[llvm-commits] CVS: llvm/lib/CodeGen/LiveIntervals.cpp RegAllocLinearScan.cpp Passes.cpp
Alkis Evlogimenos
alkis at cs.uiuc.edu
Wed Nov 19 21:33:01 PST 2003
Changes in directory llvm/lib/CodeGen:
LiveIntervals.cpp updated: 1.1 -> 1.2
RegAllocLinearScan.cpp updated: 1.1 -> 1.2
Passes.cpp updated: 1.3 -> 1.4
---
Log message:
Merging the linear scan register allocator in trunk. It currently passes most tests under test/Programs/SingleSource/Benchmarks/Shootout so development will continue on trunk. The allocator is not enabled by default. You will need to pass -regallo=linearscan to lli or llc to use it.
---
Diffs of the changes: (+1085 -3)
Index: llvm/lib/CodeGen/LiveIntervals.cpp
diff -u /dev/null llvm/lib/CodeGen/LiveIntervals.cpp:1.2
--- /dev/null Wed Nov 19 21:32:36 2003
+++ llvm/lib/CodeGen/LiveIntervals.cpp Wed Nov 19 21:32:25 2003
@@ -0,0 +1,302 @@
+//===-- LiveIntervals.cpp - Live Interval Analysis ------------------------===//
+//
+// 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 LiveInterval analysis pass which is used
+// by the Linear Scan Register allocator. This pass linearizes the
+// basic blocks of the function in DFS order and uses the
+// LiveVariables pass to conservatively compute live intervals for
+// each virtual and physical register.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "liveintervals"
+#include "llvm/CodeGen/LiveIntervals.h"
+#include "llvm/Function.h"
+#include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/SSARegMap.h"
+#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegInfo.h"
+#include "llvm/Support/CFG.h"
+#include "Support/Debug.h"
+#include "Support/DepthFirstIterator.h"
+#include "Support/Statistic.h"
+#include <iostream>
+
+using namespace llvm;
+
+namespace {
+ RegisterAnalysis<LiveIntervals> X("liveintervals",
+ "Live Interval Analysis");
+
+ Statistic<> numIntervals("liveintervals", "Number of intervals");
+};
+
+void LiveIntervals::getAnalysisUsage(AnalysisUsage &AU) const
+{
+ AU.setPreservesAll();
+ AU.addRequired<LiveVariables>();
+ AU.addRequiredID(PHIEliminationID);
+ MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+/// runOnMachineFunction - Register allocate the whole function
+///
+bool LiveIntervals::runOnMachineFunction(MachineFunction &fn) {
+ DEBUG(std::cerr << "Machine Function\n");
+ mf_ = &fn;
+ tm_ = &fn.getTarget();
+ mri_ = tm_->getRegisterInfo();
+ lv_ = &getAnalysis<LiveVariables>();
+ allocatableRegisters_.clear();
+ mbbi2mbbMap_.clear();
+ mi2iMap_.clear();
+ r2iMap_.clear();
+ r2iMap_.clear();
+ intervals_.clear();
+
+ // mark allocatable registers
+ allocatableRegisters_.resize(MRegisterInfo::FirstVirtualRegister);
+ // Loop over all of the register classes...
+ for (MRegisterInfo::regclass_iterator
+ rci = mri_->regclass_begin(), rce = mri_->regclass_end();
+ rci != rce; ++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) {
+ allocatableRegisters_[*i] = true; // The reg is allocatable!
+ }
+ }
+
+ // number MachineInstrs
+ unsigned miIndex = 0;
+ for (MachineFunction::iterator mbb = mf_->begin(), mbbEnd = mf_->end();
+ mbb != mbbEnd; ++mbb) {
+ const std::pair<MachineBasicBlock*, unsigned>& entry =
+ lv_->getMachineBasicBlockInfo(&*mbb);
+ bool inserted = mbbi2mbbMap_.insert(std::make_pair(entry.second,
+ entry.first)).second;
+ assert(inserted && "multiple index -> MachineBasicBlock");
+
+ for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
+ mi != miEnd; ++mi) {
+ inserted = mi2iMap_.insert(std::make_pair(*mi, miIndex)).second;
+ assert(inserted && "multiple MachineInstr -> index mappings");
+ ++miIndex;
+ }
+ }
+
+ computeIntervals();
+
+ return true;
+}
+
+void LiveIntervals::printRegName(unsigned reg) const
+{
+ if (reg < MRegisterInfo::FirstVirtualRegister)
+ std::cerr << mri_->getName(reg);
+ else
+ std::cerr << '%' << reg;
+}
+
+void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock* mbb,
+ MachineBasicBlock::iterator mi,
+ unsigned reg)
+{
+ DEBUG(std::cerr << "\t\t\tregister: ";printRegName(reg); std::cerr << '\n');
+
+ unsigned instrIndex = getInstructionIndex(*mi);
+
+ LiveVariables::VarInfo& vi = lv_->getVarInfo(reg);
+
+ Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
+ // handle multiple definition case (machine instructions violating
+ // ssa after phi-elimination
+ if (r2iit != r2iMap_.end()) {
+ unsigned ii = r2iit->second;
+ Interval& interval = intervals_[ii];
+ unsigned end = getInstructionIndex(mbb->back()) + 1;
+ DEBUG(std::cerr << "\t\t\t\tadding range: ["
+ << instrIndex << ',' << end << "]\n");
+ interval.addRange(instrIndex, end);
+ DEBUG(std::cerr << "\t\t\t\t" << interval << '\n');
+ }
+ else {
+ // add new interval
+ intervals_.push_back(Interval(reg));
+ Interval& interval = intervals_.back();
+ // update interval index for this register
+ r2iMap_[reg] = intervals_.size() - 1;
+
+ for (MbbIndex2MbbMap::iterator
+ it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
+ it != itEnd; ++it) {
+ unsigned liveBlockIndex = it->first;
+ MachineBasicBlock* liveBlock = it->second;
+ if (liveBlockIndex < vi.AliveBlocks.size() &&
+ vi.AliveBlocks[liveBlockIndex]) {
+ unsigned start = getInstructionIndex(liveBlock->front());
+ unsigned end = getInstructionIndex(liveBlock->back()) + 1;
+ DEBUG(std::cerr << "\t\t\t\tadding range: ["
+ << start << ',' << end << "]\n");
+ interval.addRange(start, end);
+ }
+ }
+
+ bool killedInDefiningBasicBlock = false;
+ for (int i = 0, e = vi.Kills.size(); i != e; ++i) {
+ MachineBasicBlock* killerBlock = vi.Kills[i].first;
+ MachineInstr* killerInstr = vi.Kills[i].second;
+ killedInDefiningBasicBlock |= mbb == killerBlock;
+ unsigned start = (mbb == killerBlock ?
