//===-- LiveVariables.cpp - Live Variable Analysis for Machine Code -------===//
-//
+//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
-//
+//
//===----------------------------------------------------------------------===//
-//
+//
// This file implements the LiveVariable analysis pass. For each machine
// instruction in the function, this pass calculates the set of registers that
// are immediately dead after the instruction (i.e., the instruction calculates
#include "llvm/CodeGen/LiveVariables.h"
#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
-#include "llvm/Support/CFG.h"
-#include "Support/DepthFirstIterator.h"
-
-static RegisterAnalysis<LiveVariables> X("livevars", "Live Variable Analysis");
-
-const std::pair<MachineBasicBlock*, unsigned> &
-LiveVariables::getMachineBasicBlockInfo(MachineBasicBlock *MBB) const{
- return BBMap.find(MBB->getBasicBlock())->second;
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Config/alloca.h"
+#include <algorithm>
+#include <iostream>
+using namespace llvm;
+
+static RegisterPass<LiveVariables> X("livevars", "Live Variable Analysis");
+
+void LiveVariables::VarInfo::dump() const {
+ std::cerr << "Register Defined by: ";
+ if (DefInst)
+ std::cerr << *DefInst;
+ else
+ std::cerr << "<null>\n";
+ std::cerr << " Alive in blocks: ";
+ for (unsigned i = 0, e = AliveBlocks.size(); i != e; ++i)
+ if (AliveBlocks[i]) std::cerr << i << ", ";
+ std::cerr << "\n Killed by:";
+ if (Kills.empty())
+ std::cerr << " No instructions.\n";
+ else {
+ for (unsigned i = 0, e = Kills.size(); i != e; ++i)
+ std::cerr << "\n #" << i << ": " << *Kills[i];
+ std::cerr << "\n";
+ }
}
LiveVariables::VarInfo &LiveVariables::getVarInfo(unsigned RegIdx) {
- assert(RegIdx >= MRegisterInfo::FirstVirtualRegister &&
+ assert(MRegisterInfo::isVirtualRegister(RegIdx) &&
"getVarInfo: not a virtual register!");
RegIdx -= MRegisterInfo::FirstVirtualRegister;
if (RegIdx >= VirtRegInfo.size()) {
return VirtRegInfo[RegIdx];
}
+/// registerOverlap - Returns true if register 1 is equal to register 2
+/// or if register 1 is equal to any of alias of register 2.
+static bool registerOverlap(unsigned Reg1, unsigned Reg2,
+ const MRegisterInfo *RegInfo) {
+ bool isVirt1 = MRegisterInfo::isVirtualRegister(Reg1);
+ bool isVirt2 = MRegisterInfo::isVirtualRegister(Reg2);
+ if (isVirt1 != isVirt2)
+ return false;
+ if (Reg1 == Reg2)
+ return true;
+ else if (isVirt1)
+ return false;
+ for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg2);
+ unsigned Alias = *AliasSet; ++AliasSet) {
+ if (Reg1 == Alias)
+ return true;
+ }
+ return false;
+}
+bool LiveVariables::KillsRegister(MachineInstr *MI, unsigned Reg) const {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isKill()) {
+ if (registerOverlap(Reg, MO.getReg(), RegInfo))
+ return true;
+ }
+ }
+ return false;
+}
+
+bool LiveVariables::RegisterDefIsDead(MachineInstr *MI, unsigned Reg) const {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isDead())
+ if (registerOverlap(Reg, MO.getReg(), RegInfo))
+ return true;
+ }
+ return false;
+}
+
+bool LiveVariables::ModifiesRegister(MachineInstr *MI, unsigned Reg) const {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isDef()) {
+ if (registerOverlap(Reg, MO.getReg(), RegInfo))
+ return true;
+ }
+ }
+ return false;
+}
void LiveVariables::MarkVirtRegAliveInBlock(VarInfo &VRInfo,
- const BasicBlock *BB) {
- const std::pair<MachineBasicBlock*,unsigned> &Info = BBMap.find(BB)->second;
- MachineBasicBlock *MBB = Info.first;
- unsigned BBNum = Info.second;
+ MachineBasicBlock *MBB) {
+ unsigned BBNum = MBB->getNumber();
// Check to see if this basic block is one of the killing blocks. If so,
// remove it...
for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i)
- if (VRInfo.Kills[i].first == MBB) {
+ if (VRInfo.Kills[i]->getParent() == MBB) {
VRInfo.Kills.erase(VRInfo.Kills.begin()+i); // Erase entry
break;
}
- if (MBB == VRInfo.DefBlock) return; // Terminate recursion
+ if (MBB == VRInfo.DefInst->getParent()) return; // Terminate recursion
if (VRInfo.AliveBlocks.size() <= BBNum)
VRInfo.AliveBlocks.resize(BBNum+1); // Make space...
