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Incorrect byte instruction optimization.md

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86 - Incorrect byte instruction optimization

The optimizer incorrectly handles byte opcodes whose second argument is 31 or a constant expression that evaluates to 31. This can result in unexpected values. This can happen when performing index access on bytesNN types with a compile time constant value (not index) of 31 or when using the byte opcode in inline assembly. This is due to a compiler bug introduced in v0.5.5 and fixed in v0.5.7. (see here)

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Slide Text

  • byte Opcodes Second Arg = 31
  • Optimizer bytesNN Index or byte
  • Unexpected Value
  • Compiler Bug -> Fixed
  • solc 0.5.5 -> 0.5.7

References

  • Youtube Reference

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