LiveIntervalAnalysis: Factor out code to update liveness on vreg def removal

This cleans up code and is more in line with the general philosophy of
modifying LiveIntervals through LiveIntervalAnalysis instead of changing
them directly.

This also fixes a case where SplitEditor::removeBackCopies() would miss
the subregister ranges.

llvm-svn: 226690

4 files changed, 41 insertions, 53 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 48daf2ccd06..c03773f8037 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -1375,3 +1375,17 @@ void LiveIntervals::removePhysRegDefAt(unsigned Reg, SlotIndex Pos) {
         LR->removeValNo(VNI);
   }
 }
+
+void LiveIntervals::removeVRegDefAt(LiveInterval &LI, SlotIndex Pos) {
+  VNInfo *VNI = LI.getVNInfoAt(Pos);
+  if (VNI == nullptr)
+    return;
+  LI.removeValNo(VNI);
+
+  // Also remove the value in subranges.
+  for (LiveInterval::SubRange &S : LI.subranges()) {
+    if (VNInfo *SVNI = S.getVNInfoAt(Pos))
+      S.removeValNo(SVNI);
+  }
+  LI.removeEmptySubRanges();
+}
diff --git a/llvm/lib/CodeGen/LiveRangeEdit.cpp b/llvm/lib/CodeGen/LiveRangeEdit.cpp
index c4bfc0e876c..189da659626 100644
--- a/llvm/lib/CodeGen/LiveRangeEdit.cpp
+++ b/llvm/lib/CodeGen/LiveRangeEdit.cpp
@@ -273,21 +273,11 @@ void LiveRangeEdit::eliminateDeadDef(MachineInstr *MI, ToShrinkSet &ToShrink) {
 
     // Remove defined value.
     if (MOI->isDef()) {
-      if (VNInfo *VNI = LI.getVNInfoAt(Idx)) {
-        if (TheDelegate)
-          TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
-        LI.removeValNo(VNI);
-        if (LI.empty()) {
-          RegsToErase.push_back(Reg);
-        } else {
-          // Also remove the value in subranges.
-          for (LiveInterval::SubRange &S : LI.subranges()) {
-            if (VNInfo *SVNI = S.getVNInfoAt(Idx))
-              S.removeValNo(SVNI);
-          }
-          LI.removeEmptySubRanges();
-        }
-      }
+      if (TheDelegate && LI.getVNInfoAt(Idx) != nullptr)
+        TheDelegate->LRE_WillShrinkVirtReg(LI.reg);
+      LIS.removeVRegDefAt(LI, Idx);
+      if (LI.empty())
+        RegsToErase.push_back(Reg);
     }
   }
 
diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
index 70d2e0e18ce..c136916dc27 100644
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -802,7 +802,6 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
         VNInfo *BSubValNo = NewRange->getNextValue(CopyIdx, Allocator);
         addSegmentsWithValNo(*NewRange, BSubValNo, SA, ASubValNo);
       }
-      SA.removeValNo(ASubValNo);
     }
   }
 
@@ -810,17 +809,8 @@ bool RegisterCoalescer::removeCopyByCommutingDef(const CoalescerPair &CP,
   addSegmentsWithValNo(IntB, BValNo, IntA, AValNo);
   DEBUG(dbgs() << "\t\textended: " << IntB << '\n');
 
-  IntA.removeValNo(AValNo);
-  // Remove valuenos in subranges (the A+B have subranges case has already been
-  // handled above)
-  if (!IntB.hasSubRanges()) {
-    SlotIndex AIdx = CopyIdx.getRegSlot(true);
-    for (LiveInterval::SubRange &SA : IntA.subranges()) {
-      VNInfo *ASubValNo = SA.getVNInfoAt(AIdx);
-      assert(ASubValNo != nullptr);
-      SA.removeValNo(ASubValNo);
-    }
-  }
+  LIS->removeVRegDefAt(IntA, AValNo->def);
+
   DEBUG(dbgs() << "\t\ttrimmed:  " << IntA << '\n');
   ++numCommutes;
   return true;
@@ -1013,13 +1003,6 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
   return true;
 }
 
-static void removeUndefValue(LiveRange &LR, SlotIndex At)
-{
-  VNInfo *VNInfo = LR.getVNInfoAt(At);
-  assert(VNInfo != nullptr && SlotIndex::isSameInstr(VNInfo->def, At));
-  LR.removeValNo(VNInfo);
-}
-
 bool RegisterCoalescer::eliminateUndefCopy(MachineInstr *CopyMI) {
   // ProcessImpicitDefs may leave some copies of <undef> values, it only removes
   // local variables. When we have a copy like:
@@ -1053,22 +1036,25 @@ bool RegisterCoalescer::eliminateUndefCopy(MachineInstr *CopyMI) {
 
   // Remove any DstReg segments starting at the instruction.
   LiveInterval &DstLI = LIS->getInterval(DstReg);
-  unsigned DstMask = TRI->getSubRegIndexLaneMask(DstSubIdx);
   SlotIndex RegIndex = Idx.getRegSlot();
-  for (LiveInterval::SubRange &SR : DstLI.subranges()) {
-    if ((SR.LaneMask & DstMask) == 0)
-      continue;
-    removeUndefValue(SR, RegIndex);
-
-    DstLI.removeEmptySubRanges();
-  }
   // Remove value or merge with previous one in case of a subregister def.
   if (VNInfo *PrevVNI = DstLI.getVNInfoAt(Idx)) {
-    VNInfo *VNInfo = DstLI.getVNInfoAt(RegIndex);
-    DstLI.MergeValueNumberInto(VNInfo, PrevVNI);
-  } else {
-    removeUndefValue(DstLI, RegIndex);
-  }
+    VNInfo *VNI = DstLI.getVNInfoAt(RegIndex);
+    DstLI.MergeValueNumberInto(VNI, PrevVNI);
+
+    // The affected subregister segments can be removed.
+    unsigned DstMask = TRI->getSubRegIndexLaneMask(DstSubIdx);
+    for (LiveInterval::SubRange &SR : DstLI.subranges()) {
+      if ((SR.LaneMask & DstMask) == 0)
+        continue;
+
+      VNInfo *SVNI = SR.getVNInfoAt(RegIndex);
+      assert(SVNI != nullptr && SlotIndex::isSameInstr(SVNI->def, RegIndex));
+      SR.removeValNo(SVNI);
+    }
+    DstLI.removeEmptySubRanges();
+  } else
+    LIS->removeVRegDefAt(DstLI, RegIndex);
 
   // Mark uses as undef.
   for (MachineOperand &MO : MRI->reg_nodbg_operands(DstReg)) {
diff --git a/llvm/lib/CodeGen/SplitKit.cpp b/llvm/lib/CodeGen/SplitKit.cpp
index 4c8801a3611..dab1dfe4f1f 100644
--- a/llvm/lib/CodeGen/SplitKit.cpp
+++ b/llvm/lib/CodeGen/SplitKit.cpp
@@ -623,8 +623,7 @@ void SplitEditor::removeBackCopies(SmallVectorImpl<VNInfo*> &Copies) {
   AssignI.setMap(RegAssign);
 
   for (unsigned i = 0, e = Copies.size(); i != e; ++i) {
-    VNInfo *VNI = Copies[i];
-    SlotIndex Def = VNI->def;
+    SlotIndex Def = Copies[i]->def;
     MachineInstr *MI = LIS.getInstructionFromIndex(Def);
     assert(MI && "No instruction for back-copy");
 
@@ -635,13 +634,12 @@ void SplitEditor::removeBackCopies(SmallVectorImpl<VNInfo*> &Copies) {
     while (!AtBegin && (--MBBI)->isDebugValue());
 
     DEBUG(dbgs() << "Removing " << Def << '\t' << *MI);
-    LI->removeValNo(VNI);
+    LIS.removeVRegDefAt(*LI, Def);
     LIS.RemoveMachineInstrFromMaps(MI);
     MI->eraseFromParent();
 
-    // Adjust RegAssign if a register assignment is killed at VNI->def.  We
-    // want to avoid calculating the live range of the source register if
-    // possible.
+    // Adjust RegAssign if a register assignment is killed at Def. We want to
+    // avoid calculating the live range of the source register if possible.
     AssignI.find(Def.getPrevSlot());
     if (!AssignI.valid() || AssignI.start() >= Def)
       continue;