Fix PR9960 by teaching SimpleRegisterCoalescing::AdjustCopiesBackFrom() to preserve

[oota-llvm.git] / lib / CodeGen / SimpleRegisterCoalescing.cpp

diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 06ed66fee7d308ab5936f33d7c3aebbd980bf02a..c33ce24c5e8bb2534fd75a6ae4cf5d31a54d7235 100644 (file)
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -252,7 +252,12 @@ bool SimpleRegisterCoalescing::AdjustCopiesBackFrom(const CoalescerPair &CP,
 
   // Okay, merge "B1" into the same value number as "B0".
   if (BValNo != ValLR->valno) {
+    // If B1 is killed by a PHI, then the merged live range must also be killed
+    // by the same PHI, as B0 and B1 can not overlap.
+    bool HasPHIKill = BValNo->hasPHIKill();
     IntB.MergeValueNumberInto(BValNo, ValLR->valno);
+    if (HasPHIKill)
+      ValLR->valno->setHasPHIKill(true);
   }
   DEBUG({
       dbgs() << "   result = ";