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(ld.info)H8/300

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`ld' and the H8/300
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   For the H8/300, `ld' can perform these global optimizations when you
specify the `--relax' command-line option.

_relaxing address modes_
     `ld' finds all `jsr' and `jmp' instructions whose targets are
     within eight bits, and turns them into eight-bit program-counter
     relative `bsr' and `bra' instructions, respectively.

_synthesizing instructions_
     `ld' finds all `mov.b' instructions which use the sixteen-bit
     absolute address form, but refer to the top page of memory, and
     changes them to use the eight-bit address form.  (That is: the
     linker turns `mov.b `@'AA:16' into `mov.b `@'AA:8' whenever the
     address AA is in the top page of memory).