LiveRangeCalc: Rewrite subrange calculation

This changes subrange calculation to calculate subranges sequentially
instead of in parallel. The code is easier to understand that way and
addresses the code review issues raised about LiveOutData being
hard to understand/needing more comments by removing them :)

llvm-svn: 224272

1 files changed, 6 insertions, 14 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index f48be4d5eb0..b71e819f0d3 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -192,8 +192,7 @@ void LiveIntervals::computeVirtRegInterval(LiveInterval &LI) {
   assert(LRCalc && "LRCalc not initialized.");
   assert(LI.empty() && "Should only compute empty intervals.");
   LRCalc->reset(MF, getSlotIndexes(), DomTree, &getVNInfoAllocator());
-  LRCalc->createDeadDefs(LI);
-  LRCalc->extendToUses(LI);
+  LRCalc->calculate(LI);
   computeDeadValues(LI, LI);
 }
 
@@ -254,19 +253,12 @@ void LiveIntervals::computeRegUnitRange(LiveRange &LR, unsigned Unit) {
   for (MCRegUnitRootIterator Roots(Unit, TRI); Roots.isValid(); ++Roots) {
     for (MCSuperRegIterator Supers(*Roots, TRI, /*IncludeSelf=*/true);
          Supers.isValid(); ++Supers) {
-      if (!MRI->reg_empty(*Supers))
-        LRCalc->createDeadDefs(LR, *Supers);
-    }
-  }
-
-  // Now extend LR to reach all uses.
-  // Ignore uses of reserved registers. We only track defs of those.
-  for (MCRegUnitRootIterator Roots(Unit, TRI); Roots.isValid(); ++Roots) {
-    for (MCSuperRegIterator Supers(*Roots, TRI, /*IncludeSelf=*/true);
-         Supers.isValid(); ++Supers) {
       unsigned Reg = *Supers;
-      if (!MRI->isReserved(Reg) && !MRI->reg_empty(Reg))
-        LRCalc->extendToUses(LR, Reg);
+      if (MRI->reg_empty(Reg))
+        continue;
+      // Ignore uses of reserved registers. We only track defs of those.
+      bool IgnoreUses = MRI->isReserved(Reg);
+      LRCalc->calculate(LR, *Supers, IgnoreUses);
     }
   }
 }