How can I turn an op address into the right kind of B::OP?

[rockyb]

O Omnificent Omnipotent Ones -

In a running Perl program if I have an Op address (either by B::Concise, Devel::Callsite or via mysterious other ways) is there a simple way to cast that into the right kind of B::OP, short of walking an Opcode tree?

[haukex]

Crossposted to StackOverflow, with more details there. Crossposting is acceptable, but it is considered polite to inform about it so that efforts are not duplicated. (I understand the crosspost, because you didn't get any responses here - although feel free to add the additional information here as well.)

[rockyb]

Yes, I understand. Thanks for pointing that out both here and on StackOverflow.

I will update this as soon as there is some sort of closure on this.

Note that I waited a day for some response here; currently there is nothing much to report either here or in StackOverflow. In StackOverflow though, there was a little more verbiage if only to get more clarification. So right now see StackOverflow if this question is as confusing to you as appearently it was (is?) to Mike Schwern.

Again, I will update with condensed summary information here when there is something to report, as I have done in the past where I have received help on StackOverflow but also asked on PerlMongers first. To do it while things are in the air doesn't seem like a worthwhile use of time and and may be confusing for folks as well.

Similarly, if there is activity here, I'll update the StackOverflow side when there is some sort of closure.

Of course, monks and others can just follow one place if that's what they prefer. Ultimately, you'll find the same information (albeit in condensed form) in either place.

[haukex]

So right now see StackOverflow for this if this question is as confusing to you as appearently it was (is?) to Mike Schwern.

I'm not an expert on the internals, so I just don't have an answer to your question in this case (at least not yet, maybe someday ;-) ). Also, I'm not sure what your use case is, that is, I can't judge if this might be an XY Problem or not.

[ikegami]

Answered

[rockyb]

Actually, I thought so at first, but perhaps not. op_class[] is not available on Perl 5.24.4 and earlier. But leaving that aside, although the "name" method seems to return the right thing, other fields don't

When I try with:

sub testing
{
    my $site = sub { callsite() };
    my $addr =  $site->();
    printf "Op address is 0x%x\n", $addr;
    my $op = make_op_object($addr);
    printf("op %s, name: %s, parent: %s\n", $op, $op->name, $op->paren
+t);

    # I can get OPs by walking and looking for $op_addr,
    # but I don't want to do that.
    my $walker = B::Concise::compile('-terse', '-src', \&testing);
    B::Concise::walk_output(\my $buf);
    $walker->();   # walks and renders into $buf;
    print $buf;
}

testing();

I get:

Op address is 0x55eddbdfba80
op B::OP=SCALAR(0x55eddba2c578), name: padsv, parent: B::BINOP=SCALAR(
+0x55eddba422d0)
B::Concise::compile(CODE(0x55eddbe20a80))
UNOP (0x55eddbe1ab10) leavesub [1] 
    LISTOP (0x55eddbdfb9a0) lineseq 
# 37:     my $site = sub { callsite() };
        COP (0x55eddbab2048) nextstate 
        BINOP (0x55eddbdfb9f8) sassign 
            UNOP (0x55eddbdfba40) srefgen 
                UNOP (0x55eddbdfbab8) null [157] 
                    SVOP (0x55eddbdfbb00) anoncode [2] CV (0x55eddba4d
+0f8) 
            OP (0x55eddbdfbb40) padsv [1] 
# 38:     my $addr =  $site->();
        COP (0x55eddbab1e68) nextstate 
        BINOP (0x55eddbab1ec8) sassign 
            UNOP (0x55eddbab1f10) entersub [4] 
                UNOP (0x55eddbab1f88) null [157] 
                    OP (0x55eddbab1f50) pushmark 
                    UNOP (0x55eddbab1fd0) null [16] 
                        OP (0x55eddbab2010) padsv [1] 
            OP (0x55eddbdfba80) padsv [3]

Note that the address is different as is the parent.

[ikegami]

You're printing the address of the B objects, not the address of the ops themselves.

printf("op: %s (0x%x), parent: %s (0x%x)\n",
   $op->name, $$op, $parent->name, $$parent);

op: padsv (0x104cc20), parent: sassign (0xfc7788)

# 42:     my $addr =  $site->();
        COP (0xfc7728) nextstate
        BINOP (0xfc7788) sassign
            UNOP (0xfc77d0) entersub [4]
                UNOP (0xfc7848) null [157]
                    OP (0xfc7810) pushmark
                    UNOP (0xfc7890) null [16]
                        OP (0xfc78d0) padsv [1]
            OP (0x104cc20) padsv [3]