Abstract: Toggling between accessing an entry in a global history with a stew created from branch predictions implied by the ordering of instructions within a trace of a trace cache when a trace is read out of a trace cache, and accessing an entry in a global history with repeatable variations of a stew when there is more than branch instruction within a trace within the trace cache and at least a second branch instruction is read out.

Abstract: A method and apparatus for loop detection for improved branch prediction accuracy. In one embodiment, the method may comprise executing a branch instruction, updating a plurality of event counts corresponding to the branch instruction in response to its executing, determining a loop behavior status corresponding to the branch instruction in response to the event count updating, and promoting the branch instruction to a loop branch prediction type in response to the determination of loop behavior status.

Abstract: One embodiment of the present invention provides a system that facilitates deferring execution of instructions with unresolved data dependencies as they are issued for execution in program order. During a normal execution mode, the system issues instructions for execution in program order. Upon encountering an unresolved data dependency during execution of an instruction, the system generates a checkpoint that can subsequently be used to return execution of the program to the point of the instruction. Next, the system executes subsequent instructions in an execute-ahead mode, wherein instructions that cannot be executed because of an unresolved data dependency are deferred, and wherein other non-deferred instructions are executed in program order.