Lesson 11--Optimizations for Code Size

Question 1

Dead register

Answer 1

A register that contains a value that was live, but now is dead.

Question 2

Unused register

Answer 2

A register that is carrying a live value for a long live range, but for much of the live range the value is unused.

Question 3

Postpass Optimization

Answer 3

­--dead/unused register identification
­--hot region identification
­--spill identification
­--weighted bipartite graph matching
­--compensation code cost analysis
­--unused register allocation

Question 4

Compensation code starts by considering 3 regions

Answer 4

Current
Predecessor
Successor

Question 5

Current Region

Answer 5

Basic blocks corresponding to the edges in an analysis unit extension

Question 6

Predecessor Region

Answer 6

Basic blocks not in the current region, and their predecessors in current region

Question 7

Successor Region

Answer 7

Basic blocks not in the current region and their successors in the current region