AMDGPU: Rename variable from undef to poison (#130460)

Author: arsenm

llvm/lib/Target/AMDGPU/SIAnnotateControlFlow.cpp

@@ -48,7 +48,7 @@ class SIAnnotateControlFlow {
 
   ConstantInt *BoolTrue;
   ConstantInt *BoolFalse;
-  UndefValue *BoolUndef;
+  PoisonValue *BoolPoison;
   Constant *IntMaskZero;
 
   Function *If = nullptr;
@@ -120,7 +120,7 @@ void SIAnnotateControlFlow::initialize(const GCNSubtarget &ST) {
 
   BoolTrue = ConstantInt::getTrue(Context);
   BoolFalse = ConstantInt::getFalse(Context);
-  BoolUndef = PoisonValue::get(Boolean);
+  BoolPoison = PoisonValue::get(Boolean);
   IntMaskZero = ConstantInt::get(IntMask, 0);
 }