X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FProcessImplicitDefs.cpp;h=1ad3479afb4ca70416bd9fbf2772c983babe4844;hb=082120053fdccb7eb21681c09365175f130df210;hp=75875d2835b1cb4428663b6753f4f56eb72b409f;hpb=9cc9bfaf86510790c36198b033f241635614a8d0;p=oota-llvm.git

diff --git a/lib/CodeGen/ProcessImplicitDefs.cpp b/lib/CodeGen/ProcessImplicitDefs.cpp
index 75875d2835b..1ad3479afb4 100644
--- a/lib/CodeGen/ProcessImplicitDefs.cpp
+++ b/lib/CodeGen/ProcessImplicitDefs.cpp
@@ -26,14 +26,18 @@
 using namespace llvm;
 
 char ProcessImplicitDefs::ID = 0;
-static RegisterPass<ProcessImplicitDefs> X("processimpdefs",
-                                           "Process Implicit Definitions.");
+char &llvm::ProcessImplicitDefsID = ProcessImplicitDefs::ID;
+
+INITIALIZE_PASS_BEGIN(ProcessImplicitDefs, "processimpdefs",
+                "Process Implicit Definitions", false, false)
+INITIALIZE_PASS_DEPENDENCY(LiveVariables)
+INITIALIZE_PASS_END(ProcessImplicitDefs, "processimpdefs",
+                "Process Implicit Definitions", false, false)
 
 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);
@@ -41,18 +45,32 @@ void ProcessImplicitDefs::getAnalysisUsage(AnalysisUsage &AU) const {
   MachineFunctionPass::getAnalysisUsage(AU);
 }
 
-bool ProcessImplicitDefs::CanTurnIntoImplicitDef(MachineInstr *MI,
-                                                 unsigned Reg, unsigned OpIdx,
-                                                 const TargetInstrInfo *tii_) {
-  unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
-  if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
-      Reg == SrcReg)
-    return true;
-
-  if (OpIdx == 2 && MI->isSubregToReg())
-    return true;
-  if (OpIdx == 1 && MI->isExtractSubreg())
-    return true;
+bool
+ProcessImplicitDefs::CanTurnIntoImplicitDef(MachineInstr *MI,
+                                            unsigned Reg, unsigned OpIdx,
+                                            SmallSet<unsigned, 8> &ImpDefRegs) {
+  switch(OpIdx) {
+  case 1:
+    return MI->isCopy() && (!MI->getOperand(0).readsReg() ||
+                            ImpDefRegs.count(MI->getOperand(0).getReg()));
+  case 2:
+    return MI->isSubregToReg() && (!MI->getOperand(0).readsReg() ||
+                                  ImpDefRegs.count(MI->getOperand(0).getReg()));
+  default: return false;
+  }
+}
+
+static bool isUndefCopy(MachineInstr *MI, unsigned Reg,
+                        SmallSet<unsigned, 8> &ImpDefRegs) {
+  if (MI->isCopy()) {
+    MachineOperand &MO0 = MI->getOperand(0);
+    MachineOperand &MO1 = MI->getOperand(1);
+    if (MO1.getReg() != Reg)
+      return false;
+    if (!MO0.readsReg() || ImpDefRegs.count(MO0.getReg()))
+      return true;
+    return false;
+  }
   return false;
 }
 
@@ -67,11 +85,10 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
 
   bool Changed = false;
 
-  const TargetInstrInfo *tii_ = fn.getTarget().getInstrInfo();
-  const TargetRegisterInfo *tri_ = fn.getTarget().getRegisterInfo();
-  MachineRegisterInfo *mri_ = &fn.getRegInfo();
-
-  LiveVariables *lv_ = &getAnalysis<LiveVariables>();
+  TII = fn.getTarget().getInstrInfo();
+  TRI = fn.getTarget().getRegisterInfo();
+  MRI = &fn.getRegInfo();
+  LV = getAnalysisIfAvailable<LiveVariables>();
 
   SmallSet<unsigned, 8> ImpDefRegs;
   SmallVector<MachineInstr*, 8> ImpDefMIs;
@@ -89,29 +106,35 @@ 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);
         if (TargetRegisterInfo::isPhysicalRegister(Reg)) {
-          for (const unsigned *SS = tri_->getSubRegisters(Reg); *SS; ++SS)
+          for (const uint16_t *SS = TRI->getSubRegisters(Reg); *SS; ++SS)
             ImpDefRegs.insert(*SS);
         }
-        ImpDefMIs.push_back(MI);
         continue;
       }
 
