Code Generation for a Virtual Machine - Crafting a Compiler - page 439

AST JVM Instructions

StaticReferencing

; Instruction saved for later use:

putstatic
Ljava/io/PrintStream; java/lang/System/out

System.out

n

The box shows the instruction saved by Marker 59 for an assignment to the
static field out of the java.lang.System class.

11.4.3 Field References

/ Visitor code for Marker 56 /

procedure visit (FieldReferencing n )

call n . getInstance() . accept( valueVisitor )

60

( new FieldStore( n . getType(), n . getName())) call set S tore

61

end

For a field reference, the instance containing the field must be evaluated first.
Marker 60 causes the relevant code to be generated by having the AST sub-
tree that represents the object instance accept the MethodBodyVisitor that was
captured at Marker 53 . The instruction for storing the field is then saved for
later use at Marker 61 .

AST JVM Instructions

FieldReferencing

; AST and code for storing the

name

; field name from class MyClass:

;
;

n

o.name

;
; Code generated for the instance

aload 4

LocalReferencing
o

; Instruction saved for later use:

putfield Ljava/lang/String; MyClass/name

11.4.4 Array References

/ Visitor code for Marker 57 /

procedure visit (ArrayReferencing n )

call n . getArray() . accept( valueVisitor )

62

call n . getIndex() . accept( valueVisitor )

63

( new ArrayStore( n . getArray() . getType( ))) call set S tore

64

end