-//===-- RegAllocBasic.cpp - basic register allocator ----------------------===//
+//===-- RegAllocBasic.cpp - Basic Register Allocator ----------------------===//
//
// The LLVM Compiler Infrastructure
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "regalloc"
+#include "RegAllocBase.h"
#include "LiveDebugVariables.h"
-#include "LiveIntervalUnion.h"
#include "LiveRangeEdit.h"
-#include "RegAllocBase.h"
#include "RenderMachineFunction.h"
#include "Spiller.h"
#include "VirtRegMap.h"
-#include "llvm/ADT/OwningPtr.h"
-#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Function.h"
#include "llvm/PassAnalysisSupport.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/CodeGen/RegAllocRegistry.h"
-#include "llvm/CodeGen/RegisterCoalescer.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
-#ifndef NDEBUG
-#include "llvm/ADT/SparseBitVector.h"
-#endif
#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/Support/Timer.h"
#include <cstdlib>
#include <queue>
using namespace llvm;
-STATISTIC(NumAssigned , "Number of registers assigned");
-STATISTIC(NumUnassigned , "Number of registers unassigned");
-STATISTIC(NumNewQueued , "Number of new live ranges queued");
-
static RegisterRegAlloc basicRegAlloc("basic", "basic register allocator",
createBasicRegisterAllocator);
-// Temporary verification option until we can put verification inside
-// MachineVerifier.
-static cl::opt<bool, true>
-VerifyRegAlloc("verify-regalloc", cl::location(RegAllocBase::VerifyEnabled),
- cl::desc("Verify during register allocation"));
-
-const char *RegAllocBase::TimerGroupName = "Register Allocation";
-bool RegAllocBase::VerifyEnabled = false;
-
namespace {
struct CompSpillWeight {
bool operator()(LiveInterval *A, LiveInterval *B) const {
{
// context
MachineFunction *MF;
- BitVector ReservedRegs;
// analyses
LiveStacks *LS;
std::auto_ptr<Spiller> SpillerInstance;
std::priority_queue<LiveInterval*, std::vector<LiveInterval*>,
CompSpillWeight> Queue;
+
+ // Scratch space. Allocated here to avoid repeated malloc calls in
+ // selectOrSplit().
+ BitVector UsableRegs;
+
public:
RABasic();
/// Perform register allocation.
virtual bool runOnMachineFunction(MachineFunction &mf);
+ // Helper for spilling all live virtual registers currently unified under preg
+ // that interfere with the most recently queried lvr. Return true if spilling
+ // was successful, and append any new spilled/split intervals to splitLVRs.
+ bool spillInterferences(LiveInterval &VirtReg, unsigned PhysReg,
+ SmallVectorImpl<LiveInterval*> &SplitVRegs);
+
+ void spillReg(LiveInterval &VirtReg, unsigned PhysReg,
+ SmallVectorImpl<LiveInterval*> &SplitVRegs);
+
static char ID;
};
initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
- initializeStrongPHIEliminationPass(*PassRegistry::getPassRegistry());
- initializeRegisterCoalescerAnalysisGroup(*PassRegistry::getPassRegistry());
+ initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
+ initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
initializeLiveStacksPass(*PassRegistry::getPassRegistry());
initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
AU.addPreserved<SlotIndexes>();
AU.addRequired<LiveDebugVariables>();
AU.addPreserved<LiveDebugVariables>();
- if (StrongPHIElim)
- AU.addRequiredID(StrongPHIEliminationID);
- AU.addRequiredTransitive<RegisterCoalescer>();
AU.addRequired<CalculateSpillWeights>();
AU.addRequired<LiveStacks>();
AU.addPreserved<LiveStacks>();
RegAllocBase::releaseMemory();
}
-#ifndef NDEBUG
-// Verify each LiveIntervalUnion.
-void RegAllocBase::verify() {
- LiveVirtRegBitSet VisitedVRegs;
- OwningArrayPtr<LiveVirtRegBitSet>
- unionVRegs(new LiveVirtRegBitSet[PhysReg2LiveUnion.numRegs()]);
-
- // Verify disjoint unions.
- for (unsigned PhysReg = 0; PhysReg < PhysReg2LiveUnion.numRegs(); ++PhysReg) {
- DEBUG(PhysReg2LiveUnion[PhysReg].print(dbgs(), TRI));
- LiveVirtRegBitSet &VRegs = unionVRegs[PhysReg];
- PhysReg2LiveUnion[PhysReg].verify(VRegs);
- // Union + intersection test could be done efficiently in one pass, but
- // don't add a method to SparseBitVector unless we really need it.
