Assign indices to empty basic blocks. This will be necessary for StrongPHIElimination in the near future.

llvm-svn: 52300

1 files changed, 9 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
index 37e3895b3c4..5bb3cfa4596 100644
--- a/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -100,11 +100,14 @@ void LiveIntervals::computeNumbering() {
       i2miMap_.push_back(I);
       MIIndex += InstrSlots::NUM;
     }
-
+    
+    if (StartIdx == MIIndex) {
+      // Empty MBB
+      MIIndex += InstrSlots::NUM;
+      i2miMap_.push_back(0);
+    }
     // Set the MBB2IdxMap entry for this MBB.
-    MBB2IdxMap[MBB->getNumber()] = (StartIdx == MIIndex)
-      ? std::make_pair(StartIdx, StartIdx)  // Empty MBB
-      : std::make_pair(StartIdx, MIIndex - 1);
+    MBB2IdxMap[MBB->getNumber()] = std::make_pair(StartIdx, MIIndex - 1);
     Idx2MBBMap.push_back(std::make_pair(StartIdx, MBB));
   }
   std::sort(Idx2MBBMap.begin(), Idx2MBBMap.end(), Idx2MBBCompare());
@@ -661,6 +664,8 @@ void LiveIntervals::computeIntervals() {
       
       MIIndex += InstrSlots::NUM;
     }
+    
+    if (MBB->begin() == miEnd) MIIndex += InstrSlots::NUM; // Empty MBB
   }
 }