From 8fe00540fc6e1531d909d0688cc75a77b7dfa330 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Tue, 31 Mar 2009 08:26:26 +0000
Subject: Revert r68073. It's causing a failure in the Apple-style builds.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68092 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/Spiller.cpp | 93 ++++++++++++++++++++++++++++++++-----------------
 1 file changed, 62 insertions(+), 31 deletions(-)

(limited to 'lib/CodeGen/Spiller.cpp')

diff --git a/lib/CodeGen/Spiller.cpp b/lib/CodeGen/Spiller.cpp
index 7b2a32f1c7..4bfae39c42 100644
--- a/lib/CodeGen/Spiller.cpp
+++ b/lib/CodeGen/Spiller.cpp
@@ -578,6 +578,20 @@ bool LocalSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
   DOUT << "**** Post Machine Instrs ****\n";
   DEBUG(MF.dump());
 
+  // See if any of the spills we added are actually dead and can be deleted.
+  for (std::vector<MachineInstr*> >::iterator
+         I = AddedSpills.begin(), E = AddedSpills.end(); I != E; ++I) {
+    MachineInstr *MI = *I;
+
+    if (VRM.OnlyUseOfStackSlot(MI)) {
+      MachineBasicBlock *MBB = MI->getParent();
+      DOUT << "Removed dead store:\t" << *MI;
+      VRM.RemoveMachineInstrFromMaps(MI);
+      MBB->erase(MI);
+      ++NumDSE;
+    }
+  }
+
   // Mark unused spill slots.
   MachineFrameInfo *MFI = MF.getFrameInfo();
   int SS = VRM.getLowSpillSlot();
@@ -588,6 +602,7 @@ bool LocalSpiller::runOnMachineFunction(MachineFunction &MF, VirtRegMap &VRM) {
         ++NumDSS;
       }
 
+  AddedSpills.clear();
   return true;
 }
 
@@ -798,9 +813,50 @@ bool LocalSpiller::CommuteToFoldReload(MachineBasicBlock &MBB,
   return false;
 }
 
+void LocalSpiller::RemoveDeadStore(MachineInstr *Store,
+                                   MachineBasicBlock &MBB,
+                                   MachineBasicBlock::iterator &MII,
+                                   SmallSet<MachineInstr*, 4> &ReMatDefs,
+                                   BitVector &RegKills,
+                                   std::vector<MachineOperand*> &KillOps,
+                                   VirtRegMap &VRM) {
+  // If there is a dead store to this stack slot, nuke it now.
+  DOUT << "Removed dead store:\t" << *Store;
+  ++NumDSE;
+  SmallVector<unsigned, 2> KillRegs;
+  InvalidateKills(*Store, RegKills, KillOps, &KillRegs);
+
+  MachineBasicBlock::iterator PrevMII = Store;
+  bool CheckDef = PrevMII != MBB.begin();
+  if (CheckDef) --PrevMII;
+
+  VRM.RemoveMachineInstrFromMaps(Store);
+  MBB.erase(Store);
+
+  if (CheckDef) {
+    // Look at defs of killed registers on the store. Mark the defs as dead
+    // since the store has been deleted and they aren't being reused.
+    for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
+      bool HasOtherDef = false;
+
+      if (InvalidateRegDef(PrevMII, *MII, KillRegs[j], HasOtherDef)) {
+        MachineInstr *DeadDef = PrevMII;
+
+        if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
+          // FIXME: This assumes a remat def does not have side effects.
+          VRM.RemoveMachineInstrFromMaps(DeadDef);
+          MBB.erase(DeadDef);
+          ++NumDRM;
+        }
+      }
+    }
+  }
+}
+
 /// SpillRegToStackSlot - Spill a register to a specified stack slot. Check if
 /// the last store to the same slot is now dead. If so, remove the last store.
-void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
+void
+LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator &MII,
                                   int Idx, unsigned PhysReg, int StackSlot,
                                   const TargetRegisterClass *RC,
@@ -816,36 +872,8 @@ void LocalSpiller::SpillRegToStackSlot(MachineBasicBlock &MBB,
   DOUT << "Store:\t" << *StoreMI;
 
   // If there is a dead store to this stack slot, nuke it now.
-  if (LastStore) {
-    DOUT << "Removed dead store:\t" << *LastStore;
-    ++NumDSE;
-    SmallVector<unsigned, 2> KillRegs;
-    InvalidateKills(*LastStore, RegKills, KillOps, &KillRegs);
-    MachineBasicBlock::iterator PrevMII = LastStore;
-    bool CheckDef = PrevMII != MBB.begin();
-    if (CheckDef)
-      --PrevMII;
-    VRM.RemoveMachineInstrFromMaps(LastStore);
-    MBB.erase(LastStore);
-    if (CheckDef) {
-      // Look at defs of killed registers on the store. Mark the defs
-      // as dead since the store has been deleted and they aren't
-      // being reused.
-      for (unsigned j = 0, ee = KillRegs.size(); j != ee; ++j) {
-        bool HasOtherDef = false;
-        if (InvalidateRegDef(PrevMII, *MII, KillRegs[j], HasOtherDef)) {
-          MachineInstr *DeadDef = PrevMII;
-          if (ReMatDefs.count(DeadDef) && !HasOtherDef) {
-            // FIXME: This assumes a remat def does not have side
-            // effects.
-            VRM.RemoveMachineInstrFromMaps(DeadDef);
-            MBB.erase(DeadDef);
-            ++NumDRM;
-          }
-        }
-      }
-    }
-  }
+  if (LastStore)
+    RemoveDeadStore(LastStore, MBB, MII, ReMatDefs, RegKills, KillOps, VRM);
 
   LastStore = next(MII);
 
@@ -1060,6 +1088,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
     if (VRM.isSpillPt(&MI)) {
       std::vector<std::pair<unsigned,bool> > &SpillRegs =
         VRM.getSpillPtSpills(&MI);
+
       for (unsigned i = 0, e = SpillRegs.size(); i != e; ++i) {
         unsigned VirtReg = SpillRegs[i].first;
         bool isKill = SpillRegs[i].second;
@@ -1073,7 +1102,9 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM,
         VRM.addSpillSlotUse(StackSlot, StoreMI);
         DOUT << "Store:\t" << *StoreMI;
         VRM.virtFolded(VirtReg, StoreMI, VirtRegMap::isMod);
+        AddedSpills.push_back(StoreMI);
       }
+
       NextMII = next(MII);
     }
 
-- 
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