#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Support/CommandLine.h"
+#include "llvm/Target/TargetMachine.h"
using namespace llvm;
-MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI) {
+MachineRegisterInfo::MachineRegisterInfo(const TargetRegisterInfo &TRI)
+ : TRI(&TRI), IsSSA(true) {
VRegInfo.reserve(256);
RegAllocHints.reserve(256);
- RegClass2VRegMap.resize(TRI.getNumRegClasses()+1); // RC ID starts at 1.
UsedPhysRegs.resize(TRI.getNumRegs());
// Create the physreg use/def lists.
MachineRegisterInfo::~MachineRegisterInfo() {
#ifndef NDEBUG
- for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i)
- assert(VRegInfo[i].second == 0 && "Vreg use list non-empty still?");
+ for (unsigned i = 0, e = getNumVirtRegs(); i != e; ++i)
+ assert(VRegInfo[TargetRegisterInfo::index2VirtReg(i)].second == 0 &&
+ "Vreg use list non-empty still?");
for (unsigned i = 0, e = UsedPhysRegs.size(); i != e; ++i)
assert(!PhysRegUseDefLists[i] &&
"PhysRegUseDefLists has entries after all instructions are deleted");
///
void
MachineRegisterInfo::setRegClass(unsigned Reg, const TargetRegisterClass *RC) {
- unsigned VR = Reg;
- Reg -= TargetRegisterInfo::FirstVirtualRegister;
- assert(Reg < VRegInfo.size() && "Invalid vreg!");
- const TargetRegisterClass *OldRC = VRegInfo[Reg].first;
VRegInfo[Reg].first = RC;
+}
+
+const TargetRegisterClass *
+MachineRegisterInfo::constrainRegClass(unsigned Reg,
+ const TargetRegisterClass *RC,
+ unsigned MinNumRegs) {
+ const TargetRegisterClass *OldRC = getRegClass(Reg);
+ if (OldRC == RC)
+ return RC;
+ const TargetRegisterClass *NewRC = TRI->getCommonSubClass(OldRC, RC);
+ if (!NewRC || NewRC == OldRC)
+ return NewRC;
+ if (NewRC->getNumRegs() < MinNumRegs)
+ return 0;
+ setRegClass(Reg, NewRC);
+ return NewRC;
+}
- // Remove from old register class's vregs list. This may be slow but
- // fortunately this operation is rarely needed.
- std::vector<unsigned> &VRegs = RegClass2VRegMap[OldRC->getID()];
- std::vector<unsigned>::iterator I=std::find(VRegs.begin(), VRegs.end(), VR);
- VRegs.erase(I);
+bool
+MachineRegisterInfo::recomputeRegClass(unsigned Reg, const TargetMachine &TM) {
+ const TargetInstrInfo *TII = TM.getInstrInfo();
+ const TargetRegisterClass *OldRC = getRegClass(Reg);
+ const TargetRegisterClass *NewRC = TRI->getLargestLegalSuperClass(OldRC);
- // Add to new register class's vregs list.
- RegClass2VRegMap[RC->getID()].push_back(VR);
+ // Stop early if there is no room to grow.
+ if (NewRC == OldRC)
+ return false;
+
+ // Accumulate constraints from all uses.
+ for (reg_nodbg_iterator I = reg_nodbg_begin(Reg), E = reg_nodbg_end(); I != E;
+ ++I) {
+ // TRI doesn't have accurate enough information to model this yet.
+ if (I.getOperand().getSubReg())
+ return false;
+ const TargetRegisterClass *OpRC =
+ I->getRegClassConstraint(I.getOperandNo(), TII, TRI);
+ if (OpRC)
+ NewRC = TRI->getCommonSubClass(NewRC, OpRC);
+ if (!NewRC || NewRC == OldRC)
+ return false;
+ }
+ setRegClass(Reg, NewRC);
+ return true;
}
/// createVirtualRegister - Create and return a new virtual register in the
unsigned
MachineRegisterInfo::createVirtualRegister(const TargetRegisterClass *RegClass){
assert(RegClass && "Cannot create register without RegClass!");
+ assert(RegClass->isAllocatable() &&
+ "Virtual register RegClass must be allocatable.");
+
+ // New virtual register number.
