//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "stackcoloring"
-#include "VirtRegMap.h"
+#include "llvm/Function.h"
+#include "llvm/Module.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
cl::init(false), cl::Hidden,
cl::desc("Suppress slot sharing during stack coloring"));
-static cl::opt<bool>
-ColorWithRegsOpt("color-ss-with-regs",
- cl::init(false), cl::Hidden,
- cl::desc("Color stack slots with free registers"));
-
-
static cl::opt<int> DCELimit("ssc-dce-limit", cl::init(-1), cl::Hidden);
STATISTIC(NumEliminated, "Number of stack slots eliminated due to coloring");
-STATISTIC(NumRegRepl, "Number of stack slot refs replaced with reg refs");
-STATISTIC(NumLoadElim, "Number of loads eliminated");
-STATISTIC(NumStoreElim, "Number of stores eliminated");
STATISTIC(NumDead, "Number of trivially dead stack accesses eliminated");
namespace {
class StackSlotColoring : public MachineFunctionPass {
bool ColorWithRegs;
LiveStacks* LS;
- VirtRegMap* VRM;
MachineFrameInfo *MFI;
- MachineRegisterInfo *MRI;
const TargetInstrInfo *TII;
- const TargetRegisterInfo *TRI;
const MachineLoopInfo *loopInfo;
// SSIntervals - Spill slot intervals.
public:
static char ID; // Pass identification
StackSlotColoring() :
- MachineFunctionPass(&ID), ColorWithRegs(false), NextColor(-1) {}
- StackSlotColoring(bool RegColor) :
- MachineFunctionPass(&ID), ColorWithRegs(RegColor), NextColor(-1) {}
-
+ MachineFunctionPass(ID), ColorWithRegs(false), NextColor(-1) {
+ initializeStackSlotColoringPass(*PassRegistry::getPassRegistry());
+ }
+
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesCFG();
AU.addRequired<SlotIndexes>();
AU.addPreserved<SlotIndexes>();
AU.addRequired<LiveStacks>();
- AU.addRequired<VirtRegMap>();
- AU.addPreserved<VirtRegMap>();
AU.addRequired<MachineLoopInfo>();
AU.addPreserved<MachineLoopInfo>();
AU.addPreservedID(MachineDominatorsID);
}
virtual bool runOnMachineFunction(MachineFunction &MF);
- virtual const char* getPassName() const {
- return "Stack Slot Coloring";
- }
private:
void InitializeSlots();
bool OverlapWithAssignments(LiveInterval *li, int Color) const;
int ColorSlot(LiveInterval *li);
bool ColorSlots(MachineFunction &MF);
- bool ColorSlotsWithFreeRegs(SmallVector<int, 16> &SlotMapping,
- SmallVector<SmallVector<int, 4>, 16> &RevMap,
- BitVector &SlotIsReg);
void RewriteInstruction(MachineInstr *MI, int OldFI, int NewFI,
MachineFunction &MF);
- bool PropagateBackward(MachineBasicBlock::iterator MII,
- MachineBasicBlock *MBB,
- unsigned OldReg, unsigned NewReg);
- bool PropagateForward(MachineBasicBlock::iterator MII,
- MachineBasicBlock *MBB,
- unsigned OldReg, unsigned NewReg);
- void UnfoldAndRewriteInstruction(MachineInstr *MI, int OldFI,
- unsigned Reg, const TargetRegisterClass *RC,
- SmallSet<unsigned, 4> &Defs,
- MachineFunction &MF);
- bool AllMemRefsCanBeUnfolded(int SS);
bool RemoveDeadStores(MachineBasicBlock* MBB);
};
} // end anonymous namespace
char StackSlotColoring::ID = 0;
+char &llvm::StackSlotColoringID = StackSlotColoring::ID;
-static RegisterPass<StackSlotColoring>
-X("stack-slot-coloring", "Stack Slot Coloring");
-
-FunctionPass *llvm::createStackSlotColoringPass(bool RegColor) {
- return new StackSlotColoring(RegColor);
-}
+INITIALIZE_PASS_BEGIN(StackSlotColoring, "stack-slot-coloring",
+ "Stack Slot Coloring", false, false)
+INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
+INITIALIZE_PASS_DEPENDENCY(LiveStacks)
+INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
+INITIALIZE_PASS_END(StackSlotColoring, "stack-slot-coloring",
+ "Stack Slot Coloring", false, false)
namespace {
// IntervalSorter - Comparison predicate that sort live intervals by
if (!LS->hasInterval(FI))
continue;
LiveInterval &li = LS->getInterval(FI);
- li.weight += LiveIntervals::getSpillWeight(false, true, loopDepth);
+ if (!MI->isDebugValue())
+ li.weight += LiveIntervals::getSpillWeight(false, true, loopDepth);
SSRefs[FI].push_back(MI);
}
}
for (LiveStacks::iterator i = LS->begin(), e = LS->end(); i != e; ++i) {
LiveInterval &li = i->second;
DEBUG(li.dump());
- int FI = li.getStackSlotIndex();
+ int FI = TargetRegisterInfo::stackSlot2Index(li.reg);
if (MFI->isDeadObjectIndex(FI))
continue;
SSIntervals.push_back(&li);
return false;
}
-/// ColorSlotsWithFreeRegs - If there are any free registers available, try
-/// replacing spill slots references with registers instead.
