Processor Register System Shadow State Handling

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Solution Overview

Problem

Conventional implementations of shadow registers in processors require two sets of physical registers and mapping tables, leading to inefficient hardware usage and high power consumption due to the need to switch between them during normal and abnormal states.

Innovation Solution

A register system that uses a single set of physical registers with operational states to distinguish between normal and abnormal states, allowing data to be stored and retrieved from only the appropriate set during abnormal states without switching, thus eliminating the need for a duplicate set of registers and mapping tables.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two sets of physical registers are used to implement shadow registers, then the processor can handle abnormal states, but hardware usage becomes inefficient and power consumption increases

Engineering Contradiction:

Improveabnormal state handlingVSAvoidhardware usage efficiency

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the physical registers into two groups based on their operational states (first operational state and second operational state). This segmentation allows the system to distinguish between registers available for normal operations and those available for shadow register operations, eliminating the need for completely separate register sets while maintaining functional separation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically assigns different operational states to physical registers based on the processor's current state (normal or abnormal). The register renaming logic dynamically determines which physical registers are in the first operational state and which are in the second operational state, allowing flexible switching between normal and shadow register modes without hardware changes.

Inventive Principle:

Principle #15Dynamics

2Reliability

If two sets of physical registers are used, then shadow register functionality is achieved, but power consumption increases due to switching operations

Engineering Contradiction:

Improveshadow register functionalityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent merges the functionality of two separate physical register sets into a single set of physical registers by using operational state differentiation. Instead of having completely separate register sets that require switching, the system uses one register set where registers are dynamically assigned to different operational states, eliminating the need for physical switching operations and reducing power consumption.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent changes the parameter of operational state assignment to distinguish between normal and shadow register modes. By modifying which physical registers are assigned to the first operational state versus the second operational state, the system achieves shadow register functionality without physical switching, thereby reducing power consumption associated with register switching operations.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If register switching is performed during state changes, then normal and abnormal states can be handled, but processor performance decreases due to time consumption

Engineering Contradiction:

Improvestate transition capabilityVSAvoidprocessor performance

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent performs preliminary assignment of physical registers to operational states before state transitions are needed. The register renaming logic pre-determines which physical registers will be in the first operational state and which will be in the second operational state, allowing seamless state transitions without time-consuming switching operations during actual state changes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of physically switching between two register sets, the patent uses the operational state differentiation to create a virtual copy of register availability. The system copies the operational state assignments rather than copying physical register data, allowing state transitions to occur without actual register switching, thereby maintaining processor performance.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS9015450B2Apparatus utilizing efficient hardware implementation of shadow registers and method thereof

Publication Date: 2015.04.21 STMICROELECTRONICS BEIJING R& D

AI summary

Embodiments of a processor architecture efficiently implement shadow registers in hardware. A register system in a processor includes a set of physical data registers coupled to register renaming logic. The register renaming logic stores data in and retrieves data from the set of physical registers when the processor is in a first processor state. The register renaming logic identifies ones of the set of physical registers that have a first operational state as a first group of registers and identifies the remaining ones of the set of physical registers as a second group of registers in response to an indication that the processor is to enter a second processor state from the first processor state. The register renaming logic stores data in and retrieves data from the second group of registers but not the first group of registers when the processor is in the second processor state.