1 files changed, 293 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/RegAllocBasic.cpp b/contrib/llvm/lib/CodeGen/RegAllocBasic.cpp
new file mode 100644
index 0000000..0b6dc68
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/RegAllocBasic.cpp
@@ -0,0 +1,293 @@
+//===-- RegAllocBasic.cpp - Basic Register Allocator ----------------------===//
+//
+//                     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 RABasic function pass, which provides a minimal
+// implementation of the basic register allocator.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "regalloc"
+#include "llvm/CodeGen/Passes.h"
+#include "AllocationOrder.h"
+#include "LiveDebugVariables.h"
+#include "RegAllocBase.h"
+#include "Spiller.h"
+#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/CodeGen/CalcSpillWeights.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/LiveRangeEdit.h"
+#include "llvm/CodeGen/LiveRegMatrix.h"
+#include "llvm/CodeGen/LiveStackAnalysis.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegAllocRegistry.h"
+#include "llvm/CodeGen/VirtRegMap.h"
+#include "llvm/PassAnalysisSupport.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include <cstdlib>
+#include <queue>
+
+using namespace llvm;
+
+static RegisterRegAlloc basicRegAlloc("basic", "basic register allocator",
+                                      createBasicRegisterAllocator);
+
+namespace {
+  struct CompSpillWeight {
+    bool operator()(LiveInterval *A, LiveInterval *B) const {
+      return A->weight < B->weight;
+    }
+  };
+}
+
+namespace {
+/// RABasic provides a minimal implementation of the basic register allocation
+/// algorithm. It prioritizes live virtual registers by spill weight and spills
+/// whenever a register is unavailable. This is not practical in production but
+/// provides a useful baseline both for measuring other allocators and comparing
+/// the speed of the basic algorithm against other styles of allocators.
+class RABasic : public MachineFunctionPass, public RegAllocBase
+{
+  // context
+  MachineFunction *MF;
+
+  // state
+  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();
+
+  /// Return the pass name.
+  virtual const char* getPassName() const {
+    return "Basic Register Allocator";
+  }
+
+  /// RABasic analysis usage.
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+
+  virtual void releaseMemory();
+
+  virtual Spiller &spiller() { return *SpillerInstance; }
+
+  virtual float getPriority(LiveInterval *LI) { return LI->weight; }
+
+  virtual void enqueue(LiveInterval *LI) {
+    Queue.push(LI);
+  }
+
+  virtual LiveInterval *dequeue() {
+    if (Queue.empty())
+      return 0;
+    LiveInterval *LI = Queue.top();
+    Queue.pop();
+    return LI;
+  }
+
+  virtual unsigned selectOrSplit(LiveInterval &VirtReg,
+                                 SmallVectorImpl<LiveInterval*> &SplitVRegs);
+
+  /// 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);
+
+  static char ID;
+};
+
+char RABasic::ID = 0;
+
+} // end anonymous namespace
+
+RABasic::RABasic(): MachineFunctionPass(ID) {
+  initializeLiveDebugVariablesPass(*PassRegistry::getPassRegistry());
+  initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
+  initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
+  initializeRegisterCoalescerPass(*PassRegistry::getPassRegistry());
+  initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
+  initializeCalculateSpillWeightsPass(*PassRegistry::getPassRegistry());
+  initializeLiveStacksPass(*PassRegistry::getPassRegistry());
+  initializeMachineDominatorTreePass(*PassRegistry::getPassRegistry());
+  initializeMachineLoopInfoPass(*PassRegistry::getPassRegistry());
+  initializeVirtRegMapPass(*PassRegistry::getPassRegistry());
+  initializeLiveRegMatrixPass(*PassRegistry::getPassRegistry());
+}
+
+void RABasic::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.setPreservesCFG();
+  AU.addRequired<AliasAnalysis>();
+  AU.addPreserved<AliasAnalysis>();
+  AU.addRequired<LiveIntervals>();
+  AU.addPreserved<LiveIntervals>();
+  AU.addPreserved<SlotIndexes>();
+  AU.addRequired<LiveDebugVariables>();
+  AU.addPreserved<LiveDebugVariables>();
+  AU.addRequired<CalculateSpillWeights>();
+  AU.addRequired<LiveStacks>();
+  AU.addPreserved<LiveStacks>();
+  AU.addRequiredID(MachineDominatorsID);
+  AU.addPreservedID(MachineDominatorsID);
+  AU.addRequired<MachineLoopInfo>();
+  AU.addPreserved<MachineLoopInfo>();
+  AU.addRequired<VirtRegMap>();
+  AU.addPreserved<VirtRegMap>();
+  AU.addRequired<LiveRegMatrix>();
+  AU.addPreserved<LiveRegMatrix>();
+  MachineFunctionPass::getAnalysisUsage(AU);
+}
+
+void RABasic::releaseMemory() {
+  SpillerInstance.reset(0);
+}
+
+
+// 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 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.
+  SmallVector<LiveInterval*, 8> Intfs;
+
+  // Collect interferences assigned to any alias of the physical register.
