// the instruction, but are never used after the instruction (i.e., they are
// killed).
//
-// This class computes live variables using are sparse implementation based on
+// This class computes live variables using a sparse implementation based on
// the machine code SSA form. This class computes live variable information for
// each virtual and _register allocatable_ physical register in a function. It
// uses the dominance properties of SSA form to efficiently compute live
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallSet.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
-#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/ADT/DepthFirstIterator.h"
-#include "llvm/ADT/SmallPtrSet.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/Config/alloca.h"
#include <algorithm>
using namespace llvm;
char LiveVariables::ID = 0;
-static RegisterPass<LiveVariables> X("livevars", "Live Variable Analysis");
+char &llvm::LiveVariablesID = LiveVariables::ID;
+INITIALIZE_PASS_BEGIN(LiveVariables, "livevars",
+ "Live Variable Analysis", false, false)
+INITIALIZE_PASS_DEPENDENCY(UnreachableMachineBlockElim)
+INITIALIZE_PASS_END(LiveVariables, "livevars",
+ "Live Variable Analysis", false, false)
void LiveVariables::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequiredID(UnreachableMachineBlockElimID);
AU.setPreservesAll();
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+MachineInstr *
+LiveVariables::VarInfo::findKill(const MachineBasicBlock *MBB) const {
+ for (unsigned i = 0, e = Kills.size(); i != e; ++i)
+ if (Kills[i]->getParent() == MBB)
+ return Kills[i];
+ return nullptr;
}
void LiveVariables::VarInfo::dump() const {
- cerr << " Alive in blocks: ";
- for (unsigned i = 0, e = AliveBlocks.size(); i != e; ++i)
- if (AliveBlocks[i]) cerr << i << ", ";
- cerr << " Used in blocks: ";
- for (unsigned i = 0, e = UsedBlocks.size(); i != e; ++i)
- if (UsedBlocks[i]) cerr << i << ", ";
- cerr << "\n Killed by:";
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+ dbgs() << " Alive in blocks: ";
+ for (SparseBitVector<>::iterator I = AliveBlocks.begin(),
+ E = AliveBlocks.end(); I != E; ++I)
+ dbgs() << *I << ", ";
+ dbgs() << "\n Killed by:";
if (Kills.empty())
- cerr << " No instructions.\n";
+ dbgs() << " No instructions.\n";
else {
for (unsigned i = 0, e = Kills.size(); i != e; ++i)
- cerr << "\n #" << i << ": " << *Kills[i];
- cerr << "\n";
+ dbgs() << "\n #" << i << ": " << *Kills[i];
+ dbgs() << "\n";
}
+#endif
}
/// getVarInfo - Get (possibly creating) a VarInfo object for the given vreg.
LiveVariables::VarInfo &LiveVariables::getVarInfo(unsigned RegIdx) {
assert(TargetRegisterInfo::isVirtualRegister(RegIdx) &&
"getVarInfo: not a virtual register!");
- RegIdx -= TargetRegisterInfo::FirstVirtualRegister;
- if (RegIdx >= VirtRegInfo.size()) {
- if (RegIdx >= 2*VirtRegInfo.size())
- VirtRegInfo.resize(RegIdx*2);
- else
- VirtRegInfo.resize(2*VirtRegInfo.size());
- }
- VarInfo &VI = VirtRegInfo[RegIdx];
- VI.AliveBlocks.resize(MF->getNumBlockIDs());
- VI.UsedBlocks.resize(MF->getNumBlockIDs());
- return VI;
+ VirtRegInfo.grow(RegIdx);
+ return VirtRegInfo[RegIdx];
}
void LiveVariables::MarkVirtRegAliveInBlock(VarInfo& VRInfo,
MachineBasicBlock *MBB,
std::vector<MachineBasicBlock*> &WorkList) {
unsigned BBNum = MBB->getNumber();
-
+
// Check to see if this basic block is one of the killing blocks. If so,
// remove it.
for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i)
VRInfo.Kills.erase(VRInfo.Kills.begin()+i); // Erase entry
break;
}
-
+
if (MBB == DefBlock) return; // Terminate recursion
- if (VRInfo.AliveBlocks[BBNum])
+ if (VRInfo.AliveBlocks.test(BBNum))
return; // We already know the block is live
// Mark the variable known alive in this bb
- VRInfo.AliveBlocks[BBNum] = true;
+ VRInfo.AliveBlocks.set(BBNum);
- for (MachineBasicBlock::const_pred_reverse_iterator PI = MBB->pred_rbegin(),
- E = MBB->pred_rend(); PI != E; ++PI)
- WorkList.push_back(*PI);
+ assert(MBB != &MF->front() && "Can't find reaching def for virtreg");
+ WorkList.insert(WorkList.end(), MBB->pred_rbegin(), MBB->pred_rend());
}
void LiveVariables::MarkVirtRegAliveInBlock(VarInfo &VRInfo,
unsigned BBNum = MBB->getNumber();
VarInfo& VRInfo = getVarInfo(reg);
- VRInfo.UsedBlocks[BBNum] = true;
- VRInfo.NumUses++;
// Check to see if this basic block is already a kill block.
if (!VRInfo.Kills.empty() && VRInfo.Kills.back()->getParent() == MBB) {
// Add a new kill entry for this basic block. If this virtual register is
// already marked as alive in this basic block, that means it is alive in at
// least one of the successor blocks, it's not a kill.
