1. A computer-implemented method of dynamically canceling execution of an unnecessary operation specified by a program instruction during execution of the program instruction, comprising: determining that a condition code comparison operation is specified by the program instruction; obtaining condition code values for data being processed by the program instruction; applying the condition code comparison operation to the condition code values to produce a condition code result; combining the condition code result with a writemask to produce a dynamic writemask indicating determine whether or not an operation specified by the program instruction is unnecessary and should be canceled; determining that a first condition code value should be updated; generating a new condition code value based on the condition code result; updating the first condition code value with the new condition code value, wherein the new condition code value may be used to determine whether an operation specified by a subsequent program instruction should be canceled; and storing the new condition code value in a memory.