Handle cases where a register and one of its super-register are both marked as

defined on the same instruction. This fixes PR1767.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43699 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 2 deletions

diff --git a/lib/CodeGen/LiveVariables.cpp b/lib/CodeGen/LiveVariables.cpp
index 57396b7..7e8965e 100644
--- a/lib/CodeGen/LiveVariables.cpp
+++ b/lib/CodeGen/LiveVariables.cpp
@@ -203,7 +203,7 @@ bool LiveVariables::addRegisterKilled(unsigned IncomingReg, MachineInstr *MI,
                  RegInfo->isSuperRegister(IncomingReg, Reg) &&
                  MO.isKill())
         // A super-register kill already exists.
-        return true;
+        Found = true;
     }
   }
 
@@ -357,7 +357,9 @@ void LiveVariables::HandlePhysRegDef(unsigned Reg, MachineInstr *MI) {
     } else if (PhysRegPartUse[Reg])
       // Add implicit use / kill to last partial use.
       addRegisterKilled(Reg, PhysRegPartUse[Reg], true);
-    else
+    else if (LastRef != MI)
+      // Defined, but not used. However, watch out for cases where a super-reg
+      // is also defined on the same MI.
       addRegisterDead(Reg, LastRef);
   }