- if (!VRInfo.AliveBlocks[BBNum])
+ if (!VRInfo.AliveBlocks.test(BBNum))
VRInfo.Kills.push_back(MI);
// Update all dominating blocks to mark them as "known live".
void LiveVariables::HandleVirtRegDef(unsigned Reg, MachineInstr *MI) {
VarInfo &VRInfo = getVarInfo(Reg);
- if (VRInfo.AliveBlocks.none())
+ if (VRInfo.AliveBlocks.empty())
// If vr is not alive in any block, then defaults to dead.
VRInfo.Kills.push_back(MI);
}
/// FindLastPartialDef - Return the last partial def of the specified register.
-/// Also returns the sub-register that's defined.
+/// Also returns the sub-registers that're defined by the instruction.
MachineInstr *LiveVariables::FindLastPartialDef(unsigned Reg,
- unsigned &PartDefReg) {
+ SmallSet<unsigned,4> &PartDefRegs) {
unsigned LastDefReg = 0;
unsigned LastDefDist = 0;
- MachineInstr *LastDef = NULL;
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
+ MachineInstr *LastDef = nullptr;
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
MachineInstr *Def = PhysRegDef[SubReg];
if (!Def)
continue;
LastDefDist = Dist;
}
}
- PartDefReg = LastDefReg;
+
+ if (!LastDef)
+ return nullptr;
+
+ PartDefRegs.insert(LastDefReg);
+ for (unsigned i = 0, e = LastDef->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = LastDef->getOperand(i);
+ if (!MO.isReg() || !MO.isDef() || MO.getReg() == 0)
+ continue;
+ unsigned DefReg = MO.getReg();
+ if (TRI->isSubRegister(Reg, DefReg)) {
+ for (MCSubRegIterator SubRegs(DefReg, TRI, /*IncludeSelf=*/true);
+ SubRegs.isValid(); ++SubRegs)
+ PartDefRegs.insert(*SubRegs);
+ }
+ }
return LastDef;
}
/// implicit defs to a machine instruction if there was an earlier def of its
/// super-register.
void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) {
+ MachineInstr *LastDef = PhysRegDef[Reg];
// If there was a previous use or a "full" def all is well.
- if (!PhysRegDef[Reg] && !PhysRegUse[Reg]) {
+ if (!LastDef && !PhysRegUse[Reg]) {
// Otherwise, the last sub-register def implicitly defines this register.
// e.g.
// AH =
// ...
// = EAX
// All of the sub-registers must have been defined before the use of Reg!
- unsigned PartDefReg = 0;
- MachineInstr *LastPartialDef = FindLastPartialDef(Reg, PartDefReg);
+ SmallSet<unsigned, 4> PartDefRegs;
+ MachineInstr *LastPartialDef = FindLastPartialDef(Reg, PartDefRegs);
// If LastPartialDef is NULL, it must be using a livein register.
if (LastPartialDef) {
LastPartialDef->addOperand(MachineOperand::CreateReg(Reg, true/*IsDef*/,
true/*IsImp*/));
PhysRegDef[Reg] = LastPartialDef;
SmallSet<unsigned, 8> Processed;
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
if (Processed.count(SubReg))
continue;
- if (SubReg == PartDefReg || TRI->isSubRegister(PartDefReg, SubReg))
+ if (PartDefRegs.count(SubReg))
continue;
// This part of Reg was defined before the last partial def. It's killed
// here.
false/*IsDef*/,
true/*IsImp*/));
PhysRegDef[SubReg] = LastPartialDef;
- for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
+ for (MCSubRegIterator SS(SubReg, TRI); SS.isValid(); ++SS)
Processed.insert(*SS);
}
}
- }
+ } else if (LastDef && !PhysRegUse[Reg] &&
+ !LastDef->findRegisterDefOperand(Reg))
+ // Last def defines the super register, add an implicit def of reg.
+ LastDef->addOperand(MachineOperand::CreateReg(Reg, true/*IsDef*/,
+ true/*IsImp*/));
- // There was an earlier def of a super-register. Add implicit def to that MI.
- //
- // A: EAX = ...
- // B: ... = AX
- //
- // Add implicit def to A if there isn't a use of AX (or EAX) before B.
- if (!PhysRegUse[Reg]) {
- MachineInstr *Def = PhysRegDef[Reg];
- if (Def && !Def->modifiesRegister(Reg))
- Def->addOperand(MachineOperand::CreateReg(Reg,
- true /*IsDef*/,
- true /*IsImp*/));
- }
-
// Remember this use.
- PhysRegUse[Reg] = MI;
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs)
- PhysRegUse[SubReg] = MI;
+ for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
+ SubRegs.isValid(); ++SubRegs)
+ PhysRegUse[*SubRegs] = MI;
}
-/// hasRegisterUseBelow - Return true if the specified register is used after
-/// the current instruction and before it's next definition.
-bool LiveVariables::hasRegisterUseBelow(unsigned Reg,
- MachineBasicBlock::iterator I,
- MachineBasicBlock *MBB) {
- if (I == MBB->end())
- return false;
+/// FindLastRefOrPartRef - Return the last reference or partial reference of
+/// the specified register.
+MachineInstr *LiveVariables::FindLastRefOrPartRef(unsigned Reg) {
+ MachineInstr *LastDef = PhysRegDef[Reg];
+ MachineInstr *LastUse = PhysRegUse[Reg];
+ if (!LastDef && !LastUse)
+ return nullptr;
- // First find out if there are any uses / defs below.