+ unsigned Reg = TargetRegisterInfo::index2VirtReg(getNumVirtRegs());
+
// Add a reg, but keep track of whether the vector reallocated or not.
- void *ArrayBase = VRegInfo.empty() ? 0 : &VRegInfo[0];
- VRegInfo.push_back(std::make_pair(RegClass, (MachineOperand*)0));
- RegAllocHints.push_back(std::make_pair(0, 0));
+ const unsigned FirstVirtReg = TargetRegisterInfo::index2VirtReg(0);
+ void *ArrayBase = getNumVirtRegs() == 0 ? 0 : &VRegInfo[FirstVirtReg];
+ VRegInfo.grow(Reg);
+ VRegInfo[Reg].first = RegClass;
+ RegAllocHints.grow(Reg);
- if (!((&VRegInfo[0] == ArrayBase || VRegInfo.size() == 1)))
+ if (ArrayBase && &VRegInfo[FirstVirtReg] != ArrayBase)
// The vector reallocated, handle this now.
HandleVRegListReallocation();
- unsigned VR = getLastVirtReg();
- RegClass2VRegMap[RegClass->getID()].push_back(VR);
- return VR;
+ return Reg;
}
/// HandleVRegListReallocation - We just added a virtual register to the
void MachineRegisterInfo::HandleVRegListReallocation() {
// The back pointers for the vreg lists point into the previous vector.
// Update them to point to their correct slots.
- for (unsigned i = 0, e = VRegInfo.size(); i != e; ++i) {
- MachineOperand *List = VRegInfo[i].second;
+ for (unsigned i = 0, e = getNumVirtRegs(); i != e; ++i) {
+ unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+ MachineOperand *List = VRegInfo[Reg].second;
if (!List) continue;
// Update the back-pointer to be accurate once more.
- List->Contents.Reg.Prev = &VRegInfo[i].second;
+ List->Contents.Reg.Prev = &VRegInfo[Reg].second;
}
}
/// register or null if none is found. This assumes that the code is in SSA
/// form, so there should only be one definition.
MachineInstr *MachineRegisterInfo::getVRegDef(unsigned Reg) const {
- assert(Reg-TargetRegisterInfo::FirstVirtualRegister < VRegInfo.size() &&
- "Invalid vreg!");
// Since we are in SSA form, we can use the first definition.
if (!def_empty(Reg))
return &*def_begin(Reg);
return 0;
}
-static cl::opt<bool>
-SchedLiveInCopies("schedule-livein-copies", cl::Hidden,
- cl::desc("Schedule copies of livein registers"),
- cl::init(false));
-
-/// EmitLiveInCopy - Emit a copy for a live in physical register. If the
-/// physical register has only a single copy use, then coalesced the copy
-/// if possible.
-static void EmitLiveInCopy(MachineBasicBlock *MBB,
- MachineBasicBlock::iterator &InsertPos,
- unsigned VirtReg, unsigned PhysReg,
- const TargetRegisterClass *RC,
- DenseMap<MachineInstr*, unsigned> &CopyRegMap,
- const MachineRegisterInfo &MRI,
- const TargetRegisterInfo &TRI,
- const TargetInstrInfo &TII) {
- unsigned NumUses = 0;
- MachineInstr *UseMI = NULL;
- for (MachineRegisterInfo::use_iterator UI = MRI.use_begin(VirtReg),
- UE = MRI.use_end(); UI != UE; ++UI) {
- UseMI = &*UI;
- if (++NumUses > 1)
- break;
- }
-
- // If the number of uses is not one, or the use is not a move instruction,
- // don't coalesce. Also, only coalesce away a virtual register to virtual
- // register copy.
- bool Coalesced = false;
- unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
- if (NumUses == 1 &&
- TII.isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
- TargetRegisterInfo::isVirtualRegister(DstReg)) {
- VirtReg = DstReg;
- Coalesced = true;
- }
-
- // Now find an ideal location to insert the copy.
- MachineBasicBlock::iterator Pos = InsertPos;
- while (Pos != MBB->begin()) {
- MachineInstr *PrevMI = prior(Pos);
- DenseMap<MachineInstr*, unsigned>::iterator RI = CopyRegMap.find(PrevMI);
- // copyRegToReg might emit multiple instructions to do a copy.
