//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "stackcoloring"
-#include "VirtRegMap.h"
#include "llvm/CodeGen/Passes.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
#include "llvm/CodeGen/LiveStackAnalysis.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
+#include "llvm/IR/Module.h"
#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/ADT/BitVector.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/Statistic.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
#include <vector>
using namespace llvm;
+#define DEBUG_TYPE "stackslotcoloring"
+
static cl::opt<bool>
DisableSharing("no-stack-slot-sharing",
cl::init(false), cl::Hidden,
cl::desc("Suppress slot sharing during stack coloring"));
-static cl::opt<bool>
-ColorWithRegs("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(NumDead, "Number of trivially dead stack accesses eliminated");
-STATISTIC(NumRegRepl, "Number of stack slot refs replaced with reg refs");
namespace {
- class VISIBILITY_HIDDEN StackSlotColoring : public MachineFunctionPass {
+ class StackSlotColoring : public MachineFunctionPass {
LiveStacks* LS;
- VirtRegMap* VRM;
MachineFrameInfo *MFI;
- MachineRegisterInfo *MRI;
const TargetInstrInfo *TII;
- const TargetRegisterInfo *TRI;
- const MachineLoopInfo *loopInfo;
+ const MachineBlockFrequencyInfo *MBFI;
// SSIntervals - Spill slot intervals.
std::vector<LiveInterval*> SSIntervals;
- // SSRefs - Keep a list of frame index references for each spill slot.
- SmallVector<SmallVector<MachineInstr*, 8>, 16> SSRefs;
+ // SSRefs - Keep a list of MachineMemOperands for each spill slot.
+ // MachineMemOperands can be shared between instructions, so we need
+ // to be careful that renames like [FI0, FI1] -> [FI1, FI2] do not
+ // become FI0 -> FI1 -> FI2.
+ SmallVector<SmallVector<MachineMemOperand *, 8>, 16> SSRefs;
// OrigAlignments - Alignments of stack objects before coloring.
SmallVector<unsigned, 16> OrigAlignments;
public:
static char ID; // Pass identification
- StackSlotColoring() : MachineFunctionPass(&ID), NextColor(-1) {}
-
- virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ StackSlotColoring() :
+ MachineFunctionPass(ID), NextColor(-1) {
+ initializeStackSlotColoringPass(*PassRegistry::getPassRegistry());
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override {
+ AU.setPreservesCFG();
+ AU.addRequired<SlotIndexes>();
+ AU.addPreserved<SlotIndexes>();
AU.addRequired<LiveStacks>();
- AU.addRequired<VirtRegMap>();
- AU.addPreserved<VirtRegMap>();
- AU.addRequired<MachineLoopInfo>();
- AU.addPreserved<MachineLoopInfo>();
+ AU.addRequired<MachineBlockFrequencyInfo>();
+ AU.addPreserved<MachineBlockFrequencyInfo>();
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
- virtual bool runOnMachineFunction(MachineFunction &MF);
- virtual const char* getPassName() const {
- return "Stack Slot Coloring";
- }
+ bool runOnMachineFunction(MachineFunction &MF) override;
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,
+ void RewriteInstruction(MachineInstr *MI, SmallVectorImpl<int> &SlotMapping,
MachineFunction &MF);
- void UnfoldAndRewriteInstruction(MachineInstr *MI, int OldFI,
- unsigned Reg, 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() {
- return new StackSlotColoring();
-}
+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
for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
MBBI != E; ++MBBI) {
MachineBasicBlock *MBB = &*MBBI;
- unsigned loopDepth = loopInfo->getLoopDepth(MBB);
for (MachineBasicBlock::iterator MII = MBB->begin(), EE = MBB->end();
MII != EE; ++MII) {
MachineInstr *MI = &*MII;
if (!LS->hasInterval(FI))
continue;
LiveInterval &li = LS->getInterval(FI);
- li.weight += LiveIntervals::getSpillWeight(false, true, loopDepth);
- SSRefs[FI].push_back(MI);
+ if (!MI->isDebugValue())
+ li.weight += LiveIntervals::getSpillWeight(false, true, MBFI, MI);
+ }
+ for (MachineInstr::mmo_iterator MMOI = MI->memoperands_begin(),
+ EE = MI->memoperands_end(); MMOI != EE; ++MMOI) {
+ MachineMemOperand *MMO = *MMOI;
+ if (const FixedStackPseudoSourceValue *FSV =
+ dyn_cast_or_null<FixedStackPseudoSourceValue>(
+ MMO->getPseudoValue())) {
+ int FI = FSV->getFrameIndex();
+ if (FI >= 0)
+ SSRefs[FI].push_back(MMO);
+ }
}
}
}
UsedColors.resize(LastFI);
Assignments.resize(LastFI);
+ typedef std::iterator_traits<LiveStacks::iterator>::value_type Pair;
+ SmallVector<Pair *, 16> Intervals;
+ Intervals.reserve(LS->getNumIntervals());
+ for (auto &I : *LS)
+ Intervals.push_back(&I);
+ std::sort(Intervals.begin(), Intervals.end(),
+ [](Pair *LHS, Pair *RHS) { return LHS->first < RHS->first; });
+
// Gather all spill slots into a list.
