Processor Partial Width Load Mode Handling
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Solution Overview
Problem
The existing instruction sets in processors are limited by the length of operation codes (opcodes), which restricts the number of unique instructions that can be identified, leading to increased instruction length and complexity, and challenges in adding new instructions without increasing opcode length or using additional bits to differentiate between operations.
Innovation Solution
Implementing a processor with multiple modes to handle partial width load instructions, allowing different operations to be performed without additional opcodes, by using partial width load modes such as sign extension, zero extension, and merging modes to interpret and decode instructions based on the current mode, thereby reducing the need for longer opcodes and increasing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If additional bits are added to differentiate between different versions of instructions, then the number of distinguishable operations increases, but the instruction length increases
Solution Approach 1:
The patent applies dynamics by making the interpretation of the opcode dynamic based on a mode bit. The same opcode can represent different operations (32-bit load or 64-bit load) depending on the current mode, allowing the instruction set to adapt its behavior without requiring additional distinguishing bits in the instruction encoding itself
Solution Approach 2:
The patent changes the parameter of opcode interpretation based on the mode bit. By switching between different modes (32-bit mode and 64-bit mode), the system can interpret the same opcode differently, effectively doubling the number of distinguishable operations without increasing instruction length
2Adaptability or versatility
If opcode length is increased, then the number of unique instructions that can be identified increases, but the decoder size and complexity increase
Solution Approach 1:
The mode bit serves multiple functions: it determines the interpretation of opcodes, controls the width of data transfers, and influences register selection behavior. This single bit enables the decoder to handle multiple instruction types without requiring separate decoding logic for each variant
Solution Approach 2:
The decoder complexity is reduced by changing the interpretation parameter (mode bit) rather than adding more opcode bits. The same decoder hardware can handle both 32-bit and 64-bit load operations by simply switching its interpretation based on the mode bit, avoiding the need for more complex decoding logic
3Adaptability or versatility
If instruction length is increased, then more operations can be uniquely identified, but the program space usage increases
Solution Approach 1:
The instruction length is kept dynamic through mode-dependent interpretation. The same physical instruction encoding can represent different operations based on the current mode, effectively doubling the operational capacity without increasing the physical space required to store instructions in program memory
Data Source
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AI summary
A method of an aspect is performed by a processor. The method includes receiving a partial width load instruction. The partial width load instruction indicates a memory location of a memory as a source operand and indicates a register as a destination operand. The method includes loading data from the indicated memory location to the processor in response to the partial width load instruction. The method includes writing at least a portion of the loaded data to a partial width of the register in response to the partial width load instruction. The method includes finishing writing the register with a set of bits stored in a remaining width of the register that have bit values that depend on a partial width load mode of the processor. The partial width load instruction does not indicate the partial width load mode. Other methods, processors, and systems are also disclosed.