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Refactor some code from being inline to being out in a new class with methods.

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This gets rid of two gotos, which is always nice, and also adds some comments.

No functionality change, this is just a refactor.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26367 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-02-25 01:51:33 +00:00
parent cb4a38e75d
commit 540fec6b38
1 changed files with 97 additions and 42 deletions
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139
lib/CodeGen/VirtRegMap.cpp
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@ -269,6 +269,8 @@ public:
return I->second >> 1; // Remove the CanClobber bit.
return 0;
}
const MRegisterInfo *getRegInfo() const { return MRI; }
/// addAvailable - Mark that the specified stack slot is available in the
/// specified physreg. If CanClobber is true, the physreg can be modified at
@ -375,6 +377,88 @@ namespace {
: Operand(o), StackSlot(ss), PhysRegReused(prr), AssignedPhysReg(apr),
VirtReg(vreg) {}
};
/// ReuseInfo - This maintains a collection of ReuseOp's for each operand that
/// is reused instead of reloaded.
class ReuseInfo {
MachineInstr &MI;
std::vector<ReusedOp> Reuses;
public:
ReuseInfo(MachineInstr &mi) : MI(mi) {}
bool hasReuses() const {
return !Reuses.empty();
}
/// addReuse - If we choose to reuse a virtual register that is already
/// available instead of reloading it, remember that we did so.
void addReuse(unsigned OpNo, unsigned StackSlot,
unsigned PhysRegReused, unsigned AssignedPhysReg,
unsigned VirtReg) {
// If the reload is to the assigned register anyway, no undo will be
// required.
if (PhysRegReused == AssignedPhysReg) return;
// Otherwise, remember this.
Reuses.push_back(ReusedOp(OpNo, StackSlot, PhysRegReused,
AssignedPhysReg, VirtReg));
}
/// GetRegForReload - We are about to emit a reload into PhysReg. If there
/// is some other operand that is using the specified register, either pick
/// a new register to use, or evict the previous reload and use this reg.
unsigned GetRegForReload(unsigned PhysReg, MachineInstr *MI,
AvailableSpills &Spills,
std::map<int, MachineInstr*> &MaybeDeadStores) {
if (Reuses.empty()) return PhysReg; // This is most often empty.
for (unsigned ro = 0, e = Reuses.size(); ro != e; ++ro) {
ReusedOp &Op = Reuses[ro];
// If we find some other reuse that was supposed to use this register
// exactly for its reload, we can change this reload to use ITS reload
// register.
if (Op.PhysRegReused == PhysReg) {
// Yup, use the reload register that we didn't use before.
return GetRegForReload(Op.AssignedPhysReg, MI,
Spills, MaybeDeadStores);
} else {
// Otherwise, we might also have a problem if a previously reused
// value aliases the new register. If so, codegen the previous reload
// and use this one.
unsigned PRRU = Op.PhysRegReused;
const MRegisterInfo *MRI = Spills.getRegInfo();
if (MRI->areAliases(PRRU, PhysReg)) {
// Okay, we found out that an alias of a reused register
// was used. This isn't good because it means we have
// to undo a previous reuse.
MachineBasicBlock *MBB = MI->getParent();
const TargetRegisterClass *AliasRC =
MBB->getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
MRI->loadRegFromStackSlot(*MBB, MI, Op.AssignedPhysReg,
Op.StackSlot, AliasRC);
Spills.ClobberPhysReg(Op.AssignedPhysReg);
Spills.ClobberPhysReg(Op.PhysRegReused);
// Any stores to this stack slot are not dead anymore.