// Mark the variable known alive in this bb
VRInfo.AliveBlocks[BBNum] = true;
- for (pred_const_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+ for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
+ E = MBB->pred_end(); PI != E; ++PI)
MarkVirtRegAliveInBlock(VRInfo, *PI);
}
void LiveVariables::HandleVirtRegUse(VarInfo &VRInfo, MachineBasicBlock *MBB,
- MachineInstr *MI) {
+ MachineInstr *MI) {
+ assert(VRInfo.DefInst && "Register use before def!");
+
// Check to see if this basic block is already a kill block...
- if (!VRInfo.Kills.empty() && VRInfo.Kills.back().first == MBB) {
+ if (!VRInfo.Kills.empty() && VRInfo.Kills.back()->getParent() == MBB) {
// Yes, this register is killed in this basic block already. Increase the
// live range by updating the kill instruction.
- VRInfo.Kills.back().second = MI;
+ VRInfo.Kills.back() = MI;
return;
}
#ifndef NDEBUG
for (unsigned i = 0, e = VRInfo.Kills.size(); i != e; ++i)
- assert(VRInfo.Kills[i].first != MBB && "entry should be at end!");
+ assert(VRInfo.Kills[i]->getParent() != MBB && "entry should be at end!");
#endif
- assert(MBB != VRInfo.DefBlock && "Should have kill for defblock!");
+ assert(MBB != VRInfo.DefInst->getParent() &&
+ "Should have kill for defblock!");
// Add a new kill entry for this basic block.
- VRInfo.Kills.push_back(std::make_pair(MBB, MI));
+ VRInfo.Kills.push_back(MI);
// Update all dominating blocks to mark them known live.
- const BasicBlock *BB = MBB->getBasicBlock();
- for (pred_const_iterator PI = pred_begin(BB), E = pred_end(BB);
- PI != E; ++PI)
+ for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(),
+ E = MBB->pred_end(); PI != E; ++PI)
MarkVirtRegAliveInBlock(VRInfo, *PI);
}
-void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) {
- if (PhysRegInfo[Reg]) {
- PhysRegInfo[Reg] = MI;
- PhysRegUsed[Reg] = true;
- } else {
- for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
- *AliasSet; ++AliasSet) {
- if (MachineInstr *LastUse = PhysRegInfo[*AliasSet]) {
- PhysRegInfo[*AliasSet] = MI;
- PhysRegUsed[*AliasSet] = true;
- }
+void LiveVariables::addRegisterKilled(unsigned IncomingReg, MachineInstr *MI) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isUse() && MO.getReg() == IncomingReg) {
+ MO.setIsKill();
+ break;
+ }
+ }
+}
+
+void LiveVariables::addRegisterDead(unsigned IncomingReg, MachineInstr *MI) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isDef() && MO.getReg() == IncomingReg) {
+ MO.setIsDead();
+ break;
}
}
}
+void LiveVariables::HandlePhysRegUse(unsigned Reg, MachineInstr *MI) {
+ PhysRegInfo[Reg] = MI;
+ PhysRegUsed[Reg] = true;
+
+ for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
+ unsigned Alias = *AliasSet; ++AliasSet) {
+ PhysRegInfo[Alias] = MI;
+ PhysRegUsed[Alias] = true;
+ }
+}
+
void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
// Does this kill a previous version of this register?
