Method and apparatus for resteering failing speculation check instructions

A method of resteering a failing speculation check instruction comprising:

• clearing at least one pending instruction in a pipeline of a processor on which the failing speculation check instruction is being processed;
• preventing new instructions from entering the pipeline for a period of time to allow the failing instruction to be resteered;
• maintaining a current instruction pointer (IP) for the failing speculation check instruction;
• identifying a branch offset value for the instruction, wherein said branch offset value is an IP-relative branch offset;
• calculating a recovery target address for the instruction based on the current IP and the branch offset value, wherein the step of calculating comprises sending the current IP and the branch offset value to the pipeline, during the period of time, using existing instruction data paths that otherwise carry instructions;
• and
• branching the instruction to the recovery target address.

A computer system capable of resteering a failing speculation check instruction comprising:

• i. A core pipeline that receives and executes instructions;
• ii. An instruction fetch unit electrically connected to the core pipeline, which sends instructions to the core pipeline;
• and
• iii. A sequencer capable of controlling the flow of instructions through the core pipeline, wherein, upon the occurrence of a failing speculation check instruction, the sequencer
• (1) Clears a pending instruction in the core pipeline,
• (2) Prevents new instructions from being delivered to the core pipeline for a period of time after the pending instruction is cleared to allow the failing instruction to be resteered, and
• (3) Delivers a current instruction pointer (IP) value and a branch offset immediate value to the core pipeline, during the period of time, wherein the current IP value and the branch offset immediate value proceed through the core pipeline along one or more existing instruction data paths that otherwise carry instructions when the pipeline is not cleared, wherein the failing speculation check instruction is resteered to a recovery target address based on the current IP value and the branch offset immediate value.