This compiler pass eliminates redundant vreg copies. Coalescing occurs in two steps. First all redundant copies in all ##tagged>integer and ##phi instructions are handled. Then those in other instructions like vreg-insn, ##copy and ##parallel-copy.

Main entry point:

coalesce-cfg ( cfg -- )

Vreg copy elimination:

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

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