[llvm-commits] [llvm] r61802 - /llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp

[Owen Anderson]

Author: resistor
Date: Tue Jan  6 01:53:32 2009
New Revision: 61802

URL: http://llvm.org/viewvc/llvm-project?rev=61802&view=rev
Log:
The phi construction algorithm used for interval reconstruction is complicated by
two address instructions.  We need to keep track of things we've processed AS USES
independetly of whether we've processed them as defs.

This fixes all known miscompilations when reconstruction is turned on.

Modified:
    llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp

Modified: llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp?rev=61802&r1=61801&r2=61802&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp (original)
+++ llvm/trunk/lib/CodeGen/PreAllocSplitting.cpp Tue Jan  6 01:53:32 2009
@@ -175,6 +175,7 @@
     VNInfo* PerformPHIConstruction(MachineBasicBlock::iterator use,
                                    MachineBasicBlock* MBB,
                                    LiveInterval* LI,
+                                   SmallPtrSet<MachineInstr*, 4>& Visited,
             DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Defs,
             DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Uses,
                                       DenseMap<MachineInstr*, VNInfo*>& NewVNs,
@@ -593,6 +594,7 @@
                                                 MachineBasicBlock::iterator use,
                                                          MachineBasicBlock* MBB,
                                                                LiveInterval* LI,
+                                       SmallPtrSet<MachineInstr*, 4>& Visited,
              DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Defs,
              DenseMap<MachineBasicBlock*, SmallPtrSet<MachineInstr*, 2> >& Uses,
                                        DenseMap<MachineInstr*, VNInfo*>& NewVNs,
@@ -600,7 +602,9 @@
                                  DenseMap<MachineBasicBlock*, VNInfo*>& Phis,
                                               bool toplevel, bool intrablock) {
   // Return memoized result if it's available.
-  if (intrablock && NewVNs.count(use))
+  if (toplevel && Visited.count(use) && NewVNs.count(use))
+    return NewVNs[use];
+  else if (!toplevel && intrablock && NewVNs.count(use))
     return NewVNs[use];
   else if (!intrablock && LiveOut.count(MBB))
     return LiveOut[MBB];
@@ -624,8 +628,8 @@
     
     if (MBB->pred_size() == 1) {
       Phis[MBB] = ret = PerformPHIConstruction((*MBB->pred_begin())->end(),
-                                          *(MBB->pred_begin()), LI, Defs,
-                                          Uses, NewVNs, LiveOut, Phis,
+                                          *(MBB->pred_begin()), LI, Visited,
+                                          Defs, Uses, NewVNs, LiveOut, Phis,
                                           false, false);
       unsigned EndIndex = 0;
       if (intrablock) {
@@ -646,9 +650,9 @@
       DenseMap<MachineBasicBlock*, VNInfo*> IncomingVNs;
       for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(),
            PE = MBB->pred_end(); PI != PE; ++PI) {
-        VNInfo* Incoming = PerformPHIConstruction((*PI)->end(), *PI, LI, Defs,
-                                            Uses, NewVNs, LiveOut, Phis,
-                                            false, false);
+        VNInfo* Incoming = PerformPHIConstruction((*PI)->end(), *PI, LI, 
+                                            Visited, Defs, Uses, NewVNs,
+                                            LiveOut, Phis, false, false);
         if (Incoming != 0)
           IncomingVNs[*PI] = Incoming;
       }
@@ -732,7 +736,7 @@
 
     // Now, recursively phi construct the VNInfo for the use we found,
     // and then extend it to include the instruction we care about
-    ret = PerformPHIConstruction(walker, MBB, LI, Defs, Uses,
+    ret = PerformPHIConstruction(walker, MBB, LI, Visited, Defs, Uses,
                                  NewVNs, LiveOut, Phis, false, true);
     
     // FIXME: Need to set kills properly for inter-block stuff.
@@ -789,7 +793,7 @@
     if (foundDef)
       ret = NewVNs[walker];
     else
-      ret = PerformPHIConstruction(walker, MBB, LI, Defs, Uses,
+      ret = PerformPHIConstruction(walker, MBB, LI, Visited, Defs, Uses,
                                    NewVNs, LiveOut, Phis, false, true);
 
     if (foundUse && LI->isKill(ret, StartIndex))
@@ -803,8 +807,11 @@
   
   // Memoize results so we don't have to recompute them.
   if (!intrablock) LiveOut[MBB] = ret;
-  else NewVNs[use] = ret;
-  
+  else {
+    NewVNs[use] = ret;
+    Visited.insert(use);
+  }
+
   return ret;
 }
 
@@ -831,7 +838,14 @@
     unsigned DefIdx = LIs->getInstructionIndex(&*DI);
     DefIdx = LiveIntervals::getDefIndex(DefIdx);
     
-    VNInfo* NewVN = LI->getNextValue(DefIdx, /*FIXME*/ 0, Alloc);
+    VNInfo* NewVN = LI->getNextValue(DefIdx, 0, Alloc);
+    
+    // If the def is a move, set the copy field.
+    unsigned source, dest;
+    if (TII->isMoveInstr(*DI, source, dest))
+      if (dest == LI->reg)
+        NewVN->copy = &*DI;
+    
     NewVNs[&*DI] = NewVN;
   }
   
@@ -845,9 +859,10 @@
   // the way.
   DenseMap<MachineBasicBlock*, VNInfo*> LiveOut;
   DenseMap<MachineBasicBlock*, VNInfo*> Phis;
+  SmallPtrSet<MachineInstr*, 4> Visited;
   for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(LI->reg),
        UE = MRI->use_end(); UI != UE; ++UI) {
-    PerformPHIConstruction(&*UI, UI->getParent(), LI, Defs,
+    PerformPHIConstruction(&*UI, UI->getParent(), LI, Visited, Defs,
                            Uses, NewVNs, LiveOut, Phis, true, true); 
   }
   
@@ -1116,7 +1131,6 @@
   }
 
   RepairLiveInterval(CurrLI, ValNo, DefMI, RestoreIdx);
-
   ++NumSplits;
   ++NumRemats;
   return true;