 25 Feb, 2015 1 commit


Robbert Krebbers authored

 16 Feb, 2015 1 commit


Robbert Krebbers authored

 08 Feb, 2015 2 commits


Robbert Krebbers authored

Robbert Krebbers authored
Important changes in the core semantics: * Types extended with function types. Since function types are a special kind of pointer types, types now have an additional mutual part called "ptr_type". * Pointers extended with function pointers. Theses are just names that refer to an actual function in the function environment. * Typing environments extended to assign argument and return types to function names. Before we used a separate environment for these, but since the argument and return types are already needed to type function pointers, this environment would appear in pretty much every typing judgment. As a sideeffect, the frontend has been rewritten entirely. The important changes are: * Type checking of expressions is more involved: there is a special kind of expression type corresponding to a function designator. * To handle things like block scoped extern function, more statefullness was needed. To prepare for future extensions, the entire frontend now uses a state monad.

 29 Jan, 2015 2 commits


Robbert Krebbers authored

Robbert Krebbers authored
addresses. The operation "mem_force Γ m a" used to apply the identify function to pricisely the object "a", even in case "a" is an "unsigned char" address refering to an individual byte. This caused the ctree substructure of the entire subobject to disappear and had the undesired effect that: mem_force Γ a m ⊑{Γ,true@Γm} m failed to hold (i.e. unused reads cannot be removed).

 25 Jan, 2015 1 commit


Robbert Krebbers authored

 16 Dec, 2014 1 commit


Robbert Krebbers authored
The refinement relation on addresses allows union references to be refined: (β2 → β1) → RUnion i s β1 ⊆ RUnion i s β2 The result is that frozen values are below their unfrozen variant, which made it possible to prove that constant propagation (see constant_propagation.v) can be performed on the level of the memory model.

 30 Sep, 2014 1 commit


Robbert Krebbers authored
Now it only performs injection on hypotheses of the shape f .. = f ..

 24 Sep, 2014 1 commit


Robbert Krebbers authored

 06 Sep, 2014 1 commit


Robbert Krebbers authored

 03 Sep, 2014 1 commit


Robbert Krebbers authored

 06 Aug, 2014 1 commit


Robbert Krebbers authored

 10 Jul, 2014 1 commit


Robbert Krebbers authored

 25 Jun, 2014 1 commit


Robbert Krebbers authored
* Equality comparison of NULL and non NULL pointers should be defined * Pointer comparisons, casts, and truth should only be defined for pointers that are alive * Treat dead pointers as indeterminate values in refinements. The proofs that all operations preserve refinement indicate that dead pointers can be indeed by replaced by anything without affecting the program's behavior.

 23 Jun, 2014 1 commit


Robbert Krebbers authored

 16 Jun, 2014 1 commit


Robbert Krebbers authored
Major changes: * Make void a base type, and include a proper void base value. This is necessary because expressions (free, functions without return value) can yield a void. We now also allow void casts conforming to the C standard. * Various missing lemmas about typing, weakening, decidability, ... * The operations "free" and "alloc" now operate on lvalues instead of rvalues. This removes some duplication. * Improve notations of expressions and statements. Change the presence of the operators conforming to the C standard. Small changes: * Use the classes "Typed" and "TypeCheck" for validity of indexes in memory. This gives more uniform notations. * New tactic "typed_inversion" performs inversion on an inductive predicate of type "Typed" and folds the premises. * Remove a horrible hack in the definitions of the classes "FMap", "MBind", "OMap", "Alter" that was used to let "simpl" behave better. Instead, we have defined a tactic "csimpl" that folds the results after performing an ordinary "simpl". * Fast operation to remove duplicates from lists using hashsets. * Make various type constructors (mainly finite map implementations) universe polymorphic by packing them into an inductive. This way, the whole C syntax can live in type, avoiding the need for (slow) universe checks.

 06 Jun, 2014 1 commit


Robbert Krebbers authored
* Remove generic path_typed instance for lists. For the zippers in the operational semantics, it goes the other way around. * Remove constructor lemmas for values/memory_trees and use a generic tactic instead. This tactic uses the standard constructor tactic, but folds the type classes afterward.

 05 Jun, 2014 1 commit


Robbert Krebbers authored
Major changes: * A data structure to collect locked addresses in memory. * Operations to lock and unlock addresses. * Remove [ctree_Forall] and express it using [Forall] and [ctree_flatten]. This saves a lot of lines of code. * Add a [void] value. This value cannot be typed, but will be used as a dummy return value for functions with return type [void]. Minor changes: * Various deciders in preparation of the executable semantics. * Improve naming and notations. * Remove obsolete stuff.

 24 May, 2014 1 commit


Robbert Krebbers authored

 22 May, 2014 1 commit


Robbert Krebbers authored
* Parametrize refinements with memories. This way, refinements imply typing, for example [w1 ⊑{Γ,f@m1↦m2} w2 : τ → (Γ,m1) ⊢ w1 : τ]. This relieves us from various hacks. * Use addresses instead of index/references pairs for lookup and alter operations on memories. * Prove various disjointness properties.

 04 May, 2014 1 commit


Robbert Krebbers authored

 02 May, 2014 2 commits


Robbert Krebbers authored

Robbert Krebbers authored

 09 Sep, 2013 1 commit


Robbert Krebbers authored

 15 Aug, 2013 1 commit


Robbert Krebbers authored

 24 Jun, 2013 1 commit


Robbert Krebbers authored

 17 Jun, 2013 1 commit


Robbert Krebbers authored

 15 May, 2013 1 commit


Robbert Krebbers authored

 12 May, 2013 1 commit


Robbert Krebbers authored

 11 May, 2013 1 commit


Robbert Krebbers authored

 07 May, 2013 1 commit


Robbert Krebbers authored
The refactoring includes: * Use infix notations for the various list relations * More consistent naming * Put lemmas on one line whenever possible * Change proofs into oneliners when possible * Make better use of the "Implicit Types" command * Improve the order of the list module by placing all definitions at the start, then the proofs, and finally the tactics. Besides, there is some new machinery for proofs by reflection on lists. It is used for a decision procedure for permutations and list containment.

 25 Mar, 2013 1 commit


Robbert Krebbers authored

 14 Mar, 2013 1 commit


Robbert Krebbers authored

 24 Feb, 2013 1 commit


Robbert Krebbers authored

 22 Feb, 2013 1 commit


Robbert Krebbers authored

 19 Feb, 2013 1 commit


Robbert Krebbers authored
Both the operational and axiomatic semantics are extended with sequence points and a permission system based on fractional permissions. In order to achieve this, the memory model has been completely revised, and is now built on top of an abstract interface for permissions. Apart from these changed, the library on lists and sets has been heavily extended, and minor changed have been made to other parts of the prelude.

 01 Feb, 2013 1 commit


Robbert Krebbers authored

 09 Jan, 2013 1 commit


Robbert Krebbers authored
The development now corresponds exactly to the FoSSaCS 2013 paper. Also, the prelude is updated to the one of the master branch.

 05 Jan, 2013 1 commit


Robbert Krebbers authored
* Define the standard strict order on pre orders. * Prove that this strict order is well founded for finite sets and finite maps. We also provide some utilities to compute with well founded recursion. * Improve the "simplify_option_equality" tactic to handle more cases. * Axiomatize finiteness of finite maps by translation to lists, instead of by them having a finite domain. * Prove many additional properties of finite maps. * Add many functions and theorems on lists, including: permutations, resize, filter, ...
