[llvm] r307529 - This patch completely replaces the scheduling information for the SandyBridge architecture target by modifying the file X86SchedSandyBridge.td located under the X86 Target.

[Haber, Gadi via llvm-commits]

This is mainly due to missing X87 scheduling which I am currently in the process of adding for SNB.

-----Original Message-----
From: Dimitry Andric [mailto:dimitry at andric.com] 
Sent: Saturday, July 29, 2017 20:12
To: Haber, Gadi <gadi.haber at intel.com>
Cc: Xinliang David Li via llvm-commits <llvm-commits at lists.llvm.org>; Ed Maste <emaste at freebsd.org>
Subject: Re: [llvm] r307529 - This patch completely replaces the scheduling information for the SandyBridge architecture target by modifying the file X86SchedSandyBridge.td located under the X86 Target.

On 10 Jul 2017, at 11:53, Gadi Haber via llvm-commits <llvm-commits at lists.llvm.org> wrote:
> 
> Author: gadi.haber
> Date: Mon Jul 10 02:53:16 2017
> New Revision: 307529
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=307529&view=rev
> Log:
> This patch completely replaces the scheduling information for the SandyBridge architecture target by modifying the file X86SchedSandyBridge.td located under the X86 Target.
> The SandyBridge architects have provided us with a more accurate information about each instruction latency, number of uOPs and used ports and I used it to replace the existing estimated SNB instructions scheduling and to add missing scheduling information.
> 
> Please note that the patch extensively affects the X86 MC instr scheduling for SNB.
> 
> Also note that this patch will be followed by additional patches for the remaining target architectures HSW, IVB, BDW, SKL and SKX.

This particular commit seems to cause issues in FreeBSD's libm, specifically the values of sinl() are now way off.  See https://bugs.freebsd.org/220989, where I have unfortunately only been able to find out *that* the values are bad, but not been able to produce a simplified test case yet.

-Dimitry

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