- bool hasDistInfo = true;
- unsigned CurDist = DistanceMap[I];
- SmallVector<MachineInstr*, 4> Uses;
- SmallVector<MachineInstr*, 4> Defs;
- for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(Reg),
- RE = MRI->reg_end(); RI != RE; ++RI) {
- MachineOperand &UDO = RI.getOperand();
- MachineInstr *UDMI = &*RI;
- if (UDMI->getParent() != MBB)
- continue;
- DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
- bool isBelow = false;
- if (DI == DistanceMap.end()) {
- // Must be below if it hasn't been assigned a distance yet.
- isBelow = true;
- hasDistInfo = false;
- } else if (DI->second > CurDist)
- isBelow = true;
- if (isBelow) {
- if (UDO.isUse())
- Uses.push_back(UDMI);
- if (UDO.isDef())
- Defs.push_back(UDMI);
+ MachineInstr *LastRefOrPartRef = LastUse ? LastUse : LastDef;
+ unsigned LastRefOrPartRefDist = DistanceMap[LastRefOrPartRef];
+ unsigned LastPartDefDist = 0;
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
+ MachineInstr *Def = PhysRegDef[SubReg];
+ if (Def && Def != LastDef) {
+ // There was a def of this sub-register in between. This is a partial
+ // def, keep track of the last one.
+ unsigned Dist = DistanceMap[Def];
+ if (Dist > LastPartDefDist)
+ LastPartDefDist = Dist;
+ } else if (MachineInstr *Use = PhysRegUse[SubReg]) {
+ unsigned Dist = DistanceMap[Use];
+ if (Dist > LastRefOrPartRefDist) {
+ LastRefOrPartRefDist = Dist;
+ LastRefOrPartRef = Use;
+ }
}
}
- if (Uses.empty())
- // No uses below.
- return false;
- else if (!Uses.empty() && Defs.empty())
- // There are uses below but no defs below.
- return true;
- // There are both uses and defs below. We need to know which comes first.
- if (!hasDistInfo) {
- // Complete DistanceMap for this MBB. This information is computed only
- // once per MBB.
- ++I;
- ++CurDist;
- for (MachineBasicBlock::iterator E = MBB->end(); I != E; ++I, ++CurDist)
- DistanceMap.insert(std::make_pair(I, CurDist));
- }
-
- unsigned EarliestUse = DistanceMap[Uses[0]];
- for (unsigned i = 1, e = Uses.size(); i != e; ++i) {
- unsigned Dist = DistanceMap[Uses[i]];
- if (Dist < EarliestUse)
- EarliestUse = Dist;
- }
- for (unsigned i = 0, e = Defs.size(); i != e; ++i) {
- unsigned Dist = DistanceMap[Defs[i]];
- if (Dist < EarliestUse)
- // The register is defined before its first use below.
- return false;
- }
- return true;
+ return LastRefOrPartRef;
}
-bool LiveVariables::HandlePhysRegKill(unsigned Reg) {
- if (!PhysRegUse[Reg] && !PhysRegDef[Reg])
+bool LiveVariables::HandlePhysRegKill(unsigned Reg, MachineInstr *MI) {
+ MachineInstr *LastDef = PhysRegDef[Reg];
+ MachineInstr *LastUse = PhysRegUse[Reg];
+ if (!LastDef && !LastUse)
return false;
- MachineInstr *LastRefOrPartRef = PhysRegUse[Reg]
- ? PhysRegUse[Reg] : PhysRegDef[Reg];
+ MachineInstr *LastRefOrPartRef = LastUse ? LastUse : LastDef;
unsigned LastRefOrPartRefDist = DistanceMap[LastRefOrPartRef];
// The whole register is used.
// AL =
// Or whole register is defined, but only partly used.
// AX<dead> = AL<imp-def>
// = AL<kill>
- // AX =
+ // AX =
+ MachineInstr *LastPartDef = nullptr;
+ unsigned LastPartDefDist = 0;
SmallSet<unsigned, 8> PartUses;
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
+ MachineInstr *Def = PhysRegDef[SubReg];
+ if (Def && Def != LastDef) {
+ // There was a def of this sub-register in between. This is a partial
+ // def, keep track of the last one.
+ unsigned Dist = DistanceMap[Def];
+ if (Dist > LastPartDefDist) {
+ LastPartDefDist = Dist;
+ LastPartDef = Def;
+ }
+ continue;
+ }
if (MachineInstr *Use = PhysRegUse[SubReg]) {
- PartUses.insert(SubReg);
- for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
+ for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true); SS.isValid();
+ ++SS)
PartUses.insert(*SS);
unsigned Dist = DistanceMap[Use];
if (Dist > LastRefOrPartRefDist) {
}
}
}
- if (LastRefOrPartRef == PhysRegDef[Reg])
- // Not used at all.
- LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
-
- /* Partial uses. Mark register def dead and add implicit def of
- sub-registers which are used.
- FIXME: LiveIntervalAnalysis can't handle this yet!
- EAX<dead> = op AL<imp-def>
- That is, EAX def is dead but AL def extends pass it.
- Enable this after live interval analysis is fixed to improve codegen!
- else if (!PhysRegUse[Reg]) {
+
+ if (!PhysRegUse[Reg]) {
+ // Partial uses. Mark register def dead and add implicit def of
+ // sub-registers which are used.
+ // EAX<dead> = op AL<imp-def>
+ // That is, EAX def is dead but AL def extends pass it.
