Recompute register class and hint for registers created during spilling.

The spill weight is not recomputed for an unspillable register - it stays infinite.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128490 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 87 insertions, 60 deletions

diff --git a/lib/CodeGen/CalcSpillWeights.cpp b/lib/CodeGen/CalcSpillWeights.cpp
index 5637f4e024..86ab2b6f27 100644
--- a/lib/CodeGen/CalcSpillWeights.cpp
+++ b/lib/CodeGen/CalcSpillWeights.cpp
@@ -103,6 +103,9 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) {
   // 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_iterator I = mri.reg_begin(li.reg);
        MachineInstr *mi = I.skipInstruction();) {
     if (mi->isIdentityCopy() || mi->isImplicitDef() || mi->isDebugValue())
@@ -110,25 +113,28 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) {
     if (!visited.insert(mi))
       continue;
 
-    // Get loop info for mi.
-    if (mi->getParent() != mbb) {
-      mbb = mi->getParent();
-      loop = loops_.getLoopFor(mbb);
-      loopDepth = loop ? loop->getLoopDepth() : 0;
-      isExiting = loop ? loop->isLoopExiting(mbb) : false;
+    float weight = 1.0f;
+    if (Spillable) {
+      // Get loop info for mi.
+      if (mi->getParent() != mbb) {
+        mbb = mi->getParent();
+        loop = loops_.getLoopFor(mbb);
+        loopDepth = loop ? loop->getLoopDepth() : 0;
+        isExiting = loop ? loop->isLoopExiting(mbb) : false;
+      }
+
+      // Calculate instr weight.
+      bool reads, writes;
+      tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg);
+      weight = LiveIntervals::getSpillWeight(writes, reads, loopDepth);
+
+      // Give extra weight to what looks like a loop induction variable update.
+      if (writes && isExiting && lis_.isLiveOutOfMBB(li, mbb))
+        weight *= 3;
+
+      totalWeight += weight;
     }
 
-    // Calculate instr weight.
-    bool reads, writes;
-    tie(reads, writes) = mi->readsWritesVirtualRegister(li.reg);
-    float weight = LiveIntervals::getSpillWeight(writes, reads, loopDepth);
-
-    // 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;
@@ -150,10 +156,14 @@ void VirtRegAuxInfo::CalculateWeightAndHint(LiveInterval &li) {
   // Always prefer the physreg hint.
   if (unsigned hint = hintPhys ? hintPhys : hintVirt) {
     mri.setRegAllocationHint(li.reg, 0, hint);
-    // Weakly boost the spill weifght of hinted registers.
+    // 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()) {
     li.markNotSpillable();
diff --git a/lib/CodeGen/InlineSpiller.cpp b/lib/CodeGen/InlineSpiller.cpp
index 397943bf3c..d0c750777f 100644
--- a/lib/CodeGen/InlineSpiller.cpp
+++ b/lib/CodeGen/InlineSpiller.cpp
@@ -139,6 +139,7 @@ private:
                    MachineBasicBlock::iterator MI);
 
   void spillAroundUses(unsigned Reg);
+  void spillAll();
 };
 }
 
@@ -629,10 +630,6 @@ bool InlineSpiller::reMaterializeFor(LiveInterval &VirtReg,
   LiveInterval &NewLI = Edit->createFrom(VirtReg.reg, LIS, VRM);
   NewLI.markNotSpillable();
 
-  // Rematting for a copy: Set allocation hint to be the destination register.
-  if (MI->isCopy())
-    MRI.setRegAllocationHint(NewLI.reg, 0, MI->getOperand(0).getReg());
-
   // Finally we can rematerialize OrigMI before MI.
   SlotIndex DefIdx = Edit->rematerializeAt(*MI->getParent(), MI, NewLI.reg, RM,
                                            LIS, TII, TRI);
@@ -718,6 +715,11 @@ void InlineSpiller::reMaterializeAll() {
   DEBUG(dbgs() << RegsToSpill.size() << " registers to spill after remat.\n");
 }
 
