Abstract: A computer-implemented method is provided for compiling software code that performs nested conditional constructs in vector data processors (10). A vector bit stack (128) to record which processing elements (16) were activated and which processing elements were deactivated during execution of a nested conditional construct. Subsequently, when an end of a first nested conditional construct is encountered, a state of the processing elements at a point in time in which the first nested conditional construct was initiated may be popped off of the vector bit stack and a second conditional construct or any other operation may be executed. Therefore, conditional constructs may be executed while ensuring the proper state of the processing elements. The compiler program effectively utilizes the vector bit stack to store prior states of each of the processing elements of the vector data processor such that the processing elements may be efficiently restored to a correct intermediate value.

Abstract: A "vnmvh" instruction reduces a substantial number of instructions and the temporary use of a register in a software code which executes nested conditional constructs in a vector data processor (10). When the vnmvh instruction is executed, all processing elements in the vector data processor participate in the function regardless of a setting of a status bit (Vt bit) (FIG. 6). During execution of the vnmvh instruction, the least significant bits of vector register specified in an operand are negated and moved into a plurality of history bits (Vh bits) (FIG. 6). The functionality provided by execution of vnmvh instruction allows a user to execute a nested conditional construct efficiently and effectively.