mark_operand_necessary in tree-ssa-dce.c

[Andrew MacLeod]

On Wed, 2005-01-26 at 15:08, Daniel Berlin wrote:
> Can someone (ben, i think you wrote this code) please explain to me why we 
> require a processed sbitmap in this function?
> 

many fingers have touched and changed the meaning of some of these
functions. I've lost track myself :-)

> ISTM that if we are here, we are going to always mark the statement as 
> necessary. And if it was already marked as necessary, we return before we 
> put it on the worklist again anyway.
> 
yes.

this code looks different than I remember. It look sto me like the
processed bitmap now reflects the necessary attribute as well.
especially from the comment its implied too:

/* Vector indicating an SSA name has already been processed and marked
as necessary.  */
static sbitmap processed;


> My thinking goes like this:
<...>
> Anyone disagree?
> If not, i'll bootstrap and regtest a patch to remove it


Giving it a try seems worthwhile. It appears to be the only place its
set, so it seems to be the same thing.

Andrew