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--- simd-openmp [June 11, 2026 at 11:06] – Ivan Janevski
+++ simd-openmp [June 13, 2026 at 03:13] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 # SIMD (OpenMP)
-A modern CPU can add four floats in a single instruction rather than one, loading them into a wide register and operating on all four lanes simultaneously.
+A modern CPU can add four floats in a single instruction rather than one, loading them into a wide register and operating on all four lanes simultaneously. This is **SIMD** (single instruction, multiple data), exposed on x86 as SSE/AVX and on ARM as NEON. The compiler attempts to use these instructions automatically (auto-vectorisation), but it can be blocked by pointer aliasing, non-unit strides, or conditionals it cannot prove safe. `#pragma omp simd` is an explicit assertion that a loop is safe to vectorise, allowing the compiler to emit SIMD instructions even when it would otherwise be cautious.
-This is **SIMD** (single instruction, multiple data), exposed on x86 as SSE/AVX and on ARM as NEON. The compiler attempts to use these instructions automatically (auto-vectorisation), but it can be blocked by pointer aliasing, non-unit strides, or conditionals it cannot prove safe. `#pragma omp simd` is an explicit assertion that a loop is safe to vectorise, allowing the compiler to emit SIMD instructions even when it would otherwise be cautious.
 ```c