Remove special-casing of return blocks for liveness.

Now that return value registers are return instruction uses, there is no
need for special treatment of return blocks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174416 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 57 deletions

diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index 8d849dc55b..840ddb123e 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -177,7 +177,6 @@ namespace {
                                        unsigned VirtReg, unsigned Hint);
     void spillAll(MachineBasicBlock::iterator MI);
     bool setPhysReg(MachineInstr *MI, unsigned OpNum, unsigned PhysReg);
-    void addRetOperands(MachineBasicBlock *MBB);
   };
   char RAFast::ID = 0;
 }
@@ -774,59 +773,6 @@ void RAFast::handleThroughOperands(MachineInstr *MI,
     UsedInInstr.insert(PartialDefs[i]);
 }
 
-/// addRetOperand - ensure that a return instruction has an operand for each
-/// value live out of the function.
-///
-/// Things marked both call and return are tail calls; do not do this for them.
-/// The tail callee need not take the same registers as input that it produces
-/// as output, and there are dependencies for its input registers elsewhere.
-///
-/// FIXME: This should be done as part of instruction selection, and this helper
-/// should be deleted. Until then, we use custom logic here to create the proper
-/// operand under all circumstances. We can't use addRegisterKilled because that
-/// doesn't make sense for undefined values. We can't simply avoid calling it
-/// for undefined values, because we must ensure that the operand always exists.
-void RAFast::addRetOperands(MachineBasicBlock *MBB) {
-  if (MBB->empty() || !MBB->back().isReturn() || MBB->back().isCall())
-    return;
-
-  MachineInstr *MI = &MBB->back();
-
-  for (MachineRegisterInfo::liveout_iterator
-         I = MBB->getParent()->getRegInfo().liveout_begin(),
-         E = MBB->getParent()->getRegInfo().liveout_end(); I != E; ++I) {
-    unsigned Reg = *I;
-    assert(TargetRegisterInfo::isPhysicalRegister(Reg) &&
-           "Cannot have a live-out virtual register.");
-
-    bool hasDef = PhysRegState[Reg] == regReserved;
-
-    // Check if this register already has an operand.
-    bool Found = false;
-    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
-      MachineOperand &MO = MI->getOperand(i);
-      if (!MO.isReg() || !MO.isUse())
-        continue;
-
-      unsigned OperReg = MO.getReg();
-      if (!TargetRegisterInfo::isPhysicalRegister(OperReg))
-        continue;
-
-      if (OperReg == Reg || TRI->isSuperRegister(OperReg, Reg)) {
-        // If the ret already has an operand for this physreg or a superset,
-        // don't duplicate it. Set the kill flag if the value is defined.
-        if (hasDef && !MO.isKill())
-          MO.setIsKill();
-        Found = true;
-        break;
-      }
-    }
-    if (!Found)
-      MachineInstrBuilder(*MF, MI)
-        .addReg(Reg, llvm::RegState::Implicit | getKillRegState(hasDef));
-  }
-}
-
 void RAFast::AllocateBasicBlock() {
   DEBUG(dbgs() << "\nAllocating " << *MBB);
 
@@ -1109,9 +1055,6 @@ void RAFast::AllocateBasicBlock() {
     MBB->erase(Coalesced[i]);
   NumCopies += Coalesced.size();
 
-  // addRetOperands must run after we've seen all defs in this block.
-  addRetOperands(MBB);
-
   DEBUG(MBB->dump());
 }