[GHC] #13624: loadObj() does not respect alignment

[GHC]

#13624: loadObj() does not respect alignment
-------------------------------------+-------------------------------------
        Reporter:  tmcdonell         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.10.1
       Component:  Runtime System    |              Version:  8.0.1
  (Linker)                           |             Keywords:  linker,
      Resolution:                    |  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |            Test Case:
      Blocked By:                    |             Blocking:  8949
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by artempyanykh):

 FWIW, `map.ll` needs to be compiled with `-mcpu=sandybridge`. Otherwise on
 Haswell the compiler emits `vbroadcastss` instead of `vmovaps` and the
 issue doesn't manifest itself.

 -----

 I'm currently figuring out Mach-O part. I've adjusted section placement on
 x86_64 analogous to aarch64, but it's not enough as current x86_64
 relocation code works directly with macho_sections. I need to take a
 closer look at it.

 I have concerns re: allocating a page per section. It seems feasible do
 some prep work before `ocGetNames` to calculate the size of future r-x
 segment and rw- segment and exact placement of sections inside the mmaped
 areas (although, currently not sure about subsequent changes to
 mprotecting and unloading code).

 Oh, and If somebody's already working on this, please let me know :)
 ----


 One question, if I may. Moritz, for iOS you use regular `mmap` instead of
 `mmapForLinker`. I don't know much about ARM and wonder if allocating in
 low 2GB is not necessary there?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13624#comment:17>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler