[PATCH] D61604: [InstCombine] sink FP negation of operands through select

[Kevin Neal via llvm-commits]

What I did was run the test suite and examine every failure. In every test that had an fsub get changed into an fneg I updated the test. That only left a few failures:


    LLVM :: Transforms/InstCombine/cos-1.ll

    LLVM :: Transforms/InstCombine/fsub.ll

    LLVM :: Transforms/Reassociate/canonicalize-neg-const.ll

    LLVM :: Transforms/Reassociate/reassoc-intermediate-fnegs.ll

These four need work beyond changing fsub’s into fneg’s.
--
Kevin P. Neal
SAS/C and SAS/C++ Compiler
Host Research and Development
SAS Institute, Inc.



From: Sanjay Patel <spatel at rotateright.com>
Sent: Tuesday, May 07, 2019 11:44 AM
To: Kevin Neal <Kevin.Neal at sas.com>
Cc: cameron.mcinally at nyu.edu; Matthew.Arsenault at amd.com; andrew.kaylor at intel.com; mcrosier at codeaurora.org; wei.ding2 at amd.com; hiraditya at msn.com; llvm-commits at lists.llvm.org; jun.l at samsung.com
Subject: Re: [PATCH] D61604: [InstCombine] sink FP negation of operands through select


EXTERNAL

On Tue, May 7, 2019 at 7:16 AM Kevin Neal <Kevin.Neal at sas.com<mailto:Kevin.Neal at sas.com>> wrote:

How should we handle regressions in code quality that are exposed by tests?

One idea I had (or I may be remembering someone else's suggestion) was to grep the existing IR regression tests for 'fsub -0.0', then create a sibling test using fneg. If that doesn't result in the same output, then we need to do some pattern matching enhancement.
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