+ instrIndex :
+ getInstructionIndex(killerBlock->front()));
+ unsigned end = getInstructionIndex(killerInstr) + 1;
+ DEBUG(std::cerr << "\t\t\t\tadding range: ["
+ << start << ',' << end << "]\n");
+ interval.addRange(start, end);
+ }
+
+ if (!killedInDefiningBasicBlock) {
+ unsigned end = getInstructionIndex(mbb->back()) + 1;
+ interval.addRange(instrIndex, end);
+ }
+
+ DEBUG(std::cerr << "\t\t\t\t" << interval << '\n');
+ }
+}
+
+void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock* mbb,
+ MachineBasicBlock::iterator mi,
+ unsigned reg)
+{
+ DEBUG(std::cerr << "\t\t\tregister: ";printRegName(reg); std::cerr << '\n');
+
+ unsigned start = getInstructionIndex(*mi);
+ unsigned end = start;
+
+ for (MachineBasicBlock::iterator e = mbb->end(); mi != e; ++mi) {
+ for (LiveVariables::killed_iterator
+ ki = lv_->dead_begin(*mi),
+ ke = lv_->dead_end(*mi);
+ ki != ke; ++ki) {
+ if (reg == ki->second) {
+ end = getInstructionIndex(ki->first) + 1;
+ goto exit;
+ }
+ }
+
+ for (LiveVariables::killed_iterator
+ ki = lv_->killed_begin(*mi),
+ ke = lv_->killed_end(*mi);
+ ki != ke; ++ki) {
+ if (reg == ki->second) {
+ end = getInstructionIndex(ki->first) + 1;
+ goto exit;
+ }
+ }
+ }
+exit:
+ assert(start < end && "did not find end of interval?");
+
+ Reg2IntervalMap::iterator r2iit = r2iMap_.find(reg);
+ if (r2iit != r2iMap_.end()) {
+ unsigned ii = r2iit->second;
+ Interval& interval = intervals_[ii];
+ DEBUG(std::cerr << "\t\t\t\tadding range: ["
+ << start << ',' << end << "]\n");
+ interval.addRange(start, end);
+ DEBUG(std::cerr << "\t\t\t\t" << interval << '\n');
+ }
+ else {
+ intervals_.push_back(Interval(reg));
+ Interval& interval = intervals_.back();
+ // update interval index for this register
+ r2iMap_[reg] = intervals_.size() - 1;
+ DEBUG(std::cerr << "\t\t\t\tadding range: ["
+ << start << ',' << end << "]\n");
+ interval.addRange(start, end);
+ DEBUG(std::cerr << "\t\t\t\t" << interval << '\n');
+ }
+}
+
+void LiveIntervals::handleRegisterDef(MachineBasicBlock* mbb,
+ MachineBasicBlock::iterator mi,
+ unsigned reg)
+{
+ if (reg < MRegisterInfo::FirstVirtualRegister) {
+ if (allocatableRegisters_[reg]) {
+ handlePhysicalRegisterDef(mbb, mi, reg);
+ }
+ }
+ else {
+ handleVirtualRegisterDef(mbb, mi, reg);
+ }
+}
+
+unsigned LiveIntervals::getInstructionIndex(MachineInstr* instr) const
+{
+ assert(mi2iMap_.find(instr) != mi2iMap_.end() &&
+ "instruction not assigned a number");
+ return mi2iMap_.find(instr)->second;
+}
+
+/// computeIntervals - computes the live intervals for virtual
+/// registers. for some ordering of the machine instructions [1,N] a
+/// live interval is an interval [i, j] where 1 <= i <= j <= N for
+/// which a variable is live
+void LiveIntervals::computeIntervals()
+{
+ DEBUG(std::cerr << "computing live intervals:\n");
+
+ for (MbbIndex2MbbMap::iterator
+ it = mbbi2mbbMap_.begin(), itEnd = mbbi2mbbMap_.end();
+ it != itEnd; ++it) {
+ MachineBasicBlock* mbb = it->second;
+ DEBUG(std::cerr << "machine basic block: "
+ << mbb->getBasicBlock()->getName() << "\n");
+ for (MachineBasicBlock::iterator mi = mbb->begin(), miEnd = mbb->end();
+ mi != miEnd; ++mi) {
+ MachineInstr* instr = *mi;
+ const TargetInstrDescriptor& tid =
+ tm_->getInstrInfo().get(instr->getOpcode());
+ DEBUG(std::cerr << "\t\tinstruction["
+ << getInstructionIndex(instr) << "]: ";
+ instr->print(std::cerr, *tm_););
+
+ // handle implicit defs
+ for (const unsigned* id = tid.ImplicitDefs; *id; ++id) {
+ unsigned physReg = *id;
+ handlePhysicalRegisterDef(mbb, mi, physReg);
+ }
+
+ // handle explicit defs
+ for (int i = instr->getNumOperands() - 1; i >= 0; --i) {
+ MachineOperand& mop = instr->getOperand(i);
+
+ if (!mop.isVirtualRegister())
+ continue;
+
+ if (mop.opIsDefOnly() || mop.opIsDefAndUse()) {
+ unsigned reg = mop.getAllocatedRegNum();
+ handleVirtualRegisterDef(mbb, mi, reg);
+ }
+ }
+ }
+ }
+
+ DEBUG(std::copy(intervals_.begin(), intervals_.end(),
+ std::ostream_iterator<Interval>(std::cerr, "\n")));
+}
Index: llvm/lib/CodeGen/RegAllocLinearScan.cpp
