Sent: Thursday, January 2, 2025 11:02 PM
To: François Dumont ; Jonathan Wakely
Cc: gcc-patches@gcc.gnu.org; nd ; libstd...@gcc.gnu.org
Subject: RE: [PATCH 2/2][libstdc++]: Adjust probabilities of hashmap loop
conditions
Hi,
> It means that we consider that hasher is not perfect, we have seve
I’ll run the numbers with this change.
Thanks,
Tamar
From: François Dumont
Sent: Monday, December 30, 2024 5:08 PM
To: Jonathan Wakely
Cc: Tamar Christina ; gcc-patches@gcc.gnu.org; nd
; libstd...@gcc.gnu.org
Subject: Re: [PATCH 2/2][libstdc++]: Adjust probabilities of hashmap loop
condition
Sorry to react so late on this patch.
I'm only surprised by the expected result of the added __builtin_expect
which is 0.
It means that we consider that hasher is not perfect, we have several
entries in the same bucket. Shouldn't we reward those that are spending
time on their hasher to make it a
On Wed, 18 Dec 2024 at 14:14, Tamar Christina wrote:
>
> > e791e52ec329277474f3218d8a44cd37ded14ac3..8101d868d0c5f7ac4f97931a
> > > ffcf71d826c88094 100644
> > > > --- a/libstdc++-v3/include/bits/hashtable.h
> > > > +++ b/libstdc++-v3/include/bits/hashtable.h
> > > > @@ -2171,7 +2171,7 @@ _GLIBCXX
> e791e52ec329277474f3218d8a44cd37ded14ac3..8101d868d0c5f7ac4f97931a
> > ffcf71d826c88094 100644
> > > --- a/libstdc++-v3/include/bits/hashtable.h
> > > +++ b/libstdc++-v3/include/bits/hashtable.h
> > > @@ -2171,7 +2171,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > if (this->_M_equals(__k,
> On Fri, 13 Dec 2024 at 17:13, Tamar Christina wrote:
> >
> > Hi All,
> >
> > We are currently generating a loop which has more comparisons than you'd
> > typically need as the probablities on the small size loop are such that it
> > assumes the likely case is that an element is not found.
> >
>
On Fri, 13 Dec 2024 at 17:13, Tamar Christina wrote:
>
> Hi All,
>
> We are currently generating a loop which has more comparisons than you'd
> typically need as the probablities on the small size loop are such that it
> assumes the likely case is that an element is not found.
>
> This again gener
