Abstract: A method and apparatus for steering instructions dynamically, at issue time, so as to maximize the efficiency of use of execution units being shared by multiple threads being processed by an SMT processor. Resource vectors are used at issue time to redirect instructions, from threads being processed simultaneously, to shared resources for which the multiple threads are competing. The existing resource vectors for instructions that are queued for issuance are analyzed and, where appropriate, dynamically recalculated and modified for maximum efficiency.

Abstract: A method and apparatus for steering instructions dynamically, at issue time, so as to maximize the efficiency of use of execution units being shared by multiple threads being processed by an SMT processor. Resource vectors are used at issue time to redirect instructions, from threads being processed simultaneously, to shared resources for which the multiple threads are competing. The existing resource vectors for instructions that are queued for issuance are analyzed and, where appropriate, dynamically recalculated and modified for maximum efficiency.

Abstract: A method of data processing includes fetching a sequence of instructions, assigning each instruction within the sequence a respective unique instruction tag, and associating a respective destination vector with each instruction. The destination vectors, which are of uniform size, identify which of a plurality of possible destinations for execution results are targeted by the associated instructions. Data dependency between instructions in the sequence is managed by reference to the destination vectors associated with the instructions.

Abstract: A method, completion table and processor for tracking a larger number of outstanding instructions. The completion table may include a plurality of entries where each entry tracks a consecutive number of outstanding instructions. Each entry may be configured to store an instruction address and an identification of a first of the consecutive number of outstanding instructions. By being able to track a consecutive number of outstanding instructions, such as the length of a cache line, in each entry in the completion table by only storing the instruction address and identification of the first of the consecutive number of outstanding instruction in that entry, the completion table may be able to track a larger number of outstanding instruction without increasing its size.

Abstract: An instruction buffer and a method of buffering instructions.

Abstract: A methodology to process flushes in an SMT processor with a dynamically shared group completion table (GCT) and a Flush table comprises identification of incoming flush sources by thread. This uses the forward link array by flush source to determine the next instruction group following the group indicated by the flush source (for example, for mispredicts and load/store flush-next type flushes). Presentation of flush completion table entry numbers or instruction group identifiers (Gtags) to the flush table for computation of oldest flushed group tag corresponding to each thread. The flush selection cycle wherein the flush table outputs are compared against saved versions of all the flush Gtags presented to determine which flush source matches the oldest group output from the flush table. The flush source information is used with the selected oldest Gtag to determine the appropriate additional flushing action to take during the flush cycle.

Abstract: A single rename register array is used in an SMT processor. Two bits are added to each register address of the rename register array, one for bit for thread zero (CTB0) and one bit for thread one (CTB1). The CTB bits are all set to a logic value on power on or start-up. A control instruction (CI) that sets control bits used by other instructions is assigned a register in the rename register array having an address designated as pointer (PTR) address. When a control instruction with an assigned entry with PTR address M completes, then the CTB bit at the PTR address M is flipped to its opposite logic state; likewise, its Valid bit is set to a “not” Valid state. The self resetting CTB bit is used to determine whether an issued instruction sources a register in the rename register array or a corresponding architected register.

Abstract: A methodology to process flushes in an SMT processor with a dynamically shared group completion table (GCT) and a Flush table comprises identification of incoming flush sources by thread. This uses the forward link array by flush source to determine the next instruction group following the group indicated by the flush source (for example, for mispredicts and load/store flush-next type flushes). Presentation of flush completion table entry numbers or instruction group identifiers (Gtags) to the flush table for computation of oldest flushed group tag corresponding to each thread. The flush selection cycle wherein the flush table outputs are compared against saved versions of all the flush Gtags presented to determine which flush source matches the oldest group output from the flush table. The flush source information is used with the selected oldest Gtag to determine the appropriate additional flushing action to take during the flush cycle.

Abstract: A single rename register array is used in an SMT processor. Two bits are added to each register address of the rename register array, one for bit for thread zero (CTB0) and one bit for thread one (CTB1). The CTB bits are all set to a logic value on power on or start-up. A control instruction (CI) that sets control bits used by other instructions is assigned a register in the rename register array having an address designated as pointer (PTR) address. When a control instruction with an assigned entry with PTR address M completes, then the CTB bit at the PTR address M is flipped to its opposite logic state; likewise, its Valid bit is set to a “not” Valid state. The self resetting CTB bit is used to determine whether an issued instruction sources a register in the rename register array or a corresponding architected register.

Abstract: A method of handling instructions in a load/store unit of a processor by dispatching instructions to the load/store unit, filling all physical entries of a reorder queue with tags corresponding to the instructions, and further dispatching one or more additional instructions to the load/store unit while all of the physical entries in the reorder queue are still full, i.e., still contain tags for uncompleted instructions. The invention may be implemented in either a load reorder queue or a store reorder queue. Multiple logical instruction tags are assigned in a count greater than the number of physical entries in the reorder queue. Of the multiple logical instruction tags assigned to a single one of the physical entries in the reorder queue, only the tag for the oldest instruction is allowed to execute. At least one virtual bit (VT) is provided to tag allocations for the load/store unit. This VT bit is flipped when a corresponding tag allocation wraps.

Abstract: A method and device for handling fetch and store requests in a data processing system is provided. A fetch and store buffer comprises a store queue, a fetch queue, a register, a comparator, and a controller. The store queue and the fetch queue receive requests from one or more execution units. When the fetch queue receives a fetch request from an execution unit, it sets a mark in a field associated with the request indicating the store queue entries present at the time the fetch request is entered, and further, removing a mark from the field when the associated store queue entry is drained. The controller gates a copy of the fetch request in the fetch queue into the memory unit address register and to the memory unit, when the memory unit is ready to accept a request. The comparator determines if there is a dependency between the gated request in the memory unit address register and any store queue entries marked in the gated request's field.