+  for (MCRegUnitIterator Units(PhysReg, TRI); Units.isValid(); ++Units) {
+    LiveIntervalUnion::Query &Q = Matrix->query(VirtReg, *Units);
+    Q.collectInterferingVRegs();
+    if (Q.seenUnspillableVReg())
+      return false;
+    for (unsigned i = Q.interferingVRegs().size(); i; --i) {
+      LiveInterval *Intf = Q.interferingVRegs()[i - 1];
+      if (!Intf->isSpillable() || Intf->weight > VirtReg.weight)
+        return false;
+      Intfs.push_back(Intf);
+    }
+  }
+  DEBUG(dbgs() << "spilling " << TRI->getName(PhysReg) <<
+        " interferences with " << VirtReg << "\n");
+  assert(!Intfs.empty() && "expected interference");
+
+  // Spill each interfering vreg allocated to PhysReg or an alias.
+  for (unsigned i = 0, e = Intfs.size(); i != e; ++i) {
+    LiveInterval &Spill = *Intfs[i];
+
+    // Skip duplicates.
+    if (!VRM->hasPhys(Spill.reg))
+      continue;
+
+    // Deallocate the interfering vreg by removing it from the union.
+    // A LiveInterval instance may not be in a union during modification!
+    Matrix->unassign(Spill);
+
+    // Spill the extracted interval.
+    LiveRangeEdit LRE(&Spill, SplitVRegs, *MF, *LIS, VRM);
+    spiller().spill(LRE);
+  }
+  return true;
+}
+
+// Driver for the register assignment and splitting heuristics.
+// Manages iteration over the LiveIntervalUnions.
+//
+// This is a minimal implementation of register assignment and splitting that
+// spills whenever we run out of registers.
+//
+// selectOrSplit can only be called once per live virtual register. We then do a
+// single interference test for each register the correct class until we find an
+// available register. So, the number of interference tests in the worst case is
+// |vregs| * |machineregs|. And since the number of interference tests is
+// minimal, there is no value in caching them outside the scope of
+// selectOrSplit().
+unsigned RABasic::selectOrSplit(LiveInterval &VirtReg,
+                                SmallVectorImpl<LiveInterval*> &SplitVRegs) {
+  // Populate a list of physical register spill candidates.
+  SmallVector<unsigned, 8> PhysRegSpillCands;
+
+  // Check for an available register in this class.
+  AllocationOrder Order(VirtReg.reg, *VRM, RegClassInfo);
+  while (unsigned PhysReg = Order.next()) {
+    // Check for interference in PhysReg
+    switch (Matrix->checkInterference(VirtReg, PhysReg)) {
+    case LiveRegMatrix::IK_Free:
+      // PhysReg is available, allocate it.
+      return PhysReg;
+
+    case LiveRegMatrix::IK_VirtReg:
+      // Only virtual registers in the way, we may be able to spill them.
+      PhysRegSpillCands.push_back(PhysReg);
+      continue;
+
+    default:
+      // RegMask or RegUnit interference.
+      continue;
+    }
+  }
+
+  // Try to spill another interfering reg with less spill weight.
+  for (SmallVectorImpl<unsigned>::iterator PhysRegI = PhysRegSpillCands.begin(),
+       PhysRegE = PhysRegSpillCands.end(); PhysRegI != PhysRegE; ++PhysRegI) {
+    if (!spillInterferences(VirtReg, *PhysRegI, SplitVRegs))
+      continue;
+
+    assert(!Matrix->checkInterference(VirtReg, *PhysRegI) &&
+           "Interference after spill.");
+    // Tell the caller to allocate to this newly freed physical register.
+    return *PhysRegI;
+  }
+
+  // No other spill candidates were found, so spill the current VirtReg.
+  DEBUG(dbgs() << "spilling: " << VirtReg << '\n');
+  if (!VirtReg.isSpillable())
+    return ~0u;
+  LiveRangeEdit LRE(&VirtReg, SplitVRegs, *MF, *LIS, VRM);
+  spiller().spill(LRE);
+
+  // The live virtual register requesting allocation was spilled, so tell
+  // the caller not to allocate anything during this round.
+  return 0;
+}
+
+bool RABasic::runOnMachineFunction(MachineFunction &mf) {
+  DEBUG(dbgs() << "********** BASIC REGISTER ALLOCATION **********\n"
+               << "********** Function: "
+               << mf.getName() << '\n');
+
+  MF = &mf;
+  RegAllocBase::init(getAnalysis<VirtRegMap>(),
+                     getAnalysis<LiveIntervals>(),
+                     getAnalysis<LiveRegMatrix>());
+  SpillerInstance.reset(createInlineSpiller(*this, *MF, *VRM));
+
+  allocatePhysRegs();
+
+  // Diagnostic output before rewriting
+  DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *VRM << "\n");
+
+  releaseMemory();
+  return true;
+}
+
+FunctionPass* llvm::createBasicRegisterAllocator()
+{
+  return new RABasic();
+}