On Thu, 2017-10-05 at 03:52 +0200, Adam Borowski wrote: [..] > The package in question, lepton, is a tool to losslessly recompress JPEG > files. It does so faster if your CPU is equipped with SSE4.1, thus the > upstream build system hard-codes this requirement, even though it seems > that generic code paths are present, broken only by completely bogus > ifdeffage: it has gems like: [...] > if(SSE_VECTORIZATION) > set(VECTOR_FLAGS "-mssse3 -msse4.2") > else() > set(VECTOR_FLAGS "") > endif() > > (Needless to say, build status is mostly red.) > > In this case, there's no reason to exclude older computers: x86 with no > SSE4.1 isn't rare (especially on AMD), and it's a legitimate use case: > people with weak computers also tend to have low bandwidth, so reducing > file size of photos is nice. > > So, let's list packages that want non-baseline: > * multiple variants: package src:x provides x-unoptimized, x-sse3 and > x-avx1048576. Clearly legitimate and a good idea. [...]
This should be unnecessary since gcc 6, as you can easily tell the compiler to generate and select between multiple versions of the functions. See <https://lwn.net/Articles/691932/>. Ben. -- Ben Hutchings Make three consecutive correct guesses and you will be considered an expert.
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