Computer system with logic for writing instruction identifying data into array control lists for precise post-branch recoveries

Claim 1

A register management system for use in a computer having a first number of architected logical registers and provision for executing a stream of instructions following a conditional branch instruction based on a branch direction guess, and provision for determing correctness of said branch direction guess, wherein a plurality of said instructions in said stream comprise a field designating an address of a first one of said logical registers, said register management system comprising: a register array coupled with said computer system, said register array comprising a second number of physical registers, said second number of physical registers being larger than said first number of logical registers, a first list, comprising said first number of entries, each of said entries corresponding to one of said logical registers and comprising a field indicative of one of said physical registers, a second lost comprising said first number of entries, a third list comprising said second number of entries, each of said entries in said third list corresponding to one of said physical registers and comprising an instruction identification field indicative of one instruction in said stream of instructions, a branch status field indicative of presence of an unresolved branch instructions and a control field indicative of a state of use of one of said physical registers, and logic means, coupled with said computer, said first list said second list, and said third list, for: performing assignment of first and second ones of said physical registers to said first one of said logical registers responsive to said state of use, writing first data indicative of said assignments into said first list, and writing data indicative of first and second instructions in said plurality into respective ones of said instruction identification field corresponding to said first and second physical registers; transferring said first data indicative of said assignments from said first list to said second list responsive to decoding of a conditional branch instruction by said computer, and writing third data indicative occurrence of said conditional branch instruction in said branch status field; and transferring said first data indicative of said assignments from said second list to said first list responsive to a determination by said computer that said branch direction guess is not correct.

Claim 7

A method of managing registers in a computer system having a first number of architected logical registers, a second number, greater than said first number, of physical registers, provision for processing a stream of instructions including a conditional branch instruction, provision for processing ones of said instructions following said conditional branch instruction based on a branch direction guess, and provision for determining whether said branch direction guess was correct, wherein a plurality of said instructions in said stream include a field addressing a first one of said logical registers, comprising the steps of: decoding a first instruction in said plurality; responsive to said decoding of said first instruction, performing assignment of a first one of said physical registers to receive data for said first one of said local registers; storing first data indicative of said assignment of said first one of said physical registers in a first table; decoding said conditional branch instruction; responsive to said decoding of said conditional branch instruction, copying said first data indicative of said assignment from said first table into a second table; after said copying, decoding a second instruction in said plurality; responsive to said decoding of said second instruction, assigning a second one of said physical registers to receive data for said first one of said logical registers; storing second data indicative of said assignment of said second one of said physical registers in said first table; after said decoding of said second instruction, determining if said branch direction guess was correct; and responsive to a determination by said determining step, that said branch direction guess was not correct, copying said first data back from said second table into said first table.

Claim 8

A method of managing registers in a computer system having a first number of architected logical registers, a second number, greater than said first number, of physical registers, provision for processing a stream of instructions including a conditional branch instruction, provision for processing ones of said instructions following said conditional branch instruction based on a branch direction guess, and provision for determining whether said branch direction guess was correct, wherein a plurality of said instructions in said stream include a field addressing a first one of said logical registers, comprising the steps of: decoding a first instruction in said plurality; responsive to said decoding of said first instruction, performing assignment of a first one of said physical registers to receive data for said first one of said local registers; storing first data indicative of said assignment of said first one of said physical registers in a first table; decoding said conditional branch instruction; responsive to said decoding of said conditional branch instruction, copying said first data indicative of said assignment from said first table into a second table; after said copying, decoding a second instruction in said plurality; responsive to said decoding of said second instruction, assigning a second one of said physical registers to receive data for said first one of said logical registers; storing second data indicative of said assignment of said second one of said physical registers in said first table; after said decoding of said second instruction, determining if said branch direction guess was correct; and responsive to a determination by said determining step, that said branch direction guess was not correct, copying said first data back from said second table into said first table.