-//===-- 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 "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/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 {
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;
- MRI->freezeReservedRegs(vrm.getMachineFunction());
- RegClassInfo.runOnMachineFunction(vrm.getMachineFunction());
-
- 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!
- const char *Msg = "ran out of registers during register allocation";
- // Probably caused by an inline asm.
- MachineInstr *MI;
- for (MachineRegisterInfo::reg_iterator I = MRI->reg_begin(VirtReg->reg);
- (MI = I.skipInstruction());)
- if (MI->isInlineAsm())
- break;
- if (MI)
- MI->emitError(Msg);
- else
- report_fatal_error(Msg);
- // Keep going after reporting the error.
- VRM->assignVirt2Phys(VirtReg->reg,
- RegClassInfo.getOrder(MRI->getRegClass(VirtReg->reg)).front());
- continue;
- }
-
- 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
-// assigned to this physical register.
-void RegAllocBase::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();
-
- for (SmallVectorImpl<LiveInterval*>::const_iterator I = PendingSpills.begin(),
- E = PendingSpills.end(); I != E; ++I) {
- LiveInterval &SpilledVReg = **I;
- DEBUG(dbgs() << "extracting from " <<
- TRI->getName(PhysReg) << " " << SpilledVReg << '\n');
-
- // Deallocate the interfering vreg by removing it from the union.
- // A LiveInterval instance may not be in a union during modification!
- unassign(SpilledVReg, PhysReg);
-
- // Spill the extracted interval.
- LiveRangeEdit LRE(SpilledVReg, SplitVRegs, 0, &PendingSpills);
- spiller().spill(LRE);
- }
- // After extracting segments, the query's results are invalid. But keep the
- // contents valid until we're done accessing pendingSpills.
- Q.clear();
-}
-
-// 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,
- SmallVectorImpl<LiveInterval*> &SplitVRegs) {
- // Record each interference and determine if all are spillable before mutating
- // either the union or live intervals.
- unsigned NumInterferences = 0;
- // Collect interferences assigned to any alias of the physical register.
- for (const unsigned *asI = TRI->getOverlaps(PhysReg); *asI; ++asI) {
- LiveIntervalUnion::Query &QAlias = query(VirtReg, *asI);
- NumInterferences += QAlias.collectInterferingVRegs();
- if (QAlias.seenUnspillableVReg()) {
- return false;
- }
- }
- DEBUG(dbgs() << "spilling " << TRI->getName(PhysReg) <<
- " interferences with " << VirtReg << "\n");
- assert(NumInterferences > 0 && "expect interference");
-
- // Spill each interfering vreg allocated to PhysReg or an alias.
- for (const unsigned *AliasI = TRI->getOverlaps(PhysReg); *AliasI; ++AliasI)
- spillReg(VirtReg, *AliasI, SplitVRegs);
- 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;
- DEBUG(dbgs() << PrintReg(PhysReg, TRI) << " live-in:");
- 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);
- DEBUG(dbgs() << "\tBB#" << MBB->getNumber() << ':'
- << PrintReg(SI.value()->reg, TRI));
- } else if (SI.start() > Stop)
- MBB = Indexes->getMBBFromIndex(SI.start().getPrevIndex());
- if (++MBB == MFE)
- break;
- tie(Start, Stop) = Indexes->getMBBRange(MBB);
- SI.advanceTo(Start);
- }
- DEBUG(dbgs() << '\n');
- }
-}
-
-
-//===----------------------------------------------------------------------===//
-// RABasic Implementation
-//===----------------------------------------------------------------------===//
-
// Driver for the register assignment and splitting heuristics.
// Manages iteration over the LiveIntervalUnions.
//
projects / oota-llvm.git / blobdiff