diff -u /dev/null llvm/lib/CodeGen/RegAllocLinearScan.cpp:1.2
--- /dev/null Wed Nov 19 21:32:36 2003
+++ llvm/lib/CodeGen/RegAllocLinearScan.cpp Wed Nov 19 21:32:25 2003
@@ -0,0 +1,777 @@
+//===-- RegAllocLinearScan.cpp - Linear Scan register allocator -----------===//
+//
+// 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 a linear scan register allocator.
+//
+//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "regalloc"
+#include "llvm/Function.h"
+#include "llvm/CodeGen/LiveIntervals.h"
+#include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/SSARegMap.h"
+#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegInfo.h"
+#include "llvm/Support/CFG.h"
+#include "Support/Debug.h"
+#include "Support/DepthFirstIterator.h"
+#include "Support/Statistic.h"
+#include "Support/STLExtras.h"
+#include <iostream>
+
+using namespace llvm;
+
+namespace {
+ Statistic<> numSpilled ("ra-linearscan", "Number of registers spilled");
+ Statistic<> numReloaded("ra-linearscan", "Number of registers reloaded");
+
+ class RA : public MachineFunctionPass {
+ public:
+ typedef std::vector<const LiveIntervals::Interval*> IntervalPtrs;
+
+ private:
+ MachineFunction* mf_;
+ const TargetMachine* tm_;
+ const MRegisterInfo* mri_;
+ MachineBasicBlock* currentMbb_;
+ MachineBasicBlock::iterator currentInstr_;
+ typedef LiveIntervals::Intervals Intervals;
+ const Intervals* li_;
+ IntervalPtrs active_, inactive_;
+
+ typedef std::vector<unsigned> Regs;
+ Regs tempUseOperands_;
+ Regs tempDefOperands_;
+
+ Regs reserved_;
+
+ typedef LiveIntervals::MachineBasicBlockPtrs MachineBasicBlockPtrs;
+ MachineBasicBlockPtrs mbbs_;
+
+ typedef std::vector<unsigned> Phys2VirtMap;
+ Phys2VirtMap p2vMap_;
+
+ typedef std::map<unsigned, unsigned> Virt2PhysMap;
+ Virt2PhysMap v2pMap_;
+
+ typedef std::map<unsigned, int> Virt2StackSlotMap;
+ Virt2StackSlotMap v2ssMap_;
+
+ int instrAdded_;
+
+ public:
+ virtual const char* getPassName() const {
+ return "Linear Scan Register Allocator";
+ }
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.addRequired<LiveVariables>();
+ AU.addRequired<LiveIntervals>();
+ MachineFunctionPass::getAnalysisUsage(AU);
+ }
+
+ private:
+ /// runOnMachineFunction - register allocate the whole function
+ bool runOnMachineFunction(MachineFunction&);
+
+ /// processActiveIntervals - expire old intervals and move
+ /// non-overlapping ones to the incative list
+ void processActiveIntervals(Intervals::const_iterator cur);
+
+ /// processInactiveIntervals - expire old intervals and move
+ /// overlapping ones to the active list
+ void processInactiveIntervals(Intervals::const_iterator cur);
+
+ /// assignStackSlotAtInterval - choose and spill
+ /// interval. Currently we spill the interval with the last
+ /// end point in the active and inactive lists and the current
+ /// interval
+ void assignStackSlotAtInterval(Intervals::const_iterator cur);
+
+ ///
+ /// register handling helpers
+ ///
+
+ /// reservePhysReg - reserves a physical register and spills
+ /// any value assigned to it if any
+ void reservePhysReg(unsigned reg);
+
+ /// clearReservedPhysReg - marks pysical register as free for
+ /// use
+ void clearReservedPhysReg(unsigned reg);
+
+ /// physRegAvailable - returns true if the specifed physical
+ /// register is available
+ bool physRegAvailable(unsigned physReg);
+
+ /// getFreePhysReg - return a free physical register for this
+ /// virtual register if we have one, otherwise return 0
+ unsigned getFreePhysReg(unsigned virtReg);
+
+
+ /// tempPhysRegAvailable - returns true if the specifed
+ /// temporary physical register is available
+ bool tempPhysRegAvailable(unsigned physReg);
+
+ /// getFreeTempPhysReg - return a free temprorary physical
+ /// register for this register class if we have one (should
+ /// never return 0)
+ unsigned getFreeTempPhysReg(const TargetRegisterClass* rc);
+
+ /// getFreeTempPhysReg - return a free temprorary physical
+ /// register for this virtual register if we have one (should
+ /// never return 0)
+ unsigned getFreeTempPhysReg(unsigned virtReg) {
+ const TargetRegisterClass* rc =
+ mf_->getSSARegMap()->getRegClass(virtReg);
+ return getFreeTempPhysReg(rc);
+ }
+
+ /// assignVirt2PhysReg - assigns the free physical register to
+ /// the virtual register passed as arguments
+ void assignVirt2PhysReg(unsigned virtReg, unsigned physReg);
+
+ /// clearVirtReg - free the physical register associated with this
+ /// virtual register and disassociate virtual->physical and
+ /// physical->virtual mappings
+ void clearVirtReg(unsigned virtReg);
+
+ /// assignVirt2StackSlot - assigns this virtual register to a
+ /// stack slot
+ void assignVirt2StackSlot(unsigned virtReg);
+
+ /// findOrCreateStackSlot - returns the offset of the
+ /// specified register on the stack allocating space if
+ /// necessary
+ int findOrCreateStackSlot(unsigned virtReg);
+
+ /// spillVirtReg - spills the virtual register
+ void spillVirtReg(unsigned virtReg);
+
+ /// loadPhysReg - loads to the physical register the value of
+ /// the virtual register specifed. Virtual register must have
+ /// an assigned stack slot
+ void loadVirt2PhysReg(unsigned virtReg, unsigned physReg);
+
+ void printVirt2PhysMap() const {
+ std::cerr << "allocated registers:\n";
+ for (Virt2PhysMap::const_iterator
+ i = v2pMap_.begin(), e = v2pMap_.end(); i != e; ++i) {
+ std::cerr << '[' << i->first << ','
+ << mri_->getName(i->second) << "]\n";
+ }
+ std::cerr << '\n';
+ }
+ void printIntervals(const char* const str,
+ RA::IntervalPtrs::const_iterator i,
+ RA::IntervalPtrs::const_iterator e) const {
+ if (str) std::cerr << str << " intervals:\n";
+ for (; i != e; ++i) {
+ std::cerr << "\t\t" << **i << " -> ";
+ if ((*i)->reg < MRegisterInfo::FirstVirtualRegister) {
+ std::cerr << mri_->getName((*i)->reg);
+ }
+ else {
+ std::cerr << mri_->getName(v2pMap_.find((*i)->reg)->second);
+ }
+ std::cerr << '\n';
+ }
+ }
+ };
+}
+
+bool RA::runOnMachineFunction(MachineFunction &fn) {
+ mf_ = &fn;
+ tm_ = &fn.getTarget();
+ mri_ = tm_->getRegisterInfo();
+ li_ = &getAnalysis<LiveIntervals>().getIntervals();
+ active_.clear();
+ inactive_.clear();
+ mbbs_ = getAnalysis<LiveIntervals>().getOrderedMachineBasicBlockPtrs();
+ p2vMap_.resize(MRegisterInfo::FirstVirtualRegister-1);
+ p2vMap_.clear();
+ v2pMap_.clear();
+ v2ssMap_.clear();
+
+ // FIXME: this will work only for the X86 backend. I need to
+ // device an algorthm to select the minimal (considering register
+ // aliasing) number of temp registers to reserve so that we have 2
+ // registers for each register class available.
+
+ // reserve R32: EDI, EBX,
+ // R16: DI, BX,
+ // R8: DH, BH,
+ // RFP: FP5, FP6
+ reserved_.push_back(19); /* EDI */
+ reserved_.push_back(17); /* EBX */
+ reserved_.push_back(12); /* DI */
+ reserved_.push_back( 7); /* BX */
+ reserved_.push_back(11); /* DH */
+ reserved_.push_back( 4); /* BH */
+ reserved_.push_back(28); /* FP5 */
+ reserved_.push_back(29); /* FP6 */
+
+ // liner scan algorithm
+ for (Intervals::const_iterator
+ i = li_->begin(), e = li_->end(); i != e; ++i) {
+ DEBUG(std::cerr << "processing current interval: " << *i << '\n');
+
+ DEBUG(printIntervals("\tactive", active_.begin(), active_.end()));
+ DEBUG(printIntervals("\tinactive", inactive_.begin(), inactive_.end()));
+
+ processActiveIntervals(i);
+ // processInactiveIntervals(i);
+
+ // if this register is preallocated, look for an interval that
+ // overlaps with it and assign it to a memory location
+ if (i->reg < MRegisterInfo::FirstVirtualRegister) {
+ for (IntervalPtrs::iterator
+ ai = active_.begin(), ae = active_.end(); ai != ae; ++ai) {
+ unsigned virtReg = (*ai)->reg;
+ Virt2PhysMap::const_iterator it = v2pMap_.find(virtReg);
+ if (it != v2pMap_.end() && it->second == i->reg) {
+ active_.erase(ai);
+ clearVirtReg(virtReg);
+ break;
+ }
+ }
+ reservePhysReg(i->reg);
+ active_.push_back(&*i);
+ }
+ // otherwise we are allocating a virtual register. try to find
+ // a free physical register or spill an interval in order to
+ // assign it one (we could spill the current though).
