 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.

 25 Jan, 2015 1 commit


Robbert Krebbers authored

 15 Nov, 2014 1 commit


Robbert Krebbers authored
Integers with the same size, are no longer supposed to have the same rank. As a result, the C integer types (char, short, int, long, long long) are different (and thus cannot alias) even if they have the same size. We now have to use a more involved definition of integer promotions and usual arithmetic conversions. However, this new definition follows the C standard literally.

 10 Oct, 2014 1 commit


Robbert Krebbers authored
The proof now uses the stronger notion of memory permutation instead of a more general memory refinement. We have also proven that memory permutations are symmetric.

 30 Sep, 2014 1 commit


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

 06 Sep, 2014 1 commit


Robbert Krebbers authored

 22 Aug, 2014 1 commit


Robbert Krebbers authored
memory instead of the whole memory itself. This has the following advantages: * Avoid parametrization in {addresses,pointers,pointer_bits,bits}.v * Make {base_values,values}.v independent of the memory, this makes better parallelized compilation possible. * Allow small memories (e.g. singletons as used in separation logic) with addresses to objects in another part to be typed. * Some proofs become easier, because the memory environments are preserved under many operations (insert, force, lock, unlock). It also as the following disadvantages: * At all kinds of places we now have explicit casts from memories to memory environments. This is kind of ugly. Note, we cannot declare memenv_of as a Coercion because it is nonuniform. * It is a bit inefficient with respect to the interpreter, because memory environments are finite functions instead of proper functions, so calling memenv_of often (which we do) is not too good.

 10 Jul, 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.

 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.

 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.

 02 May, 2014 2 commits


Robbert Krebbers authored

Robbert Krebbers authored

 12 Aug, 2013 1 commit


Robbert Krebbers authored
This commit includes the following changes: * More theorems about pre, partial and total orders. * Define the lexicographic order on various commonly used data types. * Mergesort and its correctness proof. * Implement finite maps and sets using ordered association lists.

 17 Jun, 2013 1 commit


Robbert Krebbers authored

 15 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.

 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.

 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, ...

 12 Nov, 2012 1 commit


Robbert Krebbers authored
Most interestingly: * Use [lia] instead of [omega] everywhere * More many generic lemmas on the memory to the theory on finite maps. * Many additional list lemmas. * A new interface for a monad for collections, which is now also used by the collection tactics. * Provide an additional finite collection implementation using unordered lists without duplicates removed. This implementation forms a monad (just the list monad in disguise).

 19 Oct, 2012 1 commit


Robbert Krebbers authored
The following things have been changed in this revision: * We now give a small step semantics for expressions. The denotational semantics only works for sideeffect free expressions. * Dynamically allocated memory through alloc and free is now supported. * The following expressions are added: assignment, function call, unary operators, conditional, alloc, and free. * Some customary induction schemes for expressions are proven. * The axiomatic semantics (and its interpretation) have been changed in order to deal with nondeterministic expressions. * We have added inversion schemes based on small inversions for the operational semantics. Inversions using these schemes are much faster. * We improved the statement preservation proof of the operational semantics. * We now use a variant of SsReflect's [by] and [done], instead of Coq's [now] and [easy]. The [done] tactic is much faster as it does not perform inversions. * Add theory, definitions and notations on vectors. * Separate theory on contexts. * Change [Arguments] declarations to ensure better unfolding.

 10 Oct, 2012 1 commit


Robbert Krebbers authored
* Introduce a type class and notation for disjointness. * Define unions of finite maps (a lot of theory has still to be moved from memory to fin_maps). * Prove the Hoare rule for function calls with arguments. * Prove the Hoare rule to add sets of functions. * Some additional theory on lifting of assertions.

 04 Sep, 2012 1 commit


Robbert Krebbers authored

 29 Aug, 2012 1 commit


Robbert Krebbers authored
improve some definitions, simplify some proofs.

 21 Aug, 2012 1 commit


Robbert Krebbers authored
The main changes are: * Function calls in the operational semantics * Mutually recursive function calls in the axiomatic semantics * A general definition of the interpretation of the axiomatic semantics so as to improve reusability (useful for function calls, and also for expressions in future versions) * Type classes for stack independent, memory independent, and memory extensible assertions, and a lot of instances to automatically derive these properties. * Many additional lemmas on the memory and more robust tactics to simplify goals involving is_free and mem_disjoint * Proof of preservation of statements in the smallstep semantics * Some new tactics: feed, feed destruct, feed inversion, etc... * More robust tactic scripts using bullets and structured scripts * Truncate most lines at 80 characters

 14 Jun, 2012 1 commit


Robbert Krebbers authored
Before, it just ensured that whenever one can split up the memory into two parts before running the program, the framing part can be split off when the program is finished. Now it also ensure that it can be split off at any moment during the execution of the program. When we extend to nondeterministic expressions/sequence points we certainly need this for the Hoare judgment for expressions, as C allows evaluation of them to interleave. However, for consistency, and further extensions, it is nice to have this property for statements too.

 11 Jun, 2012 1 commit


Robbert Krebbers authored