PhysRegDef[Reg]->addRegisterDead(Reg, TRI, true);
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
- if (PartUses.count(SubReg)) {
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
+ if (!PartUses.count(SubReg))
+ continue;
+ bool NeedDef = true;
+ if (PhysRegDef[Reg] == PhysRegDef[SubReg]) {
+ MachineOperand *MO = PhysRegDef[Reg]->findRegisterDefOperand(SubReg);
+ if (MO) {
+ NeedDef = false;
+ assert(!MO->isDead());
+ }
+ }
+ if (NeedDef)
PhysRegDef[Reg]->addOperand(MachineOperand::CreateReg(SubReg,
- true, true));
+ true/*IsDef*/, true/*IsImp*/));
+ MachineInstr *LastSubRef = FindLastRefOrPartRef(SubReg);
+ if (LastSubRef)
+ LastSubRef->addRegisterKilled(SubReg, TRI, true);
+ else {
LastRefOrPartRef->addRegisterKilled(SubReg, TRI, true);
- for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
- PartUses.erase(*SS);
+ for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true);
+ SS.isValid(); ++SS)
+ PhysRegUse[*SS] = LastRefOrPartRef;
}
+ for (MCSubRegIterator SS(SubReg, TRI); SS.isValid(); ++SS)
+ PartUses.erase(*SS);
}
- } */
- else
+ } else if (LastRefOrPartRef == PhysRegDef[Reg] && LastRefOrPartRef != MI) {
+ if (LastPartDef)
+ // The last partial def kills the register.
+ LastPartDef->addOperand(MachineOperand::CreateReg(Reg, false/*IsDef*/,
+ true/*IsImp*/, true/*IsKill*/));
+ else {
+ MachineOperand *MO =
+ LastRefOrPartRef->findRegisterDefOperand(Reg, false, TRI);
+ bool NeedEC = MO->isEarlyClobber() && MO->getReg() != Reg;
+ // If the last reference is the last def, then it's not used at all.
+ // That is, unless we are currently processing the last reference itself.
+ LastRefOrPartRef->addRegisterDead(Reg, TRI, true);
+ if (NeedEC) {
+ // If we are adding a subreg def and the superreg def is marked early
+ // clobber, add an early clobber marker to the subreg def.
+ MO = LastRefOrPartRef->findRegisterDefOperand(Reg);
+ if (MO)
+ MO->setIsEarlyClobber();
+ }
+ }
+ } else
LastRefOrPartRef->addRegisterKilled(Reg, TRI, true);
return true;
}
-void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
+void LiveVariables::HandleRegMask(const MachineOperand &MO) {
+ // Call HandlePhysRegKill() for all live registers clobbered by Mask.
+ // Clobbered registers are always dead, sp there is no need to use
+ // HandlePhysRegDef().
+ for (unsigned Reg = 1, NumRegs = TRI->getNumRegs(); Reg != NumRegs; ++Reg) {
+ // Skip dead regs.
+ if (!PhysRegDef[Reg] && !PhysRegUse[Reg])
+ continue;
+ // Skip mask-preserved regs.
+ if (!MO.clobbersPhysReg(Reg))
+ continue;
+ // Kill the largest clobbered super-register.
+ // This avoids needless implicit operands.
+ unsigned Super = Reg;
+ for (MCSuperRegIterator SR(Reg, TRI); SR.isValid(); ++SR)
+ if ((PhysRegDef[*SR] || PhysRegUse[*SR]) && MO.clobbersPhysReg(*SR))
+ Super = *SR;
+ HandlePhysRegKill(Super, nullptr);
+ }
+}
+
+void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI,
+ SmallVectorImpl<unsigned> &Defs) {
// What parts of the register are previously defined?
SmallSet<unsigned, 32> Live;
if (PhysRegDef[Reg] || PhysRegUse[Reg]) {
- Live.insert(Reg);
- for (const unsigned *SS = TRI->getSubRegisters(Reg); *SS; ++SS)
- Live.insert(*SS);
+ for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
+ SubRegs.isValid(); ++SubRegs)
+ Live.insert(*SubRegs);
} else {
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
// If a register isn't itself defined, but all parts that make up of it
// are defined, then consider it also defined.
// e.g.
// AL =
// AH =
// = AX
+ if (Live.count(SubReg))
+ continue;
if (PhysRegDef[SubReg] || PhysRegUse[SubReg]) {
- Live.insert(SubReg);
- for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
+ for (MCSubRegIterator SS(SubReg, TRI, /*IncludeSelf=*/true);
+ SS.isValid(); ++SS)
Live.insert(*SS);
}
}
// Start from the largest piece, find the last time any part of the register
// is referenced.
- if (!HandlePhysRegKill(Reg)) {
- // Only some of the sub-registers are used.
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
- if (!Live.count(SubReg))
- // Skip if this sub-register isn't defined.
- continue;
- if (HandlePhysRegKill(SubReg)) {
- Live.erase(SubReg);
- for (const unsigned *SS = TRI->getSubRegisters(SubReg); *SS; ++SS)
- Live.erase(*SS);
- }
+ HandlePhysRegKill(Reg, MI);
+ // Only some of the sub-registers are used.
+ for (MCSubRegIterator SubRegs(Reg, TRI); SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
+ if (!Live.count(SubReg))
+ // Skip if this sub-register isn't defined.
+ continue;
+ HandlePhysRegKill(SubReg, MI);
+ }
+
+ if (MI)
+ Defs.push_back(Reg); // Remember this def.
