Author: evancheng
Date: Tue Aug 14 15:23:13 2007
New Revision: 41083
URL: http://llvm.org/viewvc/llvm-project?rev=41083&view=rev
Log:
If a MI's def is remat as well as spilled, and the store is later deemed dead,
mark the def operand as isDead.
Modified:
llvm/trunk/lib/CodeGen/VirtRegMap.cpp
Modified: llvm/trunk/lib/CodeGen/VirtRegMap.cpp
URL:
http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/VirtRegMap.cpp?rev=41083&r1=41082&r2=41083&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/VirtRegMap.cpp (original)
+++ llvm/trunk/lib/CodeGen/VirtRegMap.cpp Tue Aug 14 15:23:13 2007
@@ -433,12 +433,39 @@
/// 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 @@
if (LastStore) {
DOUT << "Removed dead store:\t" << *LastStore;
++NumDSE;
- InvalidateKills(*LastStore, RegKills, KillOps);
+ InvalidateKills(*LastStore, RegKills, KillOps, &MI);
MBB.erase(LastStore);
VRM.RemoveFromFoldedVirtMap(LastStore);
}
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