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Implement Loop Unrolling and Measure the Speedup

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Remove Vectorization Barriers and Use Compiler HintsNext

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Compiler

2.0s Limit 256MB

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Implementation

Implement loop unrolling manually and compare performance to the baseline loop.

Requirements:

Implement a baseline sum loop (no unrolling)
Implement a 2x unrolled version
Implement a 4x unrolled version
Implement an 8x unrolled version
Process an array of at least 1 million elements
Ensure all versions produce the same result
Measure and print execution time for each version
Show speedup relative to baseline
Explain why larger unroll factors may not always help
Show compiler-generated assembly difference conceptually

Test:

Show all versions produce same result
Show timing comparison
Show speedup percentages
Explain optimal unroll factor

Why This Matters

Manual loop unrolling was standard practice in Duff's Device and classic Quake-era game code precisely because compilers of that era wouldn't reliably do it, and modern JIT compilers like V8's TurboFan and LLVM still make explicit unroll-versus-vectorize tradeoffs today since over-unrolling bloats the instruction cache and can hurt more than it helps. Measuring diminishing returns from 2x to 4x to 8x unrolling here is the exact experiment compiler engineers run to tune the unroll heuristics baked into -O3.

Hints

0 / 3 revealed

Validation Suite

main.c

Workspace 1.0

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