[llvm] [LV][EVL] Support cast instruction with EVL-vectorization (PR #108351)

[Mel Chen via llvm-commits]

================
@@ -1381,16 +1384,73 @@ void VPWidenCastRecipe::execute(VPTransformState &State) {
   }
 }
 
+static bool isCastInstruction(unsigned Opcode) {
----------------
Mel-Chen wrote:

Could it replaced by isCast?https://llvm.org/doxygen/classllvm_1_1Instruction.html#a27997849d8982bf226891024fd68daee 

https://github.com/llvm/llvm-project/pull/108351