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: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <202508271856.ixwxgh3g-lkp@intel.com>
[not found] ` <20250902124856.GE186519@nvidia.com>
[not found] ` <aMj38M8HeDSQHQPf@xsang-OptiPlex-9020>
2025-09-16 14:12 ` [jgunthorpe:iommu_pt_vtd 8/34] ERROR: modpost: "__udivdi3" [drivers/iommu/generic_pt/fmt/iommu_amdv1.ko] undefined! 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]
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