[GHC] #7460: Double literals generated bad core

[GHC]

#7460: Double literals generated bad core
---------------------------------+------------------------------------------
    Reporter:  tibbe             |       Owner:                         
        Type:  bug               |      Status:  new                    
    Priority:  normal            |   Milestone:                         
   Component:  Compiler          |     Version:  7.4.2                  
    Keywords:                    |          Os:  Unknown/Multiple       
Architecture:  Unknown/Multiple  |     Failure:  Runtime performance bug
  Difficulty:  Unknown           |    Testcase:                         
   Blockedby:                    |    Blocking:                         
     Related:                    |  
---------------------------------+------------------------------------------

Comment(by int-e):

 Looking at the CMM code, the most noticable difference seems that
 ghc-7.0.3 used to generate a foreign call for the second part of the
 conversion,
 {{{
           integer_cbits_encodeDouble((_c2ut::I64, `signed'),
                                      (_c2uv::I64, PtrHint), (0,
 `signed'))[_unsafe_call_];
 }}}
 while the current code (since ghc-7.2.1) sets up a stack frame and jumps
 into the integer package.

 Not sure how much of the observed differences that explains.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7460#comment:9>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler