#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegisterCoalescer.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#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 {
+ struct 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;
// Registers in UsedByAnother are PHI nodes that are themselves
- // used as operands to another another PHI node
+ // used as operands to another PHI node
std::set<unsigned> UsedByAnother;
- // RenameSets are the sets of operands to a PHI (the defining instruction
- // of the key) that can be renamed without copies
- std::map<unsigned, std::set<unsigned> > RenameSets;
+ // RenameSets are the is a map from a PHI-defined register
+ // to the input registers to be coalesced along with the
+ // predecessor block for those input registers.
+ std::map<unsigned, std::map<unsigned, MachineBasicBlock*> > RenameSets;
+
+ // PhiValueNumber holds the ID numbers of the VNs for each phi that we're
+ // eliminating, indexed by the register defined by that phi.
+ std::map<unsigned, unsigned> PhiValueNumber;
// Store the DFS-in number of each block
DenseMap<MachineBasicBlock*, unsigned> preorder;
bool runOnMachineFunction(MachineFunction &Fn);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
AU.addRequired<MachineDominatorTree>();
+ AU.addRequired<SlotIndexes>();
+ AU.addPreserved<SlotIndexes>();
AU.addRequired<LiveIntervals>();
// TODO: Actually make this true.
AU.addPreserved<LiveIntervals>();
+ AU.addPreserved<RegisterCoalescer>();
MachineFunctionPass::getAnalysisUsage(AU);
}
void computeDFS(MachineFunction& MF);
void processBlock(MachineBasicBlock* MBB);
- std::vector<DomForestNode*> computeDomForest(std::set<unsigned>& instrs,
+ std::vector<DomForestNode*> computeDomForest(
+ std::map<unsigned, MachineBasicBlock*>& instrs,
MachineRegisterInfo& MRI);
void processPHIUnion(MachineInstr* Inst,
- std::set<unsigned>& PHIUnion,
+ std::map<unsigned, MachineBasicBlock*>& PHIUnion,
std::vector<StrongPHIElimination::DomForestNode*>& DF,
std::vector<std::pair<unsigned, unsigned> >& locals);
void ScheduleCopies(MachineBasicBlock* MBB, std::set<unsigned>& pushed);
- void InsertCopies(MachineBasicBlock* MBB, std::set<MachineBasicBlock*>& v);
+ void InsertCopies(MachineDomTreeNode* MBB,
+ SmallPtrSet<MachineBasicBlock*, 16>& v);
+ bool mergeLiveIntervals(unsigned primary, unsigned secondary);
};
-
- char StrongPHIElimination::ID = 0;
- RegisterPass<StrongPHIElimination> X("strong-phi-node-elimination",
- "Eliminate PHI nodes for register allocation, intelligently");
}
-const PassInfo *llvm::StrongPHIEliminationID = X.getPassInfo();
+char StrongPHIElimination::ID = 0;
+INITIALIZE_PASS(StrongPHIElimination, "strong-phi-node-elimination",
+ "Eliminate PHI nodes for register allocation, intelligently", false, false);
+
+char &llvm::StrongPHIEliminationID = StrongPHIElimination::ID;
/// computeDFS - Computes the DFS-in and DFS-out numbers of the dominator tree
/// of the given MachineFunction. These numbers are then used in other parts
}
bool inserted = false;
- for (MachineDomTreeNode::iterator I = node->begin(), E = node->end();
+ for (MachineDomTreeNode::iterator I = currNode->begin(), E = currNode->end();
I != E; ++I)
if (!frontier.count(*I) && !visited.count(*I)) {
worklist.push_back(*I);
}
}
+namespace {
+
/// PreorderSorter - a helper class that is used to sort registers
/// according to the preorder number of their defining blocks
class PreorderSorter {
}
};
+}
+
/// computeDomForest - compute the subforest of the DomTree corresponding
/// to the defining blocks of the registers in question
std::vector<StrongPHIElimination::DomForestNode*>
-StrongPHIElimination::computeDomForest(std::set<unsigned>& regs,
+StrongPHIElimination::computeDomForest(
+ std::map<unsigned, MachineBasicBlock*>& regs,
MachineRegisterInfo& MRI) {
// Begin by creating a virtual root node, since the actual results
// may well be a forest. Assume this node has maximum DFS-out number.
// Populate a worklist with the registers
std::vector<unsigned> worklist;
worklist.reserve(regs.size());
- for (std::set<unsigned>::iterator I = regs.begin(), E = regs.end();
- I != E; ++I)
- worklist.push_back(*I);
+ for (std::map<unsigned, MachineBasicBlock*>::iterator I = regs.begin(),
+ E = regs.end(); I != E; ++I)
+ worklist.push_back(I->first);
// Sort the registers by the DFS-in number of their defining block
PreorderSorter PS(preorder, MRI);
static bool isLiveIn(unsigned r, MachineBasicBlock* MBB,
LiveIntervals& LI) {
LiveInterval& I = LI.getOrCreateInterval(r);
- unsigned idx = LI.getMBBStartIdx(MBB);
- return I.liveBeforeAndAt(idx);
+ SlotIndex idx = LI.getMBBStartIdx(MBB);
+ 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;
}
// Iterate over all the PHI nodes in this block
MachineBasicBlock::iterator P = MBB->begin();
- while (P != MBB->end() && P->getOpcode() == TargetInstrInfo::PHI) {
+ while (P != MBB->end() && P->isPHI()) {
unsigned DestReg = P->getOperand(0).getReg();
+
+ // Don't both doing PHI elimination for dead PHI's.
+ if (P->registerDefIsDead(DestReg)) {
+ ++P;
+ continue;
+ }
+
+ LiveInterval& PI = LI.getOrCreateInterval(DestReg);
+ SlotIndex pIdx = LI.getInstructionIndex(P).getDefIndex();
+ VNInfo* PVN = PI.getLiveRangeContaining(pIdx)->valno;
+ PhiValueNumber.insert(std::make_pair(DestReg, PVN->id));
// PHIUnion is the set of incoming registers to the PHI node that
// are going to be renames rather than having copies inserted. This set
// is refinded over the course of this function. UnionedBlocks is the set
// of corresponding MBBs.
- std::set<unsigned> PHIUnion;
- std::set<MachineBasicBlock*> UnionedBlocks;
+ std::map<unsigned, MachineBasicBlock*> PHIUnion;
+ SmallPtrSet<MachineBasicBlock*, 8> UnionedBlocks;
// Iterate over the operands of the PHI node
for (int i = P->getNumOperands() - 1; i >= 2; i-=2) {
unsigned SrcReg = P->getOperand(i-1).getReg();
+
+ // Don't need to try to coalesce a register with itself.
+ if (SrcReg == DestReg) {
+ ProcessedNames.insert(SrcReg);
+ continue;
+ }
+
+ // We don't need to insert copies for implicit_defs.
+ MachineInstr* DefMI = MRI.getVRegDef(SrcReg);
+ if (DefMI->isImplicitDef())
+ ProcessedNames.insert(SrcReg);
// Check for trivial interferences via liveness information, allowing us
// to avoid extra work later. Any registers that interfere cannot both
if (isLiveIn(SrcReg, P->getParent(), LI) ||
isLiveOut(P->getOperand(0).getReg(),
MRI.getVRegDef(SrcReg)->getParent(), LI) ||
- ( MRI.getVRegDef(SrcReg)->getOpcode() == TargetInstrInfo::PHI &&
+ ( MRI.getVRegDef(SrcReg)->isPHI() &&
isLiveIn(P->getOperand(0).getReg(),
MRI.getVRegDef(SrcReg)->getParent(), LI) ) ||
ProcessedNames.count(SrcReg) ||
UsedByAnother.insert(SrcReg);
} else {
// Otherwise, add it to the renaming set
- PHIUnion.insert(SrcReg);
+ PHIUnion.insert(std::make_pair(SrcReg,P->getOperand(i).getMBB()));
UnionedBlocks.insert(MRI.getVRegDef(SrcReg)->getParent());
}
}
std::vector<std::pair<unsigned, unsigned> > localInterferences;
processPHIUnion(P, PHIUnion, DF, localInterferences);
+ // If one of the inputs is defined in the same block as the current PHI
+ // then we need to check for a local interference between that input and
+ // the PHI.
+ for (std::map<unsigned, MachineBasicBlock*>::iterator I = PHIUnion.begin(),
+ E = PHIUnion.end(); I != E; ++I)
+ if (MRI.getVRegDef(I->first)->getParent() == P->getParent())
+ localInterferences.push_back(std::make_pair(I->first,
+ P->getOperand(0).getReg()));
+
// The dominator forest walk may have returned some register pairs whose
- // interference cannot be determines from dominator analysis. We now
+ // interference cannot be determined from dominator analysis. We now
// examine these pairs for local interferences.
for (std::vector<std::pair<unsigned, unsigned> >::iterator I =
localInterferences.begin(), E = localInterferences.end(); I != E; ++I) {
}
}
- // Add the renaming set for this PHI node to our overal renaming information
+ // 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) {
+ DEBUG(dbgs() << "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
// rename them for another PHI node in this block
- ProcessedNames.insert(PHIUnion.begin(), PHIUnion.end());
+ for (std::map<unsigned, MachineBasicBlock*>::iterator I = PHIUnion.begin(),
+ E = PHIUnion.end(); I != E; ++I)
+ ProcessedNames.insert(I->first);
++P;
}
/// that are known to interfere, and flag others that need to be checked for
/// local interferences.
void StrongPHIElimination::processPHIUnion(MachineInstr* Inst,
- std::set<unsigned>& PHIUnion,
+ std::map<unsigned, MachineBasicBlock*>& PHIUnion,
std::vector<StrongPHIElimination::DomForestNode*>& DF,
std::vector<std::pair<unsigned, unsigned> >& locals) {
/// of Static Single Assignment Form" by Briggs, et al.
void StrongPHIElimination::ScheduleCopies(MachineBasicBlock* MBB,
std::set<unsigned>& pushed) {
- // FIXME: This function needs to update LiveVariables
- std::map<unsigned, unsigned>& copy_set= Waiting[MBB];
+ // FIXME: This function needs to update LiveIntervals
+ 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));
- if (!UsedByAnother.count(I->first)) {
+ if (!UsedByAnother.count(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;
}
MachineRegisterInfo& MRI = MF->getRegInfo();
const TargetInstrInfo *TII = MF->getTarget().getInstrInfo();
+ SmallVector<std::pair<unsigned, MachineInstr*>, 4> InsertedPHIDests;
+
// 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);
// Insert copy from curr.second to a temporary at
// the Phi defining curr.second
MachineBasicBlock::iterator PI = MRI.getVRegDef(curr.second);
- TII->copyRegToReg(*PI->getParent(), PI, t,
- curr.second, RC, RC);
+ BuildMI(*PI->getParent(), PI, DebugLoc(), TII->get(TargetOpcode::COPY),
+ t).addReg(curr.second);
+ DEBUG(dbgs() << "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);
+ BuildMI(*MBB, MBB->getFirstTerminator(), DebugLoc(),
+ TII->get(TargetOpcode::COPY), curr.second).addReg(map[curr.first]);
map[curr.first] = curr.second;
+ DEBUG(dbgs() << "Inserted copy from " << curr.first << " to "
+ << curr.second << "\n");
+
+ // Push this copy onto InsertedPHICopies so we can
+ // update LiveIntervals with it.
+ MachineBasicBlock::iterator MI = MBB->getFirstTerminator();
+ 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);
+ std::multimap<unsigned, unsigned>::iterator CI = copy_set.begin();
+ std::pair<unsigned, unsigned> curr = *CI;
+ worklist.insert(curr);
+ copy_set.erase(CI);
- const TargetRegisterClass *RC = MF->getRegInfo().getRegClass(curr.first);
+ LiveInterval& I = LI.getInterval(curr.second);
+ MachineBasicBlock::iterator term = MBB->getFirstTerminator();
+ SlotIndex endIdx = SlotIndex();
+ if (term != MBB->end())
+ endIdx = LI.getInstructionIndex(term);
+ else
+ endIdx = LI.getMBBEndIdx(MBB);
- // 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;
+ 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);
+ BuildMI(*MBB, MBB->getFirstTerminator(), DebugLoc(),
+ TII->get(TargetOpcode::COPY), t).addReg(curr.second);
+ map[curr.second] = t;
+
+ MachineBasicBlock::iterator TI = MBB->getFirstTerminator();
+ InsertedPHIDests.push_back(std::make_pair(t, --TI));
+ }
+ }
+ }
+
+ // Renumber the instructions so that we can perform the index computations
+ // needed to create new live intervals.
+ LI.renumber();
+
+ // For copies that we inserted at the ends of predecessors, we construct
+ // live intervals. This is pretty easy, since we know that the destination
+ // register cannot have be in live at that point previously. We just have
+ // to make sure that, for registers that serve as inputs to more than one
+ // 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) {
+ LiveInterval& Int = LI.getOrCreateInterval(I->first);
+ SlotIndex instrIdx = LI.getInstructionIndex(I->second);
+ if (Int.liveAt(instrIdx.getDefIndex()))
+ Int.removeRange(instrIdx.getDefIndex(),
+ LI.getMBBEndIdx(I->second->getParent()).getNextSlot(),
+ true);
- worklist.insert(curr);
+ LiveRange R = LI.addLiveRangeToEndOfBlock(I->first, I->second);
+ R.valno->setCopy(I->second);
+ R.valno->def = LI.getInstructionIndex(I->second).getDefIndex();
}
}
}
/// InsertCopies - insert copies into MBB and all of its successors
-void StrongPHIElimination::InsertCopies(MachineBasicBlock* MBB,
- std::set<MachineBasicBlock*>& visited) {
+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->isPHI())
+ 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(LI.getInstructionIndex(I).getUseIndex());
+ 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->setHasPHIKill(false);
+ LiveRange LR (LI.getMBBStartIdx(I->getParent()),
+ LI.getInstructionIndex(I).getUseIndex().getNextSlot(),
+ 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();
}
+bool StrongPHIElimination::mergeLiveIntervals(unsigned primary,
+ unsigned secondary) {
+
+ LiveIntervals& LI = getAnalysis<LiveIntervals>();
+ LiveInterval& LHS = LI.getOrCreateInterval(primary);
+ LiveInterval& RHS = LI.getOrCreateInterval(secondary);
+
+ LI.renumber();
+
+ DenseMap<VNInfo*, VNInfo*> VNMap;
+ for (LiveInterval::iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) {
+ LiveRange R = *I;
+
+ SlotIndex Start = R.start;
+ SlotIndex 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;
+ }
+
+ 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.createValueCopy(OldVN, LI.getVNInfoAllocator());
+ }
+
+ LiveRange LR (R.start, R.end, NewVN);
+ LHS.addRange(LR);
+ }
+
+ LI.removeInterval(RHS.reg);
+
+ return true;
+}
+
bool StrongPHIElimination::runOnMachineFunction(MachineFunction &Fn) {
+ LiveIntervals& LI = getAnalysis<LiveIntervals>();
+
// Compute DFS numbers of each block
computeDFS(Fn);
// Determine which phi node operands need copies
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
- if (!I->empty() &&
- I->begin()->getOpcode() == TargetInstrInfo::PHI)
+ if (!I->empty() && I->begin()->isPHI())
processBlock(I);
+ // Break interferences where two different phis want to coalesce
+ // in the same register.
+ std::set<unsigned> seen;
+ typedef std::map<unsigned, std::map<unsigned, MachineBasicBlock*> >
+ RenameSetType;
+ for (RenameSetType::iterator I = RenameSets.begin(), E = RenameSets.end();
+ I != E; ++I) {
+ for (std::map<unsigned, MachineBasicBlock*>::iterator
+ OI = I->second.begin(), OE = I->second.end(); OI != OE; ) {
+ if (!seen.count(OI->first)) {
+ seen.insert(OI->first);
+ ++OI;
+ } else {
+ Waiting[OI->second].insert(std::make_pair(OI->first, I->first));
+ unsigned reg = OI->first;
+ ++OI;
+ I->second.erase(reg);
+ DEBUG(dbgs() << "Removing Renaming: " << reg << " -> " << I->first
+ << "\n");
+ }
+ }
+ }
+
// Insert copies
- // FIXME: This process should probably preserve LiveVariables
- std::set<MachineBasicBlock*> visited;
- InsertCopies(Fn.begin(), visited);
+ // FIXME: This process should probably preserve LiveIntervals
+ SmallPtrSet<MachineBasicBlock*, 16> visited;
+ MachineDominatorTree& MDT = getAnalysis<MachineDominatorTree>();
+ InsertCopies(MDT.getRootNode(), visited);
// Perform renaming
- typedef std::map<unsigned, std::set<unsigned> > RenameSetType;
for (RenameSetType::iterator I = RenameSets.begin(), E = RenameSets.end();
I != E; ++I)
- for (std::set<unsigned>::iterator SI = I->second.begin(),
- SE = I->second.end(); SI != SE; ++SI)
- Fn.getRegInfo().replaceRegWith(*SI, I->first);
-
- // FIXME: Insert last-minute copies
+ while (I->second.size()) {
+ std::map<unsigned, MachineBasicBlock*>::iterator SI = I->second.begin();
+
+ DEBUG(dbgs() << "Renaming: " << SI->first << " -> " << I->first << "\n");
+
+ if (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);
+ }
+ } else {
+ // Insert a last-minute copy if a conflict was detected.
