Static single assignment (SSA) form has been widely studied and used for sequential programs. This form enables many compiler optimizations to be done efficiently. Work on concurrent static single assignment form (CSSA) for concurrent programs is focused on languages that have limited, implicit barriers (e.g., cobegin/coend and parallel do). Recent programming languages for high-performance computing have general features for barrier/phase synchronization - this is essentially a dual of mutual exclusion and arises mainly in constructing synchronous systems from asynchronous systems. X10 is one such language that has features for general purpose barriers. In X10, barriers are provided through features such as clocks and finish. Since barriers provide explicit synchronization, they offer an opportunity for reducing pi interferences needed for CSSA. This paper provides a means for computing improved CSSA form of a program taking advantage of the general barriers present in it. Our algorithm is based on constructing a control-flow graph of the program and flow equations. The efficiency of analysis and optimizations for parallel programs depends on the number and complexity of pi assignments in their CSSA representations. We demonstrate that our approach of computing CSSA form for languages supporting general barrier synchronization can improve the precision of intermediate representation for computing global value numbering and loop invariant detection.

The X10 programming language is organized around the notion of places (an encapsulation of data and activities operating on the data), partitioned global address space (PGAS), and asynchronous computation and communication.

We present a novel, table-free technique for detecting all temporal and spatial memory access errors (e.g. dangling pointers, out-of-bounds check, etc.) in programs supporting general pointers. Our approach is the first technique to provide such error checking using only constant-time operations. The scheme relies on fat pointers, whose size is contained within standard scalar sizes (up to two words) so that atomic hardware support for operations upon the pointers is obtained along with meaningful casts in-between pointers and other scalars. Optimized compilation of code becomes possible since the scalarized-for-free encoded pointers get register allocated and manipulated. Backward compatibility is enabled by the scalar pointer sizes, with novel automatic support provided for encoding and decoding of fat pointers in place for interaction with unprotected code (e.g. library binaries). Implementation and benchmarks of the technique over several applications of the memory-intensive Olden suite indicate that the average time overhead of our method is about half the time cost of an unprotected application's execution (

We describe a novel approach for the on-line scheduling of storage network access in shared application-hosting environments. Our storage resource management and reservation service (RMRS) dynamically makes advance reservation of storage bandwidth for various accesses while resolving the potential for conflict unutilized storage network capacity is maintained at an optimal level for being able to support unexpected load/contingencies, while preventing any capacity underutilization. Among the novelties offered by our work are: (l)a Web-service architecture (2) an application domain of storage accesses for normal database workload, backup, replication, migration and recovery, while supporting business objectives, QoS, and service-level commitments (3) a formulation of the scheduling problem as a practical linear programming (LP) problem comprising a reshaping linearization and integer relaxation of the modeled non linear bandwidth constraints.

We present a framework and tool for porting assessment and code remediation in commercial porting projects, primarily targeting interplatform C/C++ porting. Our framework has a modular architecture for handling real-world code bases, a key part of which is an extensible knowledge base of porting issue types. Porting issue detection and remediation are achieved through dynamically-linked detector and remediation "plug-ins" which can be augmented over time. Analysis and remediation can be performed over multiple intermediate forms, such as the AST or error logs. Analysis and remediation results can be presented as a single assessment report, or the changes can be incorporated into the original code base. Furthermore our framework has been integrated into Eclipse, providing a user interface and allowing further capability for integration with other Eclipse extensions. A subset of our tool has been prototyped and benchmarked against real-world customer code.

Aperture transformation reduces metastability by trading unsafe edge arrival times with control signal metastability. We improve this further by providing 1) a new runt-free Schmitt trigger-based hardening technique using a controlled clock signal and 2) a new detection/compensation technique that overwrites controlled-clock metastability using set&clear controls.