Analyzing and transforming a computer program for executing on asymmetric multiprocessing systems

Abstract

A method is disclosed for transforming a portion of a computer program comprising a list of sequential instructions comprising control code and data processing code and a program separation indicator indicating a point where said sequential instructions may be divided to form separate sections that are capable of being separately executed and that each comprise different data processing code. The m method comprises the steps of: (i) analysing said portion of said program to determine if said sequential instructions can be divided at said point indicated by said program separation indicator and in response to determining that it can: (iia) providing data communication between said separate sections indicated by said program separation indicator, such that said separate sections can be decoupled from each other, such that at least one of said sections is capable of being separately executed by an execution mechanism that is separate from an execution mechanism executing another of said separate sections, said at least one of said sections being capable of generating data and communicating said data to at least one other of said separate sections; and in response to determining it can not: (iib) not performing step (iia). If step (iia) is not performed then a warning may be output, or the program may be amended so it can be separated at that point, or the program separation indicator may be removed and the sections that were to be separated merged.

Description

[0001]This application claims the benefit of U.S. Provisional Application No. 60 / 853,756, filed Oct. 24, 2006, the entire content of which is hereby incorporated by reference in this application.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The field of the invention relates to data processing and in particular to improving the performance of program execution.[0004]2. Description of the Prior Art[0005]It is becoming increasingly difficult to provide programs that are simple to write and yet perform efficiently on complex systems. Such complex systems may comprise a number of different processing or execution units and they may be heterogeneous or asymmetric, with specialised processing units being used to increase energy efficiency and lower gate count. In particular, the programming of embedded systems with their hardware restriction, demand for efficiency and the ever decreasing time to market is becoming a real problem.[0006]It is known in high level computing ...

AI Technical Summary

Benefits of technology

[0028]Although, in some embodiments, the data store may comprise a FIFO buffer as this is clearly the simplest arrangement where the first data to exit from a section of the program is the first data to enter the next section, it may be that the data is not required in a particular order or indeed that all the data generated by one section is not required by the other. Thus, a variety of different data stores and different arrangements can be used in some embodiments. For example, a stack which has a last in first out semantics could be used, one advantage of this is that a stack is simple to implement.

[0035]An instruction loop having several data processing steps for example can be divided by embodiments of the present invention into two sections by allowing the different sections to have different data processing codes. This can increase the performance of a system significantly. Generally this is done by duplicating the control code and in effect performing two loops, one performing one or more of the data processing steps of the original loop and the other performing the rest of the steps.

[0046]An instruction loop having several data processing steps, can be divided into two sections, and thereby increase the performance of a system significantly. The present method is able to duplicate the control code and perform in effect two loops, one performing one or more of the data processing steps of the initial loop and the other performing the rest of the steps.

[0052]It is desirable to be able to split a program having a list of instructions to be processed sequentially into sections that can be processed independently. If the program comprises program separation indictors indicating points where they may be divided then the program can be transformed by providing data communication between the separate sections at the points indicated so that they can be decoupled from each other. This allows the program to be split into sections suitable for separate execution and allows the program to be efficiently processed by a variety of different often complex devices. This enables future analysis of the program via a programmer to be relatively straight forward and yet still enable it to execute efficiently on a parallel system.

[0054]An additional step of analysing the program to ensure that it can indeed be separated at these points can be helpful and allows programs that have program separation indicators in them that are potentially in an incorrect place to still be transformed.

Problems solved by technology

It is becoming increasingly difficult to provide programs that are simple to write and yet perform efficiently on complex systems.

In particular, the programming of embedded systems with their hardware restriction, demand for efficiency and the ever decreasing time to market is becoming a real problem.

Clearly such mechanisms have an overhead of area and power.

The architectures of system on chip (SoC) platforms found in high end consumer devices are getting more and more complex as designers strive to deliver compute intensive applications on ever shrinking power budgets.

Workloads running on these platforms require the exploitation of large amounts of heterogeneous parallelism and increasingly irregular memory hierarchies.

The consequence of this is that when the core functionality of an application is mapped to the platform, its logic becomes obscured by the transformations and the glue code used during the mapping process.

This yields software which is intimately and inseparably tied to the details of the platform it was originally designed for, limiting the software's portability and ultimately the architectural choices available to future generations of platform architects.

Many of the problems experienced in mapping applications onto SoC platforms come not from deciding how to map a program onto the hardware but from the fragmentation of the application that results from implementing these decisions.

This is particularly so when the system itself decides how to parallelise the program as this becomes extremely complex and means that future analysis of the program by a programmer is very difficult.

In particular, although sequential programs can be fairly readily understood by a human being, once they are parallelised it becomes increasingly difficult for the human mind to understand them.

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