Spring 2011 CSCI 565 - Compiler Design
Spring 2011 CSCI 565 - Compiler Design
Spring 2011 CSCI 565 - Compiler Design
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Pedro Diniz<br />
pedro@isi.edu<br />
<strong>CSCI</strong> <strong>565</strong> - <strong>Compiler</strong> <strong>Design</strong><br />
Computing an Array Address<br />
A[ i ]<br />
• baseA + ( i – low ) x sizeof(baseType(A))<br />
• In general: base(A) + ( i – low ) x sizeof(baseType(A))<br />
<strong>Spring</strong> <strong>2011</strong><br />
What about A[i1 ,i2 ] ?<br />
This stuff looks expensive!<br />
Lots of implicit +, -, x ops<br />
Row-major order, two dimensions<br />
baseA + (( i1 – low1 ) x (high2 – low2 + 1) + i2 – low2 ) x sizeof(baseType(A))<br />
Column-major order, two dimensions<br />
baseA + (( i 2 – low 2 ) x (high 1 – low 1 + 1) + i 1 – low 1 ) x sizeof(baseType(A))<br />
Indirection vectors, two dimensions<br />
*(A[i 1 ])[i 2 ] — where A[i 1 ] is, itself, a 1-d array reference
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