+}
+
+void LiveVariables::UpdatePhysRegDefs(MachineInstr *MI,
+ SmallVectorImpl<unsigned> &Defs) {
+ while (!Defs.empty()) {
+ unsigned Reg = Defs.back();
+ Defs.pop_back();
+ for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
+ SubRegs.isValid(); ++SubRegs) {
+ unsigned SubReg = *SubRegs;
+ PhysRegDef[SubReg] = MI;
+ PhysRegUse[SubReg] = nullptr;
}
- assert(Live.empty() && "Not all defined registers are killed / dead?");
}
+}
- if (MI) {
- // Does this extend the live range of a super-register?
- SmallSet<unsigned, 8> Processed;
- for (const unsigned *SuperRegs = TRI->getSuperRegisters(Reg);
- unsigned SuperReg = *SuperRegs; ++SuperRegs) {
- if (Processed.count(SuperReg))
- continue;
- MachineInstr *LastRef = PhysRegUse[SuperReg]
- ? PhysRegUse[SuperReg] : PhysRegDef[SuperReg];
- if (LastRef && LastRef != MI) {
- // The larger register is previously defined. Now a smaller part is
- // being re-defined. Treat it as read/mod/write if there are uses
- // below.
- // EAX =
- // AX = EAX<imp-use,kill>, EAX<imp-def>
- // ...
- /// = EAX
- if (hasRegisterUseBelow(SuperReg, MI, MI->getParent())) {
- MI->addOperand(MachineOperand::CreateReg(SuperReg, false/*IsDef*/,
- true/*IsImp*/,true/*IsKill*/));
- MI->addOperand(MachineOperand::CreateReg(SuperReg, true/*IsDef*/,
- true/*IsImp*/));
- PhysRegDef[SuperReg] = MI;
- PhysRegUse[SuperReg] = NULL;
- Processed.insert(SuperReg);
- for (const unsigned *SS = TRI->getSubRegisters(SuperReg); *SS; ++SS) {
- PhysRegDef[*SS] = MI;
- PhysRegUse[*SS] = NULL;
- Processed.insert(*SS);
- }
- } else {
- // Otherwise, the super register is killed.
- if (HandlePhysRegKill(SuperReg)) {
- PhysRegDef[SuperReg] = NULL;
- PhysRegUse[SuperReg] = NULL;
- for (const unsigned *SS = TRI->getSubRegisters(SuperReg); *SS; ++SS) {
- PhysRegDef[*SS] = NULL;
- PhysRegUse[*SS] = NULL;
- Processed.insert(*SS);
- }
- }
- }
- }
+void LiveVariables::runOnInstr(MachineInstr *MI,
+ SmallVectorImpl<unsigned> &Defs) {
+ assert(!MI->isDebugValue());
+ // Process all of the operands of the instruction...
+ unsigned NumOperandsToProcess = MI->getNumOperands();
+
+ // Unless it is a PHI node. In this case, ONLY process the DEF, not any
+ // of the uses. They will be handled in other basic blocks.
+ if (MI->isPHI())
+ NumOperandsToProcess = 1;
+
+ // Clear kill and dead markers. LV will recompute them.
+ SmallVector<unsigned, 4> UseRegs;
+ SmallVector<unsigned, 4> DefRegs;
+ SmallVector<unsigned, 1> RegMasks;
+ for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isRegMask()) {
+ RegMasks.push_back(i);
+ continue;
}
+ if (!MO.isReg() || MO.getReg() == 0)
+ continue;
+ unsigned MOReg = MO.getReg();
+ if (MO.isUse()) {
+ if (!(TargetRegisterInfo::isPhysicalRegister(MOReg) &&
+ MRI->isReserved(MOReg)))
+ MO.setIsKill(false);
+ if (MO.readsReg())
+ UseRegs.push_back(MOReg);
+ } else /*MO.isDef()*/ {
+ if (!(TargetRegisterInfo::isPhysicalRegister(MOReg) &&
+ MRI->isReserved(MOReg)))
+ MO.setIsDead(false);
+ DefRegs.push_back(MOReg);
+ }
+ }
- // Remember this def.
- PhysRegDef[Reg] = MI;
- PhysRegUse[Reg] = NULL;
- for (const unsigned *SubRegs = TRI->getSubRegisters(Reg);
- unsigned SubReg = *SubRegs; ++SubRegs) {
- PhysRegDef[SubReg] = MI;
- PhysRegUse[SubReg] = NULL;
+ MachineBasicBlock *MBB = MI->getParent();
+ // Process all uses.
+ for (unsigned i = 0, e = UseRegs.size(); i != e; ++i) {
+ unsigned MOReg = UseRegs[i];
+ if (TargetRegisterInfo::isVirtualRegister(MOReg))
+ HandleVirtRegUse(MOReg, MBB, MI);
+ else if (!MRI->isReserved(MOReg))
+ HandlePhysRegUse(MOReg, MI);
+ }
+
+ // Process all masked registers. (Call clobbers).
+ for (unsigned i = 0, e = RegMasks.size(); i != e; ++i)
+ HandleRegMask(MI->getOperand(RegMasks[i]));
+
+ // Process all defs.
