mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-12-24 06:30:19 +00:00
Add a simple little improvement to the local spiller to keep track of stores
and delete them if they turn out to be dead. This is a useful little hack that even speeds up some programs. For example, it speeds up Ptrdist/ks from 17.53s to 15.59s, and 188.ammp from 149s to 146s. This also speeds up llc :) git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16630 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
parent
7fb64347d7
commit
52b25db3ef
@ -35,6 +35,7 @@ namespace {
|
||||
Statistic<> NumStores("spiller", "Number of stores added");
|
||||
Statistic<> NumLoads ("spiller", "Number of loads added");
|
||||
Statistic<> NumReused("spiller", "Number of values reused");
|
||||
Statistic<> NumDSE ("spiller", "Number of dead stores elided");
|
||||
|
||||
enum SpillerName { simple, local };
|
||||
|
||||
@ -283,6 +284,14 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
|
||||
// and ".second" is the virtual register that is spilled.
|
||||
std::vector<std::pair<unsigned, unsigned> > DefAndUseVReg;
|
||||
|
||||
// MaybeDeadStores - When we need to write a value back into a stack slot,
|
||||
// keep track of the inserted store. If the stack slot value is never read
|
||||
// (because the value was used from some available register, for example), and
|
||||
// subsequently stored to, the original store is dead. This map keeps track
|
||||
// of inserted stores that are not used. If we see a subsequent store to the
|
||||
// same stack slot, the original store is deleted.
|
||||
std::map<int, MachineInstr*> MaybeDeadStores;
|
||||
|
||||
for (MachineBasicBlock::iterator MII = MBB.begin(), E = MBB.end();
|
||||
MII != E; ) {
|
||||
MachineInstr &MI = *MII;
|
||||
@ -361,6 +370,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
|
||||
ClobberPhysReg(Op.AssignedPhysReg, SpillSlotsAvailable,
|
||||
PhysRegsAvailable);
|
||||
|
||||
// Any stores to this stack slot are not dead anymore.
|
||||
MaybeDeadStores.erase(Op.StackSlot);
|
||||
|
||||
MI.SetMachineOperandReg(Op.Operand, Op.AssignedPhysReg);
|
||||
PhysRegsAvailable[Op.AssignedPhysReg] = Op.StackSlot;
|
||||
SpillSlotsAvailable[Op.StackSlot] = Op.AssignedPhysReg;
|
||||
@ -383,6 +395,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
|
||||
// This invalidates PhysReg.
|
||||
ClobberPhysReg(PhysReg, SpillSlotsAvailable, PhysRegsAvailable);
|
||||
|
||||
// Any stores to this stack slot are not dead anymore.
|
||||
MaybeDeadStores.erase(StackSlot);
|
||||
|
||||
MI.SetMachineOperandReg(i, PhysReg);
|
||||
PhysRegsAvailable[PhysReg] = StackSlot;
|
||||
SpillSlotsAvailable[StackSlot] = PhysReg;
|
||||
@ -423,6 +438,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
|
||||
int SS = VRM.getStackSlot(I->second);
|
||||
DEBUG(std::cerr << " - StackSlot: " << SS << "\n");
|
||||
|
||||
// Any stores to this stack slot are not dead anymore.
|
||||
MaybeDeadStores.erase(SS);
|
||||
|
||||
std::map<int, unsigned>::iterator I = SpillSlotsAvailable.find(SS);
|
||||
if (I != SpillSlotsAvailable.end()) {
|
||||
PhysRegsAvailable.erase(I->second);
|
||||
@ -476,6 +494,14 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, const VirtRegMap &VRM) {
|
||||
DEBUG(std::cerr << "Store:\t" << *next(MII));
|
||||
MI.SetMachineOperandReg(i, PhysReg);
|
||||
|
||||
// If there is a dead store to this stack slot, nuke it now.
|
||||
MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
|
||||
if (LastStore) {
|
||||
++NumDSE;
|
||||
MBB.erase(LastStore);
|
||||
}
|
||||
LastStore = next(MII);
|
||||
|
||||
// If the stack slot value was previously available in some other
|
||||
// register, change it now. Otherwise, make the register available,
|
||||
// in PhysReg.
|
||||
|
Loading…
Reference in New Issue
Block a user