LiveInterval: Distribute subregister liveranges to new intervals in ConnectedVNInfoEqClasses::Distribute()

This improves ConnectedVNInfoEqClasses::Distribute() to distribute the
segments and value numbers in the subranges instead of conservatively
clearing all subregister info.

No separate test here, just clearing the subrange instead of properly
distributing them would however break my upcoming fix regarding dead super
register definitions.

Differential Revision: http://reviews.llvm.org/D13075

llvm-svn: 248334

Author: MatzeB

llvm/lib/CodeGen/LiveInterval.cpp

@@ -1372,6 +1372,40 @@ unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
   return EqClass.getNumClasses();
 }
 
+template<typename LiveRangeT, typename EqClassesT>
+static void DistributeRange(LiveRangeT &LR, LiveRangeT *SplitLRs[],
+                            EqClassesT VNIClasses) {
+  // Move segments to new intervals.
+  LiveRange::iterator J = LR.begin(), E = LR.end();
+  while (J != E && VNIClasses[J->valno->id] == 0)
+    ++J;
+  for (LiveRange::iterator I = J; I != E; ++I) {
+    if (unsigned eq = VNIClasses[I->valno->id]) {
+      assert((SplitLRs[eq-1]->empty() || SplitLRs[eq-1]->expiredAt(I->start)) &&
+             "New intervals should be empty");
+      SplitLRs[eq-1]->segments.push_back(*I);
+    } else
+      *J++ = *I;
+  }
+  LR.segments.erase(J, E);
+
+  // Transfer VNInfos to their new owners and renumber them.
+  unsigned j = 0, e = LR.getNumValNums();
+  while (j != e && VNIClasses[j] == 0)
+    ++j;
+  for (unsigned i = j; i != e; ++i) {
+    VNInfo *VNI = LR.getValNumInfo(i);
+    if (unsigned eq = VNIClasses[i]) {
+      VNI->id = SplitLRs[eq-1]->getNumValNums();
+      SplitLRs[eq-1]->valnos.push_back(VNI);
+    } else {
+      VNI->id = j;
+      LR.valnos[j++] = VNI;
+    }
+  }
+  LR.valnos.resize(j);
+}
+
 void ConnectedVNInfoEqClasses::Distribute(LiveInterval &LI, LiveInterval *LIV[],
                                           MachineRegisterInfo &MRI) {
   // Rewrite instructions.
@@ -1399,35 +1433,37 @@ void ConnectedVNInfoEqClasses::Distribute(LiveInterval &LI, LiveInterval *LIV[],
       MO.setReg(LIV[EqClass-1]->reg);
   }
 
-  // Move runs to new intervals.
-  LiveInterval::iterator J = LI.begin(), E = LI.end();
-  while (J != E && EqClass[J->valno->id] == 0)
-    ++J;
-  for (LiveInterval::iterator I = J; I != E; ++I) {
-    if (unsigned eq = EqClass[I->valno->id]) {
-      assert((LIV[eq-1]->empty() || LIV[eq-1]->expiredAt(I->start)) &&
-             "New intervals should be empty");
-      LIV[eq-1]->segments.push_back(*I);
-    } else
-      *J++ = *I;
-  }
-  // TODO: do not cheat anymore by simply cleaning all subranges
-  LI.clearSubRanges();
-  LI.segments.erase(J, E);
-
-  // Transfer VNInfos to their new owners and renumber them.
-  unsigned j = 0, e = LI.getNumValNums();
-  while (j != e && EqClass[j] == 0)
-    ++j;
-  for (unsigned i = j; i != e; ++i) {
-    VNInfo *VNI = LI.getValNumInfo(i);
-    if (unsigned eq = EqClass[i]) {
-      VNI->id = LIV[eq-1]->getNumValNums();
-      LIV[eq-1]->valnos.push_back(VNI);
-    } else {
-      VNI->id = j;
-      LI.valnos[j++] = VNI;
+  // Distribute subregister liveranges.
+  if (LI.hasSubRanges()) {
+    unsigned NumComponents = EqClass.getNumClasses();
+    SmallVector<unsigned, 8> VNIMapping;
+    SmallVector<LiveInterval::SubRange*, 8> SubRanges;
+    BumpPtrAllocator &Allocator = LIS.getVNInfoAllocator();
+    for (LiveInterval::SubRange &SR : LI.subranges()) {
+      // Create new subranges in the split intervals and construct a mapping
+      // for the VNInfos in the subrange.
+      unsigned NumValNos = SR.valnos.size();
+      VNIMapping.clear();
+      VNIMapping.reserve(NumValNos);
+      SubRanges.clear();
+      SubRanges.resize(NumComponents-1, nullptr);
+      for (unsigned I = 0; I < NumValNos; ++I) {
+        const VNInfo &VNI = *SR.valnos[I];
+        const VNInfo *MainRangeVNI = LI.getVNInfoAt(VNI.def);
+        assert(MainRangeVNI != nullptr
+               && "SubRange def must have corresponding main range def");
+        unsigned ComponentNum = getEqClass(MainRangeVNI);
+        VNIMapping.push_back(ComponentNum);
+        if (ComponentNum > 0 && SubRanges[ComponentNum-1] == nullptr) {
+          SubRanges[ComponentNum-1]
+            = LIV[ComponentNum-1]->createSubRange(Allocator, SR.LaneMask);
+        }
+      }
+      DistributeRange(SR, SubRanges.data(), VNIMapping);
     }
+    LI.removeEmptySubRanges();
   }
-  LI.valnos.resize(j);
+
+  // Distribute main liverange.
+  DistributeRange(LI, LIV, EqClass);
 }