervals
SmallPtrSet<MachineBasicBlock*, 16> visited;
- InsertCopies(Fn.begin(), visited);
+ MachineDominatorTree& MDT = getAnalysis<MachineDominatorTree>();
+ InsertCopies(MDT.getRootNode(), visited);
// Perform renaming
for (RenameSetType::iterator I = RenameSets.begin(), E = RenameSets.end();
while (I->second.size()) {
std::map<unsigned, MachineBasicBlock*>::iterator SI = I->second.begin();
+ DOUT << "Renaming: " << SI->first << " -> " << I->first << "\n";
+
if (SI->first != I->first) {
- mergeLiveIntervals(I->first, SI->first, SI->second);
- Fn.getRegInfo().replaceRegWith(SI->first, I->first);
+ if (mergeLiveIntervals(I->first, SI->first)) {
+ Fn.getRegInfo().replaceRegWith(SI->first, I->first);
- if (RenameSets.count(SI->first)) {
- I->second.insert(RenameSets[SI->first].begin(),
- RenameSets[SI->first].end());
- RenameSets.erase(SI->first);
+ if (RenameSets.count(SI->first)) {
+ I->second.insert(RenameSets[SI->first].begin(),
+ RenameSets[SI->first].end());
+ RenameSets.erase(SI->first);
+ }
+ } else {
+ // Insert a last-minute copy if a conflict was detected.
+ const TargetInstrInfo *TII = Fn.getTarget().getInstrInfo();
+ const TargetRegisterClass *RC = Fn.getRegInfo().getRegClass(I->first);
+ TII->copyRegToReg(*SI->second, SI->second->getFirstTerminator(),
+ I->first, SI->first, RC, RC);
+
+ LI.computeNumbering();
+
+ LiveInterval& Int = LI.getOrCreateInterval(I->first);
+ unsigned instrIdx =
+ LI.getInstructionIndex(--SI->second->getFirstTerminator());
+ if (Int.liveAt(LiveIntervals::getDefIndex(instrIdx)))
+ Int.removeRange(LiveIntervals::getDefIndex(instrIdx),
+ LI.getMBBEndIdx(SI->second)+1, true);
+
+ LiveRange R = LI.addLiveRangeToEndOfBlock(I->first,
+ --SI->second->getFirstTerminator());
+ R.valno->copy = --SI->second->getFirstTerminator();
+ R.valno->def = LiveIntervals::getDefIndex(instrIdx);
+
+ DOUT << "Renaming failed: " << SI->first << " -> "
+ << I->first << "\n";
}
-
-
}
+ LiveInterval& Int = LI.getOrCreateInterval(I->first);
+ const LiveRange* LR =
+ Int.getLiveRangeContaining(LI.getMBBEndIdx(SI->second));
+ LR->valno->hasPHIKill = true;
+
I->second.erase(SI->first);
}
- // FIXME: Insert last-minute copies
-
// Remove PHIs
std::vector<MachineInstr*> phis;
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
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