Fix PR4910: Broken logic in coalescer means when a physical register liveness is being shortened, the sub-registers were not. The symptom is the register allocator could not find a free register for this particular test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82108 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 3 deletions

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 1288e3053a..e90101a9ba 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -547,14 +547,15 @@ static void removeRange(LiveInterval &li,
       if (!li_->hasInterval(*SR))
         continue;
       LiveInterval &sli = li_->getInterval(*SR);
+      MachineInstrIndex RemoveStart = Start;
       MachineInstrIndex RemoveEnd = Start;
       while (RemoveEnd != End) {
-        LiveInterval::iterator LR = sli.FindLiveRangeContaining(Start);
+        LiveInterval::iterator LR = sli.FindLiveRangeContaining(RemoveStart);
         if (LR == sli.end())
           break;
         RemoveEnd = (LR->end < End) ? LR->end : End;
-        sli.removeRange(Start, RemoveEnd, true);
-        Start = RemoveEnd;
+        sli.removeRange(RemoveStart, RemoveEnd, true);
+        RemoveStart = RemoveEnd;
       }
     }
   }