> Am 30.11.2024 um 08:19 schrieb Mateusz Guzik via Gcc :
>
> Tested with gcc 14.2 and the Linux kernel compiling for amd64. This is
> at Linux next-20241127. This was already the case on gcc 13 (no idea
> about earlier versions), I tested 14 to see if the problem is gone.
>
> In the particula
Tested with gcc 14.2 and the Linux kernel compiling for amd64. This is
at Linux next-20241127. This was already the case on gcc 13 (no idea
about earlier versions), I tested 14 to see if the problem is gone.
In the particular case I ran into a prediction concerning the return
value of __access_ok
On Thu, Nov 21, 2024 at 1:32 PM Kamil Belter wrote:
>
> On Tue, Nov 19, 2024 at 12:58 PM Richard Biener
> wrote:
> >
> > On Tue, Nov 19, 2024 at 11:56 AM Kamil Belter via Gcc
> > wrote:
> > >
> > > Hello,
> > >
> > > I wou
On Tue, Nov 19, 2024 at 12:58 PM Richard Biener
wrote:
>
> On Tue, Nov 19, 2024 at 11:56 AM Kamil Belter via Gcc wrote:
> >
> > Hello,
> >
> > I would like to set branch prediction based on .gcda files (I know I
> > could have it automatically with -fprofi
On Tue, Nov 19, 2024 at 11:56 AM Kamil Belter via Gcc wrote:
>
> Hello,
>
> I would like to set branch prediction based on .gcda files (I know I
> could have it automatically with -fprofile-use, but with my specific
> use case I can't do it).
>
> I've tried to
Hello,
I would like to set branch prediction based on .gcda files (I know I
could have it automatically with -fprofile-use, but with my specific
use case I can't do it).
I've tried to use gcov-dump but I can't find any spec how to interpret
this output.
I've also tried to us
have strong factual basis saying such words, I can
quite accept the CPU manufacturer's ignoring branch prediction hints
for some reasons, but not this,
We just removed a __builtin_except from the dynamic linker that
indicated the wrong way for more than a decade, maybe even two decades
ld you explain a little more for this sentence, or give me some
keywords for google ?
>>> programmers tend to misuse __builtin_expect ..
I believe you must have strong factual basis saying such words, I can
quite accept the CPU manufacturer's ignoring branch prediction hints
On 08/14/2018 03:36 PM, 2016 quekong wrote:
And Intel seems don't want to talk about it any more, because the latest
material I found within Intel Document was written about ten years ago.
Since branch prediction is nowadays a security feature, I doubt you will
see detailed p
( I don't know if it's allowed to ask such question, if not, please remind
me. )
I know Intel implemented several static branch prediction mechanisms these
years:
* 80486 age: Always-not-take
* Pentium4 age: Backwards Taken/Forwards Not-Taken
* PM, Core2: Didn't use st
On 05/30/2013 03:03 PM, Raphael Clifford wrote:
> Thank you for this. My question was about something more specific
> however. I am interested specifically in branch prediction. For
> example one could add __builtin_expect or the compiler can use the
> information it finds in its pro
Thank you for this. My question was about something more specific
however. I am interested specifically in branch prediction. For
example one could add __builtin_expect or the compiler can use the
information it finds in its profiling. How is this information used
by gcc to provide optimised
> Is there any documentation for what gcc does with branch prediction
> information it gets from profiling? I am interested in this for
> modern Pentium processors where you can no longer give hints.
The profile feedback drives optimizations (i.e. decision what to optimize for
speed and
Is there any documentation for what gcc does with branch prediction
information it gets from profiling? I am interested in this for
modern Pentium processors where you can no longer give hints.
Specifically I am interested in whether there are in fact any
optimisations that work reliably from
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