1 files changed, 230 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/CalcSpillWeights.cpp b/contrib/llvm/lib/CodeGen/CalcSpillWeights.cpp
new file mode 100644
index 0000000..abc655a
--- /dev/null
+++ b/contrib/llvm/lib/CodeGen/CalcSpillWeights.cpp
@@ -0,0 +1,230 @@
+//===------------------------ CalcSpillWeights.cpp ------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/VirtRegMap.h"
+#include "llvm/CodeGen/CalcSpillWeights.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "calcspillweights"
+
+void llvm::calculateSpillWeightsAndHints(LiveIntervals &LIS,
+                           MachineFunction &MF,
+                           VirtRegMap *VRM,
+                           const MachineLoopInfo &MLI,
+                           const MachineBlockFrequencyInfo &MBFI,
+                           VirtRegAuxInfo::NormalizingFn norm) {
+  DEBUG(dbgs() << "********** Compute Spill Weights **********\n"
+               << "********** Function: " << MF.getName() << '\n');
+
+  MachineRegisterInfo &MRI = MF.getRegInfo();
+  VirtRegAuxInfo VRAI(MF, LIS, VRM, MLI, MBFI, norm);
+  for (unsigned i = 0, e = MRI.getNumVirtRegs(); i != e; ++i) {
+    unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
+    if (MRI.reg_nodbg_empty(Reg))
+      continue;
+    VRAI.calculateSpillWeightAndHint(LIS.getInterval(Reg));
+  }
+}
+
+// Return the preferred allocation register for reg, given a COPY instruction.
+static unsigned copyHint(const MachineInstr *mi, unsigned reg,
+                         const TargetRegisterInfo &tri,
+                         const MachineRegisterInfo &mri) {
+  unsigned sub, hreg, hsub;
+  if (mi->getOperand(0).getReg() == reg) {
+    sub = mi->getOperand(0).getSubReg();
+    hreg = mi->getOperand(1).getReg();
+    hsub = mi->getOperand(1).getSubReg();
+  } else {
+    sub = mi->getOperand(1).getSubReg();
+    hreg = mi->getOperand(0).getReg();
+    hsub = mi->getOperand(0).getSubReg();
+  }
+
+  if (!hreg)
+    return 0;
+
+  if (TargetRegisterInfo::isVirtualRegister(hreg))
+    return sub == hsub ? hreg : 0;
+
+  const TargetRegisterClass *rc = mri.getRegClass(reg);
+
+  // Only allow physreg hints in rc.
+  if (sub == 0)
+    return rc->contains(hreg) ? hreg : 0;
+
+  // reg:sub should match the physreg hreg.
+  return tri.getMatchingSuperReg(hreg, sub, rc);
+}
+
+// Check if all values in LI are rematerializable
+static bool isRematerializable(const LiveInterval &LI,
+                               const LiveIntervals &LIS,
+                               VirtRegMap *VRM,
+                               const TargetInstrInfo &TII) {
+  unsigned Reg = LI.reg;
+  unsigned Original = VRM ? VRM->getOriginal(Reg) : 0;
+  for (LiveInterval::const_vni_iterator I = LI.vni_begin(), E = LI.vni_end();
+       I != E; ++I) {
+    const VNInfo *VNI = *I;
+    if (VNI->isUnused())
+      continue;
+    if (VNI->isPHIDef())
+      return false;
+
+    MachineInstr *MI = LIS.getInstructionFromIndex(VNI->def);
+    assert(MI && "Dead valno in interval");
+
+    // Trace copies introduced by live range splitting.  The inline
+    // spiller can rematerialize through these copies, so the spill
+    // weight must reflect this.
+    if (VRM) {
+      while (MI->isFullCopy()) {
+        // The copy destination must match the interval register.
+        if (MI->getOperand(0).getReg() != Reg)
+          return false;
+
+        // Get the source register.
+        Reg = MI->getOperand(1).getReg();
+
+        // If the original (pre-splitting) registers match this
+        // copy came from a split.
+        if (!TargetRegisterInfo::isVirtualRegister(Reg) ||
+            VRM->getOriginal(Reg) != Original)
+          return false;
+
+        // Follow the copy live-in value.
