#!/usr/bin/perl
#
# genredmap.pl - Redundacy detector map generator
#
# Copyright 2012 by Werner Almesberger
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#

#
# This script finds the relational operators op = f(opa, opb), for which
# the following is true:
# 
# forall A, B: (A op B) -> forall X: !(X opa A) -> !(X opa B)
#
# In other words: if, with X a variable and A and B constants, we have a
# cascade of the form
#
# if (X opa A) ...;
# else if (X opa B) ...;
#
# and A op B is true, then the second branch will never be taken.
#

%op = (
	"lt"	=> sub { $_[0] < $_[1] },
	"le"	=> sub { $_[0] <= $_[1] },
	"eq"	=> sub { $_[0] == $_[1] },
	"ge"	=> sub { $_[0] >= $_[1] },
	"gt"	=> sub { $_[0] > $_[1] },
	
);

@ops = ("lt", "le", "eq", "ge", "gt");

$always = 0;

$a = 2;
@v = (0, 1, 2, 3, 4);

for $opa (@ops) {
#next unless $opa eq "lt";
	for $opb (@ops) {
#next unless $opb eq "lt";
		$best = 0;
		OP: for $op (@ops) {
			$hit = 0;
			for $b (@v) {
#print "($opa, $opb) $a $op $b\n";
				next unless $op{$op}->($a, $b);
				for $x (@v) {
#print "  A: $x $opa $a\n";
					next if $op{$opa}->($x, $a);
#print "    B: $x $opb $b\n";
					next OP
					    if $op{$opb}->($x, $b) != $always;
					$hit++;
#print "    HIT ($hit)\n";
				}
			}
			if ($hit > $best) {
				$best = $hit;
				$best_op = $op;
			}
		}
		print "\t[idx_$opa][idx_$opb] = rel_$best_op,\n" if $best;
	}
}