Matt Godbolt's blog
15 hours ago
- SIMD allows CPUs to process multiple data points with a single instruction, improving performance for array-heavy computations.
- Compilers can automatically vectorize loops with flags like -O3 and -march=skylake, but require proper data layout (e.g., arrays of integers).
- Conditional updates (e.g., max) can be vectorized using mask moves or by rewriting as unconditional operations that map to SIMD instructions like vpmaxsd.
- Compilers add runtime checks for array overlap to ensure vectorization correctness, often generating a fallback scalar loop.