diff --git a/llvm/lib/Target/X86/X86LowerAMXType.cpp b/llvm/lib/Target/X86/X86LowerAMXType.cpp
--- a/llvm/lib/Target/X86/X86LowerAMXType.cpp
+++ b/llvm/lib/Target/X86/X86LowerAMXType.cpp
@@ -912,7 +912,7 @@
   for (BasicBlock &BB : Func) {
     for (Instruction &I : BB) {
       if (isAMXCast(&I)) {
-        if (PHINode *PN = dyn_cast<PHINode>(I.getOperand(0)))
+        if (isa<PHINode>(I.getOperand(0)))
           PhiCastWorkList.push_back(&I);
       }
     }