#143 CopyFunction changes SIDs.

[az bro]

As a side effect of making a copy of a function using
CopyFunction, the statement IDs of the original function
are changed. This should either be fixed, or a note should
be added to the documentation.

method vstmt (s: stmt) : stmt visitAction =
s.sid <- !sid; incr sid;
let s' = {s with sid = s.sid} in

[Gabriel Kerneis]

This seems a feature rather than a bug to me. I've updated the documentation to mention the allocation of fresh sids.

[az bro]

OK, makes sense.

On Tue, May 27, 2014 at 6:11 PM, Gabriel Kerneis kerneis@users.sf.netwrote:

• status: open --> closed

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• [bugs:#143] http://sourceforge.net/p/cil/bugs/143/ CopyFunction
  changes SIDs.*

Status: closed
Group: Bug

Created: Tue Jan 14, 2014 08:46 PM UTC by az bro
Last Updated: Tue May 27, 2014 03:11 PM UTC
Owner: nobody

As a side effect of making a copy of a function using
CopyFunction, the statement IDs of the original function
are changed. This should either be fixed, or a note should
be added to the documentation.

method vstmt (s: stmt) : stmt visitAction =
s.sid <- !sid; incr sid;
let s' = {s with sid = s.sid} in

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[Gabriel Kerneis]

No, in fact it makes no sense… Sids must be fresh within a single function. There is no reason in principle to break them. However, notice that stmt.preds and stmt.succs are going to be broken anyway - pointing to the old statements. So I guess the right thing to do is to reset everything (sid = -1, preds = succs = []), and force recomputation of the CFG?

I'll commit this if it makes sense.

[Gabriel Kerneis]

Ha, the code abuses the sid to index the hashtable! This is horrible. Oh my... It should use the statements themselves, with physical equality. I did not realize that it resets the original sids... Oh...

I'll fix that. The new behaviour will be:

• original statement unchanged,
• new statement with sid = -1.

[Gabriel Kerneis]

There is a patch proposal in branch fix-copyfunction. Could you tell me if it solves your issue (as well as #142)? Thanks a lot.