https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #16 from Jakub Jelinek ---
Actually, there is no need to use the __COUNTER__ stuff, just use
static const int __ia64_asr_p = ...;
in the scope. It is just important __OPTIMIZE__ is on, because at -O0 the
compiler wouldn't optimize
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #15 from Jakub Jelinek ---
(In reply to Matthew Wilcox from comment #14)
> Confirmed this fixes the problem. I'll send it to Tony and see if he likes
> it. May I add your Signed-off-by to the patch?
Sure. Feel free to reformat it
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #14 from Matthew Wilcox ---
Confirmed this fixes the problem. I'll send it to Tony and see if he likes it.
May I add your Signed-off-by to the patch?
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
Jakub Jelinek changed:
What|Removed |Added
CC||jakub at gcc dot gnu.org
--- Comment
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #12 from Aldy Hernandez ---
(In reply to Matthew Wilcox from comment #9)
> Maybe I'm a little slow, but I don't see what the path is that sets 'nr' to
> 0. It's 1UL << compound_order. Typically, compound_order is 0, although it
>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #11 from Matthew Wilcox ---
I'm sorry, I still don't get it.
What I think you're saying is that GCC performs this optimisation:
nr = 1UL << compound_order(page);
atomic_sub_return(x, nr);
into:
if (PageHead(page))
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
Jeffrey A. Law changed:
What|Removed |Added
Status|WAITING |RESOLVED
CC|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #9 from Matthew Wilcox ---
Maybe I'm a little slow, but I don't see what the path is that sets 'nr' to 0.
It's 1UL << compound_order. Typically, compound_order is 0, although it may be
anything up to log2(number of pages in the
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #8 from Aldy Hernandez ---
Ah, I see what the problem is.
unsigned long i, nr = 1UL << compound_order(page);
...
page_ref_sub(page, nr); // calls __builtin_constant_p(nr) eventually
The problem is that there is a path to
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #7 from Matthew Wilcox ---
OK, so how should we write this function/macro to accomplish what we want?
And the requirement is "If the argument is one of these eight special
constants, use this special instruction, otherwise call this
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #6 from rguenther at suse dot de ---
On Thu, 11 Jan 2018, matthew at wil dot cx wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
>
> --- Comment #5 from Matthew Wilcox ---
> Hi Aldy!
>
> Thanks for looking into this.
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
--- Comment #5 from Matthew Wilcox ---
Hi Aldy!
Thanks for looking into this. Yes, I agree, there's no way that GCC can know
this is a constant, but that *should* have been taken care of. Please pardon
me copying and pasting from the original
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
Aldy Hernandez changed:
What|Removed |Added
Status|UNCONFIRMED |WAITING
Last reconfirmed|
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83653
Richard Biener changed:
What|Removed |Added
Summary|[6 Regression] GCC fails to |[6/7/8 Regression] GCC
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