- assert(!VisitedVRegs.intersects(VRegs) && "vreg in multiple unions");
- VisitedVRegs |= VRegs;
- }
-
- // Verify vreg coverage.
- for (LiveIntervals::iterator liItr = LIS->begin(), liEnd = LIS->end();
- liItr != liEnd; ++liItr) {
- unsigned reg = liItr->first;
- if (TargetRegisterInfo::isPhysicalRegister(reg)) continue;
- if (!VRM->hasPhys(reg)) continue; // spilled?
- unsigned PhysReg = VRM->getPhys(reg);
- if (!unionVRegs[PhysReg].test(reg)) {
- dbgs() << "LiveVirtReg " << reg << " not in union " <<
- TRI->getName(PhysReg) << "\n";
- llvm_unreachable("unallocated live vreg");
- }
- }
- // FIXME: I'm not sure how to verify spilled intervals.
-}
-#endif //!NDEBUG
-
-//===----------------------------------------------------------------------===//
-// RegAllocBase Implementation
-//===----------------------------------------------------------------------===//
-
-// Instantiate a LiveIntervalUnion for each physical register.
-void RegAllocBase::LiveUnionArray::init(LiveIntervalUnion::Allocator &allocator,
- unsigned NRegs) {
- NumRegs = NRegs;
- Array =
- static_cast<LiveIntervalUnion*>(malloc(sizeof(LiveIntervalUnion)*NRegs));
- for (unsigned r = 0; r != NRegs; ++r)
- new(Array + r) LiveIntervalUnion(r, allocator);
-}
-
-void RegAllocBase::init(VirtRegMap &vrm, LiveIntervals &lis) {
- NamedRegionTimer T("Initialize", TimerGroupName, TimePassesIsEnabled);
- TRI = &vrm.getTargetRegInfo();
- MRI = &vrm.getRegInfo();
- VRM = &vrm;
- LIS = &lis;
- const unsigned NumRegs = TRI->getNumRegs();
- if (NumRegs != PhysReg2LiveUnion.numRegs()) {
- PhysReg2LiveUnion.init(UnionAllocator, NumRegs);
- // Cache an interferece query for each physical reg
- Queries.reset(new LiveIntervalUnion::Query[PhysReg2LiveUnion.numRegs()]);
- }
-}
-
-void RegAllocBase::LiveUnionArray::clear() {
- if (!Array)
- return;
- for (unsigned r = 0; r != NumRegs; ++r)
- Array[r].~LiveIntervalUnion();
- free(Array);
- NumRegs = 0;
- Array = 0;
-}
-
-void RegAllocBase::releaseMemory() {
- for (unsigned r = 0, e = PhysReg2LiveUnion.numRegs(); r != e; ++r)
- PhysReg2LiveUnion[r].clear();
-}
-
-// Visit all the live registers. If they are already assigned to a physical
-// register, unify them with the corresponding LiveIntervalUnion, otherwise push
-// them on the priority queue for later assignment.
-void RegAllocBase::seedLiveRegs() {
- NamedRegionTimer T("Seed Live Regs", TimerGroupName, TimePassesIsEnabled);
- for (LiveIntervals::iterator I = LIS->begin(), E = LIS->end(); I != E; ++I) {
- unsigned RegNum = I->first;
- LiveInterval &VirtReg = *I->second;
- if (TargetRegisterInfo::isPhysicalRegister(RegNum))
- PhysReg2LiveUnion[RegNum].unify(VirtReg);
- else
- enqueue(&VirtReg);
- }
-}
-
-void RegAllocBase::assign(LiveInterval &VirtReg, unsigned PhysReg) {
- DEBUG(dbgs() << "assigning " << PrintReg(VirtReg.reg, TRI)
- << " to " << PrintReg(PhysReg, TRI) << '\n');
- assert(!VRM->hasPhys(VirtReg.reg) && "Duplicate VirtReg assignment");
- VRM->assignVirt2Phys(VirtReg.reg, PhysReg);
- MRI->setPhysRegUsed(PhysReg);
- PhysReg2LiveUnion[PhysReg].unify(VirtReg);
- ++NumAssigned;
-}
-
-void RegAllocBase::unassign(LiveInterval &VirtReg, unsigned PhysReg) {
- DEBUG(dbgs() << "unassigning " << PrintReg(VirtReg.reg, TRI)
- << " from " << PrintReg(PhysReg, TRI) << '\n');
- assert(VRM->getPhys(VirtReg.reg) == PhysReg && "Inconsistent unassign");
- PhysReg2LiveUnion[PhysReg].extract(VirtReg);
- VRM->clearVirt(VirtReg.reg);
- ++NumUnassigned;
-}
-
-// Top-level driver to manage the queue of unassigned VirtRegs and call the
-// selectOrSplit implementation.
