SplitKit requires that all defs are in place before calling useIntv().

The value mapping gets confused about which original values have multiple new
definitions so they may need phi insertions.

This could probably be simplified by letting enterIntvBefore() take a live range
to be added following the instruction. As long as the range stays inside the
same basic block, value mapping shouldn't be a problem.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123926 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 10 deletions

diff --git a/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp
index 2083c4bdc4..2b30c316f1 100644
--- a/lib/CodeGen/RegAllocGreedy.cpp
+++ b/lib/CodeGen/RegAllocGreedy.cpp
@@ -645,6 +645,9 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
   LiveRangeEdit LREdit(VirtReg, NewVRegs, SpillRegs);
   SplitEditor SE(*SA, *LIS, *VRM, *DomTree, LREdit);
 
+  // Ranges to add to the register interval after all defs are in place.
+  SmallVector<IndexPair, 8> UseRanges;
+
   // Create the main cross-block interval.
   SE.openIntv();
 
@@ -681,7 +684,7 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
       if (!BI.LiveThrough) {
         DEBUG(dbgs() << ", not live-through.\n");
         SE.enterIntvBefore(BI.Def);
-        SE.useIntv(BI.Def, Stop);
+        UseRanges.push_back(IndexPair(BI.Def, Stop));
         continue;
       }
       if (!RegIn) {
@@ -689,7 +692,7 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
         // Reload just before the first use.
         DEBUG(dbgs() << ", not live-in, enter before first use.\n");
         SE.enterIntvBefore(BI.FirstUse);
-        SE.useIntv(BI.FirstUse, Stop);
+        UseRanges.push_back(IndexPair(BI.FirstUse, Stop));
         continue;
       }
       DEBUG(dbgs() << ", live-through.\n");
@@ -707,12 +710,14 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
     if (IP.second < BI.LastUse) {
       // There are interference-free uses at the end of the block.
       // Find the first use that can get the live-out register.
-      SlotIndex Use = *std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(),
-                                        IP.second);
+      SmallVectorImpl<SlotIndex>::const_iterator UI =
+        std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(), IP.second);
+      assert(UI != SA->UseSlots.end() && "Couldn't find last use");
+      SlotIndex Use = *UI;
       DEBUG(dbgs() << ", free use at " << Use << ".\n");
-      assert(Use > IP.second && Use <= BI.LastUse);
+      assert(Use <= BI.LastUse && "Couldn't find last use");
       SE.enterIntvBefore(Use);
-      SE.useIntv(Use, Stop);
+      UseRanges.push_back(IndexPair(Use, Stop));
       continue;
     }
 
@@ -721,6 +726,12 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
     SE.enterIntvAtEnd(*BI.MBB);
   }
 
+  // Add the live-out ranges following the defs.
+  // We must wait until all defs have been inserted, otherwise SplitKit gets
+  // confused about the value mapping.
+  for (unsigned i = 0, e = UseRanges.size(); i != e; ++i)
+    SE.useIntv(UseRanges[i].first, UseRanges[i].second);
+
   // Now all defs leading to live bundles are handled, do everything else.
   for (unsigned i = 0, e = LiveBlocks.size(); i != e; ++i) {
     BlockInfo &BI = LiveBlocks[i];
@@ -786,10 +797,11 @@ void RAGreedy::splitAroundRegion(LiveInterval &VirtReg, unsigned PhysReg,
     if (IP.first > BI.FirstUse) {
       // There are interference-free uses at the beginning of the block.
       // Find the last use that can get the register.
-      SlotIndex Use = std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(),
-                                       IP.second)[-1];
-      DEBUG(dbgs() << ", free use at " << Use << ".\n");
-      Use = Use.getBoundaryIndex();
+      SmallVectorImpl<SlotIndex>::const_iterator UI =
+        std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(), IP.first);
+      assert(UI != SA->UseSlots.begin() && "Couldn't find first use");
+      SlotIndex Use = (--UI)->getBoundaryIndex();
+      DEBUG(dbgs() << ", free use at " << *UI << ".\n");
       assert(Use >= BI.FirstUse && Use < IP.first);
       SE.useIntv(Start, Use);
       SE.leaveIntvAfter(Use);