System and method for modifying program status word system mask, system access key, and address space code with overlap enabled

A computer system comprising at least one processor, each of said at least one processor comprising:

• (1) a program status word comprising interrupt masks, an access key, and an address space code;
• (2) decoder means for detecting program status word modification instructions wherein each of said program status word modification instructions is configured to modify an existing program status word;
• (3) execution means, configured to process a plurality of instructions simultaneously, coupled to said decoder means and responsive to said detected program status word modification instruction, for processing said program status word modification instructions with overlap instruction processing enabled to thereby generate a new program status word, said execution means comprising:
• register means, coupled to said decoder means, for storing an architected program status word, said architected program status word being said existing program status word in the subsystem,
• queue means for storing unarchitected program status words, said unarchitected program status words being new program status words generated by said execution unit,
• first transfer means, coupled to said queue means, for transferring said unarchitected program status word into said queue means,
• second transfer means, coupled to a completion means, said register means, and said queue means, for transferring said new program status word from said queue means to said register means in response to completion of said program status word modification instruction processing, and
• discard means, coupled to said completion means, for discarding said new program status word from said queue means in response to incomplete processing of said program status word modification instruction;
• and
• (4) said completion detection means, coupled to said execution means, for determining when said execution of said program status word modification instructions has completed,
• wherein said execution means processes each of said program status word modification instructions according to said unarchitected program status words.

In a computer system comprising at least one processor configured to overlap the processing of a plurality of instructions, the at least one processor having a program status word having a system mask, access key, and address space code, each of the at least one processor having a decoder, an execution unit coupled to the decoder, a queue coupled to the execution unit, and an architected register coupled to the execution unit and queue, a method for modifying the program status word with overlap instruction processing enabled comprising the steps of:

• (a) receiving a program status word modification instruction by the decoder;
• (b) processing said program status word modification instruction with overlap instruction processing enabled by the execution unit according to an unarchitected program status word contained in the queue, wherein said program status word modification instruction being processed generates a new program status word;
• (c) transferring said new program status word into the queue by a first transfer means coupled to the execution unit and the queue;
• (d) determining, by a completion detection unit coupled to the execution unit, whether said execution unit completely processes said program status word modification instruction;
• (e) transferring said new program status word from the queue to the architected register by a second transfer means coupled to the queue and the architected register in response to said execution unit completely processing said program status word modification instruction wherein the architected register stores an architected program status word, said architected program status word being said existing program status word in the at least one processor;
• and
• (f) discarding, by the execution unit, said new program status word from the queue in response to incomplete processing of said program status word modification instruction.