+ for (unsigned i = 0, e = DefRegs.size(); i != e; ++i) {
+ unsigned MOReg = DefRegs[i];
+ if (TargetRegisterInfo::isVirtualRegister(MOReg))
+ HandleVirtRegDef(MOReg, MI);
+ else if (!MRI->isReserved(MOReg))
+ HandlePhysRegDef(MOReg, MI, Defs);
+ }
+ UpdatePhysRegDefs(MI, Defs);
+}
+
+void LiveVariables::runOnBlock(MachineBasicBlock *MBB, const unsigned NumRegs) {
+ // Mark live-in registers as live-in.
+ SmallVector<unsigned, 4> Defs;
+ for (const auto &LI : MBB->liveins()) {
+ assert(TargetRegisterInfo::isPhysicalRegister(LI.PhysReg) &&
+ "Cannot have a live-in virtual register!");
+ HandlePhysRegDef(LI.PhysReg, nullptr, Defs);
+ }
+
+ // Loop over all of the instructions, processing them.
+ DistanceMap.clear();
+ unsigned Dist = 0;
+ for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+ I != E; ++I) {
+ MachineInstr *MI = I;
+ if (MI->isDebugValue())
+ continue;
+ DistanceMap.insert(std::make_pair(MI, Dist++));
+
+ runOnInstr(MI, Defs);
+ }
+
+ // Handle any virtual assignments from PHI nodes which might be at the
+ // bottom of this basic block. We check all of our successor blocks to see
+ // if they have PHI nodes, and if so, we simulate an assignment at the end
+ // of the current block.
+ if (!PHIVarInfo[MBB->getNumber()].empty()) {
+ SmallVectorImpl<unsigned> &VarInfoVec = PHIVarInfo[MBB->getNumber()];
+
+ for (SmallVectorImpl<unsigned>::iterator I = VarInfoVec.begin(),
+ E = VarInfoVec.end(); I != E; ++I)
+ // Mark it alive only in the block we are representing.
+ MarkVirtRegAliveInBlock(getVarInfo(*I),MRI->getVRegDef(*I)->getParent(),
+ MBB);
+ }
+
+ // MachineCSE may CSE instructions which write to non-allocatable physical
+ // registers across MBBs. Remember if any reserved register is liveout.
+ SmallSet<unsigned, 4> LiveOuts;
+ for (MachineBasicBlock::const_succ_iterator SI = MBB->succ_begin(),
+ SE = MBB->succ_end(); SI != SE; ++SI) {
+ MachineBasicBlock *SuccMBB = *SI;
+ if (SuccMBB->isEHPad())
+ continue;
+ for (const auto &LI : SuccMBB->liveins()) {
+ if (!TRI->isInAllocatableClass(LI.PhysReg))
+ // Ignore other live-ins, e.g. those that are live into landing pads.
+ LiveOuts.insert(LI.PhysReg);
}
}
+
+ // Loop over PhysRegDef / PhysRegUse, killing any registers that are
+ // available at the end of the basic block.
+ for (unsigned i = 0; i != NumRegs; ++i)
+ if ((PhysRegDef[i] || PhysRegUse[i]) && !LiveOuts.count(i))
+ HandlePhysRegDef(i, nullptr, Defs);
}
bool LiveVariables::runOnMachineFunction(MachineFunction &mf) {
MF = &mf;
MRI = &mf.getRegInfo();
- TRI = MF->getTarget().getRegisterInfo();
-
- ReservedRegisters = TRI->getReservedRegs(mf);
+ TRI = MF->getSubtarget().getRegisterInfo();
- unsigned NumRegs = TRI->getNumRegs();
- PhysRegDef = new MachineInstr*[NumRegs];
- PhysRegUse = new MachineInstr*[NumRegs];
- PHIVarInfo = new SmallVector<unsigned, 4>[MF->getNumBlockIDs()];
- std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0);
- std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0);
+ const unsigned NumRegs = TRI->getNumRegs();
+ PhysRegDef.assign(NumRegs, nullptr);
+ PhysRegUse.assign(NumRegs, nullptr);
+ PHIVarInfo.resize(MF->getNumBlockIDs());
+ PHIJoins.clear();
- /// Get some space for a respectable number of registers.
- VirtRegInfo.resize(64);
+ // FIXME: LiveIntervals will be updated to remove its dependence on
+ // LiveVariables to improve compilation time and eliminate bizarre pass
+ // dependencies. Until then, we can't change much in -O0.
+ if (!MRI->isSSA())
+ report_fatal_error("regalloc=... not currently supported with -O0");
analyzePHINodes(mf);
// function. This guarantees that we will see the definition of a virtual
// register before its uses due to dominance properties of SSA (except for PHI
// nodes, which are treated as a special case).
- MachineBasicBlock *Entry = MF->begin();
+ MachineBasicBlock *Entry = &MF->front();
SmallPtrSet<MachineBasicBlock*,16> Visited;
- for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*,16> >
- DFI = df_ext_begin(Entry, Visited), E = df_ext_end(Entry, Visited);
- DFI != E; ++DFI) {
- MachineBasicBlock *MBB = *DFI;
-
- // Mark live-in registers as live-in.
- for (MachineBasicBlock::const_livein_iterator II = MBB->livein_begin(),
- EE = MBB->livein_end(); II != EE; ++II) {
- assert(TargetRegisterInfo::isPhysicalRegister(*II) &&
- "Cannot have a live-in virtual register!");
- HandlePhysRegDef(*II, 0);
- }
-
- // Loop over all of the instructions, processing them.
- DistanceMap.clear();
- unsigned Dist = 0;
- for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
- I != E; ++I) {
- MachineInstr *MI = I;
- DistanceMap.insert(std::make_pair(MI, Dist++));
-
- // Process all of the operands of the instruction...
