Compilers: Principles and Practice by Pearson

286 Compilers – Principles and Practice

called function might overwrite those registers with values needed. Some part of the code has to take

responsibility for preserving register contents, for example by saving them on the stack. There can be

two approaches:

The caller: Knows which registers have values that must be preserved, but does not know which the

callee will actually use.

The callee: The same situation as for the caller, but reversed.

Neither one has enough information to guarantee that it can do a good job. Inter-procedural register

allocation can solve these problems if the caller and callee are in the same compilation unit.

9.5.3 ...