-bool
-StackSlotColoring::ColorSlotsWithFreeRegs(SmallVector<int, 16> &SlotMapping,
- SmallVector<SmallVector<int, 4>, 16> &RevMap,
- BitVector &SlotIsReg) {
- if (!(ColorWithRegs || ColorWithRegsOpt) || !VRM->HasUnusedRegisters())
- return false;
-
- bool Changed = false;
- DEBUG(dbgs() << "Assigning unused registers to spill slots:\n");
- for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
- LiveInterval *li = SSIntervals[i];
- int SS = li->getStackSlotIndex();
- if (!UsedColors[SS] || li->weight < 20)
- // If the weight is < 20, i.e. two references in a loop with depth 1,
- // don't bother with it.
- continue;
-
- // These slots allow to share the same registers.
- bool AllColored = true;
- SmallVector<unsigned, 4> ColoredRegs;
- for (unsigned j = 0, ee = RevMap[SS].size(); j != ee; ++j) {
- int RSS = RevMap[SS][j];
- const TargetRegisterClass *RC = LS->getIntervalRegClass(RSS);
- // If it's not colored to another stack slot, try coloring it
- // to a "free" register.
- if (!RC) {
- AllColored = false;
- continue;
- }
- unsigned Reg = VRM->getFirstUnusedRegister(RC);
- if (!Reg) {
- AllColored = false;
- continue;
- }
- if (!AllMemRefsCanBeUnfolded(RSS)) {
- AllColored = false;
- continue;
- } else {
- DEBUG(dbgs() << "Assigning fi#" << RSS << " to "
- << TRI->getName(Reg) << '\n');
- ColoredRegs.push_back(Reg);
- SlotMapping[RSS] = Reg;
- SlotIsReg.set(RSS);
- Changed = true;
- }
- }
-
- // Register and its sub-registers are no longer free.
- while (!ColoredRegs.empty()) {
- unsigned Reg = ColoredRegs.back();
- ColoredRegs.pop_back();
- VRM->setRegisterUsed(Reg);
- // If reg is a callee-saved register, it will have to be spilled in
- // the prologue.
- MRI->setPhysRegUsed(Reg);
- for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS) {
- VRM->setRegisterUsed(*AS);
- MRI->setPhysRegUsed(*AS);
- }
- }
- // This spill slot is dead after the rewrites
- if (AllColored) {
- MFI->RemoveStackObject(SS);
- ++NumEliminated;
- }
- }
- DEBUG(dbgs() << '\n');
-
- return Changed;
-}
-
/// ColorSlot - Assign a "color" (stack slot) to the specified stack slot.
///
int StackSlotColoring::ColorSlot(LiveInterval *li) {
// Record the assignment.
