15,684 research outputs found
A Verified Information-Flow Architecture
SAFE is a clean-slate design for a highly secure computer system, with
pervasive mechanisms for tracking and limiting information flows. At the lowest
level, the SAFE hardware supports fine-grained programmable tags, with
efficient and flexible propagation and combination of tags as instructions are
executed. The operating system virtualizes these generic facilities to present
an information-flow abstract machine that allows user programs to label
sensitive data with rich confidentiality policies. We present a formal,
machine-checked model of the key hardware and software mechanisms used to
dynamically control information flow in SAFE and an end-to-end proof of
noninterference for this model.
We use a refinement proof methodology to propagate the noninterference
property of the abstract machine down to the concrete machine level. We use an
intermediate layer in the refinement chain that factors out the details of the
information-flow control policy and devise a code generator for compiling such
information-flow policies into low-level monitor code. Finally, we verify the
correctness of this generator using a dedicated Hoare logic that abstracts from
low-level machine instructions into a reusable set of verified structured code
generators
An Integrated Development Environment for Declarative Multi-Paradigm Programming
In this paper we present CIDER (Curry Integrated Development EnviRonment), an
analysis and programming environment for the declarative multi-paradigm
language Curry. CIDER is a graphical environment to support the development of
Curry programs by providing integrated tools for the analysis and visualization
of programs. CIDER is completely implemented in Curry using libraries for GUI
programming (based on Tcl/Tk) and meta-programming. An important aspect of our
environment is the possible adaptation of the development environment to other
declarative source languages (e.g., Prolog or Haskell) and the extensibility
w.r.t. new analysis methods. To support the latter feature, the lazy evaluation
strategy of the underlying implementation language Curry becomes quite useful.Comment: In A. Kusalik (ed), proceedings of the Eleventh International
Workshop on Logic Programming Environments (WLPE'01), December 1, 2001,
Paphos, Cyprus. cs.PL/011104
Compiling ER Specifications into Declarative Programs
This paper proposes an environment to support high-level database programming
in a declarative programming language. In order to ensure safe database
updates, all access and update operations related to the database are generated
from high-level descriptions in the entity- relationship (ER) model. We propose
a representation of ER diagrams in the declarative language Curry so that they
can be constructed by various tools and then translated into this
representation. Furthermore, we have implemented a compiler from this
representation into a Curry program that provides access and update operations
based on a high-level API for database programming.Comment: Paper presented at the 17th Workshop on Logic-based Methods in
Programming Environments (WLPE2007
Compiling Tree Transforms to Operate on Packed Representations
When written idiomatically in most programming languages, programs
that traverse and construct trees operate over pointer-based data
structures, using one heap object per-leaf and per-node. This
representation is efficient for random access and shape-changing
modifications, but for traversals, such as compiler passes, that
process most or all of a tree in bulk, it can be inefficient. In this
work we instead compile tree traversals to operate on
pointer-free pre-order serializations of trees. On modern
architectures such programs often run significantly faster than
their pointer-based counterparts, and additionally are directly suited
to storage and transmission without requiring marshaling.
We present a prototype compiler, Gibbon, that compiles a
small first-order, purely functional language sufficient for tree
traversals. The compiler transforms this language into intermediate
representation with explicit pointers into input and output buffers
for packed data. The key compiler technologies include an effect
system for capturing traversal behavior, combined with an algorithm to
insert destination cursors. We evaluate our compiler on tree
transformations over a real-world dataset of source-code syntax trees.
For traversals touching the whole tree, such as maps and folds, packed
data allows speedups of over 2x compared to a highly-optimized
pointer-based baseline
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