1 files changed, 8 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index 1b78f50..a5302a6 100644
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -860,6 +860,14 @@ void BranchFolder::mergeCommonTails(unsigned commonTailIndex) {
       for (Register Reg : NewLiveIns) {
         if (!LiveRegs.available(*MRI, Reg))
           continue;
+
+        // Skip the register if we are about to add one of its super registers.
+        // TODO: Common this up with the same logic in addLineIns().
+        if (any_of(TRI->superregs(Reg), [&](MCPhysReg SReg) {
+              return NewLiveIns.contains(SReg) && !MRI->isReserved(SReg);
+            }))
+          continue;
+
         DebugLoc DL;
         BuildMI(*Pred, InsertBefore, DL, TII->get(TargetOpcode::IMPLICIT_DEF),
                 Reg);