if (MachineInstr *LastUse = PhysRegInfo[Reg]) {
if (PhysRegUsed[Reg])
- RegistersKilled.insert(std::make_pair(LastUse, Reg));
+ addRegisterKilled(Reg, LastUse);
else
- RegistersDead.insert(std::make_pair(LastUse, Reg));
- } else {
- for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
- *AliasSet; ++AliasSet) {
- if (MachineInstr *LastUse = PhysRegInfo[*AliasSet]) {
- if (PhysRegUsed[*AliasSet])
- RegistersKilled.insert(std::make_pair(LastUse, *AliasSet));
- else
- RegistersDead.insert(std::make_pair(LastUse, *AliasSet));
- PhysRegInfo[*AliasSet] = 0; // Kill the aliased register
- }
- }
+ addRegisterDead(Reg, LastUse);
}
PhysRegInfo[Reg] = MI;
PhysRegUsed[Reg] = false;
+
+ for (const unsigned *AliasSet = RegInfo->getAliasSet(Reg);
+ unsigned Alias = *AliasSet; ++AliasSet) {
+ if (MachineInstr *LastUse = PhysRegInfo[Alias]) {
+ if (PhysRegUsed[Alias])
+ addRegisterKilled(Alias, LastUse);
+ else
+ addRegisterDead(Alias, LastUse);
+ }
+ PhysRegInfo[Alias] = MI;
+ PhysRegUsed[Alias] = false;
+ }
}
bool LiveVariables::runOnMachineFunction(MachineFunction &MF) {
- // First time though, initialize AllocatablePhysicalRegisters for the target
- if (AllocatablePhysicalRegisters.empty()) {
- const MRegisterInfo &MRI = *MF.getTarget().getRegisterInfo();
- assert(&MRI && "Target doesn't have register information?");
-
- // Make space, initializing to false...
- AllocatablePhysicalRegisters.resize(MRegisterInfo::FirstVirtualRegister);
-
- // Loop over all of the register classes...
- for (MRegisterInfo::regclass_iterator RCI = MRI.regclass_begin(),
- E = MRI.regclass_end(); RCI != E; ++RCI)
- // Loop over all of the allocatable registers in the function...
- for (TargetRegisterClass::iterator I = (*RCI)->allocation_order_begin(MF),
- E = (*RCI)->allocation_order_end(MF); I != E; ++I)
- AllocatablePhysicalRegisters[*I] = true; // The reg is allocatable!
- }
+ const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
+ RegInfo = MF.getTarget().getRegisterInfo();
+ assert(RegInfo && "Target doesn't have register information?");
- // Build BBMap...
- unsigned BBNum = 0;
- for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
- BBMap[I->getBasicBlock()] = std::make_pair(I, BBNum++);
+ AllocatablePhysicalRegisters = RegInfo->getAllocatableSet(MF);
// PhysRegInfo - Keep track of which instruction was the last use of a
// physical register. This is a purely local property, because all physical
// register references as presumed dead across basic blocks.
//
- MachineInstr *PhysRegInfoA[MRegisterInfo::FirstVirtualRegister];
- bool PhysRegUsedA[MRegisterInfo::FirstVirtualRegister];
- std::fill(PhysRegInfoA, PhysRegInfoA+MRegisterInfo::FirstVirtualRegister,
- (MachineInstr*)0);
- PhysRegInfo = PhysRegInfoA;
- PhysRegUsed = PhysRegUsedA;
-
- const TargetInstrInfo &TII = MF.getTarget().getInstrInfo();
- RegInfo = MF.getTarget().getRegisterInfo();
+ PhysRegInfo = (MachineInstr**)alloca(sizeof(MachineInstr*) *
+ RegInfo->getNumRegs());
+ PhysRegUsed = (bool*)alloca(sizeof(bool)*RegInfo->getNumRegs());
+ std::fill(PhysRegInfo, PhysRegInfo+RegInfo->getNumRegs(), (MachineInstr*)0);
/// Get some space for a respectable number of registers...
VirtRegInfo.resize(64);
-
+
+ // Mark live-in registers as live-in.
+ for (MachineFunction::livein_iterator I = MF.livein_begin(),
+ E = MF.livein_end(); I != E; ++I) {
+ assert(MRegisterInfo::isPhysicalRegister(I->first) &&
+ "Cannot have a live-in virtual register!");
+ HandlePhysRegDef(I->first, 0);
+ }
+
+ analyzePHINodes(MF);
+
// Calculate live variable information in depth first order on the CFG of the
// function. This guarantees that we will see the definition of a virtual
// register before its uses due to dominance properties of SSA (except for PHI
// nodes, which are treated as a special case).