- unsigned NumOperandsToProcess = MI->getNumOperands();
-
- // Unless it is a PHI node. In this case, ONLY process the DEF, not any
- // of the uses. They will be handled in other basic blocks.
- if (MI->getOpcode() == TargetInstrInfo::PHI)
- NumOperandsToProcess = 1;
-
- SmallVector<unsigned, 4> UseRegs;
- SmallVector<unsigned, 4> DefRegs;
- for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
- const MachineOperand &MO = MI->getOperand(i);
- if (MO.isRegister() && MO.getReg()) {
- unsigned MOReg = MO.getReg();
- if (MO.isUse())
- UseRegs.push_back(MOReg);
- if (MO.isDef())
- DefRegs.push_back(MOReg);
- }
- }
-
- // Process all uses.
- for (unsigned i = 0, e = UseRegs.size(); i != e; ++i) {
- unsigned MOReg = UseRegs[i];
- if (TargetRegisterInfo::isVirtualRegister(MOReg))
- HandleVirtRegUse(MOReg, MBB, MI);
- else if (!ReservedRegisters[MOReg])
- HandlePhysRegUse(MOReg, MI);
- }
-
- // Process all defs.
- for (unsigned i = 0, e = DefRegs.size(); i != e; ++i) {
- unsigned MOReg = DefRegs[i];
- if (TargetRegisterInfo::isVirtualRegister(MOReg))
- HandleVirtRegDef(MOReg, MI);
- else if (!ReservedRegisters[MOReg])
- HandlePhysRegDef(MOReg, MI);
- }
- }
-
- // Handle any virtual assignments from PHI nodes which might be at the
- // bottom of this basic block. We check all of our successor blocks to see
- // if they have PHI nodes, and if so, we simulate an assignment at the end
- // of the current block.
- if (!PHIVarInfo[MBB->getNumber()].empty()) {
- SmallVector<unsigned, 4>& VarInfoVec = PHIVarInfo[MBB->getNumber()];
-
- for (SmallVector<unsigned, 4>::iterator I = VarInfoVec.begin(),
- E = VarInfoVec.end(); I != E; ++I)
- // Mark it alive only in the block we are representing.
- MarkVirtRegAliveInBlock(getVarInfo(*I),MRI->getVRegDef(*I)->getParent(),
- MBB);
- }
+ for (MachineBasicBlock *MBB : depth_first_ext(Entry, Visited)) {
+ runOnBlock(MBB, NumRegs);
- // Finally, if the last instruction in the block is a return, make sure to
- // mark it as using all of the live-out values in the function.
- if (!MBB->empty() && MBB->back().getDesc().isReturn()) {
- MachineInstr *Ret = &MBB->back();
-
- for (MachineRegisterInfo::liveout_iterator
- I = MF->getRegInfo().liveout_begin(),
- E = MF->getRegInfo().liveout_end(); I != E; ++I) {
- assert(TargetRegisterInfo::isPhysicalRegister(*I) &&
- "Cannot have a live-out virtual register!");
- HandlePhysRegUse(*I, Ret);
-
- // Add live-out registers as implicit uses.
- if (!Ret->readsRegister(*I))
- Ret->addOperand(MachineOperand::CreateReg(*I, false, true));
- }
- }
-
- // Loop over PhysRegDef / PhysRegUse, killing any registers that are
- // available at the end of the basic block.
- for (unsigned i = 0; i != NumRegs; ++i)
- if (PhysRegDef[i] || PhysRegUse[i])
- HandlePhysRegDef(i, 0);
-
- std::fill(PhysRegDef, PhysRegDef + NumRegs, (MachineInstr*)0);
- std::fill(PhysRegUse, PhysRegUse + NumRegs, (MachineInstr*)0);
+ PhysRegDef.assign(NumRegs, nullptr);
+ PhysRegUse.assign(NumRegs, nullptr);
}
// Convert and transfer the dead / killed information we have gathered into
// VirtRegInfo onto MI's.
- for (unsigned i = 0, e1 = VirtRegInfo.size(); i != e1; ++i)
- for (unsigned j = 0, e2 = VirtRegInfo[i].Kills.size(); j != e2; ++j)
- if (VirtRegInfo[i].Kills[j] ==
- MRI->getVRegDef(i + TargetRegisterInfo::FirstVirtualRegister))
- VirtRegInfo[i]
- .Kills[j]->addRegisterDead(i +
- TargetRegisterInfo::FirstVirtualRegister,
- TRI);
+ for (unsigned i = 0, e1 = VirtRegInfo.size(); i != e1; ++i) {
+ const unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+ for (unsigned j = 0, e2 = VirtRegInfo[Reg].Kills.size(); j != e2; ++j)
+ if (VirtRegInfo[Reg].Kills[j] == MRI->getVRegDef(Reg))
+ VirtRegInfo[Reg].Kills[j]->addRegisterDead(Reg, TRI);
else
- VirtRegInfo[i]
- .Kills[j]->addRegisterKilled(i +
- TargetRegisterInfo::FirstVirtualRegister,
- TRI);
+ VirtRegInfo[Reg].Kills[j]->addRegisterKilled(Reg, TRI);
+ }
// Check to make sure there are no unreachable blocks in the MC CFG for the
// function. If so, it is due to a bug in the instruction selector or some
assert(Visited.count(&*i) != 0 && "unreachable basic block found");
#endif
- delete[] PhysRegDef;
- delete[] PhysRegUse;
- delete[] PHIVarInfo;
+ PhysRegDef.clear();
+ PhysRegUse.clear();
+ PHIVarInfo.clear();
return false;
}
void LiveVariables::removeVirtualRegistersKilled(MachineInstr *MI) {
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI->getOperand(i);
- if (MO.isRegister() && MO.isKill()) {
+ if (MO.isReg() && MO.isKill()) {
MO.setIsKill(false);
unsigned Reg = MO.getReg();
if (TargetRegisterInfo::isVirtualRegister(Reg)) {
bool removed = getVarInfo(Reg).removeKill(MI);
assert(removed && "kill not in register's VarInfo?");
+ (void)removed;
}
}
}
/// which is used in a PHI node. We map that to the BB the vreg is coming from.