- DOUT << "Spill slot intervals:\n";
- for (LiveStacks::iterator i = LS->begin(), e = LS->end(); i != e; ++i) {
- LiveInterval &li = i->second;
+ DEBUG(dbgs() << "Spill slot intervals:\n");
+ for (auto *I : Intervals) {
+ 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);
OrigSizes[FI] = MFI->getObjectSize(FI);
AllColors.set(FI);
}
- DOUT << '\n';
+ DEBUG(dbgs() << '\n');
// Sort them by weight.
std::stable_sort(SSIntervals.begin(), SSIntervals.end(), IntervalSorter());
/// LiveIntervals that have already been assigned to the specified color.
bool
StackSlotColoring::OverlapWithAssignments(LiveInterval *li, int Color) const {
- const SmallVector<LiveInterval*,4> &OtherLIs = Assignments[Color];
+ const SmallVectorImpl<LiveInterval *> &OtherLIs = Assignments[Color];
for (unsigned i = 0, e = OtherLIs.size(); i != e; ++i) {
LiveInterval *OtherLI = OtherLIs[i];
if (OtherLI->overlaps(*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 || !VRM->HasUnusedRegisters())
- return false;
-
- bool Changed = false;
- DOUT << "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])
- 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 {
- DOUT << "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;
- }
- }
- DOUT << '\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();
- DOUT << "Assigning fi#" << FI << " to fi#" << Color << "\n";
+ 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
// objects sharing the same slot, then make sure the size and alignment
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);
- DOUT << "Color spill slot intervals:\n";
+ 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;
Changed |= (SS != NewSS);
}
- DOUT << "\nSpill slots after coloring:\n";
+ 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.
#ifndef NDEBUG
for (unsigned i = 0, e = SSIntervals.size(); i != e; ++i)
DEBUG(SSIntervals[i]->dump());
- DOUT << '\n';
+ 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.
+ // Rewrite all MachineMemOperands.
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;
- SmallVector<MachineInstr*, 8> &RefMIs = SSRefs[SS];
- for (unsigned i = 0, e = RefMIs.size(); i != e; ++i)
- if (isReg)
- // Rewrite to use a register instead.
- UnfoldAndRewriteInstruction(RefMIs[i], SS, NewFI, MF);
- else
- RewriteInstruction(RefMIs[i], SS, NewFI, MF);
+ const PseudoSourceValue *NewSV = PseudoSourceValue::getFixedStack(NewFI);
+ SmallVectorImpl<MachineMemOperand *> &RefMMOs = SSRefs[SS];
+ for (unsigned i = 0, e = RefMMOs.size(); i != e; ++i)
+ RefMMOs[i]->setValue(NewSV);
+ }
+
+ // Rewrite all MO_FrameIndex operands. Look for dead stores.
