2008 Reports

SHIM Optimization: Elimination Of Unstructured Loops

Ganapathi, Ravindra Babu; Edwards, Stephen A.

The SHIM compiler for the IBM CELL processor generates distinct code for the two processing units, PPE (Power Processor Element) and SPE (Synergistic Processor Elements). The SPE is specialized to give high throughput with computation intensive application operating on dense data. We propose mechanism to tune the code generated by the SHIM compiler to enable optimizing compilers to generate structured code. Although, the discussion here is related to optimizing SHIM IR (Intermediate Representation) code, the techniques discussed here can be incorporated into compilers to convert unstructured loops consisting of goto statements to structured loops such as while and do-while statements to ease back end compiler optimizations. Our research based SHIM compiler takes the code written in SHIM language and performs various static analysis and finally transforms it into C code. This generated code is compiled to binary using standard compilers available for IBM cell processor such as GCC and IBM XL compiler.