///
void LiveVariables::analyzePHINodes(const MachineFunction& Fn) {
- for (MachineFunction::const_iterator I = Fn.begin(), E = Fn.end();
- I != E; ++I)
- for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();
- BBI != BBE && BBI->getOpcode() == TargetInstrInfo::PHI; ++BBI)
- for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
- PHIVarInfo[BBI->getOperand(i + 1).getMBB()->getNumber()]
- .push_back(BBI->getOperand(i).getReg());
+ for (const auto &MBB : Fn)
+ for (const auto &BBI : MBB) {
+ if (!BBI.isPHI())
+ break;
+ for (unsigned i = 1, e = BBI.getNumOperands(); i != e; i += 2)
+ if (BBI.getOperand(i).readsReg())
+ PHIVarInfo[BBI.getOperand(i + 1).getMBB()->getNumber()]
+ .push_back(BBI.getOperand(i).getReg());
+ }
+}
+
+bool LiveVariables::VarInfo::isLiveIn(const MachineBasicBlock &MBB,
+ unsigned Reg,
+ MachineRegisterInfo &MRI) {
+ unsigned Num = MBB.getNumber();
+
+ // Reg is live-through.
+ if (AliveBlocks.test(Num))
+ return true;
+
+ // Registers defined in MBB cannot be live in.
+ const MachineInstr *Def = MRI.getVRegDef(Reg);
+ if (Def && Def->getParent() == &MBB)
+ return false;
+
+ // Reg was not defined in MBB, was it killed here?
+ return findKill(&MBB);
+}
+
+bool LiveVariables::isLiveOut(unsigned Reg, const MachineBasicBlock &MBB) {
+ LiveVariables::VarInfo &VI = getVarInfo(Reg);
+
+ SmallPtrSet<const MachineBasicBlock *, 8> Kills;
+ for (unsigned i = 0, e = VI.Kills.size(); i != e; ++i)
+ Kills.insert(VI.Kills[i]->getParent());
+
+ // Loop over all of the successors of the basic block, checking to see if
+ // the value is either live in the block, or if it is killed in the block.
+ for (const MachineBasicBlock *SuccMBB : MBB.successors()) {
+ // Is it alive in this successor?
+ unsigned SuccIdx = SuccMBB->getNumber();
+ if (VI.AliveBlocks.test(SuccIdx))
+ return true;
+ // Or is it live because there is a use in a successor that kills it?
+ if (Kills.count(SuccMBB))
+ return true;
+ }
+
+ return false;
+}
+
+/// addNewBlock - Add a new basic block BB as an empty succcessor to DomBB. All
+/// variables that are live out of DomBB will be marked as passing live through
+/// BB.
+void LiveVariables::addNewBlock(MachineBasicBlock *BB,
+ MachineBasicBlock *DomBB,
+ MachineBasicBlock *SuccBB) {
+ const unsigned NumNew = BB->getNumber();
+
+ SmallSet<unsigned, 16> Defs, Kills;
+
+ MachineBasicBlock::iterator BBI = SuccBB->begin(), BBE = SuccBB->end();
+ for (; BBI != BBE && BBI->isPHI(); ++BBI) {
+ // Record the def of the PHI node.
+ Defs.insert(BBI->getOperand(0).getReg());
+
+ // All registers used by PHI nodes in SuccBB must be live through BB.
+ for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
+ if (BBI->getOperand(i+1).getMBB() == BB)
+ getVarInfo(BBI->getOperand(i).getReg()).AliveBlocks.set(NumNew);
+ }
+
+ // Record all vreg defs and kills of all instructions in SuccBB.
+ for (; BBI != BBE; ++BBI) {
+ for (MachineInstr::mop_iterator I = BBI->operands_begin(),
+ E = BBI->operands_end(); I != E; ++I) {
+ if (I->isReg() && TargetRegisterInfo::isVirtualRegister(I->getReg())) {
+ if (I->isDef())
+ Defs.insert(I->getReg());
+ else if (I->isKill())
+ Kills.insert(I->getReg());
+ }
+ }
+ }
+
+ // Update info for all live variables
+ for (unsigned i = 0, e = MRI->getNumVirtRegs(); i != e; ++i) {
+ unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+
+ // If the Defs is defined in the successor it can't be live in BB.
+ if (Defs.count(Reg))
+ continue;
+
+ // If the register is either killed in or live through SuccBB it's also live
+ // through BB.
+ VarInfo &VI = getVarInfo(Reg);
+ if (Kills.count(Reg) || VI.AliveBlocks.test(SuccBB->getNumber()))
+ VI.AliveBlocks.set(NumNew);
+ }
}
projects / oota-llvm.git / blobdiff