//
- const BasicBlock *Entry = MF.getFunction()->begin();
- for (df_iterator<const BasicBlock*> DFI = df_begin(Entry), E = df_end(Entry);
- DFI != E; ++DFI) {
- const BasicBlock *BB = *DFI;
- std::pair<MachineBasicBlock*, unsigned> &BBRec = BBMap.find(BB)->second;
- MachineBasicBlock *MBB = BBRec.first;
- unsigned BBNum = BBRec.second;
+ MachineBasicBlock *Entry = MF.begin();
+ std::set<MachineBasicBlock*> Visited;
+ for (df_ext_iterator<MachineBasicBlock*> DFI = df_ext_begin(Entry, Visited),
+ E = df_ext_end(Entry, Visited); DFI != E; ++DFI) {
+ MachineBasicBlock *MBB = *DFI;
// Loop over all of the instructions, processing them.
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
- I != E; ++I) {
- MachineInstr *MI = *I;
- const TargetInstrDescriptor &MID = TII.get(MI->getOpcode());
+ I != E; ++I) {
+ MachineInstr *MI = I;
// Process all of the operands of the instruction...
unsigned NumOperandsToProcess = MI->getNumOperands();
// Unless it is a PHI node. In this case, ONLY process the DEF, not any
// of the uses. They will be handled in other basic blocks.
- if (MI->getOpcode() == TargetInstrInfo::PHI)
- NumOperandsToProcess = 1;
-
- // Loop over implicit uses, using them.
- for (const unsigned *ImplicitUses = MID.ImplicitUses;
- *ImplicitUses; ++ImplicitUses)
- HandlePhysRegUse(*ImplicitUses, MI);
+ if (MI->getOpcode() == TargetInstrInfo::PHI)
+ NumOperandsToProcess = 1;
- // Process all explicit uses...
+ // Process all uses...
for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (MO.opIsUse() || MO.opIsDefAndUse()) {
- if (MO.isVirtualRegister() && !MO.getVRegValueOrNull()) {
- HandleVirtRegUse(getVarInfo(MO.getReg()), MBB, MI);
- } else if (MO.isPhysicalRegister() &&
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isRegister() && MO.isUse() && MO.getReg()) {
+ if (MRegisterInfo::isVirtualRegister(MO.getReg())){
+ HandleVirtRegUse(getVarInfo(MO.getReg()), MBB, MI);
+ } else if (MRegisterInfo::isPhysicalRegister(MO.getReg()) &&
AllocatablePhysicalRegisters[MO.getReg()]) {
- HandlePhysRegUse(MO.getReg(), MI);
- }
- }
+ HandlePhysRegUse(MO.getReg(), MI);
+ }
+ }
}
- // Loop over implicit defs, defining them.
- if (const unsigned *ImplicitDefs = MID.ImplicitDefs)
- for (unsigned i = 0; ImplicitDefs[i]; ++i)
- HandlePhysRegDef(ImplicitDefs[i], MI);
-
- // Process all explicit defs...
+ // Process all defs...
for (unsigned i = 0; i != NumOperandsToProcess; ++i) {
- MachineOperand &MO = MI->getOperand(i);
- if (MO.opIsDefOnly() || MO.opIsDefAndUse()) {
- if (MO.isVirtualRegister()) {
- VarInfo &VRInfo = getVarInfo(MO.getReg());
-
- assert(VRInfo.DefBlock == 0 && "Variable multiply defined!");
- VRInfo.DefBlock = MBB; // Created here...
