Remove unused variable.

[oota-llvm.git] / lib / CodeGen / ProcessImplicitDefs.cpp

diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index c04d65637c94ad5ff12e6bd6fb76e2e2cc10dab1..4ef5b594cd9b4bc621cb414ae7db80af31022044 100644 (file)
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -26,6 +26,8 @@
 using namespace llvm;
 
 char ProcessImplicitDefs::ID = 0;
+char &llvm::ProcessImplicitDefsID = ProcessImplicitDefs::ID;
+
 INITIALIZE_PASS_BEGIN(ProcessImplicitDefs, "processimpdefs",
                 "Process Implicit Definitions", false, false)
 INITIALIZE_PASS_DEPENDENCY(LiveVariables)
@@ -36,7 +38,6 @@ void ProcessImplicitDefs::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesCFG();
   AU.addPreserved<AliasAnalysis>();
   AU.addPreserved<LiveVariables>();
-  AU.addRequired<LiveVariables>();
   AU.addPreservedID(MachineLoopInfoID);
   AU.addPreservedID(MachineDominatorsID);
   AU.addPreservedID(TwoAddressInstructionPassID);
@@ -50,10 +51,10 @@ ProcessImplicitDefs::CanTurnIntoImplicitDef(MachineInstr *MI,
                                             SmallSet<unsigned, 8> &ImpDefRegs) {
   switch(OpIdx) {
   case 1:
-    return MI->isCopy() && (MI->getOperand(0).getSubReg() == 0 ||
+    return MI->isCopy() && (!MI->getOperand(0).readsReg() ||
                             ImpDefRegs.count(MI->getOperand(0).getReg()));
   case 2:
-    return MI->isSubregToReg() && (MI->getOperand(0).getSubReg() == 0 ||
+    return MI->isSubregToReg() && (!MI->getOperand(0).readsReg() ||
                                   ImpDefRegs.count(MI->getOperand(0).getReg()));
   default: return false;
   }
@@ -66,7 +67,7 @@ static bool isUndefCopy(MachineInstr *MI, unsigned Reg,
     MachineOperand &MO1 = MI->getOperand(1);
     if (MO1.getReg() != Reg)
       return false;
-    if (!MO0.getSubReg() || ImpDefRegs.count(MO0.getReg()))
+    if (!MO0.readsReg() || ImpDefRegs.count(MO0.getReg()))
       return true;
     return false;
   }
@@ -87,7 +88,7 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
   TII = fn.getTarget().getInstrInfo();
   TRI = fn.getTarget().getRegisterInfo();
   MRI = &fn.getRegInfo();
-  LV = &getAnalysis<LiveVariables>();
+  LV = getAnalysisIfAvailable<LiveVariables>();
 
   SmallSet<unsigned, 8> ImpDefRegs;
   SmallVector<MachineInstr*, 8> ImpDefMIs;
@@ -105,7 +106,9 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
       MachineInstr *MI = &*I;
       ++I;
       if (MI->isImplicitDef()) {
-        if (MI->getOperand(0).getSubReg())
+        ImpDefMIs.push_back(MI);
+        // Is this a sub-register read-modify-write?
+        if (MI->getOperand(0).readsReg())
           continue;
         unsigned Reg = MI->getOperand(0).getReg();
         ImpDefRegs.insert(Reg);
@@ -113,20 +116,25 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
           for (const unsigned *SS = TRI->getSubRegisters(Reg); *SS; ++SS)
             ImpDefRegs.insert(*SS);
         }
-        ImpDefMIs.push_back(MI);
         continue;
       }
 
       // Eliminate %reg1032:sub<def> = COPY undef.
-      if (MI->isCopy() && MI->getOperand(0).getSubReg()) {
+      if (MI->isCopy() && MI->getOperand(0).readsReg()) {
         MachineOperand &MO = MI->getOperand(1);
         if (MO.isUndef() || ImpDefRegs.count(MO.getReg())) {
-          if (MO.isKill()) {
+          if (LV && MO.isKill()) {
             LiveVariables::VarInfo& vi = LV->getVarInfo(MO.getReg());
             vi.removeKill(MI);
           }
+          unsigned Reg = MI->getOperand(0).getReg();
           MI->eraseFromParent();
           Changed = true;
+
+          // A REG_SEQUENCE may have been expanded into partial definitions.
+          // If this was the last one, mark Reg as implicitly defined.
+          if (TargetRegisterInfo::isVirtualRegister(Reg) && MRI->def_empty(Reg))
+            ImpDefRegs.insert(Reg);
           continue;
         }
       }
@@ -134,7 +142,7 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
       bool ChangedToImpDef = false;
       for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
         MachineOperand& MO = MI->getOperand(i);
-        if (!MO.isReg() || (MO.isDef() && !MO.getSubReg()) || MO.isUndef())
+        if (!MO.isReg() || !MO.readsReg())
           continue;
         unsigned Reg = MO.getReg();
         if (!Reg)
@@ -149,8 +157,10 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
             MI->RemoveOperand(j);
           if (isKill) {
             ImpDefRegs.erase(Reg);
-            LiveVariables::VarInfo& vi = LV->getVarInfo(Reg);
-            vi.removeKill(MI);
+            if (LV) {
+              LiveVariables::VarInfo& vi = LV->getVarInfo(Reg);
+              vi.removeKill(MI);
+            }
           }
           ChangedToImpDef = true;
           Changed = true;
@@ -166,10 +176,10 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
           continue;
         }
         if (MO.isKill() || MI->isRegTiedToDefOperand(i)) {
-          // Make sure other uses of 
+          // Make sure other reads of Reg are also marked <undef>.
           for (unsigned j = i+1; j != e; ++j) {
             MachineOperand &MOJ = MI->getOperand(j);
-            if (MOJ.isReg() && MOJ.isUse() && MOJ.getReg() == Reg)
+            if (MOJ.isReg() && MOJ.getReg() == Reg && MOJ.readsReg())
               MOJ.setIsUndef();
           }
           ImpDefRegs.erase(Reg);
@@ -259,7 +269,7 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
           }
 
           // Update LiveVariables varinfo if the instruction is a kill.
-          if (isKill) {
+          if (LV && isKill) {
             LiveVariables::VarInfo& vi = LV->getVarInfo(Reg);
             vi.removeKill(RMI);
           }