SUGAR Code Selection

Normally, the goal in code selection is to allocate hardware units such that the total hardware cost meets a cost constraint and the schedules meet a performance constraint. Recall from the previous section, that SUGAR generates code before selecting code. For each routine, the code generation phase passes an AND/OR code tree representing the different code options to the code selection phase. 

Plasmids usually resemble chromosomes except that they are approximately 0.1-1.0% of the size of a bacterial chromosome, and there are a few that are linear rather than circular. Plasmid genes are not essential for the normal functioning of the cell but may code for a property that affords a survival advantage in certain environmental conditions bacteria possessing the plasmid in question would therefore be selected when such conditions exist. Properties which can be coded by plasmids include the ability to utilize unusual sugars or food sources, toxin production, production of pili that facilitate the attachment of a cell to a substrate (e.g. intestinal epithelium) and antibiotic resistance. A cell may contain multiple copies of any one plasmid and may contain two or more different plasmids. However, some plasmid combinations cannot co-exist inside the same cell and are said to be incompatible this phenomenon enables plasmids to be classified into incompatibility groups. 

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