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If a MI's def is remat as well as spilled, and the store is later deemed dead, mark the def operand as isDead.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41083 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-08-14 20:23:13 +00:00
parent a6a8663894
commit c91f0b8068
1 changed files with 29 additions and 2 deletions
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31
lib/CodeGen/VirtRegMap.cpp
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@ -433,12 +433,39 @@ void AvailableSpills::ModifyStackSlotOrReMat(int SlotOrReMat) {
/// InvalidateKills - MI is going to be deleted. If any of its operands are
/// marked kill, then invalidate the information.
static void InvalidateKills(MachineInstr &MI, BitVector &RegKills,
std::vector<MachineOperand*> &KillOps) {
std::vector<MachineOperand*> &KillOps,
MachineInstr *NewDef = NULL) {
for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
MachineOperand &MO = MI.getOperand(i);
if (!MO.isReg() || !MO.isUse() || !MO.isKill())
continue;
unsigned Reg = MO.getReg();
if (NewDef) {
// Due to remat, it's possible this reg isn't being reused. That is,
// the def of this reg (by prev MI) is now dead.
bool FoundUse = false, Done = false;
MachineBasicBlock::iterator I = MI, E = NewDef;
++I; ++E;
for (; !Done && I != E; ++I) {
MachineInstr *NMI = I;
for (unsigned j = 0, ee = NMI->getNumOperands(); j != ee; ++j) {
MachineOperand &MO = NMI->getOperand(j);
if (!MO.isReg() || MO.getReg() != Reg)
continue;
if (MO.isUse())
FoundUse = true;
Done = true; // Stop after scanning all the operands of this MI.
}
}
if (!FoundUse) {
// Def is dead!
MachineBasicBlock::iterator MII = MI;
MachineInstr *DefMI = prior(MII);
MachineOperand *DefOp = DefMI->findRegisterDefOperand(Reg);
assert(DefOp && "Missing def?");
DefOp->setIsDead();
}
}
if (KillOps[Reg] == &MO) {
RegKills.reset(Reg);
KillOps[Reg] = NULL;
@ -1081,7 +1108,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
if (LastStore) {
DOUT << "Removed dead store:\t" << *LastStore;
++NumDSE;
InvalidateKills(*LastStore, RegKills, KillOps);
InvalidateKills(*LastStore, RegKills, KillOps, &MI);
MBB.erase(LastStore);
VRM.RemoveFromFoldedVirtMap(LastStore);
}