Enable cross register class coalescing.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76281 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/VirtRegRewriter.cpp b/lib/CodeGen/VirtRegRewriter.cpp
index abaa8bd..9537c05 100644
--- a/lib/CodeGen/VirtRegRewriter.cpp
+++ b/lib/CodeGen/VirtRegRewriter.cpp
@@ -1344,6 +1344,31 @@
++NumStores;
}
+ /// isSafeToDelete - Return true if this instruction doesn't produce any side
+ /// effect and all of its defs are dead.
+ static bool isSafeToDelete(MachineInstr &MI) {
+ const TargetInstrDesc &TID = MI.getDesc();
+ if (TID.mayLoad() || TID.mayStore() || TID.isCall() || TID.isTerminator() ||
+ TID.isCall() || TID.isBarrier() || TID.isReturn() ||
+ TID.hasUnmodeledSideEffects())
+ return false;
+ if (TID.getImplicitDefs())
+ return false;
+ for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI.getOperand(i);
+ if (!MO.isReg() || !MO.getReg())
+ continue;
+ if (MO.isDef() && !MO.isDead())
+ return false;
+ if (MO.isUse() && MO.isKill())
+ // FIXME: We can't remove kill markers or else the scavenger will assert.
+ // An alternative is to add a ADD pseudo instruction to replace kill
+ // markers.
+ return false;
+ }
+ return true;
+ }
+
/// TransferDeadness - A identity copy definition is dead and it's being
/// removed. Find the last def or use and mark it as dead / kill.
void TransferDeadness(MachineBasicBlock *MBB, unsigned CurDist,
@@ -1385,9 +1410,7 @@
if (LastUD->isDef()) {
// If the instruction has no side effect, delete it and propagate
// backward further. Otherwise, mark is dead and we are done.
- const TargetInstrDesc &TID = LastUDMI->getDesc();
- if (TID.mayStore() || TID.isCall() || TID.isTerminator() ||
- TID.hasUnmodeledSideEffects()) {
+ if (!isSafeToDelete(*LastUDMI)) {
LastUD->setIsDead();
break;
}
@@ -2170,7 +2193,15 @@
}
}
ProcessNextInst:
- DistanceMap.insert(std::make_pair(&MI, Dist++));
+ // Delete dead instructions without side effects.
+ if (!Erased && !BackTracked && isSafeToDelete(MI)) {
+ InvalidateKills(MI, TRI, RegKills, KillOps);
+ VRM.RemoveMachineInstrFromMaps(&MI);
+ MBB.erase(&MI);
+ Erased = true;
+ }
+ if (!Erased)
+ DistanceMap.insert(std::make_pair(&MI, Dist++));
if (!Erased && !BackTracked) {
for (MachineBasicBlock::iterator II = &MI; II != NextMII; ++II)
UpdateKills(*II, TRI, RegKills, KillOps);