try-eliminate-copy ( follower leader must? -- )
Vreg Coalescing

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try-eliminate-copies ( pairs must? -- )

Vocabulary
compiler.cfg.ssa.destruction.coalescing

Inputs

follower	vreg
leader	vreg
must?	a boolean

Outputs
None

Word description
Tries to eliminate a vreg copy from 'leader' to 'follower'. If 'must?' is t then a vregs-shouldn't-interfere error is thrown if the vregs interfere.

See also
try-eliminate-copies, vregs-interfere?

Definition

USING: compiler.cfg.ssa.destruction.leaders kernel ;

IN: compiler.cfg.ssa.destruction.coalescing

: try-eliminate-copy ( follower leader must? -- )
    -rot leaders 2dup =
    [ 3drop ] [
        2dup vregs-interfere?
        [ drop rot [ vregs-shouldn't-interfere ] [ 2drop ] if ]
        [ -rot coalesce-vregs drop ] if
    ] if ;