- VRInfo.DefInst = MI;
- VRInfo.Kills.push_back(std::make_pair(MBB, MI)); // Defaults to dead
- } else if (MO.isPhysicalRegister() &&
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isRegister() && MO.isDef() && MO.getReg()) {
+ if (MRegisterInfo::isVirtualRegister(MO.getReg())) {
+ VarInfo &VRInfo = getVarInfo(MO.getReg());
+
+ assert(VRInfo.DefInst == 0 && "Variable multiply defined!");
+ VRInfo.DefInst = MI;
+ // Defaults to dead
+ VRInfo.Kills.push_back(MI);
+ } else if (MRegisterInfo::isPhysicalRegister(MO.getReg()) &&
AllocatablePhysicalRegisters[MO.getReg()]) {
- HandlePhysRegDef(MO.getReg(), MI);
- }
- }
+ HandlePhysRegDef(MO.getReg(), MI);
+ }
+ }
}
}
// bottom of this basic block. We check all of our successor blocks to see
// if they have PHI nodes, and if so, we simulate an assignment at the end
// of the current block.
- for (succ_const_iterator SI = succ_begin(BB), E = succ_end(BB);
- SI != E; ++SI) {
- MachineBasicBlock *Succ = BBMap.find(*SI)->second.first;
-
- // PHI nodes are guaranteed to be at the top of the block...
- for (MachineBasicBlock::iterator I = Succ->begin(), E = Succ->end();
- I != E && (*I)->getOpcode() == TargetInstrInfo::PHI; ++I) {
- MachineInstr *MI = *I;
- for (unsigned i = 1; ; i += 2)
- if (MI->getOperand(i+1).getMachineBasicBlock() == MBB) {
- MachineOperand &MO = MI->getOperand(i);
- if (!MO.getVRegValueOrNull()) {
- VarInfo &VRInfo = getVarInfo(MO.getReg());
-
- // Only mark it alive only in the block we are representing...
- MarkVirtRegAliveInBlock(VRInfo, BB);
- break; // Found the PHI entry for this block...
- }
- }
+ if (!PHIVarInfo[MBB].empty()) {
+ std::vector<unsigned>& VarInfoVec = PHIVarInfo[MBB];
+
+ for (std::vector<unsigned>::iterator I = VarInfoVec.begin(),
+ E = VarInfoVec.end(); I != E; ++I) {
+ VarInfo& VRInfo = getVarInfo(*I);
+ assert(VRInfo.DefInst && "Register use before def (or no def)!");
+
+ // Only mark it alive only in the block we are representing.
+ MarkVirtRegAliveInBlock(VRInfo, MBB);
+ }
+ }
+
+ // Finally, if the last instruction in the block is a return, make sure to mark
+ // it as using all of the live-out values in the function.
+ if (!MBB->empty() && TII.isReturn(MBB->back().getOpcode())) {
+ MachineInstr *Ret = &MBB->back();
+ for (MachineFunction::liveout_iterator I = MF.liveout_begin(),
+ E = MF.liveout_end(); I != E; ++I) {
+ assert(MRegisterInfo::isPhysicalRegister(*I) &&
+ "Cannot have a live-in virtual register!");
+ HandlePhysRegUse(*I, Ret);
+ // Add live-out registers as implicit uses.
+ Ret->addRegOperand(*I, false, true);
}
}
-
+
// Loop over PhysRegInfo, killing any registers that are available at the
// end of the basic block. This also resets the PhysRegInfo map.
- for (unsigned i = 0, e = MRegisterInfo::FirstVirtualRegister; i != e; ++i)
+ for (unsigned i = 0, e = RegInfo->getNumRegs(); i != e; ++i)
if (PhysRegInfo[i])
- HandlePhysRegDef(i, 0);
+ HandlePhysRegDef(i, 0);
}
- // Convert the information we have gathered into VirtRegInfo and transform it
- // into a form usable by RegistersKilled.
+ // Convert and transfer the dead / killed information we have gathered into
+ // VirtRegInfo onto MI's.
//
for (unsigned i = 0, e = VirtRegInfo.size(); i != e; ++i)
for (unsigned j = 0, e = VirtRegInfo[i].Kills.size(); j != e; ++j) {
- if (VirtRegInfo[i].Kills[j].second == VirtRegInfo[i].DefInst)
- RegistersDead.insert(std::make_pair(VirtRegInfo[i].Kills[j].second,
- i + MRegisterInfo::FirstVirtualRegister));
-
+ if (VirtRegInfo[i].Kills[j] == VirtRegInfo[i].DefInst)
+ addRegisterDead(i + MRegisterInfo::FirstVirtualRegister,
+ VirtRegInfo[i].Kills[j]);
else
- RegistersKilled.insert(std::make_pair(VirtRegInfo[i].Kills[j].second,
- i + MRegisterInfo::FirstVirtualRegister));
+ addRegisterKilled(i + MRegisterInfo::FirstVirtualRegister,
+ VirtRegInfo[i].Kills[j]);
}
-
+
+ // Check to make sure there are no unreachable blocks in the MC CFG for the
+ // function. If so, it is due to a bug in the instruction selector or some
+ // other part of the code generator if this happens.
