Translating JVM Code to MIPS Code - Introduction to Compiler Construction in a Java World - page 234

The layout and dispatch table for class Bar , which extends class Foo , is illustrated in Figure
6.16.
FIGURE 6.16 Layout and dispatch table for Bar .
Assuming the type tag for Bar is 5,
Bar..Tag: .word 5
The SPIM code for a template for Bar might look like
Bar..Template:
.word Bar..Tag
.word 28
.word Bar..Dispatch
.word 0
.word 0
.word 0
.word 0
Again, the fields have initial values of zero. It is the responsibility of the <init> routine for
Foo and Bar to initialize them to 1,2, 3, and 4, respectively.
The construction of the dispatch table for Bar follows these steps:
1. First the methods for Bar 's superclass ( Foo ) are copied into the table.
2. Then we add the methods defined in Bar to the dispatch table. The method Bar.f()
overrides, and so replaces Foo.f() in the table; the new Bar.bar() is simply added
to the table.
The SPIM code for this dispatch table might look something like the following: