MMIX-Expand - Using as
Description: Using as

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#### 9.28.2 Instruction expansion

When `as` encounters an instruction with an operand that is either not known or does not fit the operand size of the instruction, `as` (and `ld`) will expand the instruction into a sequence of instructions semantically equivalent to the operand fitting the instruction. Expansion will take place for the following instructions:

‘`GETA`’
  Expands to a sequence of four instructions: `SETL`, `INCML`, `INCMH` and `INCH`. The operand must be a multiple of four.
Conditional branches
  A branch instruction is turned into a branch with the complemented condition and prediction bit over five instructions; four instructions setting `$255` to the operand value, which like with `GETA` must be a multiple of four, and a final `GO $255,$255,0`.
‘`PUSHJ`’
  Similar to expansion for conditional branches; four instructions set `$255` to the operand value, followed by a `PUSHGO $255,$255,0`.
‘`JMP`’
  Similar to conditional branches and `PUSHJ`. The final instruction is `GO $255,$255,0`.

The linker `ld` is expected to shrink these expansions for code assembled with ‘`--relax`’ (though not currently implemented).