visit-gc-root ( vreg derived-roots gc-roots -- )
Liveness analysis

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lookup-base-pointer ( vreg -- vreg/f )

Vocabulary
compiler.cfg.liveness

Inputs

vreg	an integer
derived-roots	an assoc
gc-roots	a sequence

Outputs
None

Word description
Handles a vreg that is live at a gc point. The vreg is handled in three ways depending on its representation:

•	If it is tagged-rep, then the vreg contains a pointer to an object and it is added to the 'gc-roots' sequence.
•	If it is int-rep and the vreg has a base pointer, then it is added to the 'derived-roots' assoc along with that base pointer.
•	Otherwise the vreg does not contain an object reference and nothing is done with it.

See also
lookup-base-pointer

Definition

USING: combinators compiler.cfg.registers cpu.architecture
kernel sets ;

IN: compiler.cfg.liveness

: visit-gc-root ( vreg derived-roots gc-roots -- )
    pick rep-of {
        { tagged-rep [ nip adjoin ] }
        { int-rep [ visit-derived-root ] }
        [ 4drop ]
    } case ;