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No longer need to track last def / use.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@38534 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-07-11 08:47:44 +00:00
parent 0c40d72b01
commit b9591c667d
1 changed files with 15 additions and 79 deletions
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94
lib/CodeGen/VirtRegMap.cpp
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@ -277,10 +277,8 @@ 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 instructions that defined
// or used the register.
typedef std::pair<unsigned, std::vector<MachineInstr*> > SSInfo;
std::map<int, SSInfo> SpillSlotsAvailable;
// but not invalidated yet.
std::map<int, unsigned> SpillSlotsAvailable;
// PhysRegsAvailable - This is the inverse of SpillSlotsAvailable, indicating
// which stack slot values are currently held by a physreg. This is used to
@ -298,56 +296,15 @@ public:
const MRegisterInfo *getRegInfo() const { return MRI; }
/// getSpillSlotPhysReg - If the specified stack slot is available in a
/// physical register, return that PhysReg, otherwise return 0. It also
/// returns by reference the instruction that either defines or last uses
/// the register.
unsigned getSpillSlotPhysReg(int Slot, MachineInstr *&SSMI) const {
std::map<int, SSInfo>::const_iterator I = SpillSlotsAvailable.find(Slot);
/// physical register, return that PhysReg, otherwise return 0.
unsigned getSpillSlotPhysReg(int Slot) const {
std::map<int, unsigned>::const_iterator I = SpillSlotsAvailable.find(Slot);
if (I != SpillSlotsAvailable.end()) {
if (!I->second.second.empty())
SSMI = I->second.second.back();
return I->second.first >> 1; // Remove the CanClobber bit.
return I->second >> 1; // Remove the CanClobber bit.
}
return 0;
}
/// addLastUse - Add the last use information of all stack slots whose
/// values are available in the specific register.
void addLastUse(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!");
// This can be true if there are multiple uses of the same register.
if (II->second.second.back() != 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();
}
}
/// addAvailable - Mark that the specified stack slot is available in the
/// specified physreg. If CanClobber is true, the physreg can be modified at
/// any time without changing the semantics of the program.
@ -358,10 +315,7 @@ 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, DefUses);
SpillSlotsAvailable[Slot] = (Reg << 1) | (unsigned)CanClobber;
if (Slot > VirtRegMap::MAX_STACK_SLOT)
DOUT << "Remembering RM#" << Slot-VirtRegMap::MAX_STACK_SLOT-1;
@ -375,7 +329,7 @@ public:
/// stack slot must be available in a physreg for this query to make sense.
bool canClobberPhysReg(int Slot) const {
assert(SpillSlotsAvailable.count(Slot) && "Slot not available!");
return SpillSlotsAvailable.find(Slot)->second.first & 1;
return SpillSlotsAvailable.find(Slot)->second & 1;
}
/// disallowClobberPhysReg - Unset the CanClobber bit of the specified
@ -404,9 +358,9 @@ void AvailableSpills::disallowClobberPhysRegOnly(unsigned PhysReg) {
while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
int Slot = I->second;
I++;
assert((SpillSlotsAvailable[Slot].first >> 1) == PhysReg &&
assert((SpillSlotsAvailable[Slot] >> 1) == PhysReg &&
"Bidirectional map mismatch!");
SpillSlotsAvailable[Slot].first &= ~1;
SpillSlotsAvailable[Slot] &= ~1;
DOUT << "PhysReg " << MRI->getName(PhysReg)
<< " copied, it is available for use but can no longer be modified\n";
}
@ -429,7 +383,7 @@ void AvailableSpills::ClobberPhysRegOnly(unsigned PhysReg) {
while (I != PhysRegsAvailable.end() && I->first == PhysReg) {
int Slot = I->second;
PhysRegsAvailable.erase(I++);
assert((SpillSlotsAvailable[Slot].first >> 1) == PhysReg &&
assert((SpillSlotsAvailable[Slot] >> 1) == PhysReg &&
"Bidirectional map mismatch!");
SpillSlotsAvailable.erase(Slot);
DOUT << "PhysReg " << MRI->getName(PhysReg)
@ -454,9 +408,9 @@ void AvailableSpills::ClobberPhysReg(unsigned PhysReg) {
/// changes. This removes information about which register the previous value
/// for this slot lives in (as the previous value is dead now).
void AvailableSpills::ModifyStackSlot(int Slot) {
std::map<int, SSInfo>::iterator It = SpillSlotsAvailable.find(Slot);
std::map<int, unsigned>::iterator It = SpillSlotsAvailable.find(Slot);
if (It == SpillSlotsAvailable.end()) return;
unsigned Reg = It->second.first >> 1;
unsigned Reg = It->second >> 1;
SpillSlotsAvailable.erase(It);
// This register may hold the value of multiple stack slots, only remove this
@ -794,8 +748,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
unsigned PhysReg;
// Check to see if this stack slot is available.
MachineInstr *SSMI = NULL;
if ((PhysReg = Spills.getSpillSlotPhysReg(StackSlot, SSMI))) {
if ((PhysReg = Spills.getSpillSlotPhysReg(StackSlot))) {
// This spilled operand might be part of a two-address operand. If this
// is the case, then changing it will necessarily require changing the
// def part of the instruction as well. However, in some cases, we
@ -825,9 +778,6 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
<< MRI->getName(VRM.getPhys(VirtReg)) << "\n";
MI.getOperand(i).setReg(PhysReg);
if (ti == -1)
Spills.addLastUse(PhysReg, &MI);
// The only technical detail we have is that we don't know that
// PhysReg won't be clobbered by a reloaded stack slot that occurs
// later in the instruction. In particular, consider 'op V1, V2'.
@ -894,11 +844,8 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
ReusedOperands.markClobbered(DesignatedReg);
MRI->copyRegToReg(MBB, &MI, DesignatedReg, PhysReg, RC);
// Extend the live range of the MI that last kill the register if
// necessary.
MachineInstr *CopyMI = prior(MII);
UpdateKills(*CopyMI, RegKills, KillOps);
Spills.addLastUse(PhysReg, CopyMI);
// This invalidates DesignatedReg.
Spills.ClobberPhysReg(DesignatedReg);
@ -973,8 +920,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
if (FrameIdx == SS) {
// If this spill slot is available, turn it into a copy (or nothing)
// instead of leaving it as a load!
MachineInstr *SSMI = NULL;
if (unsigned InReg = Spills.getSpillSlotPhysReg(SS, SSMI)) {
if (unsigned InReg = Spills.getSpillSlotPhysReg(SS)) {
DOUT << "Promoted Load To Copy: " << MI;
if (DestReg != InReg) {
MRI->copyRegToReg(MBB, &MI, DestReg, InReg,
@ -988,14 +934,6 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
} else
DOUT << "Removing now-noop copy: " << MI;
if (NextMII != MBB.end()) {
// If NextMII uses InReg and the use is not a two address
// operand, mark it killed.
int UIdx = NextMII->findRegisterUseOperandIdx(InReg);
if (UIdx != -1)
Spills.addLastUse(InReg, &(*NextMII));
}
VRM.RemoveFromFoldedVirtMap(&MI);
MBB.erase(&MI);
Erased = true;
@ -1065,7 +1003,6 @@ 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);
Erased = true;
VRM.RemoveFromFoldedVirtMap(&MI);
@ -1143,7 +1080,6 @@ 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);
Erased = true;
VRM.RemoveFromFoldedVirtMap(&MI);