+#ifndef NDEBUG
+ for(MachineFunction::iterator i = MF.begin(), e = MF.end(); i != e; ++i)
+ assert(Visited.count(&*i) != 0 && "unreachable basic block found");
+#endif
+
+ PHIVarInfo.clear();
return false;
}
+
+/// instructionChanged - When the address of an instruction changes, this
+/// method should be called so that live variables can update its internal
+/// data structures. This removes the records for OldMI, transfering them to
+/// the records for NewMI.
+void LiveVariables::instructionChanged(MachineInstr *OldMI,
+ MachineInstr *NewMI) {
+ // If the instruction defines any virtual registers, update the VarInfo,
+ // kill and dead information for the instruction.
+ for (unsigned i = 0, e = OldMI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = OldMI->getOperand(i);
+ if (MO.isRegister() && MO.getReg() &&
+ MRegisterInfo::isVirtualRegister(MO.getReg())) {
+ unsigned Reg = MO.getReg();
+ VarInfo &VI = getVarInfo(Reg);
+ if (MO.isDef()) {
+ if (MO.isDead()) {
+ MO.unsetIsDead();
+ addVirtualRegisterDead(Reg, NewMI);
+ }
+ // Update the defining instruction.
+ if (VI.DefInst == OldMI)
+ VI.DefInst = NewMI;
+ }
+ if (MO.isUse()) {
+ if (MO.isKill()) {
+ MO.unsetIsKill();
+ addVirtualRegisterKilled(Reg, NewMI);
+ }
+ // If this is a kill of the value, update the VI kills list.
+ if (VI.removeKill(OldMI))
+ VI.Kills.push_back(NewMI); // Yes, there was a kill of it
+ }
+ }
+ }
+}
+
+/// removeVirtualRegistersKilled - Remove all killed info for the specified
+/// instruction.
+void LiveVariables::removeVirtualRegistersKilled(MachineInstr *MI) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isKill()) {
+ MO.unsetIsKill();
+ unsigned Reg = MO.getReg();
+ if (MRegisterInfo::isVirtualRegister(Reg)) {
+ bool removed = getVarInfo(Reg).removeKill(MI);
+ assert(removed && "kill not in register's VarInfo?");
+ }
+ }
+ }
+}
+
+/// removeVirtualRegistersDead - Remove all of the dead registers for the
+/// specified instruction from the live variable information.
+void LiveVariables::removeVirtualRegistersDead(MachineInstr *MI) {
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = MI->getOperand(i);
+ if (MO.isReg() && MO.isDead()) {
+ MO.unsetIsDead();
+ unsigned Reg = MO.getReg();
+ if (MRegisterInfo::isVirtualRegister(Reg)) {
+ bool removed = getVarInfo(Reg).removeKill(MI);
+ assert(removed && "kill not in register's VarInfo?");
+ }
+ }
+ }
+}
+
+/// analyzePHINodes - Gather information about the PHI nodes in here. In
+/// particular, we want to map the variable information of a virtual
+/// register which is used in a PHI node. We map that to the BB the vreg is
+/// coming from.
+///
+void LiveVariables::analyzePHINodes(const MachineFunction& Fn) {
+ for (MachineFunction::const_iterator I = Fn.begin(), E = Fn.end();
+ I != E; ++I)
+ for (MachineBasicBlock::const_iterator BBI = I->begin(), BBE = I->end();
+ BBI != BBE && BBI->getOpcode() == TargetInstrInfo::PHI; ++BBI)
+ for (unsigned i = 1, e = BBI->getNumOperands(); i != e; i += 2)
+ PHIVarInfo[BBI->getOperand(i + 1).getMachineBasicBlock()].
+ push_back(BBI->getOperand(i).getReg());
+}
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