+ else {
+ unsigned physReg = getFreePhysReg(i->reg);
+ if (!physReg) {
+ assignStackSlotAtInterval(i);
+ }
+ else {
+ assignVirt2PhysReg(i->reg, physReg);
+ active_.push_back(&*i);
+ }
+ }
+ }
+ DEBUG(std::cerr << "finished register allocation\n");
+ DEBUG(printVirt2PhysMap());
+
+ DEBUG(std::cerr << "Rewrite machine code:\n");
+ for (MachineBasicBlockPtrs::iterator
+ mbbi = mbbs_.begin(), mbbe = mbbs_.end(); mbbi != mbbe; ++mbbi) {
+ instrAdded_ = 0;
+ currentMbb_ = *mbbi;
+
+ for (currentInstr_ = currentMbb_->begin();
+ currentInstr_ != currentMbb_->end(); ++currentInstr_) {
+
+ DEBUG(std::cerr << "\tinstruction: ";
+ (*currentInstr_)->print(std::cerr, *tm_););
+ DEBUG(std::cerr << "\t\tspilling temporarily defined operands "
+ "of previous instruction:\n");
+ for (unsigned i = 0, e = tempDefOperands_.size(); i != e; ++i) {
+ spillVirtReg(tempDefOperands_[i]);
+ }
+ tempDefOperands_.clear();
+
+ // use our current mapping and actually replace and
+ // virtual register with its allocated physical registers
+ DEBUG(std::cerr << "\t\treplacing virtual registers with mapped "
+ "physical registers:\n");
+ for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
+ i != e; ++i) {
+ MachineOperand& op = (*currentInstr_)->getOperand(i);
+ if (op.isVirtualRegister()) {
+ unsigned virtReg = op.getAllocatedRegNum();
+ unsigned physReg = v2pMap_[virtReg];
+ // if this virtual registers lives on the stack,
+ // load it to a temporary physical register
+ if (physReg) {
+ DEBUG(std::cerr << "\t\t\t%reg" << virtReg
+ << " -> " << mri_->getName(physReg) << '\n');
+ (*currentInstr_)->SetMachineOperandReg(i, physReg);
+ }
+ }
+ }
+
+ DEBUG(std::cerr << "\t\tloading temporarily used operands to "
+ "registers:\n");
+ for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
+ i != e; ++i) {
+ MachineOperand& op = (*currentInstr_)->getOperand(i);
+ if (op.isVirtualRegister() && op.opIsUse()) {
+ unsigned virtReg = op.getAllocatedRegNum();
+ unsigned physReg = v2pMap_[virtReg];
+ if (!physReg) {
+ physReg = getFreeTempPhysReg(virtReg);
+ }
+ loadVirt2PhysReg(virtReg, physReg);
+ tempUseOperands_.push_back(virtReg);
+ (*currentInstr_)->SetMachineOperandReg(i, physReg);
+ }
+ }
+
+ DEBUG(std::cerr << "\t\tclearing temporarily used operands:\n");
+ for (unsigned i = 0, e = tempUseOperands_.size(); i != e; ++i) {
+ clearVirtReg(tempUseOperands_[i]);
+ }
+ tempUseOperands_.clear();
+
+ DEBUG(std::cerr << "\t\tassigning temporarily defined operands to "
+ "registers:\n");
+ for (unsigned i = 0, e = (*currentInstr_)->getNumOperands();
+ i != e; ++i) {
+ MachineOperand& op = (*currentInstr_)->getOperand(i);
+ if (op.isVirtualRegister() && !op.opIsUse()) {
+ unsigned virtReg = op.getAllocatedRegNum();
+ unsigned physReg = v2pMap_[virtReg];
+ if (!physReg) {
+ physReg = getFreeTempPhysReg(virtReg);
+ }
+ if (op.opIsDefAndUse()) {
+ loadVirt2PhysReg(virtReg, physReg);
+ }
+ else {
+ assignVirt2PhysReg(virtReg, physReg);
+ }
+ tempDefOperands_.push_back(virtReg);
+ (*currentInstr_)->SetMachineOperandReg(i, physReg);
+ }
+ }
+
+
+ // if the instruction is a two address instruction and the
+ // source operands are not identical we need to insert
+ // extra instructions.
+
+ unsigned opcode = (*currentInstr_)->getOpcode();
+ if (tm_->getInstrInfo().isTwoAddrInstr(opcode) &&
+ (*currentInstr_)->getOperand(0).getAllocatedRegNum() !=
+ (*currentInstr_)->getOperand(1).getAllocatedRegNum()) {
+ assert((*currentInstr_)->getOperand(1).isRegister() &&
+ (*currentInstr_)->getOperand(1).getAllocatedRegNum() &&
+ (*currentInstr_)->getOperand(1).opIsUse() &&
+ "Two address instruction invalid");
+
+ unsigned regA =
+ (*currentInstr_)->getOperand(0).getAllocatedRegNum();
+ unsigned regB =
+ (*currentInstr_)->getOperand(1).getAllocatedRegNum();
+ unsigned regC =
+ ((*currentInstr_)->getNumOperands() > 2 &&
+ (*currentInstr_)->getOperand(2).isRegister()) ?
+ (*currentInstr_)->getOperand(2).getAllocatedRegNum() :
+ 0;
+
+ const TargetRegisterClass* rc = mri_->getRegClass(regA);
+
+ // special case: "a = b op a". If b is a temporary
+ // reserved register rewrite as: "b = b op a; a = b"
+ // otherwise use a temporary reserved register t and
+ // rewrite as: "t = b; t = t op a; a = t"
+ if (regC && regA == regC) {
+ // b is a temp reserved register
+ if (find(reserved_.begin(), reserved_.end(),
+ regB) != reserved_.end()) {
+ (*currentInstr_)->SetMachineOperandReg(0, regB);
+ ++currentInstr_;
+ instrAdded_ += mri_->copyRegToReg(*currentMbb_,
+ currentInstr_,
+ regA,
+ regB,
+ rc);
+ --currentInstr_;
+ }
+ // b is just a normal register
+ else {
+ unsigned tempReg = getFreeTempPhysReg(rc);
+ assert (tempReg &&
+ "no free temp reserved physical register?");
+ instrAdded_ += mri_->copyRegToReg(*currentMbb_,
+ currentInstr_,
+ tempReg,
+ regB,
+ rc);
+ (*currentInstr_)->SetMachineOperandReg(0, tempReg);
+ (*currentInstr_)->SetMachineOperandReg(1, tempReg);
+ ++currentInstr_;
+ instrAdded_ += mri_->copyRegToReg(*currentMbb_,
+ currentInstr_,
+ regA,
+ tempReg,
+ rc);
+ --currentInstr_;
+ }
+ }
+ // "a = b op c" gets rewritten to "a = b; a = a op c"
+ else {
+ instrAdded_ += mri_->copyRegToReg(*currentMbb_,
+ currentInstr_,
+ regA,
+ regB,
+ rc);
+ (*currentInstr_)->SetMachineOperandReg(1, regA);
+ }
+ }
+ }
+
+ for (unsigned i = 0, e = p2vMap_.size(); i != e; ++i) {
+ assert(p2vMap_[i] != i &&
+ "reserved physical registers at end of basic block?");
+ }
+ }
+
+ return true;
+}
+
+void RA::processActiveIntervals(Intervals::const_iterator cur)
+{
+ DEBUG(std::cerr << "\tprocessing active intervals:\n");
+ for (IntervalPtrs::iterator i = active_.begin(); i != active_.end();) {
+ unsigned reg = (*i)->reg;
+ // remove expired intervals. we expire earlier because this if
+ // an interval expires this is going to be the last use. in
+ // this case we can reuse the register for a def in the same
+ // instruction
+ if ((*i)->expired(cur->start() + 1)) {
+ DEBUG(std::cerr << "\t\tinterval " << **i << " expired\n");
+ if (reg < MRegisterInfo::FirstVirtualRegister) {
+ clearReservedPhysReg(reg);
+ }
+ else {
+ p2vMap_[v2pMap_[reg]] = 0;
+ }
+ // remove interval from active
+ i = active_.erase(i);
+ }
+ // move not active intervals to inactive list
+// else if (!(*i)->overlaps(curIndex)) {
+// DEBUG(std::cerr << "\t\t\tinterval " << **i << " inactive\n");
+// unmarkReg(virtReg);
+// // add interval to inactive
+// inactive_.push_back(*i);
+// // remove interval from active
+// i = active_.erase(i);
+// }
+ else {
+ ++i;
+ }
+ }
+}
+
+void RA::processInactiveIntervals(Intervals::const_iterator cur)
+{
+// DEBUG(std::cerr << "\tprocessing inactive intervals:\n");
+// for (IntervalPtrs::iterator i = inactive_.begin(); i != inactive_.end();) {
+// unsigned virtReg = (*i)->reg;
+// // remove expired intervals
+// if ((*i)->expired(curIndex)) {
+// DEBUG(std::cerr << "\t\t\tinterval " << **i << " expired\n");
+// freePhysReg(virtReg);
+// // remove from inactive
+// i = inactive_.erase(i);
+// }
+// // move re-activated intervals in active list
+// else if ((*i)->overlaps(curIndex)) {
+// DEBUG(std::cerr << "\t\t\tinterval " << **i << " active\n");
+// markReg(virtReg);
+// // add to active
+// active_.push_back(*i);
+// // remove from inactive
+// i = inactive_.erase(i);
+// }
+// else {
+// ++i;
+// }
+// }
+}
+
+void RA::assignStackSlotAtInterval(Intervals::const_iterator cur)
+{
+ DEBUG(std::cerr << "\t\tassigning stack slot at interval "
+ << *cur << ":\n");
+ assert(!active_.empty() &&
+ "active set cannot be empty when choosing a register to spill");
+ const TargetRegisterClass* rcCur =
+ mf_->getSSARegMap()->getRegClass(cur->reg);
+
+ // find the interval for a virtual register that ends last in
+ // active and belongs to the same register class as the current
+ // interval
+ IntervalPtrs::iterator lastEndActive = active_.begin();
+ for (IntervalPtrs::iterator e = active_.end();
+ lastEndActive != e; ++lastEndActive) {
+ if ((*lastEndActive)->reg >= MRegisterInfo::FirstVirtualRegister) {
+ const TargetRegisterClass* rc =
+ mri_->getRegClass(v2pMap_[(*lastEndActive)->reg]);
+ if (rcCur == rc) {
+ break;
+ }
+ }
+ }
+ for (IntervalPtrs::iterator i = lastEndActive, e = active_.end();
+ i != e; ++i) {
+ if ((*i)->reg >= MRegisterInfo::FirstVirtualRegister) {
+ const TargetRegisterClass* rc =
+ mri_->getRegClass(v2pMap_[(*i)->reg]);
+ if (rcCur == rc &&
+ (*lastEndActive)->end() < (*i)->end()) {
+ lastEndActive = i;
+ }
+ }
+ }
+
