Sugar and Accellera Requirements

1
Sugar and Accellera Requirements

• Cindy Eisner

IBM Research Laboratory in Haifa
2
Bottom Line

• All requirements are either
• met, or
• can be met easily with minor changes to the
  language

3
What Sugar has - highlights

• Rich temporal layer
• Powerful sequences
• Support for simple clocks and resets
• Well-defined semantics
• Commercial implementations in both model checking
  (RuleBase) and simulation (FoCs)

4
What Sugar will have

• Omega-regularity
• Multiple and strong clocks
• Various cosmetic additions

5
Omega-Regularity

• Easily achieved
• Enter the Sugar Foundation Language

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The Sugar Foundation Language

• IBM will layer Sugar into
• Foundation Language (FL) original Sugar with
  linear semantics
• Optional Branching Extension (OBE) original
  Sugar (with branching semantics)
• The layering
• Preserves Sugar advantages
• Has no impact on present users

7
The Sugar Foundation Language

• Syntactically,
• the FL consists of Sugar formulas as defined in
  the original contribution, with the path
  quantifiers removed
• Semantically,
• linear semantics are given to the operators X, U,
  and G

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The Sugar Foundation Language - Example

• Original Sugar
• AG ((snoop hitm) -gt AX next_event(trans_start)(w
  riteback))
• Foundation Language
• G ((snoop hitm) -gt X next_event(trans_start)(wri
  teback))

9
The Sugar Foundation Language In Practice

• Avoids formidable branching semantics, but
• No semantic impact
• for formulas used in practice, linear and
  branching semantics are identical
• in particular, all properties in properties
  document have identical linear and branching
  semantics
• (see M. Maidl, The Common Fragment of CTL and
  LTL, In Proc. 41st Annual Symposium on
  Foundations of Computer Science, IEEE, November
  2000)

10
The Sugar Foundation Language - Theory

• Provides omega-regularity
• Computationally efficient vast majority of
  formulas can be model checked in native mode by
  both CTL and LTL model checkers

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The Sugar Foundation Language - Summary

• Preserves advantages of original Sugar
• in particular, history and track record are
  preserved, as formulas used in practice undergo
  minor syntactic changes, no semantic change
• Adds popular linear semantics
• For details, see Sugar Repackaged The
  Foundation Language

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Multiple and Strong Clocks

• Multiple clocks, main idea
• G (aclka -gt X bclkb)
• G ((a clka) -gt (!clkb W b clkb))
• Strong clocks, main idea
• Property is compiled to additional requirement
• GF clk

13
Various cosmetic additions

• All other requirements are minor cosmetic
  additions. For example
• complex data types
• no-delay, no-side-effect functions
• named assertions

14
Summary

• Sugar is an elegant, powerful temporal logic with
  a strong track record both within and outside of
  IBM
• Sugar has commercial implementations in both
  model checking (RuleBase) and simulation (FoCs)
• The Sugar Foundation Language avoids formidable
  branching semantics and adds omega-regularity,
  with no impact to existing Sugar specifications
• The Sugar Foundation Language meets or can easily
  meet all Accellera requirements