On 10/02/21 10:21, Henri Sivonen wrote: > Chrome is moving to SSE3 as the unconditional baseline, which I > personally find surprising: > https://docs.google.com/document/d/1QUzL4MGNqX4wiLvukUwBf6FdCL35kCDoEJTm2wMkahw/edit# > > A quick and very unscientific look at Searchfox suggests that > unconditional SSE3 would mainly eliminate conditional/dynamic dispatch > on YUV conversion code paths when it comes to explicit SSE3 usage. No > idea how LLVM would insert SSE3 usage on its own.
SSE3 instructions were very specialized - mostly for video processing - I doubt that LLVM can make use of them in regular code. It's unclear to me why the Chrome devs decided to jump to SSE3 given it should give very little benefit over SSE2. It would have made more sense if they jumped to SSSE3 instead, but that would have cut out all the users still on early Athlon 64 processors. Gabriele
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