+ for (MachineFunction::iterator MBBI = MF.begin(), E = MF.end();
+ MBBI != E; ++MBBI) {
+ MachineBasicBlock *MBB = &*MBBI;
+ for (MachineBasicBlock::iterator MII = MBB->begin(), EE = MBB->end();
+ MII != EE; ++MII)
+ RewriteInstruction(MII, SlotMapping, MF);
+ RemoveDeadStores(MBB);
}
// Delete unused stack slots.
while (NextColor != -1) {
- DOUT << "Removing unused stack object fi#" << NextColor << "\n";
+ DEBUG(dbgs() << "Removing unused stack object fi#" << NextColor << "\n");
MFI->RemoveStackObject(NextColor);
NextColor = AllColors.find_next(NextColor);
}
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->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,
- int NewFI, MachineFunction &MF) {
+void StackSlotColoring::RewriteInstruction(MachineInstr *MI,
+ SmallVectorImpl<int> &SlotMapping,
+ MachineFunction &MF) {
+ // Update the operands.
for (unsigned i = 0, ee = MI->getNumOperands(); i != ee; ++i) {
MachineOperand &MO = MI->getOperand(i);
if (!MO.isFI())
continue;
- int FI = MO.getIndex();
- if (FI != OldFI)
+ int OldFI = MO.getIndex();
+ if (OldFI < 0)
+ continue;
+ int NewFI = SlotMapping[OldFI];
+ if (NewFI == -1 || NewFI == OldFI)
continue;
MO.setIndex(NewFI);
}
- // Update the MachineMemOperand for the new memory location.
- // FIXME: We need a better method of managing these too.
- SmallVector<MachineMemOperand, 2> MMOs(MI->memoperands_begin(),
- MI->memoperands_end());
- MI->clearMemOperands(MF);
- const Value *OldSV = PseudoSourceValue::getFixedStack(OldFI);
- for (unsigned i = 0, ee = MMOs.size(); i != ee; ++i) {
- if (MMOs[i].getValue() != OldSV)
- MI->addMemOperand(MF, MMOs[i]);
- else {
- MachineMemOperand MMO(PseudoSourceValue::getFixedStack(NewFI),
- MMOs[i].getFlags(), MMOs[i].getOffset(),
- MMOs[i].getSize(), MMOs[i].getAlignment());
- MI->addMemOperand(MF, MMO);
- }
- }
+ // The MachineMemOperands have already been updated.
}
-/// 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,
- MachineFunction &MF) {
- MachineBasicBlock *MBB = MI->getParent();
- SmallVector<MachineInstr*, 4> NewMIs;
- bool Success = TII->unfoldMemoryOperand(MF, MI, Reg, false, false, NewMIs);
- assert(Success && "Failed to unfold!");
- MBB->insert(MI, NewMIs[0]);
- MBB->erase(MI);
- ++NumRegRepl;
-}
/// 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 = next(I);
- if (NextMI == MBB->end()) continue;
-
+
int FirstSS, SecondSS;
+ if (TII->isStackSlotCopy(I, FirstSS, SecondSS) &&
+ FirstSS == SecondSS &&
+ FirstSS != -1) {
+ ++NumDead;
+ changed = true;
+ toErase.push_back(I);
+ continue;
+ }
+
+ MachineBasicBlock::iterator NextMI = std::next(I);
+ if (NextMI == MBB->end()) continue;
+
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) {
+
+ if (NextMI->findRegisterUseOperandIdx(LoadReg, true, nullptr) != -1) {
++NumDead;
toErase.push_back(I);
}
-
+
toErase.push_back(NextMI);
++I;
}
-
- for (SmallVector<MachineInstr*, 4>::iterator I = toErase.begin(),
+
+ for (SmallVectorImpl<MachineInstr *>::iterator I = toErase.begin(),
E = toErase.end(); I != E; ++I)
(*I)->eraseFromParent();
-
+
return changed;
}
bool StackSlotColoring::runOnMachineFunction(MachineFunction &MF) {
- DOUT << "********** Stack Slot Coloring **********\n";
+ DEBUG({
+ dbgs() << "********** Stack Slot Coloring **********\n"
+ << "********** Function: " << MF.getName() << '\n';
+ });
MFI = MF.getFrameInfo();
- MRI = &MF.getRegInfo();
- TII = MF.getTarget().getInstrInfo();
- TRI = MF.getTarget().getRegisterInfo();
+ TII = MF.getSubtarget().getInstrInfo();
LS = &getAnalysis<LiveStacks>();
- VRM = &getAnalysis<VirtRegMap>();
- loopInfo = &getAnalysis<MachineLoopInfo>();
+ MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
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);
Assignments[i].clear();
Assignments.clear();
- if (Changed) {
- for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
- Changed |= RemoveDeadStores(I);
- }
-
return Changed;
}
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