https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
Richard Biener changed:
What|Removed |Added
Status|NEW |RESOLVED
Resolution|---
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #21 from Richard Biener ---
Author: rguenth
Date: Fri May 23 10:11:03 2014
New Revision: 210848
URL: http://gcc.gnu.org/viewcvs?rev=210848&root=gcc&view=rev
Log:
2014-05-22 Paul Eggert
PR other/56955
* doc/extend.texi (Fu
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
Paul Eggert changed:
What|Removed |Added
Attachment #32832|0 |1
is obsolete|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #19 from rguenther at suse dot de ---
On May 21, 2014 5:14:27 PM CEST, eggert at gnu dot org
wrote:
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
>
>--- Comment #18 from Paul Eggert ---
>(In reply to Richard Biener from commen
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #18 from Paul Eggert ---
(In reply to Richard Biener from comment #16)
> void foo (int *p)
> {
> int *q = realloc (p, sizeof (int));
> *q = 2;
> }
>
> may I remove the store *q = 2 as dead?
Yes, the consensus nowadays is that y
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #17 from Dan Gohman ---
(In reply to Richard Biener from comment #16)
> One reason for why realloc is "hard" is that there is no language that says
> it is undefined to access the object via the old pointer, but there is only
> langua
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #16 from Richard Biener ---
One reason for why realloc is "hard" is that there is no language that says
it is undefined to access the object via the old pointer, but there is only
language that says the old and the new pointer values
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
Richard Biener changed:
What|Removed |Added
Status|UNCONFIRMED |NEW
Last reconfirmed|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #14 from Paul Eggert ---
(In reply to Dan Gohman from comment #13)
> *p can't alias a or b without violating the weaker assumption.
Sorry, you've lost me there. Pointers in realloc'ed storage can alias
already-existing pointers, an
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #13 from Dan Gohman ---
(In reply to Paul Eggert from comment #12)
> (In reply to Rich Felker from comment #10)
> > This assumption only aids
> > optimization in the case where a pointer residing in the obtained memory is
> > used (e.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #12 from Paul Eggert ---
(In reply to Rich Felker from comment #10)
> This assumption only aids
> optimization in the case where a pointer residing in the obtained memory is
> used (e.g. dereferenced or compared with another pointer)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #11 from Paul Eggert ---
Created attachment 32834
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32834&action=edit
Sample illustrating GCC's optimization with __attribute__ ((malloc))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #10 from Rich Felker ---
I don't see how it's at all helpful for GCC to assume that memory obtained by
__attribute__((__malloc__)) functions does not contain pointers to anything
that existed before the call. This assumption only aids
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
Paul Eggert changed:
What|Removed |Added
Attachment #32831|0 |1
is obsolete|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #8 from Paul Eggert ---
Comment on attachment 32831
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32831
Clarify documentation for __attribute__ ((malloc)).
>Index: gcc/ChangeLog
>===
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
Carlos O'Donell changed:
What|Removed |Added
CC||carlos at redhat dot com
--- Comment #
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
Paul Eggert changed:
What|Removed |Added
CC||eggert at gnu dot org
--- Comment #6 from
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
davidxl at google dot com changed:
What|Removed |Added
CC||davidxl at google dot c
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #4 from Dan Gohman 2013-04-15 14:53:06
UTC ---
(In reply to comment #3)
> Well, it _is_ actually about the content. There must be no way to compute
> a valid pointer to another object from the contents of the pointed-to
> mem
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #3 from Richard Biener 2013-04-15
10:19:22 UTC ---
(In reply to comment #2)
> (In reply to comment #1)
> > I think it is talking about the memory returned by malloc/calloc will not
> > point
> > to another memory location whi
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #2 from Dan Gohman 2013-04-14 19:47:42
UTC ---
(In reply to comment #1)
> I think it is talking about the memory returned by malloc/calloc will not
> point
> to another memory location while realloc can.
I agree that's esse
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56955
--- Comment #1 from Andrew Pinski 2013-04-14
19:05:00 UTC ---
I think it is talking about the memory returned by malloc/calloc will not point
to another memory location while realloc can.
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