Move RegAllocBase into its own cpp file separate from RABasic.

No functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147972 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 334 insertions, 0 deletions

diff --git a/lib/CodeGen/RegAllocBase.cpp b/lib/CodeGen/RegAllocBase.cpp
new file mode 100644
index 0000000..3f77df3
--- /dev/null
+++ b/lib/CodeGen/RegAllocBase.cpp
@@ -0,0 +1,334 @@
+//===-- RegAllocBase.cpp - Register Allocator Base Class ------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the RegAllocBase class which provides comon functionality
+// for LiveIntervalUnion-based register allocators.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "regalloc"
+#include "RegAllocBase.h"
+#include "LiveRangeEdit.h"
+#include "Spiller.h"
+#include "VirtRegMap.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#ifndef NDEBUG
+#include "llvm/ADT/SparseBitVector.h"
+#endif
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Timer.h"
+
+using namespace llvm;
+
+STATISTIC(NumAssigned     , "Number of registers assigned");
+STATISTIC(NumUnassigned   , "Number of registers unassigned");
+STATISTIC(NumNewQueued    , "Number of new live ranges queued");
+
+// 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;
+
+#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');
+  }
+}
+