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Revert r160194, which switched to use LV information for finding local

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kills.

This is causing miscompiles that I'm working on tracking down.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160196 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chandler Carruth 2012-07-13 22:23:32 +00:00
parent 5583415909
commit cb41e5f6f2
1 changed files with 54 additions and 19 deletions
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73
lib/CodeGen/TwoAddressInstructionPass.cpp
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@ -483,6 +483,32 @@ 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
@ -879,18 +905,13 @@ 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 = LV->getVarInfo(Reg).findKill(MBB);
MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
// Don't mess with copies, they may be coalesced later.
return false;
@ -991,9 +1012,19 @@ TwoAddressInstructionPass::RescheduleMIBelowKill(MachineBasicBlock *MBB,
MBB->splice(KillPos, MBB, From, To);
DistanceMap.erase(DI);
// Update live variables
LV->removeVirtualRegisterKilled(Reg, KillMI);
LV->addVirtualRegisterKilled(Reg, MI);
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);
}
return true;
}
@ -1030,18 +1061,13 @@ 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 = LV->getVarInfo(Reg).findKill(MBB);
MachineInstr *KillMI = findLocalKill(Reg, MBB, mi, MRI, DistanceMap);
if (!KillMI || KillMI->isCopy() || KillMI->isCopyLike())
// Don't mess with copies, they may be coalesced later.
return false;
@ -1139,10 +1165,19 @@ TwoAddressInstructionPass::RescheduleKillAboveMI(MachineBasicBlock *MBB,
nmi = llvm::prior(InsertPos); // Backtrack so we process the moved instr.
DistanceMap.erase(DI);
// Update live variables
LV->removeVirtualRegisterKilled(Reg, KillMI);
LV->addVirtualRegisterKilled(Reg, MI);
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);
}
return true;
}