-void RegAllocBase::allocatePhysRegs() {
- seedLiveRegs();
-
- // Continue assigning vregs one at a time to available physical registers.
- while (LiveInterval *VirtReg = dequeue()) {
- assert(!VRM->hasPhys(VirtReg->reg) && "Register already assigned");
-
- // Unused registers can appear when the spiller coalesces snippets.
- if (MRI->reg_nodbg_empty(VirtReg->reg)) {
- DEBUG(dbgs() << "Dropping unused " << *VirtReg << '\n');
- LIS->removeInterval(VirtReg->reg);
- continue;
- }
-
- // Invalidate all interference queries, live ranges could have changed.
- invalidateVirtRegs();
-
- // selectOrSplit requests the allocator to return an available physical
- // register if possible and populate a list of new live intervals that
- // result from splitting.
- DEBUG(dbgs() << "\nselectOrSplit "
- << MRI->getRegClass(VirtReg->reg)->getName()
- << ':' << *VirtReg << '\n');
- typedef SmallVector<LiveInterval*, 4> VirtRegVec;
- VirtRegVec SplitVRegs;
- unsigned AvailablePhysReg = selectOrSplit(*VirtReg, SplitVRegs);
-
- if (AvailablePhysReg == ~0u) {
- // selectOrSplit failed to find a register!
- std::string msg;
- raw_string_ostream Msg(msg);
- Msg << "Ran out of registers during register allocation!"
- "\nCannot allocate: " << *VirtReg;
- for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(VirtReg->reg);
- MachineInstr *MI = I.skipInstruction();) {
- if (!MI->isInlineAsm())
- continue;
- Msg << "\nPlease check your inline asm statement for "
- "invalid constraints:\n";
- MI->print(Msg, &VRM->getMachineFunction().getTarget());
- }
- report_fatal_error(Msg.str());
- }
-
- if (AvailablePhysReg)
- assign(*VirtReg, AvailablePhysReg);
-
- for (VirtRegVec::iterator I = SplitVRegs.begin(), E = SplitVRegs.end();
- I != E; ++I) {
- LiveInterval *SplitVirtReg = *I;
- assert(!VRM->hasPhys(SplitVirtReg->reg) && "Register already assigned");
- if (MRI->reg_nodbg_empty(SplitVirtReg->reg)) {
- DEBUG(dbgs() << "not queueing unused " << *SplitVirtReg << '\n');
- LIS->removeInterval(SplitVirtReg->reg);
- continue;
- }
- DEBUG(dbgs() << "queuing new interval: " << *SplitVirtReg << "\n");
- assert(TargetRegisterInfo::isVirtualRegister(SplitVirtReg->reg) &&
- "expect split value in virtual register");
- enqueue(SplitVirtReg);
- ++NumNewQueued;
- }
- }
-}
-
-// Check if this live virtual register interferes with a physical register. If
-// not, then check for interference on each register that aliases with the
-// physical register. Return the interfering register.
-unsigned RegAllocBase::checkPhysRegInterference(LiveInterval &VirtReg,
- unsigned PhysReg) {
- for (const unsigned *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI)
- if (query(VirtReg, *AliasI).checkInterference())
- return *AliasI;
- return 0;
-}
-
-// Helper for spillInteferences() that spills all interfering vregs currently
+// Helper for spillInterferences() that spills all interfering vregs currently
// assigned to this physical register.
-void RegAllocBase::spillReg(LiveInterval& VirtReg, unsigned PhysReg,
- SmallVectorImpl<LiveInterval*> &SplitVRegs) {
+void RABasic::spillReg(LiveInterval& VirtReg, unsigned PhysReg,
+ SmallVectorImpl<LiveInterval*> &SplitVRegs) {
LiveIntervalUnion::Query &Q = query(VirtReg, PhysReg);
assert(Q.seenAllInterferences() && "need collectInterferences()");
const SmallVectorImpl<LiveInterval*> &PendingSpills = Q.interferingVRegs();
// Spill or split all live virtual registers currently unified under PhysReg
// that interfere with VirtReg. The newly spilled or split live intervals are
// returned by appending them to SplitVRegs.
