<!--
title: prefer const variables
domain: llm-infra
topic: Code Style
language: CUDA
source: ggml-org/llama.cpp
updated: 2025-07-22
url: https://awesomereviewers.com/reviewers/llama.cpp-prefer-const-variables/
-->

Add the `const` qualifier to variables that are not modified after initialization. This improves code clarity, prevents accidental modifications, and makes the code's intent more explicit to both compilers and other developers.

Apply `const` to:
- Local variables that are initialized once and never changed
- Function parameters that are not modified within the function
- Any variable where the value remains constant throughout its scope

Example transformations:
```cpp
// Before
float2 dsB;
dsB = __half22float2(y_dm[j*MMQ_TILE_Y_K + k01/QI8_1]);

int global_idx = blockIdx.x * blockDim.x + threadIdx.x;
int total_elements = batches * channels * out_h * out_w;

// After  
const float2 dsB = __half22float2(y_dm[j*MMQ_TILE_Y_K + k01/QI8_1]);

const int global_idx = blockIdx.x * blockDim.x + threadIdx.x;
const int total_elements = batches * channels * out_h * out_w;
```

This practice is especially important in CUDA kernels and performance-critical code where clarity about data mutability helps with optimization and debugging.