There are a number of ways to do this. Easy way is with cascading "greps", like in my first example. Regex is wonderful at "or" but the "and" kind of thing can be complex in the syntax.

I would suggest one of the below formulations. Tweak to suit your needs.

oops, my brain is really out to lunch today...sorry.see update

#!/usr/bin/perl -w
use strict;

my @input = ("Exception : CEX",
             "Exception : TEX",
             "abc def ljj");
             
print grep{/TEX/} grep{/^\s*Exception/}@input;
print "\n";
print grep{/Exception/ && /TEX/}@input;
print "\n";
print grep{/^\s*Exception.*? TEX/}@input;

__END__
prints:
Exception : TEX
Exception : TEX
Exception : TEX
[download]

#!/usr/bin/perl -w
use strict;

my @input = ("Exception : CEX",
             "Exception : TEX",
             "abc def ljj");
             
print grep{!/CEX/}grep{/^\s*Exception/}@input;
print "\n";
print grep{/Exception/ && !/CEX/}@input;
print "\n";
__END__
prints:
Exception : TEX
Exception : TEX
[download]

I wouldn't get overly concerned about performance unless this code is going to be executed lots of times. Clarity should be the first priority.