M68HC11/68HC12 - Untitled
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### 4.3 `ld` and the Motorola 68HC11 and 68HC12 families

#### 4.3.1 Linker Relaxation

For the Motorola 68HC11, `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.

  `ld` also looks at all 16-bit extended addressing modes and transforms them in a direct addressing mode when the address is in page 0 (between 0 and 0x0ff).

relaxing gcc instruction group
  When `gcc` is called with `-mrelax`, it can emit group of instructions that the linker can optimize to use a 68HC11 direct addressing mode. These instructions consists of `bclr` or `bset` instructions.

#### 4.3.2 Trampoline Generation

For 68HC11 and 68HC12, `ld` can generate trampoline code to call a far function using a normal `jsr` instruction. The linker will also change the relocation to some far function to use the trampoline address instead of the function address. This is typically the case when a pointer to a function is taken. The pointer will in fact point to the function trampoline.