Instruction Fetch
TLDR: Instruction fetch is the first stage of the CPU pipeline structure where the processor retrieves an instruction from memory to be executed. This operation is essential for initializing the execution process and involves accessing the program counter (PC) to determine the address of the next instruction. The fetched instruction is then sent to the instruction decode stage for further processing. Efficient instruction fetch is critical for maintaining smooth pipeline flow and maximizing processor performance.
https://en.wikipedia.org/wiki/Instruction_fetch
The instruction fetch stage interacts closely with the processor’s cache memory to reduce latency. Most modern CPUs use L1 instruction caches to store frequently accessed instructions, ensuring rapid retrieval. If an instruction is not found in the cache, the processor must fetch it from the main memory, which can lead to delays. To mitigate these delays, prefetching techniques are employed to predict and load upcoming instructions into the cache proactively.
https://www.intel.com/content/www/us/en/architecture-and-technology/cache-memory.html
Advanced processors optimize the instruction fetch stage using features like branch prediction and speculative execution to handle control flow changes efficiently. These techniques predict the next instruction in cases of conditional branches, minimizing pipeline stalls caused by incorrect predictions. By improving the speed and accuracy of instruction fetch, modern processors ensure high throughput and enable smooth execution of multi-threaded and computationally intensive workloads.