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Use the LiveVariables information to efficiently get local kills. This 

removes the largest scaling problem in the test cases from PR13225 when
ASan is switched to insert basic blocks in the natural CFG order.

It may also solve some scaling problems for more normal code with large
numbers of basic blocks and variables.

llvm-svn: 160194
This commit is contained in:
Chandler Carruth 2012-07-13 21:18:38 +00:00
parent a4056004bf
commit 58c470dc68
1 changed files with 19 additions and 54 deletions
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73
llvm/lib/CodeGen/TwoAddressInstructionPass.cpp
View File

@ -483,32 +483,6 @@ static bool isTwoAddrUse(MachineInstr &MI, unsigned Reg, unsigned &DstReg) {
return false;
}
/// findLocalKill - Look for an instruction below MI in the MBB that kills the
/// specified register. Returns null if there are any other Reg use between the
/// instructions.
static
MachineInstr *findLocalKill(unsigned Reg, MachineBasicBlock *MBB,
MachineInstr *MI, MachineRegisterInfo *MRI,
DenseMap<MachineInstr*, unsigned> &DistanceMap) {
MachineInstr *KillMI = 0;
for (MachineRegisterInfo::use_nodbg_iterator
UI = MRI->use_nodbg_begin(Reg),
UE = MRI->use_nodbg_end(); UI != UE; ++UI) {
MachineInstr *UseMI = &*UI;
if (UseMI == MI || UseMI->getParent() != MBB)
continue;
if (DistanceMap.count(UseMI))
continue;
if (!UI.getOperand().isKill())
return 0;
if (KillMI)
return 0; // -O0 kill markers cannot be trusted?
KillMI = UseMI;
}
return KillMI;
}
/// findOnlyInterestingUse - Given a register, if has a single in-basic block
/// use, return the use instruction if it's a copy or a two-address use.
static
@ -905,13 +879,18 @@ TwoAddressInstructionPass::RescheduleMIBelowKill(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
unsigned Reg) {
// Bail immediately if we don't have LV available. We use it to find kills
// efficiently.
if (!LV)
return false;
MachineInstr *MI = &*mi;
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
if (DI == DistanceMap.end())
// Must be created from unfolded load. Don't waste time trying this.
return false;
MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
MachineInstr *KillMI = LV->getVarInfo(Reg).findKill(MBB);
if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
// Don't mess with copies, they may be coalesced later.
return false;
@ -1012,19 +991,9 @@ TwoAddressInstructionPass::RescheduleMIBelowKill(MachineBasicBlock *MBB,
MBB->splice(KillPos, MBB, From, To);
DistanceMap.erase(DI);
if (LV) {
// Update live variables
LV->removeVirtualRegisterKilled(Reg, KillMI);
LV->addVirtualRegisterKilled(Reg, MI);
} else {
for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = KillMI->getOperand(i);
if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
continue;
MO.setIsKill(false);
}
MI->addRegisterKilled(Reg, 0);
}
// Update live variables
LV->removeVirtualRegisterKilled(Reg, KillMI);
LV->addVirtualRegisterKilled(Reg, MI);
return true;
}
@ -1061,13 +1030,18 @@ TwoAddressInstructionPass::RescheduleKillAboveMI(MachineBasicBlock *MBB,
MachineBasicBlock::iterator &mi,
MachineBasicBlock::iterator &nmi,
unsigned Reg) {
// Bail immediately if we don't have LV available. We use it to find kills
// efficiently.
if (!LV)
return false;
MachineInstr *MI = &*mi;
DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(MI);
if (DI == DistanceMap.end())
// Must be created from unfolded load. Don't waste time trying this.
return false;
MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
MachineInstr *KillMI = LV->getVarInfo(Reg).findKill(MBB);
if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
// Don't mess with copies, they may be coalesced later.
return false;
@ -1165,19 +1139,10 @@ TwoAddressInstructionPass::RescheduleKillAboveMI(MachineBasicBlock *MBB,
nmi = llvm::prior(InsertPos); // Backtrack so we process the moved instr.
DistanceMap.erase(DI);
if (LV) {
// Update live variables
LV->removeVirtualRegisterKilled(Reg, KillMI);
LV->addVirtualRegisterKilled(Reg, MI);
} else {
for (unsigned i = 0, e = KillMI->getNumOperands(); i != e; ++i) {
MachineOperand &MO = KillMI->getOperand(i);
if (!MO.isReg() || !MO.isUse() || MO.getReg() != Reg)
continue;
MO.setIsKill(false);
}
MI->addRegisterKilled(Reg, 0);
}
// Update live variables
LV->removeVirtualRegisterKilled(Reg, KillMI);
LV->addVirtualRegisterKilled(Reg, MI);
return true;
}