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Re: [RFC PATCH] add auto_bitmap
- From: Jeff Law <law at redhat dot com>
- To: tsaunders at mozilla dot com, gcc-patches at gcc dot gnu dot org
- Date: Thu, 14 Nov 2013 13:35:57 -0700
- Subject: Re: [RFC PATCH] add auto_bitmap
- Authentication-results: sourceware.org; auth=none
- References: <1384427080-13613-1-git-send-email-tsaunders at mozilla dot com>
On 11/14/13 04:04, tsaunders@mozilla.com wrote:
From: Trevor Saunders <tsaunders@mozilla.com>
Hi,
this patch adds and starts to use a class auto_bitmap, which is a very thin
wrapper around bitmap. Its advantage is that it takes care of delocation
automatically. So you can do things like
int
f ()
{
auto_bitmap x;
// do stuff with x
}
Another advantage of this class is it puts the bitmap_head struct on the stack
instead of mallocing it or using a obstack.
I Think the biggest question is if I should make auto_bitmap a full c++ified
wrapper around bitmap or if I should contiune just taking the address of it
and passing it as a bitmap, but other comments are of course welcome too.
I'd prefer to see it fully c++ified.
In response to one of Richi's comments, I spot checked the patch and
only found two occurrences where this lengthened the lifetime of the
bitmap in any significant way. The vast majority of the time any
increase in length was trivial.
Those instances are in tree-ssa-loop-ivopts.c and the other in
tree-ssa-strlen.c. I don't think you need to change anything for them,
I'm just pointed out that of all the stuff you changed, these were the
only ones I saw where lifetimes were changed significantly.
jeff