Inferring Parametric Energy Consumption Functions at Different Software Levels:ISA vs. LLVM IR

The static estimation of the energy consumed by program executions is an important challenge, which has applications in program optimization and verification, and is instrumental in energy-aware software development. Our objective is to estimate such energy consumption in the form of functions on the input data sizes of programs. We have developed a tool for experimentation with static analysis which infers such energy functions at two levels, the instruction set architecture (ISA) and the intermediate code (LLVM IR) levels, and re ects it upwards to the higher source code level. This required the development of a translation from LLVM IR to an intermediate representation and its integration with existing components, a translation from ISA to the same representation, a resource analyzer, an ISA-level energy model, and a mapping from this model to LLVM IR. The approach has been applied to programs written in the XC language running on XCore architectures, but is general enough to be applied to other languages. Experimental results show that our LLVM IR level analysis is reasonably accurate (less than 6:4% average error vs. hardware measurements) and more powerful than analysis at the ISA level. This paper provides insights into the trade-off of precision versus analyzability at these levels

Transient asynchronous testicular growth in adolescent males with a varicocele.

PURPOSE: We assessed the testicular growth of adolescent males followed nonsurgically for the presence of left varicocele. MATERIALS AND METHODS: We retrospectively reviewed the charts of adolescent males with a diagnosis of unilateral left varicocele and ultrasound testis volume measurements seen during a 10-year period. A total of 161 boys underwent at least 2 testicular ultrasounds as part of the evaluation for left varicocele. Patients were excluded from study for a history of inguinal/scrotal pathology or endocrinopathy that could affect testicular size. Sonographic testicular volume was calculated using the Lambert volume (length x width x height x 0.71). The resulting volumes were compared to previously published criteria for surgical repair (15%, 20% and 2 cc size differentials). RESULTS: Of the 71 boys with 3 followup ultrasounds 38 (54%) initially had a 15% or greater volume differential. After nonsurgical followup with ultrasounds for 2 years 60 boys (85%) had testicular volume differentials in the normal range (less than 15%). Of the patients 71% were spared potential surgery by size criteria and 50% were spared surgery by the same 15% volume differential criteria. CONCLUSIONS: Adolescent males with unilateral left varicocele often demonstrate asynchronous testicular growth that usually equalizes in time. Therefore, sonographic testicular size measurement at a single point during adolescence is insufficient to determine the need for varicocelectomy. When contemplating varicocelectomy we recommend at least 2, and preferably 3, testicular volume measurements 1 year apart to establish accurately decreased left testicular volume compared to a normal right testis