Opcodes for i860 - Using as
Description: Using as

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#### 9.14.4 i860 Opcodes

All of the Intel i860XR and i860XP machine instructions are supported. Please see either i860 Microprocessor Programmer's Reference Manual or i860 Microprocessor Architecture for more information.

##### 9.14.4.1 Other instruction support (pseudo-instructions)

For compatibility with some other i860 assemblers, a number of pseudo-instructions are supported. While these are supported, they are a very undesirable feature that should be avoided – in particular, when they result in an expansion to multiple actual i860 instructions. Below are the pseudo-instructions that result in expansions.

- Load large immediate into general register:

  The pseudo-instruction `mov imm,%rn` (where the immediate does not fit within a signed 16-bit field) will be expanded into:

                orh large_imm@h,%r0,%rn
                or large_imm@l,%rn,%rn

- Load/store with relocatable address expression:

  For example, the pseudo-instruction `ld.b addr_exp(%rx),%rn` will be expanded into:

                orh addr_exp@ha,%rx,%r31
                ld.l addr_exp@l(%r31),%rn

  The analogous expansions apply to `ld.x, st.x, fld.x, pfld.x, fst.x`, and `pst.x` as well.

- Signed large immediate with add/subtract:

  If any of the arithmetic operations `adds, addu, subs, subu` are used with an immediate larger than 16-bits (signed), then they will be expanded. For instance, the pseudo-instruction `adds large_imm,%rx,%rn` expands to:

                orh large_imm@h,%r0,%r31
                or large_imm@l,%r31,%r31
                adds %r31,%rx,%rn

- Unsigned large immediate with logical operations:

  Logical operations (`or, andnot, or, xor`) also result in expansions. The pseudo-instruction `or large_imm,%rx,%rn` results in:

                orh large_imm@h,%rx,%r31
                or large_imm@l,%r31,%rn

  Similarly for the others, except for `and` which expands to:

                andnot (-1 - large_imm)@h,%rx,%r31
                andnot (-1 - large_imm)@l,%r31,%rn