Don't assume that only Uses can be kills. Defs are marked as kills initially

when there are no uses. This fixes a dangling-pointer bug, where pointers to
deleted instructions were not removed from kills lists. More info here:
http://lists.cs.uiuc.edu/pipermail/llvmdev/2007-July/009749.html


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40131 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 8 deletions

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 504b607b85..d1ebaf102f 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -582,15 +582,13 @@ void LiveVariables::instructionChanged(MachineInstr *OldMI,
         if (VI.DefInst == OldMI)
           VI.DefInst = NewMI;
       }
-      if (MO.isUse()) {
-        if (MO.isKill()) {
-          MO.unsetIsKill();
-          addVirtualRegisterKilled(Reg, NewMI);
-        }
-        // If this is a kill of the value, update the VI kills list.
-        if (VI.removeKill(OldMI))
-          VI.Kills.push_back(NewMI);   // Yes, there was a kill of it
+      if (MO.isKill()) {
+        MO.unsetIsKill();
+        addVirtualRegisterKilled(Reg, NewMI);
       }
+      // If this is a kill of the value, update the VI kills list.
+      if (VI.removeKill(OldMI))
+        VI.Kills.push_back(NewMI);   // Yes, there was a kill of it
     }
   }
 }