1. A computer program product for data operand fetching control in a computer processor pipeline, the computer program product comprising: a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising: calculating a summation weight value for each instruction or group of instructions in the computer processor pipeline, the summation weight value calculated as a function of branch uncertainty and a pendency in which the instruction or group of instructions reside in the computer processor pipeline relative to other instructions in the computer processor pipeline; mapping the summation weight value of a selected instruction that is attempting to access system memory to one of a number of pre-defined memory access controls, each of the pre-defined memory access controls specifying a manner of handling data fetching operations; and performing a memory access operation for the selected instruction based upon the mapping.