- unsigned CopyDstReg = (RI == CopyRegMap.end()) ? 0 : RI->second;
- if (CopyDstReg && !TRI.regsOverlap(CopyDstReg, PhysReg))
- // This is what the BB looks like right now:
- // r1024 = mov r0
- // ...
- // r1 = mov r1024
- //
- // We want to insert "r1025 = mov r1". Inserting this copy below the
- // move to r1024 makes it impossible for that move to be coalesced.
- //
- // r1025 = mov r1
- // r1024 = mov r0
- // ...
- // r1 = mov 1024
- // r2 = mov 1025
- break; // Woot! Found a good location.
- --Pos;
- }
-
- bool Emitted = TII.copyRegToReg(*MBB, Pos, VirtReg, PhysReg, RC, RC,
- DebugLoc());
- assert(Emitted && "Unable to issue a live-in copy instruction!\n");
- (void) Emitted;
-
- CopyRegMap.insert(std::make_pair(prior(Pos), VirtReg));
- if (Coalesced) {
- if (&*InsertPos == UseMI) ++InsertPos;
- MBB->erase(UseMI);
- }
+/// getLiveInVirtReg - If PReg is a live-in physical register, return the
+/// corresponding live-in physical register.
+unsigned MachineRegisterInfo::getLiveInVirtReg(unsigned PReg) const {
+ for (livein_iterator I = livein_begin(), E = livein_end(); I != E; ++I)
+ if (I->first == PReg)
+ return I->second;
+ return 0;
}
/// EmitLiveInCopies - Emit copies to initialize livein virtual registers
MachineRegisterInfo::EmitLiveInCopies(MachineBasicBlock *EntryMBB,
const TargetRegisterInfo &TRI,
const TargetInstrInfo &TII) {
- if (SchedLiveInCopies) {
- // Emit the copies at a heuristically-determined location in the block.
- DenseMap<MachineInstr*, unsigned> CopyRegMap;
- MachineBasicBlock::iterator InsertPos = EntryMBB->begin();
- for (MachineRegisterInfo::livein_iterator LI = livein_begin(),
- E = livein_end(); LI != E; ++LI)
- if (LI->second) {
- const TargetRegisterClass *RC = getRegClass(LI->second);
- EmitLiveInCopy(EntryMBB, InsertPos, LI->second, LI->first,
- RC, CopyRegMap, *this, TRI, TII);
- }
- } else {
- // Emit the copies into the top of the block.
- for (MachineRegisterInfo::livein_iterator LI = livein_begin(),
- E = livein_end(); LI != E; ++LI)
- if (LI->second) {
- const TargetRegisterClass *RC = getRegClass(LI->second);
- bool Emitted = TII.copyRegToReg(*EntryMBB, EntryMBB->begin(),
- LI->second, LI->first, RC, RC,
- DebugLoc());
- assert(Emitted && "Unable to issue a live-in copy instruction!\n");
- (void) Emitted;
- }
- }
+ // Emit the copies into the top of the block.
+ for (unsigned i = 0, e = LiveIns.size(); i != e; ++i)
+ if (LiveIns[i].second) {
+ if (use_empty(LiveIns[i].second)) {
+ // The livein has no uses. Drop it.
+ //
+ // It would be preferable to have isel avoid creating live-in
+ // records for unused arguments in the first place, but it's
+ // complicated by the debug info code for arguments.
+ LiveIns.erase(LiveIns.begin() + i);
+ --i; --e;
+ } else {
+ // Emit a copy.
+ BuildMI(*EntryMBB, EntryMBB->begin(), DebugLoc(),
+ TII.get(TargetOpcode::COPY), LiveIns[i].second)
+ .addReg(LiveIns[i].first);
- // Add function live-ins to entry block live-in set.
- for (MachineRegisterInfo::livein_iterator I = livein_begin(),
- E = livein_end(); I != E; ++I)
- EntryMBB->addLiveIn(I->first);
+ // Add the register to the entry block live-in set.
+ EntryMBB->addLiveIn(LiveIns[i].first);
+ }
+ } else {
+ // Add the register to the entry block live-in set.
+ EntryMBB->addLiveIn(LiveIns[i].first);
+ }
}
void MachineRegisterInfo::closePhysRegsUsed(const TargetRegisterInfo &TRI) {
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