3 files changed, 74 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp b/llvm/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
index 3b61e1e6b78..633b621d805 100644
--- a/llvm/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
+++ b/llvm/lib/CodeGen/RegAlloc/PhyRegAlloc.cpp
@@ -22,7 +22,7 @@ PhyRegAlloc::PhyRegAlloc(const Method *const M,
 			  Meth(M), TM(tm), LVI(Lvi), LRI(M, tm, RegClassList), 
 			  MRI( tm.getRegInfo() ),
                           NumOfRegClasses(MRI.getNumOfRegClasses()),
-			  AddedInstrMap(), StackOffsets()
+			  AddedInstrMap(), StackOffsets(), PhiInstList()
 
 {
   // **TODO: use an actual reserved color list 
@@ -227,7 +227,7 @@ void PhyRegAlloc::buildInterferenceGraphs()
     // iterate over all the machine instructions in BB
     for( ; MInstIterator != MIVec.end(); ++MInstIterator) {  
 
-      const MachineInstr *const MInst = *MInstIterator; 
+      const MachineInstr * MInst = *MInstIterator; 
 
       // get the LV set after the instruction
       const LiveVarSet *const LVSetAI = 
@@ -268,6 +268,12 @@ void PhyRegAlloc::buildInterferenceGraphs()
 	    addInterference( MInst->getImplicitRef(z), LVSetAI, isCallInst );
       }
 
+
+      // record phi instrns in PhiInstList
+      if( TM.getInstrInfo().isDummyPhiInstr(MInst->getOpCode()) )
+	PhiInstList.push_back( MInst );
+
+
     } // for all machine instructions in BB
     
   } // for all BBs in method
@@ -1115,6 +1121,53 @@ void PhyRegAlloc::allocateStackSpace4SpilledLRs()
 
 
 
+void PhyRegAlloc::insertPhiEleminateInstrns() {
+
+  vector< const MachineInstr *>:: const_iterator It = PhiInstList.begin();
+
+  for( ; It !=  PhiInstList.end(); ++It ) {
+
+    const MachineInstr *PhiMI = *It;
+
+    Value *Def =  (PhiMI->getOperand(0)).getVRegValue();
+    const LiveRange *LROfDef = LRI.getLiveRangeForValue( Def );
+
+    assert(LROfDef && "NO LR for a def of phi");
+
+    for(unsigned OpNum=1; OpNum < PhiMI->getNumOperands(); ++OpNum) {
+
+      if( OpNum % 2) {   // i.e., the  
+
+	Value *Use =  (PhiMI->getOperand(OpNum)).getVRegValue();
+
+	const LiveRange *LROfUse = LRI.getLiveRangeForValue( Use );
+
+	if( LROfUse != LROfDef) {
+
+	  // the result of the phi received a live range different to
+	  // that of this use, so copy it
+
+	  const BasicBlock *BB =  
+	    (BasicBlock *) (PhiMI->getOperand(OpNum+1)).getVRegValue();
+
+	  MachineCodeForBasicBlock& MIVec = (BB)->getMachineInstrVec();
+
+	  MachineInstr *AdI = MRI.cpValue2Value(Use, Def);
+
+	  MIVec.push_back( AdI );
+
+	  cerr << "\n%%% Added a phi elimination instr: " << *AdI;
+
+	} // if LRs are different
+	
+      } // if operand is an incoming Value (i.e., not a BB)
+      
+    } // for all phi operands
+
+  } // for all phi instrns in PhiInstMap
+    
+}
+
 
 
 //----------------------------------------------------------------------------
@@ -1150,6 +1203,10 @@ void PhyRegAlloc::allocateRegisters()
   
   LRI.coalesceLRs();                    // coalesce all live ranges
   
+  // coalscing could not get rid of all phi's, add phi elimination
+  // instructions
+  // insertPhiEleminateInstrns();
+
   if( DEBUG_RA) {
     // print all LRs in all reg classes
     for( unsigned int rc=0; rc < NumOfRegClasses  ; rc++)  
diff --git a/llvm/lib/Target/Sparc/SparcInternals.h b/llvm/lib/Target/Sparc/SparcInternals.h
index 653a2018a77..72b234f72cb 100644
--- a/llvm/lib/Target/Sparc/SparcInternals.h
+++ b/llvm/lib/Target/Sparc/SparcInternals.h
@@ -401,6 +401,9 @@ class UltraSparcRegInfo : public MachineRegInfo
   MachineInstr * cpMem2RegMI(const unsigned SrcPtrReg, const int Offset,
 			     const unsigned DestReg, const int RegType) const;
 
+  MachineInstr* cpValue2Value(Value *Src, Value *Dest) const;
+
+
   inline bool isRegVolatile(const int RegClassID, const int Reg) const {
     return  (MachineRegClassArr[RegClassID])->isRegVolatile(Reg);
   }
diff --git a/llvm/lib/Target/Sparc/SparcRegInfo.cpp b/llvm/lib/Target/Sparc/SparcRegInfo.cpp
index 11180f5995b..a34a5305ae7 100644
--- a/llvm/lib/Target/Sparc/SparcRegInfo.cpp
+++ b/llvm/lib/Target/Sparc/SparcRegInfo.cpp
@@ -979,7 +979,19 @@ MachineInstr * UltraSparcRegInfo::cpMem2RegMI(const unsigned SrcPtrReg,
 }
 
 
+MachineInstr* UltraSparcRegInfo::cpValue2Value(Value *Src, Value *Dest) const {
 
+  MachineInstr * MI = NULL;
+
+  MI = new MachineInstr(ADD, 3);
+  MI->SetMachineOperand(0, MachineOperand:: MO_VirtualRegister, Src, false);
+  MI->SetMachineOperand(1, SparcIntRegOrder::g0, false);
+  MI->SetMachineOperand(2, MachineOperand:: MO_VirtualRegister, Dest, true);
+  
+
+  return MI;
+
+}