Fix PR8815 by checking for an explicit clobber def tied to a use operand in

ConnectedVNInfoEqClasses::Classify().

llvm-svn: 122202

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/LiveInterval.cpp b/llvm/lib/CodeGen/LiveInterval.cpp
index 3c18017..16551ab 100644
--- a/llvm/lib/CodeGen/LiveInterval.cpp
+++ b/llvm/lib/CodeGen/LiveInterval.cpp
@@ -769,6 +769,14 @@ unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) {
       // operand constraint?
       if (const VNInfo *UVNI = LI->getVNInfoAt(VNI->def.getUseIndex()))
         Connect(VNI->id, UVNI->id);
+
+      // Check for a tied operand constraint involving an early clobber def,
+      // where one VN ends right before the use index and the next VN is defined
+      // at the same use index.
+      if (VNI->def.isUse()) {
+        if (const VNInfo *PVNI = LI->getVNInfoAt(VNI->def.getLoadIndex()))
+          Connect(PVNI->id, VNI->id);
+      }
     }
   }