Assignments[Color].push_back(li);
- int FI = li->getStackSlotIndex();
+ int FI = TargetRegisterInfo::stackSlot2Index(li->reg);
DEBUG(dbgs() << "Assigning fi#" << FI << " to fi#" << Color << "\n");
// Change size and alignment of the allocated slot. If there are multiple
SmallVector<int, 16> SlotMapping(NumObjs, -1);
SmallVector<float, 16> SlotWeights(NumObjs, 0.0);
SmallVector<SmallVector<int, 4>, 16> RevMap(NumObjs);
- BitVector SlotIsReg(NumObjs);
BitVector UsedColors(NumObjs);
DEBUG(dbgs() << "Color spill slot intervals:\n");
bool Changed = false;
for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
LiveInterval *li = SSIntervals[i];
- int SS = li->getStackSlotIndex();
+ int SS = TargetRegisterInfo::stackSlot2Index(li->reg);
int NewSS = ColorSlot(li);
assert(NewSS >= 0 && "Stack coloring failed?");
SlotMapping[SS] = NewSS;
DEBUG(dbgs() << "\nSpill slots after coloring:\n");
for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i) {
LiveInterval *li = SSIntervals[i];
- int SS = li->getStackSlotIndex();
+ int SS = TargetRegisterInfo::stackSlot2Index(li->reg);
li->weight = SlotWeights[SS];
}
// Sort them by new weight.
DEBUG(dbgs() << '\n');
#endif
- // Can we "color" a stack slot with a unused register?
- Changed |= ColorSlotsWithFreeRegs(SlotMapping, RevMap, SlotIsReg);
-
if (!Changed)
return false;
// Rewrite all MO_FrameIndex operands.
SmallVector<SmallSet<unsigned, 4>, 4> NewDefs(MF.getNumBlockIDs());
for (unsigned SS = 0, SE = SSRefs.size(); SS != SE; ++SS) {
- bool isReg = SlotIsReg[SS];
int NewFI = SlotMapping[SS];
- if (NewFI == -1 || (NewFI == (int)SS && !isReg))
+ if (NewFI == -1 || (NewFI == (int)SS))
continue;
- const TargetRegisterClass *RC = LS->getIntervalRegClass(SS);
SmallVector<MachineInstr*, 8> &RefMIs = SSRefs[SS];
for (unsigned i = 0, e = RefMIs.size(); i != e; ++i)
- if (!isReg)
- RewriteInstruction(RefMIs[i], SS, NewFI, MF);
- else {
- // Rewrite to use a register instead.
- unsigned MBBId = RefMIs[i]->getParent()->getNumber();
- SmallSet<unsigned, 4> &Defs = NewDefs[MBBId];
- UnfoldAndRewriteInstruction(RefMIs[i], SS, NewFI, RC, Defs, MF);
- }
+ RewriteInstruction(RefMIs[i], SS, NewFI, MF);
}
// Delete unused stack slots.
return true;
}
-/// AllMemRefsCanBeUnfolded - Return true if all references of the specified
-/// spill slot index can be unfolded.
-bool StackSlotColoring::AllMemRefsCanBeUnfolded(int SS) {
- SmallVector<MachineInstr*, 8> &RefMIs = SSRefs[SS];
- for (unsigned i = 0, e = RefMIs.size(); i != e; ++i) {
- MachineInstr *MI = RefMIs[i];
- if (TII->isLoadFromStackSlot(MI, SS) ||
- TII->isStoreToStackSlot(MI, SS))
- // Restore and spill will become copies.
- return true;
- if (!TII->getOpcodeAfterMemoryUnfold(MI->getOpcode(), false, false))
- return false;
- for (unsigned j = 0, ee = MI->getNumOperands(); j != ee; ++j) {
- MachineOperand &MO = MI->getOperand(j);
- if (MO.isFI() && MO.getIndex() != SS)
- // If it uses another frameindex, we can, currently* unfold it.
- return false;
- }
- }
- return true;
-}
-
/// RewriteInstruction - Rewrite specified instruction by replacing references
/// to old frame index with new one.
void StackSlotColoring::RewriteInstruction(MachineInstr *MI, int OldFI,
(*I)->setValue(NewSV);
}
-/// PropagateBackward - Traverse backward and look for the definition of
-/// OldReg. If it can successfully update all of the references with NewReg,
-/// do so and return true.
-bool StackSlotColoring::PropagateBackward(MachineBasicBlock::iterator MII,
- MachineBasicBlock *MBB,
- unsigned OldReg, unsigned NewReg) {
- if (MII == MBB->begin())
- return false;
-
- SmallVector<MachineOperand*, 4> Uses;
- SmallVector<MachineOperand*, 4> Refs;
- while (--MII != MBB->begin()) {
- bool FoundDef = false; // Not counting 2address def.