+
+//===----------------------------------------------------------------------===//
+//                                 Spilling
+//===----------------------------------------------------------------------===//
+
 /// If MI is a load or store of StackSlot, it can be removed.
 bool InlineSpiller::coalesceStackAccess(MachineInstr *MI, unsigned Reg) {
   int FI = 0;
@@ -906,31 +908,8 @@ void InlineSpiller::spillAroundUses(unsigned Reg) {
   }
 }
 
-void InlineSpiller::spill(LiveRangeEdit &edit) {
-  Edit = &edit;
-  assert(!TargetRegisterInfo::isStackSlot(edit.getReg())
-         && "Trying to spill a stack slot.");
-  // Share a stack slot among all descendants of Original.
-  Original = VRM.getOriginal(edit.getReg());
-  StackSlot = VRM.getStackSlot(Original);
-  StackInt = 0;
-
-  DEBUG(dbgs() << "Inline spilling "
-               << MRI.getRegClass(edit.getReg())->getName()
-               << ':' << edit.getParent() << "\nFrom original "
-               << LIS.getInterval(Original) << '\n');
-  assert(edit.getParent().isSpillable() &&
-         "Attempting to spill already spilled value.");
-  assert(DeadDefs.empty() && "Previous spill didn't remove dead defs");
-
-  collectRegsToSpill();
-  analyzeSiblingValues();
-  reMaterializeAll();
-
-  // Remat may handle everything.
-  if (RegsToSpill.empty())
-    return;
-
+/// spillAll - Spill all registers remaining after rematerialization.
+void InlineSpiller::spillAll() {
   // Update LiveStacks now that we are committed to spilling.
   if (StackSlot == VirtRegMap::NO_STACK_SLOT) {
     StackSlot = VRM.assignVirt2StackSlot(Original);
@@ -939,8 +918,8 @@ void InlineSpiller::spill(LiveRangeEdit &edit) {
   } else
     StackInt = &LSS.getInterval(StackSlot);
 
-  if (Original != edit.getReg())
-    VRM.assignVirt2StackSlot(edit.getReg(), StackSlot);
+  if (Original != Edit->getReg())
+    VRM.assignVirt2StackSlot(Edit->getReg(), StackSlot);
 
   assert(StackInt->getNumValNums() == 1 && "Bad stack interval values");
   for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i)
@@ -959,7 +938,7 @@ void InlineSpiller::spill(LiveRangeEdit &edit) {
   }
 
   // Finally delete the SnippetCopies.
-  for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(edit.getReg());
+  for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Edit->getReg());
        MachineInstr *MI = RI.skipInstruction();) {
     assert(SnippetCopies.count(MI) && "Remaining use wasn't a snippet copy");
     // FIXME: Do this with a LiveRangeEdit callback.
@@ -968,6 +947,35 @@ void InlineSpiller::spill(LiveRangeEdit &edit) {
     MI->eraseFromParent();
   }
 
+  // Delete all spilled registers.
   for (unsigned i = 0, e = RegsToSpill.size(); i != e; ++i)
-    edit.eraseVirtReg(RegsToSpill[i], LIS);
+    Edit->eraseVirtReg(RegsToSpill[i], LIS);
+}
+
+void InlineSpiller::spill(LiveRangeEdit &edit) {
+  Edit = &edit;
+  assert(!TargetRegisterInfo::isStackSlot(edit.getReg())
+         && "Trying to spill a stack slot.");
+  // Share a stack slot among all descendants of Original.
+  Original = VRM.getOriginal(edit.getReg());
+  StackSlot = VRM.getStackSlot(Original);
+  StackInt = 0;
+
+  DEBUG(dbgs() << "Inline spilling "
+               << MRI.getRegClass(edit.getReg())->getName()
+               << ':' << edit.getParent() << "\nFrom original "
+               << LIS.getInterval(Original) << '\n');
+  assert(edit.getParent().isSpillable() &&
+         "Attempting to spill already spilled value.");
+  assert(DeadDefs.empty() && "Previous spill didn't remove dead defs");
+
+  collectRegsToSpill();
+  analyzeSiblingValues();
+  reMaterializeAll();
+
+  // Remat may handle everything.
+  if (!RegsToSpill.empty())
+    spillAll();
+
+  Edit->calculateRegClassAndHint(MF, LIS, Loops);
 }
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index 94a3fc1ed0..6b8a533b66 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -15,6 +15,7 @@
 #include "LiveRangeEdit.h"
 #include "VirtRegMap.h"
 #include "llvm/ADT/SetVector.h"
+#include "llvm/CodeGen/CalcSpillWeights.h"
 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
@@ -236,3 +237,13 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
   }
 }
 
