# $Id: ABI_CHANGES 11501 2006-02-10 18:27:13Z particle $

This document describes changes to the Parrot ABI.

2004.11.27 leo

Removed oppodes:

  abs I, N		- irregular operand mix
  lcm N, I, I		- duplicate of lcm I,I,I with float result
  rand *		- deprecated before 0.1.1

Internally handled opcodes:

All binary, unary, compare, and branch opcodes with evaluable constant
arguments are replaced with equivalent results of the opcode, e.g.

  add I0, 10, 20      => set I0, 30
  eq 10, 10, L1       => branch L1
  ne 10, 10, L1       => gets deleted
  iseq I0, "a", "a"   => set I0, 1

Opcodes with mixed I and N source arguments are replaced to take
either a FLOATVAL constant or with a sequence of opcodes, e.g.:

  add N0, N1, 1       => add N0, N1, 1.0
  add N0, N1, I2      => set $N0, I2
                         add N0, N1, $N0
  sin N0, 2           => sin N0, 2.0

The compare and branch opcodes gt, ge, isgt, and isge for I, N, S
arguments are not emitted any more. They are replaced with their
counterparts with swapped arguments, e.g. :

  gt I0, I1, L1	      => lt I1, I0, L1
  isge I0, 100, I2    => isle I0, I2, 100


While all these opcodes are valid to use, these are no more listed in
ops/ops.num nor generated. Compilers shouldn't emit these opcodes, as
it's slightly inefficient to create the equivalent opcodes.

2004.11.15 leo

The variables P0, P1, P2, S0 aren't visible in the called subroutine
anymore.  See docs/pdds/pdd03_calling_conventions.pod.