Alpha Register Set

Integer Registers

$0 (v0)

Used for expression evaluations and to hold the integer function results. Not preserved acrossprocedure calls.

$1-$8 (t0-t7)

Temporary registers used for expression evaluations. Not preserved across procedure calls.

$9-$14 (s0-s5)

Saved registers. Preserved across procedure calls.

$15 or $fp (s6 or fp)

Contains the frame pointer (if needed); otherwise, a saved register.

$16-$21 (a0-a5)

Used to pass the first six integer type arguments. Not preserved across procedure calls.

$22-$25 (t8-t11)

Temporary registers used for expression evaluations. Not preserved across procedure calls.

$26 (ra)

Contains the return address. Preserved across procedure calls.

$27 (pv or t12)

Contains the procedure value and used for expression evaluation. Notpreserved across procedure calls.

$28 or $at (AT)

Reserved for the assembler. Not preserved across procedure calls.

$29 or $gp (gp)

Contains the global pointer. Not preserved across procedure calls.

$30 or $sp(sp)

Contains the stack pointer. Preserved across procedure calls.

$31(zero)

Always has the value 0.

Float Registers

$f0

Holds the float function result. Not preserved acrossprocedure calls.

$f1

Holds the imaginary part of a complex function result. Not preserved across procedure calls.

$f2-$f9

Saved registers. Preserved across procedure calls.

$f10-$15

Temporary registers used for expression evaluations. Not preserved across procedure calls.

$f16-$f21

Used to pass the first six float type arguments. Not preserved across procedure calls.

$f22-$30

Temporary registers used for expression evaluations. Not preserved across procedure calls.

$f31

Always has the value 0.0 .