MaybeDeadStores.erase(Op.StackSlot);
MI->SetMachineOperandReg(Op.Operand, Op.AssignedPhysReg);
Spills.addAvailable(Op.StackSlot, Op.AssignedPhysReg);
++NumLoads;
DEBUG(MachineBasicBlock::iterator MII = MI;
std::cerr << '\t' << *prior(MII));
DEBUG(std::cerr << "Reuse undone!\n");
Reuses.erase(Reuses.begin()+ro);
--NumReused;
return PhysReg;
}
}
}
return PhysReg;
}
};
}
@ -388,8 +472,6 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
// that we can choose to reuse the physregs instead of emitting reloads.
AvailableSpills Spills(MRI, TII);
std::vector<ReusedOp> ReusedOperands;
// DefAndUseVReg - When we see a def&use operand that is spilled, keep track
// of it. ".first" is the machine operand index (should always be 0 for now),
// and ".second" is the virtual register that is spilled.
@ -405,12 +487,18 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
bool *PhysRegsUsed = MBB.getParent()->getUsedPhysregs();
if (MBB.getBasicBlock()->getName() == "endif.3.i")
std::cerr << "HERE\n";
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
MII != E; ) {
MachineInstr &MI = *MII;
MachineBasicBlock::iterator NextMII = MII; ++NextMII;
ReusedOperands.clear();
/// ReusedOperands - Keep track of operand reuse in case we need to undo
/// reuse.
ReuseInfo ReusedOperands(MI);
DefAndUseVReg.clear();
// Process all of the spilled uses and all non spilled reg references.
@ -480,8 +568,8 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
// or R0 and R1 might not be compatible with each other. In this
// case, we actually insert a reload for V1 in R1, ensuring that
// we can get at R0 or its alias.
ReusedOperands.push_back(ReusedOp(i, StackSlot, PhysReg,
VRM.getPhys(VirtReg), VirtReg));
ReusedOperands.addReuse(i, StackSlot, PhysReg,
VRM.getPhys(VirtReg), VirtReg);
++NumReused;
continue;
}
@ -492,47 +580,14 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
const TargetRegisterClass* RC =
MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);
RecheckRegister:
// Note that, if we reused a register for a previous operand, the
// register we want to reload into might not actually be
// available. If this occurs, use the register indicated by the
// reuser.
if (!ReusedOperands.empty()) // This is most often empty.
for (unsigned ro = 0, e = ReusedOperands.size(); ro != e; ++ro)
if (ReusedOperands[ro].PhysRegReused == PhysReg) {
// Yup, use the reload register that we didn't use before.
PhysReg = ReusedOperands[ro].AssignedPhysReg;
goto RecheckRegister;
} else {
ReusedOp &Op = ReusedOperands[ro];
unsigned PRRU = Op.PhysRegReused;
if (MRI->areAliases(PRRU, PhysReg)) {
// Okay, we found out that an alias of a reused register
// was used. This isn't good because it means we have
// to undo a previous reuse.
const TargetRegisterClass *AliasRC =
MBB.getParent()->getSSARegMap()->getRegClass(Op.VirtReg);
MRI->loadRegFromStackSlot(MBB, &MI, Op.AssignedPhysReg,
Op.StackSlot, AliasRC);
Spills.ClobberPhysReg(Op.AssignedPhysReg);
Spills.ClobberPhysReg(Op.PhysRegReused);
// Any stores to this stack slot are not dead anymore.
MaybeDeadStores.erase(Op.StackSlot);
MI.SetMachineOperandReg(Op.Operand, Op.AssignedPhysReg);
Spills.addAvailable(Op.StackSlot, Op.AssignedPhysReg);
++NumLoads;
DEBUG(std::cerr << '\t' << *prior(MII));
DEBUG(std::cerr << "Reuse undone!\n");
ReusedOperands.erase(ReusedOperands.begin()+ro);
--NumReused;
goto ContinueReload;
}
}
ContinueReload:
if (ReusedOperands.hasReuses())
PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI,
Spills, MaybeDeadStores);
PhysRegsUsed[PhysReg] = true;
MRI->loadRegFromStackSlot(MBB, &MI, PhysReg, StackSlot, RC);
// This invalidates PhysReg.