+ const TargetInstrInfo *TII = Fn.getTarget().getInstrInfo();
+ BuildMI(*SI->second, SI->second->getFirstTerminator(), DebugLoc(),
+ TII->get(TargetOpcode::COPY), I->first).addReg(SI->first);
+
+ LI.renumber();
+
+ LiveInterval& Int = LI.getOrCreateInterval(I->first);
+ SlotIndex instrIdx =
+ LI.getInstructionIndex(--SI->second->getFirstTerminator());
+ if (Int.liveAt(instrIdx.getDefIndex()))
+ Int.removeRange(instrIdx.getDefIndex(),
+ LI.getMBBEndIdx(SI->second).getNextSlot(), true);
+
+ LiveRange R = LI.addLiveRangeToEndOfBlock(I->first,
+ --SI->second->getFirstTerminator());
+ R.valno->setCopy(--SI->second->getFirstTerminator());
+ R.valno->def = instrIdx.getDefIndex();
+
+ DEBUG(dbgs() << "Renaming failed: " << SI->first << " -> "
+ << I->first << "\n");
+ }
+ }
+
+ LiveInterval& Int = LI.getOrCreateInterval(I->first);
+ const LiveRange* LR =
+ Int.getLiveRangeContaining(LI.getMBBEndIdx(SI->second));
+ LR->valno->setHasPHIKill(true);
+
+ I->second.erase(SI->first);
+ }
// Remove PHIs
std::vector<MachineInstr*> phis;
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I) {
for (MachineBasicBlock::iterator BI = I->begin(), BE = I->end();
BI != BE; ++BI)
- if (BI->getOpcode() == TargetInstrInfo::PHI)
+ if (BI->isPHI())
phis.push_back(BI);
}
for (std::vector<MachineInstr*>::iterator I = phis.begin(), E = phis.end();
- I != E; ++I)
- (*I)->eraseFromParent();
+ I != E; ) {
+ MachineInstr* PInstr = *(I++);
+
+ // If this is a dead PHI node, then remove it from LiveIntervals.
+ unsigned DestReg = PInstr->getOperand(0).getReg();
+ LiveInterval& PI = LI.getInterval(DestReg);
+ if (PInstr->registerDefIsDead(DestReg)) {
+ if (PI.containsOneValue()) {
+ LI.removeInterval(DestReg);
+ } else {
+ SlotIndex idx = LI.getInstructionIndex(PInstr).getDefIndex();
+ PI.removeRange(*PI.getLiveRangeContaining(idx), true);
+ }
+ } else {
+ // Trim live intervals of input registers. They are no longer live into
+ // this block if they died after the PHI. If they lived after it, don't
+ // trim them because they might have other legitimate uses.
+ for (unsigned i = 1; i < PInstr->getNumOperands(); i += 2) {
+ unsigned reg = PInstr->getOperand(i).getReg();
+
+ MachineBasicBlock* MBB = PInstr->getOperand(i+1).getMBB();
+ LiveInterval& InputI = LI.getInterval(reg);
+ if (MBB != PInstr->getParent() &&
+ InputI.liveAt(LI.getMBBStartIdx(PInstr->getParent())) &&
+ InputI.expiredAt(LI.getInstructionIndex(PInstr).getNextIndex()))
+ InputI.removeRange(LI.getMBBStartIdx(PInstr->getParent()),
+ LI.getInstructionIndex(PInstr),
+ true);
+ }
+
+ // If the PHI is not dead, then the valno defined by the PHI
+ // now has an unknown def.
+ SlotIndex idx = LI.getInstructionIndex(PInstr).getDefIndex();
+ const LiveRange* PLR = PI.getLiveRangeContaining(idx);
+ PLR->valno->setIsPHIDef(true);
+ LiveRange R (LI.getMBBStartIdx(PInstr->getParent()),
+ PLR->start, PLR->valno);
+ PI.addRange(R);
+ }
+
+ LI.RemoveMachineInstrFromMaps(PInstr);
+ PInstr->eraseFromParent();
+ }
- return false;
+ LI.renumber();
+
+ return true;
}