+ // find the interval for a virtual register that ends last in
+ // inactive and belongs to the same register class as the current
+ // interval
+ IntervalPtrs::iterator lastEndInactive = inactive_.begin();
+ for (IntervalPtrs::iterator e = inactive_.end();
+ lastEndInactive != e; ++lastEndInactive) {
+ if ((*lastEndInactive)->reg >= MRegisterInfo::FirstVirtualRegister) {
+ const TargetRegisterClass* rc =
+ mri_->getRegClass(v2pMap_[(*lastEndInactive)->reg]);
+ if (rcCur == rc) {
+ break;
+ }
+ }
+ }
+ for (IntervalPtrs::iterator i = lastEndInactive, e = inactive_.end();
+ i != e; ++i) {
+ if ((*i)->reg >= MRegisterInfo::FirstVirtualRegister) {
+ const TargetRegisterClass* rc =
+ mri_->getRegClass(v2pMap_[(*i)->reg]);
+ if (rcCur == rc &&
+ (*lastEndInactive)->end() < (*i)->end()) {
+ lastEndInactive = i;
+ }
+ }
+ }
+
+ unsigned lastEndActiveInactive = 0;
+ if (lastEndActive != active_.end() &&
+ lastEndActiveInactive < (*lastEndActive)->end()) {
+ lastEndActiveInactive = (*lastEndActive)->end();
+ }
+ if (lastEndInactive != inactive_.end() &&
+ lastEndActiveInactive < (*lastEndInactive)->end()) {
+ lastEndActiveInactive = (*lastEndInactive)->end();
+ }
+
+ if (lastEndActiveInactive > cur->end()) {
+ if (lastEndInactive == inactive_.end() ||
+ (*lastEndActive)->end() > (*lastEndInactive)->end()) {
+ assignVirt2StackSlot((*lastEndActive)->reg);
+ active_.erase(lastEndActive);
+ }
+ else {
+ assignVirt2StackSlot((*lastEndInactive)->reg);
+ inactive_.erase(lastEndInactive);
+ }
+ unsigned physReg = getFreePhysReg(cur->reg);
+ assert(physReg && "no free physical register after spill?");
+ assignVirt2PhysReg(cur->reg, physReg);
+ active_.push_back(&*cur);
+ }
+ else {
+ assignVirt2StackSlot(cur->reg);
+ }
+}
+
+void RA::reservePhysReg(unsigned physReg)
+{
+ DEBUG(std::cerr << "\t\t\treserving physical physical register: "
+ << mri_->getName(physReg) << '\n');
+ // if this register holds a value spill it
+ unsigned virtReg = p2vMap_[physReg];
+ if (virtReg != 0) {
+ assert(virtReg != physReg && "reserving an already reserved phus reg?");
+ // remove interval from active
+ for (IntervalPtrs::iterator i = active_.begin(), e = active_.end();
+ i != e; ++i) {
+ if ((*i)->reg == virtReg) {
+ active_.erase(i);
+ break;
+ }
+ }
+ spillVirtReg(virtReg);
+ }
+ p2vMap_[physReg] = physReg; // this denotes a reserved physical register
+}
+
+void RA::clearReservedPhysReg(unsigned physReg)
+{
+ DEBUG(std::cerr << "\t\t\tclearing reserved physical physical register: "
+ << mri_->getName(physReg) << '\n');
+ assert(p2vMap_[physReg] == physReg &&
+ "attempt to clear a non reserved physical register");
+ p2vMap_[physReg] = 0;
+}
+
+bool RA::physRegAvailable(unsigned physReg)
+{
+ if (p2vMap_[physReg]) {
+ return false;
+ }
+
+ // if it aliases other registers it is still not free
+ for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as) {
+ if (p2vMap_[*as]) {
+ return false;
+ }
+ }
+
+ // if it is one of the reserved registers it is still not free
+ if (find(reserved_.begin(), reserved_.end(), physReg) != reserved_.end()) {
+ return false;
+ }
+
+ return true;
+}
+
+unsigned RA::getFreePhysReg(unsigned virtReg)
+{
+ DEBUG(std::cerr << "\t\tgetting free physical register: ");
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
+ TargetRegisterClass::iterator reg = rc->allocation_order_begin(*mf_);
+ TargetRegisterClass::iterator regEnd = rc->allocation_order_end(*mf_);
+
+ for (; reg != regEnd; ++reg) {
+ if (physRegAvailable(*reg)) {
+ assert(*reg != 0 && "Cannot use register!");
+ DEBUG(std::cerr << mri_->getName(*reg) << '\n');
+ return *reg; // Found an unused register!
+ }
+ }
+
+ DEBUG(std::cerr << "no free register\n");
+ return 0;
+}
+
+bool RA::tempPhysRegAvailable(unsigned physReg)
+{
+ assert(find(reserved_.begin(), reserved_.end(), physReg) != reserved_.end()
+ && "cannot call this method with a non reserved temp register");
+
+ if (p2vMap_[physReg]) {
+ return false;
+ }
+
+ // if it aliases other registers it is still not free
+ for (const unsigned* as = mri_->getAliasSet(physReg); *as; ++as) {
+ if (p2vMap_[*as]) {
+ return false;
+ }
+ }
+
+ return true;
+}
+
+unsigned RA::getFreeTempPhysReg(const TargetRegisterClass* rc)
+{
+ DEBUG(std::cerr << "\t\tgetting free temporary physical register: ");
+
+ for (Regs::const_iterator
+ reg = reserved_.begin(), regEnd = reserved_.end();
+ reg != regEnd; ++reg) {
+ if (rc == mri_->getRegClass(*reg) && tempPhysRegAvailable(*reg)) {
+ assert(*reg != 0 && "Cannot use register!");
+ DEBUG(std::cerr << mri_->getName(*reg) << '\n');
+ return *reg; // Found an unused register!