+        const LiveInterval &SrcLI = LIS.getInterval(Reg);
+        LiveQueryResult SrcQ = SrcLI.Query(VNI->def);
+        VNI = SrcQ.valueIn();
+        assert(VNI && "Copy from non-existing value");
+        if (VNI->isPHIDef())
+          return false;
+        MI = LIS.getInstructionFromIndex(VNI->def);
+        assert(MI && "Dead valno in interval");
+      }
+    }
+
+    if (!TII.isTriviallyReMaterializable(MI, LIS.getAliasAnalysis()))
+      return false;
+  }
+  return true;
+}
+
+void
+VirtRegAuxInfo::calculateSpillWeightAndHint(LiveInterval &li) {
+  MachineRegisterInfo &mri = MF.getRegInfo();
+  const TargetRegisterInfo &tri = *MF.getSubtarget().getRegisterInfo();
+  MachineBasicBlock *mbb = nullptr;
+  MachineLoop *loop = nullptr;
+  bool isExiting = false;
+  float totalWeight = 0;
+  unsigned numInstr = 0; // Number of instructions using li
+  SmallPtrSet<MachineInstr*, 8> visited;
+
+  // Find the best physreg hint and the best virtreg hint.
+  float bestPhys = 0, bestVirt = 0;
+  unsigned hintPhys = 0, hintVirt = 0;
+
+  // Don't recompute a target specific hint.
+  bool noHint = mri.getRegAllocationHint(li.reg).first != 0;
+
+  // Don't recompute spill weight for an unspillable register.
+  bool Spillable = li.isSpillable();
+
+  for (MachineRegisterInfo::reg_instr_iterator
+       I = mri.reg_instr_begin(li.reg), E = mri.reg_instr_end();
+       I != E; ) {
+    MachineInstr *mi = &*(I++);
+    numInstr++;
+    if (mi->isIdentityCopy() || mi->isImplicitDef() || mi->isDebugValue())
+      continue;
+    if (!visited.insert(mi).second)
+      continue;
+
+    float weight = 1.0f;
+    if (Spillable) {
+      // Get loop info for mi.
+      if (mi->getParent() != mbb) {
+        mbb = mi->getParent();
+        loop = Loops.getLoopFor(mbb);
+        isExiting = loop ? loop->isLoopExiting(mbb) : false;
+      }
+
+      // Calculate instr weight.
+      bool reads, writes;
+      std::tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg);
+      weight = LiveIntervals::getSpillWeight(
+        writes, reads, &MBFI, mi);
+
+      // Give extra weight to what looks like a loop induction variable update.
+      if (writes && isExiting && LIS.isLiveOutOfMBB(li, mbb))
+        weight *= 3;
+
+      totalWeight += weight;
+    }
+
+    // Get allocation hints from copies.
+    if (noHint || !mi->isCopy())
+      continue;
+    unsigned hint = copyHint(mi, li.reg, tri, mri);
+    if (!hint)
+      continue;
+    // Force hweight onto the stack so that x86 doesn't add hidden precision,
+    // making the comparison incorrectly pass (i.e., 1 > 1 == true??).
+    //
+    // FIXME: we probably shouldn't use floats at all.
+    volatile float hweight = Hint[hint] += weight;
+    if (TargetRegisterInfo::isPhysicalRegister(hint)) {
+      if (hweight > bestPhys && mri.isAllocatable(hint))
+        bestPhys = hweight, hintPhys = hint;
+    } else {
+      if (hweight > bestVirt)
+        bestVirt = hweight, hintVirt = hint;
+    }
+  }
+
+  Hint.clear();
+
+  // Always prefer the physreg hint.
+  if (unsigned hint = hintPhys ? hintPhys : hintVirt) {
+    mri.setRegAllocationHint(li.reg, 0, hint);
+    // Weakly boost the spill weight of hinted registers.
+    totalWeight *= 1.01F;
+  }
+
+  // If the live interval was already unspillable, leave it that way.
+  if (!Spillable)
+    return;
+
+  // Mark li as unspillable if all live ranges are tiny.
+  if (li.isZeroLength(LIS.getSlotIndexes())) {
+    li.markNotSpillable();
+    return;
+  }
+
+  // If all of the definitions of the interval are re-materializable,
+  // it is a preferred candidate for spilling.
+  // FIXME: this gets much more complicated once we support non-trivial
+  // re-materialization.
+  if (isRematerializable(li, LIS, VRM, *MF.getSubtarget().getInstrInfo()))
+    totalWeight *= 0.5F;
+
+  li.weight = normalize(totalWeight, li.getSize(), numInstr);
+}