-
- Uses.clear();
- const TargetInstrDesc &TID = MII->getDesc();
- for (unsigned i = 0, e = MII->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MII->getOperand(i);
- if (!MO.isReg())
- continue;
- unsigned Reg = MO.getReg();
- if (Reg == 0)
- continue;
- if (Reg == OldReg) {
- if (MO.isImplicit())
- return false;
-
- // Abort the use is actually a sub-register def. We don't have enough
- // information to figure out if it is really legal.
- if (MO.getSubReg() ||
- TID.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG ||
- TID.getOpcode() == TargetInstrInfo::INSERT_SUBREG ||
- TID.getOpcode() == TargetInstrInfo::SUBREG_TO_REG)
- return false;
-
- const TargetRegisterClass *RC = TID.OpInfo[i].getRegClass(TRI);
- if (RC && !RC->contains(NewReg))
- return false;
-
- if (MO.isUse()) {
- Uses.push_back(&MO);
- } else {
- Refs.push_back(&MO);
- if (!MII->isRegTiedToUseOperand(i))
- FoundDef = true;
- }
- } else if (TRI->regsOverlap(Reg, NewReg)) {
- return false;
- } else if (TRI->regsOverlap(Reg, OldReg)) {
- if (!MO.isUse() || !MO.isKill())
- return false;
- }
- }
-
- if (FoundDef) {
- // Found non-two-address def. Stop here.
- for (unsigned i = 0, e = Refs.size(); i != e; ++i)
- Refs[i]->setReg(NewReg);
- return true;
- }
-
- // Two-address uses must be updated as well.
- for (unsigned i = 0, e = Uses.size(); i != e; ++i)
- Refs.push_back(Uses[i]);
- }
- return false;
-}
-
-/// PropagateForward - Traverse forward and look for the kill of OldReg. If
-/// it can successfully update all of the uses with NewReg, do so and
-/// return true.
-bool StackSlotColoring::PropagateForward(MachineBasicBlock::iterator MII,
- MachineBasicBlock *MBB,
- unsigned OldReg, unsigned NewReg) {
- if (MII == MBB->end())
- return false;
-
- SmallVector<MachineOperand*, 4> Uses;
- while (++MII != MBB->end()) {
- bool FoundKill = false;
- const TargetInstrDesc &TID = MII->getDesc();
- for (unsigned i = 0, e = MII->getNumOperands(); i != e; ++i) {
- MachineOperand &MO = MII->getOperand(i);
- if (!MO.isReg())
- continue;
- unsigned Reg = MO.getReg();
- if (Reg == 0)
- continue;
- if (Reg == OldReg) {
- if (MO.isDef() || MO.isImplicit())
- return false;
-
- // Abort the use is actually a sub-register use. We don't have enough
- // information to figure out if it is really legal.
- if (MO.getSubReg() ||
- TID.getOpcode() == TargetInstrInfo::EXTRACT_SUBREG)
- return false;
-
- const TargetRegisterClass *RC = TID.OpInfo[i].getRegClass(TRI);
- if (RC && !RC->contains(NewReg))
- return false;
- if (MO.isKill())
- FoundKill = true;
-
- Uses.push_back(&MO);
- } else if (TRI->regsOverlap(Reg, NewReg) ||
- TRI->regsOverlap(Reg, OldReg))
- return false;
- }
- if (FoundKill) {
- for (unsigned i = 0, e = Uses.size(); i != e; ++i)
- Uses[i]->setReg(NewReg);
- return true;
- }
- }
- return false;
-}
-
-/// UnfoldAndRewriteInstruction - Rewrite specified instruction by unfolding
-/// folded memory references and replacing those references with register
-/// references instead.
-void
-StackSlotColoring::UnfoldAndRewriteInstruction(MachineInstr *MI, int OldFI,
- unsigned Reg,
- const TargetRegisterClass *RC,
- SmallSet<unsigned, 4> &Defs,
- MachineFunction &MF) {
- MachineBasicBlock *MBB = MI->getParent();
- if (unsigned DstReg = TII->isLoadFromStackSlot(MI, OldFI)) {
- if (PropagateForward(MI, MBB, DstReg, Reg)) {
- DEBUG(dbgs() << "Eliminated load: ");
- DEBUG(MI->dump());
- ++NumLoadElim;
- } else {
- TII->copyRegToReg(*MBB, MI, DstReg, Reg, RC, RC);
- ++NumRegRepl;
- }
-
- if (!Defs.count(Reg)) {
- // If this is the first use of Reg in this MBB and it wasn't previously
- // defined in MBB, add it to livein.