+ }
+ }
+ assert(0 && "no free temporary physical register?");
+ return 0;
+}
+
+void RA::assignVirt2PhysReg(unsigned virtReg, unsigned physReg)
+{
+ assert((physRegAvailable(physReg) ||
+ find(reserved_.begin(),
+ reserved_.end(),
+ physReg) != reserved_.end()) &&
+ "attempt to allocate to a not available physical register");
+ v2pMap_[virtReg] = physReg;
+ p2vMap_[physReg] = virtReg;
+}
+
+void RA::clearVirtReg(unsigned virtReg)
+{
+ Virt2PhysMap::iterator it = v2pMap_.find(virtReg);
+ assert(it != v2pMap_.end() &&
+ "attempting to clear a not allocated virtual register");
+ unsigned physReg = it->second;
+ p2vMap_[physReg] = 0;
+ v2pMap_[virtReg] = 0; // this marks that this virtual register
+ // lives on the stack
+ DEBUG(std::cerr << "\t\t\tcleared register " << mri_->getName(physReg)
+ << "\n");
+}
+
+void RA::assignVirt2StackSlot(unsigned virtReg)
+{
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
+ int frameIndex = mf_->getFrameInfo()->CreateStackObject(rc);
+
+ bool inserted = v2ssMap_.insert(std::make_pair(virtReg, frameIndex)).second;
+ assert(inserted &&
+ "attempt to assign stack slot to already assigned register?");
+ // if the virtual register was previously assigned clear the mapping
+ // and free the virtual register
+ if (v2pMap_.find(virtReg) != v2pMap_.end()) {
+ clearVirtReg(virtReg);
+ }
+}
+
+int RA::findOrCreateStackSlot(unsigned virtReg)
+{
+ // use lower_bound so that we can do a possibly O(1) insert later
+ // if necessary
+ Virt2StackSlotMap::iterator it = v2ssMap_.lower_bound(virtReg);
+ if (it != v2ssMap_.end() && it->first == virtReg) {
+ return it->second;
+ }
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
+ int frameIndex = mf_->getFrameInfo()->CreateStackObject(rc);
+
+ v2ssMap_.insert(it, std::make_pair(virtReg, frameIndex));
+
+ return frameIndex;
+}
+
+void RA::spillVirtReg(unsigned virtReg)
+{
+ DEBUG(std::cerr << "\t\t\tspilling register: " << virtReg);
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
+ int frameIndex = findOrCreateStackSlot(virtReg);
+ DEBUG(std::cerr << " to stack slot #" << frameIndex << '\n');
+ ++numSpilled;
+ instrAdded_ += mri_->storeRegToStackSlot(*currentMbb_, currentInstr_,
+ v2pMap_[virtReg], frameIndex, rc);
+ clearVirtReg(virtReg);
+}
+
+void RA::loadVirt2PhysReg(unsigned virtReg, unsigned physReg)
+{
+ DEBUG(std::cerr << "\t\t\tloading register: " << virtReg);
+ const TargetRegisterClass* rc = mf_->getSSARegMap()->getRegClass(virtReg);
+ int frameIndex = findOrCreateStackSlot(virtReg);
+ DEBUG(std::cerr << " from stack slot #" << frameIndex << '\n');
+ ++numReloaded;
+ instrAdded_ += mri_->loadRegFromStackSlot(*currentMbb_, currentInstr_,
+ physReg, frameIndex, rc);
+ assignVirt2PhysReg(virtReg, physReg);
+}
+
+FunctionPass* llvm::createLinearScanRegisterAllocator() {
+ return new RA();
+}
Index: llvm/lib/CodeGen/Passes.cpp
diff -u llvm/lib/CodeGen/Passes.cpp:1.3 llvm/lib/CodeGen/Passes.cpp:1.4
--- llvm/lib/CodeGen/Passes.cpp:1.3 Tue Nov 11 16:41:32 2003
+++ llvm/lib/CodeGen/Passes.cpp Wed Nov 19 21:32:25 2003
@@ -18,14 +18,15 @@
namespace llvm {
namespace {
- enum RegAllocName { simple, local };
+ enum RegAllocName { simple, local, linearscan };
cl::opt<RegAllocName>
RegAlloc("regalloc",
cl::desc("Register allocator to use: (default = simple)"),
cl::Prefix,
- cl::values(clEnumVal(simple, " simple register allocator"),
- clEnumVal(local, " local register allocator"),
+ cl::values(clEnumVal(simple, " simple register allocator"),
+ clEnumVal(local, " local register allocator"),
+ clEnumVal(linearscan, " linear-scan global register allocator"),
0),
cl::init(local));
}
@@ -37,6 +38,8 @@
return createSimpleRegisterAllocator();
case local:
return createLocalRegisterAllocator();
+ case linearscan:
+ return createLinearScanRegisterAllocator();
default:
assert(0 && "no register allocator selected");
return 0; // not reached
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