Instruction-set architecture exploration of VLIW ASIPs using a genetic algorithm

Genetic algorithms are commonly used for automatically solving complex design problem because exploration using genetic algorithms can consistently deliver good results when the algorithm is given a long enough run-time. However, the exploration time for problems with huge design spaces can be very long, often making exploration using a genetic algorithm practically infeasible. In this work, we present a genetic algorithm for exploring the instruction-set architecture of VLIW ASIPs and demonstrate its effectiveness by comparing it to two heuristic algorithms. We present several optimizations to the genetic algorithm configuration, and demonstrate how caching of intermediate compilation and simulation results can reduce the exploration time by an order of magnitude

MoviCompile : An LLVM based compiler for heterogeneous SIMD code generation

Numerous applications in communication and multimedia domains show significant data-level parallelism (DLP). The amount of DLP varies between applications in the same domain or even within a single application. Most architectures support a single vector-, SIMD-width which may not be optimal. This may cause performance and energy inefficiency. We propose the use of multiple (heterogeneous) vector-widths to better serve applications with varying DLP. The SHAVE (Streaming Hybrid Architecture Vector Engine) VLIW vector processor shown in Figure 1 is an example of such an architecture. SHAVE is a unique VLIW processor that provides hardware support for native 32-bit (short) and 128-bit (long) vector operations. Vector arithmetic unit (VAU) supports 128-bit vector arithmetic of 8/16/32-bit integer and 16/32-bit floating point types. Scalar arithmetic unit (SAU) supports 32-bit vector arithmetic of 8/16-bit integer and 16-bit floating point types. The moviCompile compiler is an LLVM based commercial compiler targeting code generation for SHAVE processor family. The moviCompile compiler is capable of SIMD code generation for 128-bit (long) and 64-bit vector operations. This work focuses on compiler backend support for 32-bit (short) vector operations. More specifically, this work aims to generate SIMD code for short vector types (e.g. 4 x i8, 2 x i16, 2 x f16) that can be executed on 32-bit SAU next to the 128/64-bit SIMD code. As a result, moviCompile is able to generate heterogeneous assembly code consisting of both short and long vector SIMD operations. Currently, we are testing the compiler using TSVC (Test Suite for Vectorizing Compilers) and intend to measure the performance improvements

Mixed-length SIMD code generation for VLIW architectures with multiple native vector-widths

The degree of DLP parallelism in applications is not fixed and varies due to different computational characteristics of applications. On the contrary, most of the processors today include single-width SIMD (vector) hardware to exploit DLP. However, single-width SIMD architectures may not be optimal to serve applications with varying DLP and they may cause performance and energy inefficiency. We propose the usage of VLIW processors with multiple native vector-widths to better serve applications with changing DLP. SHAVE is an example of such VLIW processor and provides hardware support for the native 32-bit and 128-bit wide vector operations. This paper researches and implements the mixed-length SIMD code generation support for SHAVE processor. More specifically, we target generating 32-bit and 128/64-bit SIMD code for the native 32-bit and 128-bit wide vector units of SHAVE processor. In this way, we improved the performance of compiler generated SIMD code by reducing the number of overhead operations and by increasing the SIMD hardware utilization. Experimental results demonstrated that our methodology implemented in the compiler improves the performance of synthetic benchmarks up to 47%

Suicidal ideation and behaviour among community and health care seeking populations in five low- and middle-income countries: a cross-sectional study.

: Aims Suicidal behaviour is an under-reported and hidden cause of death in most low- and middle-income countries (LMIC) due to lack of national systematic reporting for cause-specific mortality, high levels of stigma and religious or cultural sanctions. The lack of information on non-fatal suicidal behaviour (ideation, plans and attempts) in LMIC is a major barrier to design and implementation of prevention strategies. This study aims to determine the prevalence of non-fatal suicidal behaviour within community- and health facility-based populations in LMIC. : Twelve-month prevalence of suicidal ideation, plans and attempts were established through community samples (n = 6689) and primary care attendees (n = 6470) from districts in Ethiopia, Uganda, South Africa, India and Nepal using the Composite International Diagnostic Interview suicidality module. Participants were also screened for depression and alcohol use disorder. : We found that one out of ten persons (10.3%) presenting at primary care facilities reported suicidal ideation within the past year, and 1 out of 45 (2.2%) reported attempting suicide in the same period. The range of suicidal ideation was 3.5-11.1% in community samples and 5.0-14.8% in health facility samples. A higher proportion of facility attendees reported suicidal ideation than community residents (10.3 and 8.1%, respectively). Adults in the South African facilities were most likely to endorse suicidal ideation (14.8%), planning (9.5%) and attempts (7.4%). Risk profiles associated with suicidal behaviour (i.e. being female, younger age, current mental disorders and lower educational and economic status) were highly consistent across countries. : The high prevalence of suicidal ideation in primary care points towards important opportunities to implement suicide risk reduction initiatives. Evidence-supported strategies including screening and treatment of depression in primary care can be implemented through the World Health Organization's mental health Global Action Programme suicide prevention and depression treatment guidelines. Suicidal ideation and behaviours in the community sample will require detection strategies to identify at risks persons not presenting to health facilities.<br/