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Summary: This is one solution to #11688, wherein (==) was inlined to soon defeating a rewrite rule provided by bytestring. Since the RHSs of Eq's methods are simple, there is little to be gained and much to be lost by inlining them early. For instance, the bytestring library provides, ```lang=haskell break :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString) breakByte :: Word8 -> ByteString -> (ByteString, ByteString) ``` and a rule ``` forall x. break ((==) x) = breakByte x ``` since `breakByte` implments an optimized version of `break (== x)` for known `x :: Word8`. If we allow `(==)` to be inlined too early, we will prevent this rule from firing. This was the cause of #11688. This patch just defers the `Eq` methods, although it's likely worthwhile giving `Ord` this same treatment. This regresses compiler allocations for T9661 by about 8% due to the additional inlining that we now require the simplifier to perform. Updates the `bytestring` submodule to include updated rewrite rules which match on `eqWord8` instead of `(==)`. Test Plan: * Validate, examine performance impact Reviewers: simonpj, hvr, austin Subscribers: thomie Differential Revision: https://phabricator.haskell.org/D1980 GHC Trac Issues: #11688
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