unsafeCoerce# causing invalid assembly generation

Discovered by MichaelBurge on IRC:

{-# LANGUAGE MagicHash #-}

import GHC.Prim
import GHC.Types

x = D# ((unsafeCoerce# (5# :: Int#) :: Double#) +## 5.0##)

main = putStrLn $ show x

Compile with GHC 7.8, 8.0.1 or HEAD:

[1 of 1] Compiling Main             ( weird.hs, weird.o )
/tmp/ghc23262_0/ghc_2.s: Assembler messages:

/tmp/ghc23262_0/ghc_2.s:43:0: error:
     Error: junk `naughty x86_64 register' after expression
`gcc' failed in phase `Assembler'. (Exit code: 1)

Trac metadata

Trac field	Value
Version	8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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