PUSHP

Operation

Pushes one canonical Rn register pair selected by an inline pair index.

Assembler Syntax

PUSHP PAIRn(i)

Privilege

Unprivileged

Repeat eligibility

REP eligible

Pushes the canonical register pair selected by the pair ID. The canonical pair sequence is pair 0 (R0, R1), pair 1 (R2, R3), pair 2 (R4, R5), pair 3 (R6, R7), pair 4 (R8, R9), pair 5 (R10, R11), pair 6 (R12, R13), and pair 7 (R14, R15). All eight pair IDs are valid and each selects one pair.

PUSHP selects one canonical pair using the unsigned 3-bit pair index and captures both register values and the old SS:SP context. It validates the complete two-slot stack range before either slot or SP is changed. For a listed pair (first, second), the second register is stored at old SP minus 16 and the first register is stored at old SP minus 8. Both stores and the SP update to old SP minus 16 commit together. A preceding fault changes neither slot nor SP.

Multiple PUSHP instructions can be used in canonical prologue order to save multiple pairs.

2.75in

Encodings

PUSHP PAIRn(i)

Format: Instruction format for PUSHP PAIRn(i)