Re-enable branchfolding common code hoisting optimization. Fixed a liveness test bug and also taught it to update liveins.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131241 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index 6fc077b..0ca54ac 100644
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -1354,10 +1354,6 @@
/// NOTE: This optimization does not update live-in information so it must be
/// run after all passes that require correct liveness information.
bool BranchFolder::HoistCommonCode(MachineFunction &MF) {
-#if 1
- // FIXME: Temporarily disabled.
- return false;
-#endif
bool MadeChange = false;
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ) {
MachineBasicBlock *MBB = I++;
@@ -1472,10 +1468,10 @@
Uses.erase(Reg);
for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR)
Uses.erase(*SR); // Use getSubRegisters to be conservative
- Defs.insert(Reg);
- for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
- Defs.insert(*AS);
}
+ Defs.insert(Reg);
+ for (const unsigned *AS = TRI->getAliasSet(Reg); *AS; ++AS)
+ Defs.insert(*AS);
}
}
@@ -1511,7 +1507,8 @@
return false;
bool HasDups = false;
- SmallSet<unsigned, 4> LocalDefs;
+ SmallVector<unsigned, 4> LocalDefs;
+ SmallSet<unsigned, 4> LocalDefsSet;
MachineBasicBlock::iterator TIB = TBB->begin();
MachineBasicBlock::iterator FIB = FBB->begin();
MachineBasicBlock::iterator TIE = TBB->end();
@@ -1568,11 +1565,7 @@
IsSafe = false;
break;
}
-
- LocalDefs.insert(Reg);
- for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR)
- LocalDefs.insert(*SR);
- } else if (!LocalDefs.count(Reg)) {
+ } else if (!LocalDefsSet.count(Reg)) {
if (Defs.count(Reg)) {
// Use is defined by the instruction at the point of insertion.
IsSafe = false;
@@ -1587,6 +1580,28 @@
if (!TIB->isSafeToMove(TII, 0, DontMoveAcrossStore))
break;
+ // Track local defs so we can update liveins.
+ for (unsigned i = 0, e = TIB->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = TIB->getOperand(i);
+ if (!MO.isReg())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!Reg)
+ continue;
+ if (MO.isDef()) {
+ if (!MO.isDead()) {
+ LocalDefs.push_back(Reg);
+ LocalDefsSet.insert(Reg);
+ for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR)
+ LocalDefsSet.insert(*SR);
+ }
+ } else if (MO.isKill() && LocalDefsSet.count(Reg)) {
+ LocalDefsSet.erase(Reg);
+ for (const unsigned *SR = TRI->getSubRegisters(Reg); *SR; ++SR)
+ LocalDefsSet.erase(*SR);
+ }
+ }
+
HasDups = true;;
++TIB;
++FIB;
@@ -1597,6 +1612,16 @@
MBB->splice(Loc, TBB, TBB->begin(), TIB);
FBB->erase(FBB->begin(), FIB);
+
+ // Update livein's.
+ for (unsigned i = 0, e = LocalDefs.size(); i != e; ++i) {
+ unsigned Def = LocalDefs[i];
+ if (LocalDefsSet.count(Def)) {
+ TBB->addLiveIn(Def);
+ FBB->addLiveIn(Def);
+ }
+ }
+
++NumHoist;
return true;
}