Processor Register File Merging Avoidance via Zero Bit Detection
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Solution Overview
Problem
Processor architectures face inefficiencies and increased power usage due to the need for register renaming and merging of results when switching between different instruction widths, particularly in supporting SSE, AVX, and AVX-512 instructions, which can lead to performance degradation and unnecessary power consumption.
Innovation Solution
A processor employs a shadow-latch based register file with a register rename map table that uses multiple zero data values to detect sequential zeros, allowing it to operate at partial instruction widths (128 bits or 256 bits) instead of full 512 bits, thereby avoiding unnecessary merging and reconfiguration, and utilizing temporary storage to manage data during bit width changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If register renaming is performed during arithmetic operations to support different instruction widths, then the processor can maintain architectural register states, but additional power is consumed and processing time increases due to copying data to new physical registers
Solution Approach 1:
The patent applies partial action by detecting sequential zero bits in register data and performing renaming operations only on the necessary portion of the register (e.g., only renaming 128 bits or 256 bits when upper bits are zero) rather than always renaming the full 512 bits. This reduces power consumption and processing time while maintaining correctness for the actual data being processed.
Solution Approach 2:
The patent implements local quality by treating different portions of the register differently based on their content. When upper bits contain sequential zeros, those portions are handled differently (not renamed or merged) compared to the lower bits containing actual data. This allows the processor to adapt the renaming behavior locally to match the actual data requirements.
2Productivity
If full 512-bit operations are performed regardless of actual data width, then the processor can simplify control logic, but performance decreases due to unnecessary merging and reconfiguration operations
Solution Approach 1:
The patent applies preliminary action by detecting sequential zero bits and determining the actual data width before executing the arithmetic operation. This allows the processor to configure the register file and execution units appropriately in advance, avoiding unnecessary merging operations during execution and improving overall performance.
Solution Approach 2:
The patent implements dynamics by making the register file configuration and operation width dynamic based on the detected sequential zero bits. The processor can switch between different operational modes (128-bit, 256-bit, or 512-bit) depending on the actual data requirements, allowing optimal performance for each case while maintaining a unified hardware structure.
3Adaptability or versatility
If merging of results is performed in the register file to support SSE instructions, then compatibility with different instruction widths is maintained, but unnecessary power usage occurs and performance is reduced due to repeated merging and copying operations
Solution Approach 1:
The patent applies partial action by performing merging operations only when necessary - specifically when the upper bits of the register contain non-zero data that needs to be preserved. When sequential zero bits are detected in the upper portions, the processor skips the merging operation for those portions, reducing power consumption and improving performance while maintaining correctness.
Data Source
AI summary
A processor includes a register file and control logic that detects multiple different sets of sequential zero bits of a register in the register file, wherein each of the multiple different sets has a bit length that corresponds to a partial instruction width and operates at a first partial instruction width or a second partial instruction width with the register file depending on number of sets of zero bits detected in the register. In certain examples, the control logic causes operating at first instruction width that avoids merging of a first bit length of data in the register and operating at the second instruction width that avoids merging of a second bit length of data in the register. In some examples, a register rename map table incudes multiple zero bits that identify the detected multiple different sets of bits of sequential zeros.