Recommit r129383. PreRA scheduler heuristic fixes: VRegCycle, TokenFactor latency.

[oota-llvm.git] / lib / CodeGen / LiveRangeEdit.cpp

diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index d1a2fafca84762441d6ffd4909fb1ec37a622b4e..88ee457f4fb32e7114bb6bda921c8c5f29cf8384 100644 (file)
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -11,9 +11,11 @@
 // is spilled or split.
 //===----------------------------------------------------------------------===//
 
+#define DEBUG_TYPE "regalloc"
 #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"
@@ -147,12 +149,61 @@ void LiveRangeEdit::eraseVirtReg(unsigned Reg, LiveIntervals &LIS) {
     LIS.removeInterval(Reg);
 }
 
+bool LiveRangeEdit::foldAsLoad(LiveInterval *LI,
+                               SmallVectorImpl<MachineInstr*> &Dead,
+                               MachineRegisterInfo &MRI,
+                               LiveIntervals &LIS,
+                               const TargetInstrInfo &TII) {
+  MachineInstr *DefMI = 0, *UseMI = 0;
+
+  // Check that there is a single def and a single use.
+  for (MachineRegisterInfo::reg_nodbg_iterator I = MRI.reg_nodbg_begin(LI->reg),
+       E = MRI.reg_nodbg_end(); I != E; ++I) {
+    MachineOperand &MO = I.getOperand();
+    MachineInstr *MI = MO.getParent();
+    if (MO.isDef()) {
+      if (DefMI && DefMI != MI)
+        return false;
+      if (!MI->getDesc().canFoldAsLoad())
+        return false;
+      DefMI = MI;
+    } else if (!MO.isUndef()) {
+      if (UseMI && UseMI != MI)
+        return false;
+      // FIXME: Targets don't know how to fold subreg uses.
+      if (MO.getSubReg())
+        return false;
+      UseMI = MI;
+    }
+  }
+  if (!DefMI || !UseMI)
+    return false;
+
+  DEBUG(dbgs() << "Try to fold single def: " << *DefMI
+               << "       into single use: " << *UseMI);
+
+  SmallVector<unsigned, 8> Ops;
+  if (UseMI->readsWritesVirtualRegister(LI->reg, &Ops).second)
+    return false;
+
+  MachineInstr *FoldMI = TII.foldMemoryOperand(UseMI, Ops, DefMI);
+  if (!FoldMI)
+    return false;
+  DEBUG(dbgs() << "                folded: " << *FoldMI);
+  LIS.ReplaceMachineInstrInMaps(UseMI, FoldMI);
+  UseMI->eraseFromParent();
+  DefMI->addRegisterDead(LI->reg, 0);
+  Dead.push_back(DefMI);
+  return true;
+}
+
 void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
                                       LiveIntervals &LIS, VirtRegMap &VRM,
                                       const TargetInstrInfo &TII) {
   SetVector<LiveInterval*,
             SmallVector<LiveInterval*, 8>,
             SmallPtrSet<LiveInterval*, 8> > ToShrink;
+  MachineRegisterInfo &MRI = VRM.getRegInfo();
 
   for (;;) {
     // Erase all dead defs.
@@ -186,8 +237,13 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
           continue;
         LiveInterval &LI = LIS.getInterval(Reg);
 
-        // Shrink read registers.
-        if (MI->readsVirtualRegister(Reg))
+        // Shrink read registers, unless it is likely to be expensive and
+        // unlikely to change anything. We typically don't want to shrink the
+        // PIC base register that has lots of uses everywhere.
+        // Always shrink COPY uses that probably come from live range splitting.
+        if (MI->readsVirtualRegister(Reg) &&
+            (MI->isCopy() || MOI->isDef() || MRI.hasOneNonDBGUse(Reg) ||
+             LI.killedAt(Idx)))
           ToShrink.insert(&LI);
 
         // Remove defined value.
@@ -216,6 +272,8 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
     // Shrink just one live interval. Then delete new dead defs.
     LiveInterval *LI = ToShrink.back();
     ToShrink.pop_back();
+    if (foldAsLoad(LI, Dead, MRI, LIS, TII))
+      continue;
     if (delegate_)
       delegate_->LRE_WillShrinkVirtReg(LI->reg);
     if (!LIS.shrinkToUses(LI, &Dead))
@@ -229,9 +287,22 @@ void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
       continue;
     DEBUG(dbgs() << NumComp << " components: " << *LI << '\n');
     SmallVector<LiveInterval*, 8> Dups(1, LI);
-    for (unsigned i = 1; i != NumComp; ++i)
+    for (unsigned i = 1; i != NumComp; ++i) {
       Dups.push_back(&createFrom(LI->reg, LIS, VRM));
-    ConEQ.Distribute(&Dups[0], VRM.getRegInfo());
+      if (delegate_)
+        delegate_->LRE_DidCloneVirtReg(Dups.back()->reg, LI->reg);
+    }
+    ConEQ.Distribute(&Dups[0], MRI);
   }
 }
 
+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);
+  }
+}