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- Keep track all def and uses of stack slot available in register.

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- Available value use may be deleted (e.g. noop move).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34841 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-03-02 08:52:00 +00:00
parent 68cbcee824
commit 6b448092bf
1 changed files with 51 additions and 28 deletions
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79
lib/CodeGen/VirtRegMap.cpp
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@ -254,9 +254,9 @@ class VISIBILITY_HIDDEN AvailableSpills {
// SpillSlotsAvailable - This map keeps track of all of the spilled virtual
// register values that are still available, due to being loaded or stored to,
// but not invalidated yet. It also tracks the instruction that last defined
// but not invalidated yet. It also tracks the instructions that defined
// or used the register.
typedef std::pair<unsigned, MachineInstr*> SSInfo;
typedef std::pair<unsigned, std::vector<MachineInstr*> > SSInfo;
std::map<int, SSInfo> SpillSlotsAvailable;
// PhysRegsAvailable - This is the inverse of SpillSlotsAvailable, indicating
@ -281,15 +281,16 @@ public:
unsigned getSpillSlotPhysReg(int Slot, MachineInstr *&SSMI) const {
std::map<int, SSInfo>::const_iterator I = SpillSlotsAvailable.find(Slot);
if (I != SpillSlotsAvailable.end()) {
SSMI = I->second.second;
if (!I->second.second.empty())
SSMI = I->second.second.back();
return I->second.first >> 1; // Remove the CanClobber bit.
}
return 0;
}
/// UpdateLastUses - Update the last use information of all stack slots whose
/// addLastUse - Add the last use information of all stack slots whose
/// values are available in the specific register.
void UpdateLastUse(unsigned PhysReg, MachineInstr *Use) {
void addLastUse(unsigned PhysReg, MachineInstr *Use) {
std::multimap<unsigned, int>::iterator I =
PhysRegsAvailable.lower_bound(PhysReg);
while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
@ -300,8 +301,25 @@ public:
assert(II != SpillSlotsAvailable.end() && "Slot not available!");
unsigned Val = II->second.first;
assert((Val >> 1) == PhysReg && "Bidirectional map mismatch!");
SpillSlotsAvailable.erase(Slot);
SpillSlotsAvailable[Slot] = std::make_pair(Val, Use);
II->second.second.push_back(Use);
}
}
/// removeLastUse - Remove the last use information of all stack slots whose
/// values are available in the specific register.
void removeLastUse(unsigned PhysReg, MachineInstr *Use) {
std::multimap<unsigned, int>::iterator I =
PhysRegsAvailable.lower_bound(PhysReg);
while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
int Slot = I->second;
I++;
std::map<int, SSInfo>::iterator II = SpillSlotsAvailable.find(Slot);
assert(II != SpillSlotsAvailable.end() && "Slot not available!");
unsigned Val = II->second.first;
assert((Val >> 1) == PhysReg && "Bidirectional map mismatch!");
if (II->second.second.back() == Use)
II->second.second.pop_back();
}
}
@ -315,8 +333,10 @@ public:
ModifyStackSlot(Slot);
PhysRegsAvailable.insert(std::make_pair(Reg, Slot));
std::vector<MachineInstr*> DefUses;
DefUses.push_back(MI);
SpillSlotsAvailable[Slot] =
std::make_pair((Reg << 1) | (unsigned)CanClobber, MI);
std::make_pair((Reg << 1) | (unsigned)CanClobber, DefUses);
DOUT << "Remembering SS#" << Slot << " in physreg "
<< MRI->getName(Reg) << "\n";
@ -683,15 +703,16 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// Extend the live range of the MI that last kill the register if
// necessary.
MachineOperand *MOK = SSMI->findRegisterUseOperand(PhysReg, true);
if (MOK) {
MOK->unsetIsKill();
if (ti == -1) {
// Unless it's the use of a two-address code, transfer the kill
// of the reused register to this use.
MI.getOperand(i).setIsKill();
Spills.UpdateLastUse(PhysReg, &MI);
}
if (SSMI) {
MachineOperand *MOK = SSMI->findRegisterUseOperand(PhysReg, true);
if (MOK)
MOK->unsetIsKill();
}
if (ti == -1) {
// Unless it's the use of a two-address code, transfer the kill
// of the reused register to this use.
MI.getOperand(i).setIsKill();
Spills.addLastUse(PhysReg, &MI);
}
// The only technical detail we have is that we don't know that
@ -763,14 +784,13 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// necessary.
if (SSMI) {
MachineOperand *MOK = SSMI->findRegisterUseOperand(PhysReg, true);
if (MOK) {
MachineInstr *CopyMI = prior(MII);
MachineOperand *MOU = CopyMI->findRegisterUseOperand(PhysReg);
MOU->setIsKill();
if (MOK)
MOK->unsetIsKill();
Spills.UpdateLastUse(PhysReg, &MI);
}
}
MachineInstr *CopyMI = prior(MII);
MachineOperand *MOU = CopyMI->findRegisterUseOperand(PhysReg);
MOU->setIsKill();
Spills.addLastUse(PhysReg, &MI);
// This invalidates DesignatedReg.
Spills.ClobberPhysReg(DesignatedReg);
@ -857,14 +877,17 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
// Either way, the live range of the last kill of InReg has been
// extended. Remove its kill.
MachineOperand *MOK = SSMI->findRegisterUseOperand(InReg, true);
if (MOK && NextMII != MBB.end()) {
MOK->unsetIsKill();
if (SSMI) {
MachineOperand *MOK = SSMI->findRegisterUseOperand(InReg, true);
if (MOK)
MOK->unsetIsKill();
}
if (NextMII != MBB.end()) {
// If NextMII uses InReg (must be the copy?), mark it killed.
MachineOperand *MOU = NextMII->findRegisterUseOperand(InReg);
if (MOU) {
MOU->setIsKill();
Spills.UpdateLastUse(InReg, &(*NextMII));
Spills.addLastUse(InReg, &(*NextMII));
}
}
@ -935,9 +958,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
++NumDCE;
DOUT << "Removing now-noop copy: " << MI;
Spills.removeLastUse(Src, &MI);
MBB.erase(&MI);
VRM.RemoveFromFoldedVirtMap(&MI);
Spills.UpdateLastUse(Src, NULL);
Spills.disallowClobberPhysReg(VirtReg);
goto ProcessNextInst;
}