- MBB->addLiveIn(Reg);
- Defs.insert(Reg);
- }
- } else if (unsigned SrcReg = TII->isStoreToStackSlot(MI, OldFI)) {
- if (MI->killsRegister(SrcReg) && PropagateBackward(MI, MBB, SrcReg, Reg)) {
- DEBUG(dbgs() << "Eliminated store: ");
- DEBUG(MI->dump());
- ++NumStoreElim;
- } else {
- TII->copyRegToReg(*MBB, MI, Reg, SrcReg, RC, RC);
- ++NumRegRepl;
- }
-
- // Remember reg has been defined in MBB.
- Defs.insert(Reg);
- } else {
- SmallVector<MachineInstr*, 4> NewMIs;
- bool Success = TII->unfoldMemoryOperand(MF, MI, Reg, false, false, NewMIs);
- Success = Success; // Silence compiler warning.
- assert(Success && "Failed to unfold!");
- MachineInstr *NewMI = NewMIs[0];
- MBB->insert(MI, NewMI);
- ++NumRegRepl;
-
- if (NewMI->readsRegister(Reg)) {
- if (!Defs.count(Reg))
- // If this is the first use of Reg in this MBB and it wasn't previously
- // defined in MBB, add it to livein.
- MBB->addLiveIn(Reg);
- Defs.insert(Reg);
- }
- }
- MBB->erase(MI);
-}
/// RemoveDeadStores - Scan through a basic block and look for loads followed
/// by stores. If they're both using the same stack slot, then the store is
I != E; ++I) {
if (DCELimit != -1 && (int)NumDead >= DCELimit)
break;
-
+
MachineBasicBlock::iterator NextMI = llvm::next(I);
if (NextMI == MBB->end()) continue;
-
+
int FirstSS, SecondSS;
unsigned LoadReg = 0;
unsigned StoreReg = 0;
if (!(LoadReg = TII->isLoadFromStackSlot(I, FirstSS))) continue;
if (!(StoreReg = TII->isStoreToStackSlot(NextMI, SecondSS))) continue;
if (FirstSS != SecondSS || LoadReg != StoreReg || FirstSS == -1) continue;
-
+
++NumDead;
changed = true;
-
+
if (NextMI->findRegisterUseOperandIdx(LoadReg, true, 0) != -1) {
++NumDead;
toErase.push_back(I);
}
-
+
toErase.push_back(NextMI);
++I;
}
-
+
for (SmallVector<MachineInstr*, 4>::iterator I = toErase.begin(),
E = toErase.end(); I != E; ++I)
(*I)->eraseFromParent();
-
+
return changed;
}
bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
- DEBUG(dbgs() << "********** Stack Slot Coloring **********\n");
+ DEBUG({
+ dbgs() << "********** Stack Slot Coloring **********\n"
+ << "********** Function: "
+ << MF.getFunction()->getName() << '\n';
+ });
MFI = MF.getFrameInfo();
- MRI = &MF.getRegInfo();
TII = MF.getTarget().getInstrInfo();
- TRI = MF.getTarget().getRegisterInfo();
LS = &getAnalysis<LiveStacks>();
- VRM = &getAnalysis<VirtRegMap>();
loopInfo = &getAnalysis<MachineLoopInfo>();
bool Changed = false;
unsigned NumSlots = LS->getNumIntervals();
- if (NumSlots < 2) {
- if (NumSlots == 0 || !VRM->HasUnusedRegisters())
- // Nothing to do!
- return false;
- }
+ if (NumSlots == 0)
+ // Nothing to do!
+ return false;
+
+ // If there are calls to setjmp or sigsetjmp, don't perform stack slot
+ // coloring. The stack could be modified before the longjmp is executed,
+ // resulting in the wrong value being used afterwards. (See
+ // <rdar://problem/8007500>.)
+ if (MF.exposesReturnsTwice())
+ return false;
// Gather spill slot references
ScanForSpillSlotRefs(MF);