This paper examines a problem that arises during global register allocation -- rematerialization. If a value cannot be kept in a register, the allocator should recognize when it is cheaper to recompute the value (rematerialize it) than to store and reload it. Chaitin's original graph

Reversible computing could be in more or less long term mandatory for minimizing heat dissipation inherent to computing. It aims at keeping all information on input and intermediate values available at any step of the computation. Rematerialization in register allocation amounts to recomputing

In the face of several recent proposals for rematerializing social and cultural geography this paper argues that we should look to the ‘new ’ urban geography for inspiration. Because of its subdisciplinary history – its relatively greater attachment to quantitative and applied work, the strong

aims at addressing the issues of reducing spill code via rematerialization for a VLIW DSP processor with distributed register files. Rematerialization is a strategy for register allocator to de-termine if it is cheaper to recompute the value than to use memory load/store. In the paper, we propose a

Much scientific data is not obtained from measurements' but rather derived from other data by the application of computational procedures. We hypothesize that explicit representation of these procedures can enable documentation of data provenance, discovery of available methods', and on-demand data generation (socalled "virtual data"). To explore this' idea, we have developed the Chimera virtual data system, which combines a virtual data catalog, for representing data derivation procedures and derived data, with a virtual data language interpreter that translates user requests' into data definition and query operations on the database. We couple the Chimera system with distributed "Data Grid" services to enable on-demand execution of computation schedules constructed from database queries. We have applied this system to two challenge problems, the reconstruction of simulated collision event data from a high-energy physics experiment, and the search of digital sky survey data for galactic clusters', with promising results'.

This paper describes both the techniques themselves and our experience building and using register allocators that incorporate them. It provides a detailed description of optimistic coloring and rematerialization. It presents experimental data to show the performance of several versions

. It is widely recognized that production rules in database systems can be used to automatically maintain derived data such as views. However, writing a correct set of rules for efficiently maintaining a given view can be a difficult and ad-hoc process. We provide a facility whereby a user defines a view as an SQL select expression, from which the system automatically derives set-oriented production rules that maintain a materialization of that view. The maintenance rules are triggered by operations on the view's base tables. Generally, the rules perform incremental maintenance: the materialized view is modified according to the sets of changes made to the base tables, which are accessible through logical tables provided by the rule language. However, for some operations substantial recomputation may be required. We give algorithms that, based on key information, perform syntactic analysis on a view definition to determine when efficient maintenance is possible. 1 Introduction In rel...

heuristic is emphasized when trying to color register pairs. My heuristic handles pairs as a natural consequence of its optimism. Rematerialization Chaitin et al. introduced the idea of rematerialization to avoid the expense of spilling and reloading certain simple values. By propagating rematerialization

In this paper we introduce the concept of continual queries, describe the design of a distributed event-driven continual query system -- OpenCQ, and outline the initial implementation of OpenCQ on top of the distributed interoperable information mediation system DIOM [21, 19]. Continual queries are standing queries that monitor update of interest and return results whenever the update reaches specified thresholds. In OpenCQ, users may specify to the system the information they would like to monitor (such as the events or the update thresholds they are interested in). Whenever the information of interest becomes available, the system immediately delivers it to the relevant users; otherwise, the system continually monitors the arrival of the desired information and pushes it to the relevant users as it meets the specified update thresholds. In contrast to conventional pull-based data management systems such as DBMSs and Web search engines, OpenCQ exhibits two important featu...

In research about the Internet, too much attention is paid to its ability to provide access to information. This thesis argues that the Internet can be used not just as a conduit for information, but as a context for learning through community-supported collaborative construction. A "constructionist" approach to use of the Internet makes particularly good use of its educational potential. The Internet provides opportunities to move beyond the creation of constructionist tools and activities to the creation of "constructionist cultures." These issues are explored through a specific example: MOOSE Crossing, a text-based virtual world (or "MUD") designed to be a constructionist learning environment for children ages 8 to 13. On MOOSE Crossing, children have constructed a virtual world together, making new places, objects, and creatures. Kids have made baby penguins that respond differently to five kinds of food, fortune tellers who predict the future, and the place at the end of the rainbow--- answer a riddle, and you get the pot of gold. This thesis discusses the design principles underlying a new programming language (MOOSE) and client interface (MacMOOSE) designed to make it easier for children to learn to program on MOOSE Crossing. It presents a detailed analysis, using an ethnographic methodology, of children's activities and learning experiences on MOOSE Crossing, with special focus on seven children who participated in a weekly after-school program from October 1995 through February 1997. In its analysis of children's activities, this thesis explores the relationship between construction and community. It describes how the MOOSE Crossing children motivated and supported one another's learning experiences: community provided support for learning through design and...