generation of highly parallel code for tigersharc processors an introduction this presentation will...

Generation of highly parallel code for TigerSHARC

processors An introduction

04/18/23Introduction to highly parallel TigerSHARC code Copyright M. Smith and S. Lei Contact [email protected] / 45 + B14

Background assumed

Familiarity with TigerSHARC architecture

Familiarity with TigerSHARC programmer’s model for registers

Some assembly experienceAn interest in beating the compiler

in those special cases when you need the last drop of blood out of the CPU :-)

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To be tackledWhat’s causing the problem– General limitations of instruction sets

How to recognize when you might be coming up against TigerSHARC architecture limitations

A process for optimizing the TigerSHARC parallelism– Example -- Temperature conversion

– Bonus if time permits -- Average and instantaneous power

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When are DSP instructions valid?

You are going to customize– When can you use the DSP instructions?

– Most -- From Monday to Friday

– Some Only between 9:00 a.m. and 9:00 p.m.Check against architectureMIMD -- Parallel ops MUST be able to do this

– Can it be fetched in one cycle (1 instruction line)– Can it be executed in one cycle (resource question)– Can it execute without conflicting with other instructions?– Then PROBABLY legal

HOWEVER -- The designers had the final decision and you have to live by that decision!

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Under best conditionsIf instruction described the right way– 2 data memory access (in or out) with a

REQUIRED post modification operation possibly with a modify register containing the value 0

– 1 add compute operation on data registers

– 1 multiply compute operation on data registers

– Ability to redo code using both X and Y

– Sometimes – audio for example – do left channel in X and right channel in Y

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Introduction to PPPPIC

Professor’s Personal Process for Parallel Instruction Coding

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Basic code development -- any systemWrite the “C” code for the function

void Convert(float *temperature, float *result, int N)

which converts an array of temperatures measured in “Celsius” (Canadian Market) to “Fahrenheit” (Tourist Trade)

Convert the code to TigerSHARC assembly code, following the standard coding and documentation practices, or just use the compiler to do the job for you