[PATCH] D83913: [X86] Change the tuning settings for pentium4 to be more modern since its the default 32-bit cpu in clang

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

I don't object, but this is less sustainable than adding a generic 32-bit model to match the generic 64-bit model (the alternate D83897 <https://reviews.llvm.org/D83897> patch IIUC).

Maybe out-of-scope for this patch, but there's a bigger problem in that (AFAIK), we have no plan for updating the generic tuning. Ie, the 64-bit generic model was created 6 years ago and grows less relevant daily:

  // We currently use the Sandy Bridge model as the default scheduling model as
  // we use it across Nehalem, Westmere, Sandy Bridge, and Ivy Bridge which
  // covers a huge swath of x86 processors.

Should we create some metrics based on time or popularity that guide us on updating that? For example, are we stuck assuming SSE2-only for the generic model forever, or can we decide that 12+ years past the introduction of SSE4.1 lets us assume that is available/preferred?


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  https://reviews.llvm.org/D83913/new/

https://reviews.llvm.org/D83913