live-interval-state
Live interval utilities

Prev:	<live-interval> ( vreg -- live-interval )
Next:	vreg-use

Vocabulary
compiler.cfg.linear-scan.live-intervals

Class description
A class encoding the "liveness" of a virtual register. It has the following slots:

vreg	The vreg this live interval state is bound to.
reg	The allocated register, set in the allocate-registers step.
spill-rep	representation the vreg will have when it is spilled.
spill-to	spill-slot to use for spilling, if it needs to be spilled.
ranges	Inclusive ranges where the live interval is live. This is because the [start,end] interval can have gaps.
uses	sequence of insn# numbers which reference insructions that use the register in the live interval.

Notes
The uses and ranges will never be empty because then the interval would be unused.

Definition

USING: vectors ;

IN: compiler.cfg.linear-scan.live-intervals

TUPLE: live-interval-state
    vreg reg spill-to spill-rep reload-from reload-rep
    { ranges vector initial: V{ } }
    { uses vector initial: V{ } } ;

Methods

USING: compiler.cfg.linear-scan.allocation
compiler.cfg.linear-scan.allocation.state
compiler.cfg.linear-scan.live-intervals kernel namespaces ;

M: live-interval-state handle
    [
        live-interval-start
        [ deactivate-intervals ] [ activate-intervals ] bi
    ] [ registers get assign-register ] bi ;


USING: accessors arrays
compiler.cfg.linear-scan.allocation.state
compiler.cfg.linear-scan.live-intervals
compiler.cfg.linear-scan.ranges kernel ;

M: live-interval-state interval/sync-point-key
    [ ranges>> ranges-endpoints ] [ vreg>> ] bi 3array ;