NAME optimizer - Write your own Perl optimizer, in Perl SYNOPSIS # Use Perl's default optimizer use optimizer 'C'; # Use a Perl implementation of the default optimizer use optimizer 'perl'; # Use an extension of the default optimizer use optimizer extend => sub { warn "goto considered harmful" if $_[0]-1>name eq "goto" } # Use a simple optimizer with callbacks for each op use optimizer callback => sub { .. } # Completely implement your own optimizre use optimizer mine => sub { ... } # use the standard optimizer with an extra callback # this is the most compatible optimizer version use optimizer 'extend-c' => sub { print $_[0]->name() }; # don't provide a peep optimizer, rather get a callback # after we are finished with every code block use optimizer 'sub-detect' => sub { print $_[0]->name() }; no optimizer; # Use the simplest working optimizer DESCRIPTION This module allows you to replace the default Perl optree optimizer, "peep", with a Perl function of your own devising. It requires a Perl patched with the patch supplied with the module distribution; this patch allows the optimizer to be pluggable and replaceable with a C function pointer. This module provides the glue between the C function and a Perl subroutine. It is hoped that the patch will be integrated into the Perl core at some point soon. This patch is integrated as of perl 5.8. Your optimizer subroutine will be handed a "B::OP"-derived object representing the first (NOT the root) op in the program. You are expected to be fluent with the "B" module to know what to do with this. You can use "B::Generate" to fiddle around with the optree you are given, while traversing it in execution order. If you choose complete control over your optimizer, you must assign sequence numbers to operations. This can be done via the "optimizer::op_seqmax_inc" function, which supplies a new incremented sequence number. Do something like this: while ($$op) { $op->seq(optimizer::op_seqmax_inc); ... more optimizations ... $op = $op->next; last unless $op->can("next"); # Shouldn't get here } The "callback" option to this module will essentially do the above, calling your given subroutine with each op. If you just want to use this function to get a callback after every code block is compiled so you can do any arbitrary work on it use the "sub-detect" option, you will be passed LEAVE* ops after the standard peep optimizer has been run, this minimises the risk for bugs as we use the standard one. The op tree you are handed is also stable so you are free to work on it. This is usefull if you are limited by "CHECK" and "INIT" blocks as this works with string eval and "require" aswell. Only one callback per package is allowed. STATUS relocatetopad() fails with threaded perls. 5.10 Changes Since Perl 5.10 there are no op_seqmax and op_seq numbers in CORE anymore, so we add a package global op_seqmax for the op-tree numbering, for $B::OP::seq also. This is not thread-safe. AUTHOR Simon Cozens, C Extended functionality and current maintainer: Arthur Bergman, C 5.10 support by Reini Urban: Reini Urban, C SEE ALSO B::Generate, optimize