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10.8 Summary

  • Use the guidelines in this chapter with care; they may be hazardous to your software.

program structure​

  • Use blocks to introduce late initialization when measured performance indicates .

data structures​

  • Use constrained arrays when measured performance indicates.
  • Use zero-based indexing for arrays when measured performance indicates.
  • Use fixed-size components for records when measured performance indicates.
  • Define arrays of records as parallel arrays when measured performance indicates.
  • Use a sequence of assignments for an aggregation when measured performance indicates.

algorithms​

  • Use incremental schemes instead of mod and rem when measured performance indicates.
  • Use the short-circuit control form when measured performance indicates.
  • Use the case statement when measured performance indicates.
  • Use hard-coded constraint checking when measured performance indicates.
  • Use column-first processing of two-dimensional arrays when measured performance indicates.
  • Use overwriting for conditional assignment when measured performance indicates.
  • When measured performance indicates, perform packed Boolean array shift operations by using slice assignments rather than repeated bit-wise assignment.
  • Use static subprogram dispatching when measured performance indicates.<

types​

  • Use only simple aggregates when measured performance indicates.
  • For mutual exclusion, when measured performance indicates, use protected types as an alternative to tasking rendezvous.
  • To implement an interrupt handler, when measured performance indicates, use a protected procedure.
  • Use modular types rather than packed Boolean arrays when measured performance indicates.
  • Use the predefined bounded strings when predictable performance is an issue and measured performance indicates.
  • Use the procedural form of the string handling subprograms when measured performance indicates.
  • Use strong typing with carefully selected constraints to reduce run-time constraint checking when measured performance indicates.
  • For cases where both rendezvous and protected types are inefficient, consider the use of the Real-Time Systems Annex (Ada Reference Manual 1995, Annex D).

pragmas​

  • When measured performance indicates, use pragma Inline when calling overhead is a significant portion of the routine's execution time.
  • Use pragma Restrictions to express the user's intent to abide by certain restrictions.
  • Use pragma Preelaborate where allowed.
  • Use pragma Pure where allowed.
  • Use pragma Discard_Names when the names are not needed by the application and data space is at a premium.
  • Use pragma Suppress where necessary to achieve performance requirements.
  • Use pragma Reviewable to aid in the analysis of the generated code.
note

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