+void LiveRangeEdit::calculateRegClassAndHint(MachineFunction &MF,
+                                             LiveIntervals &LIS,
+                                             const MachineLoopInfo &Loops) {
+  VirtRegAuxInfo VRAI(MF, LIS, Loops);
+  for (iterator I = begin(), E = end(); I != E; ++I) {
+    LiveInterval &LI = **I;
+    VRAI.CalculateRegClass(LI.reg);
+    VRAI.CalculateWeightAndHint(LI);
+  }
+}
diff --git a/lib/CodeGen/LiveRangeEdit.h b/lib/CodeGen/LiveRangeEdit.h
index 04eced6d79..e02e0a872d 100644
--- a/lib/CodeGen/LiveRangeEdit.h
+++ b/lib/CodeGen/LiveRangeEdit.h
@@ -25,6 +25,7 @@ namespace llvm {
 
 class AliasAnalysis;
 class LiveIntervals;
+class MachineLoopInfo;
 class MachineRegisterInfo;
 class VirtRegMap;
 
@@ -179,6 +180,10 @@ public:
                          LiveIntervals&, VirtRegMap&,
                          const TargetInstrInfo&);
 
+  /// calculateRegClassAndHint - Recompute register class and hint for each new
+  /// register.
+  void calculateRegClassAndHint(MachineFunction&, LiveIntervals&,
+                                const MachineLoopInfo&);
 };
 
 }
diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp
index 77a172870a..098df59beb 100644
--- a/lib/CodeGen/RegAllocGreedy.cpp
+++ b/lib/CodeGen/RegAllocGreedy.cpp
@@ -1164,6 +1164,7 @@ unsigned RAGreedy::selectOrSplit(LiveInterval &VirtReg,
   NamedRegionTimer T("Spiller", TimerGroupName, TimePassesIsEnabled);
   LiveRangeEdit LRE(VirtReg, NewVRegs, this);
   spiller().spill(LRE);
+  setStage(NewVRegs.begin(), NewVRegs.end(), RS_Spill);
 
   if (VerifyEnabled)
     MF->verify(this, "After spilling");
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index b89ff0c4fc..2c8066fb63 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -17,7 +17,6 @@
 #include "LiveRangeEdit.h"
 #include "VirtRegMap.h"
 #include "llvm/ADT/Statistic.h"
-#include "llvm/CodeGen/CalcSpillWeights.h"
 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
 #include "llvm/CodeGen/MachineDominators.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
@@ -881,14 +880,7 @@ void SplitEditor::finish() {
   }
 
   // Calculate spill weight and allocation hints for new intervals.
-  VirtRegAuxInfo vrai(VRM.getMachineFunction(), LIS, SA.Loops);
-  for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){
-    LiveInterval &li = **I;
-    vrai.CalculateRegClass(li.reg);
-    vrai.CalculateWeightAndHint(li);
-    DEBUG(dbgs() << "  new interval " << MRI.getRegClass(li.reg)->getName()
-                 << ":" << li << '\n');
-  }
+  Edit->calculateRegClassAndHint(VRM.getMachineFunction(), LIS, SA.Loops);
 }