From: Jason Gunthorpe <jgg@nvidia.com>
To: Nathan Chancellor <nathan@kernel.org>
Cc: Oliver Sang <oliver.sang@intel.com>,
Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
llvm@lists.linux.dev, kernel test robot <lkp@intel.com>,
oe-kbuild-all@lists.linux.dev
Subject: Re: [jgunthorpe:iommu_pt_vtd 8/34] ERROR: modpost: "__udivdi3" [drivers/iommu/generic_pt/fmt/iommu_amdv1.ko] undefined!
Date: Wed, 17 Sep 2025 21:06:10 -0300 [thread overview]
Message-ID: <20250918000610.GK1391379@nvidia.com> (raw)
In-Reply-To: <20250917221217.GA650176@ax162>
On Wed, Sep 17, 2025 at 03:12:17PM -0700, Nathan Chancellor wrote:
> Looking at the preprocessed source and making some educated guesses, I
> am guessing with inlining and constant folding, GCC turn division into
> multiplication by the reciprocal. Clang implements some of these
> optimizations but not all, if I remember correctly.
Oh interesting, I noticed that clang was measurably slower than gcc
for this code, maybe this is some of why
Jason
prev parent reply other threads:[~2025-09-18 0:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-27 10:53 [jgunthorpe:iommu_pt_vtd 8/34] ERROR: modpost: "__udivdi3" [drivers/iommu/generic_pt/fmt/iommu_amdv1.ko] undefined! kernel test robot
2025-09-02 12:48 ` Jason Gunthorpe
2025-09-16 5:38 ` Oliver Sang
2025-09-16 14:12 ` Jason Gunthorpe
2025-09-17 2:20 ` Nathan Chancellor
2025-09-17 11:22 ` Jason Gunthorpe
2025-09-17 22:12 ` Nathan Chancellor
2025-09-18 0:06 ` Jason Gunthorpe [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250918000610.GK1391379@nvidia.com \
--to=jgg@nvidia.com \
--cc=lkp@intel.com \
--cc=llvm@lists.linux.dev \
--cc=nathan@kernel.org \
--cc=nick.desaulniers+lkml@gmail.com \
--cc=oe-kbuild-all@lists.linux.dev \
--cc=oliver.sang@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.