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mojo-simd-optimize

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Apply SIMD optimizations to Mojo code for parallel computation. Use when optimizing performance-critical tensor and array operations.

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SIMD Optimization Skill

Parallelize tensor and array operations using SIMD.

When to Use

  • Optimizing tensor operations
  • Vectorizing element-wise computations
  • Performance-critical loops (>1000 elements)
  • Benchmark results show optimization potential

Quick Reference

from sys.info import simdwidthof

comptime width = simdwidthof[DType.float32]()

# SIMD vector add
for i in range(0, size, width):
    result.store(i, a.load[width](i) + b.load[width](i))

Workflow

  1. Identify bottleneck - Profile code to find hot loops
  2. Get SIMD width - Use simdwidthof[dtype]()
  3. Vectorize loop - Process width elements per iteration
  4. Handle remainder - Process leftover elements
  5. Benchmark - Verify performance improvement (4x-8x expected)

Mojo-Specific Notes

  • SIMD width varies by CPU and dtype (usually 8-16 for float32)
  • Always handle remainder elements with scalar loop
  • Prefer alias for compile-time SIMD width constants
  • Test on target hardware - SIMD width is platform-specific

Error Handling

ErrorCauseSolution
Out of boundsRemainder not handledAdd scalar remainder loop
No speedupWrong SIMD widthUse simdwidthof[dtype]()
Compilation failsType mismatchCheck load/store types match
SegfaultMisaligned accessEnsure stride is correct

References

  • .claude/shared/mojo-guidelines.md - SIMD patterns section
  • Mojo manual: SIMD documentation