-      if (MI->isInsertSubreg()) {
-        MachineOperand &MO = MI->getOperand(2);
-        if (ImpDefRegs.count(MO.getReg())) {
-          // %reg1032<def> = INSERT_SUBREG %reg1032, undef, 2
-          // This is an identity copy, eliminate it now.
-          if (MO.isKill()) {
-            LiveVariables::VarInfo& vi = lv_->getVarInfo(MO.getReg());
+      // Eliminate %reg1032:sub<def> = COPY undef.
+      if (MI->isCopy() && MI->getOperand(0).readsReg()) {
+        MachineOperand &MO = MI->getOperand(1);
+        if (MO.isUndef() || ImpDefRegs.count(MO.getReg())) {
+          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;
         }
       }
@@ -119,7 +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.isUse() || MO.isUndef())
+        if (!MO.isReg() || !MO.readsReg())
           continue;
         unsigned Reg = MO.getReg();
         if (!Reg)
@@ -127,15 +150,17 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
         if (!ImpDefRegs.count(Reg))
           continue;
         // Use is a copy, just turn it into an implicit_def.
-        if (CanTurnIntoImplicitDef(MI, Reg, i, tii_)) {
+        if (CanTurnIntoImplicitDef(MI, Reg, i, ImpDefRegs)) {
           bool isKill = MO.isKill();
-          MI->setDesc(tii_->get(TargetOpcode::IMPLICIT_DEF));
+          MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
           for (int j = MI->getNumOperands() - 1, ee = 0; j > ee; --j)
             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;
@@ -144,11 +169,17 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
 
         Changed = true;
         MO.setIsUndef();
+        // This is a partial register redef of an implicit def.
+        // Make sure the whole register is defined by the instruction.
+        if (MO.isDef()) {
+          MI->addRegisterDefined(Reg);
+          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);
@@ -186,8 +217,8 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
       // uses.
       bool Skip = false;
       SmallVector<MachineInstr*, 4> DeadImpDefs;
-      for (MachineRegisterInfo::def_iterator DI = mri_->def_begin(Reg),
-             DE = mri_->def_end(); DI != DE; ++DI) {
+      for (MachineRegisterInfo::def_iterator DI = MRI->def_begin(Reg),
+             DE = MRI->def_end(); DI != DE; ++DI) {
         MachineInstr *DeadImpDef = &*DI;
         if (!DeadImpDef->isImplicitDef()) {
           Skip = true;
@@ -205,8 +236,8 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
       Changed = true;
 
       // Process each use instruction once.
-      for (MachineRegisterInfo::use_iterator UI = mri_->use_begin(Reg),
-             UE = mri_->use_end(); UI != UE; ++UI) {
+      for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(Reg),
+             UE = MRI->use_end(); UI != UE; ++UI) {
         if (UI.getOperand().isUndef())
           continue;
         MachineInstr *RMI = &*UI;
@@ -218,10 +249,8 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
         MachineInstr *RMI = RUses[i];
 
         // Turn a copy use into an implicit_def.
-        unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
-        if (tii_->isMoveInstr(*RMI, SrcReg, DstReg, SrcSubReg, DstSubReg) &&
-            Reg == SrcReg) {
-          RMI->setDesc(tii_->get(TargetOpcode::IMPLICIT_DEF));
+        if (isUndefCopy(RMI, Reg, ImpDefRegs)) {
+          RMI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
 
           bool isKill = false;
           SmallVector<unsigned, 4> Ops;
@@ -240,16 +269,16 @@ bool ProcessImplicitDefs::runOnMachineFunction(MachineFunction &fn) {
           }
 
           // Update LiveVariables varinfo if the instruction is a kill.
-          if (isKill) {
-            LiveVariables::VarInfo& vi = lv_->getVarInfo(Reg);
+          if (LV && isKill) {
+            LiveVariables::VarInfo& vi = LV->getVarInfo(Reg);
             vi.removeKill(RMI);
           }
           continue;
         }
 
         // Replace Reg with a new vreg that's marked implicit.
-        const TargetRegisterClass* RC = mri_->getRegClass(Reg);
-        unsigned NewVReg = mri_->createVirtualRegister(RC);
+        const TargetRegisterClass* RC = MRI->getRegClass(Reg);
+        unsigned NewVReg = MRI->createVirtualRegister(RC);
         bool isKill = true;
         for (unsigned j = 0, ee = RMI->getNumOperands(); j != ee; ++j) {
           MachineOperand &RRMO = RMI->getOperand(j);