-bool
-RegAllocBase::spillInterferences(LiveInterval &VirtReg, unsigned PhysReg,
+bool RABasic::spillInterferences(LiveInterval &VirtReg, unsigned PhysReg,
SmallVectorImpl<LiveInterval*> &SplitVRegs) {
// Record each interference and determine if all are spillable before mutating
// either the union or live intervals.
return true;
}
-// Add newly allocated physical registers to the MBB live in sets.
-void RegAllocBase::addMBBLiveIns(MachineFunction *MF) {
- NamedRegionTimer T("MBB Live Ins", TimerGroupName, TimePassesIsEnabled);
- SlotIndexes *Indexes = LIS->getSlotIndexes();
- if (MF->size() <= 1)
- return;
-
- LiveIntervalUnion::SegmentIter SI;
- for (unsigned PhysReg = 0; PhysReg < PhysReg2LiveUnion.numRegs(); ++PhysReg) {
- LiveIntervalUnion &LiveUnion = PhysReg2LiveUnion[PhysReg];
- if (LiveUnion.empty())
- continue;
- MachineFunction::iterator MBB = llvm::next(MF->begin());
- MachineFunction::iterator MFE = MF->end();
- SlotIndex Start, Stop;
- tie(Start, Stop) = Indexes->getMBBRange(MBB);
- SI.setMap(LiveUnion.getMap());
- SI.find(Start);
- while (SI.valid()) {
- if (SI.start() <= Start) {
- if (!MBB->isLiveIn(PhysReg))
- MBB->addLiveIn(PhysReg);
- } else if (SI.start() > Stop)
- MBB = Indexes->getMBBFromIndex(SI.start().getPrevIndex());
- if (++MBB == MFE)
- break;
- tie(Start, Stop) = Indexes->getMBBRange(MBB);
- SI.advanceTo(Start);
- }
- }
-}
-
-
-//===----------------------------------------------------------------------===//
-// RABasic Implementation
-//===----------------------------------------------------------------------===//
-
// Driver for the register assignment and splitting heuristics.
// Manages iteration over the LiveIntervalUnions.
//
// selectOrSplit().
unsigned RABasic::selectOrSplit(LiveInterval &VirtReg,
SmallVectorImpl<LiveInterval*> &SplitVRegs) {
+ // Check for register mask interference. When live ranges cross calls, the
+ // set of usable registers is reduced to the callee-saved ones.
+ bool CrossRegMasks = LIS->checkRegMaskInterference(VirtReg, UsableRegs);
+
// Populate a list of physical register spill candidates.
SmallVector<unsigned, 8> PhysRegSpillCands;
// Check for an available register in this class.
- const TargetRegisterClass *TRC = MRI->getRegClass(VirtReg.reg);
-
- for (TargetRegisterClass::iterator I = TRC->allocation_order_begin(*MF),
- E = TRC->allocation_order_end(*MF);
- I != E; ++I) {
-
+ ArrayRef<unsigned> Order =
+ RegClassInfo.getOrder(MRI->getRegClass(VirtReg.reg));
+ for (ArrayRef<unsigned>::iterator I = Order.begin(), E = Order.end(); I != E;
+ ++I) {
unsigned PhysReg = *I;
- if (ReservedRegs.test(PhysReg)) continue;
+
+ // If PhysReg is clobbered by a register mask, it isn't useful for
+ // allocation or spilling.
+ if (CrossRegMasks && !UsableRegs.test(PhysReg))
+ continue;
// Check interference and as a side effect, intialize queries for this
// VirtReg and its aliases.
// Found an available register.
return PhysReg;
}
- LiveInterval *interferingVirtReg =
- Queries[interfReg].firstInterference().liveUnionPos().value();
+ LiveIntervalUnion::Query &IntfQ = query(VirtReg, interfReg);
+ IntfQ.collectInterferingVRegs(1);
+ LiveInterval *interferingVirtReg = IntfQ.interferingVRegs().front();
// The current VirtReg must either be spillable, or one of its interferences
// must have less spill weight.
DEBUG(RMF = &getAnalysis<RenderMachineFunction>());
RegAllocBase::init(getAnalysis<VirtRegMap>(), getAnalysis<LiveIntervals>());
-
- ReservedRegs = TRI->getReservedRegs(*MF);
-
SpillerInstance.reset(createInlineSpiller(*this, *MF, *VRM));
allocatePhysRegs();
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