Atomic Composite Signals

Recommendation: Investigate Further

Proposal Information

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• Date Last Updated
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• Focus: Performance

Requirement Summary & Rationale

Proposal here

IEEE 200X Performance Change Proposal

ID: PERF-05

Proposer: John Ries email: johnr@modelNOSPAM.com

Status: Open Proposed: 05-May-2003 Analyzed: Date Resolved: Date

Enhancement Summary: Signal Atomicity Related issues: PERF04 Relevant LRM section:

Enhancement Detail:

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Composite signals semantics are currently defined in terms of their scalar subelements. It has been requested to allow users to control whether a composite signal is single indivisible object, one signal per scalar subelement, or a signal per composite subelement.

Analysis:

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To be performed by the 200X Performance Working Group

Resolution:

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To be performed by the 200X Performance Working Group]

Arguments For

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Arguments Against

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From Jan 31, 2013 meeting

• Normal composites track events on each subelement
• Atomic composite only tracks events on the composite
• With Atomic do I get element resolution functions or do require a resolution function for the entire composite?
• Can simulators already do this?
  • To some degree. If elements not accessed
• Are there use cases that the compiler needs help with?
  • What sort of help does the compiler need?
  • Will this provide any benefit?
• Recommend Investigate Further

General Comments

Email Reflector Comments

• Original VHDL-200X Simulation Performance Reflector Archive

From: Peter Flake (Thu Jan 03 2013 - 09:48:21 PST)

Perf 5: Signal atomicity

I do not understand the effect of this enhancement, and its purpose.

From: Brent Hayhoe (Mon Jan 21 2013 - 13:09:26 PST)

PERF-05 Signal Atomicity

I am guessing here, but could this be linked to this scenario:

   type comp_rt is
     record
sig1_l : Std_Logic;
sig2_l : Std_Logic;
     end record comp_rt;
   signal rec_grp_rs : comp_rt;
...
begin
   process a1(rec_grp_rs.sig1_l)
.....
   process a2(rec_grp_rs.sig2_l)

In order to trigger each process independently, the selected record elements would each act as a sort of sub-signal for the sensitivity lists, rather than have the processes sensitive to the entire record signal.