Re: [GHC] #8974: 64 bit windows executable built with ghc-7.9.20140405+LLVM segfaults

14 Oct 2016

      #8974: 64 bit windows executable built with ghc-7.9.20140405+LLVM segfaults
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        Reporter:  awson            |                Owner:
            Type:  bug              |               Status:  new
        Priority:  high             |            Milestone:  8.0.1
       Component:  Compiler (LLVM)  |              Version:  7.9
      Resolution:                   |             Keywords:
Operating System:  Windows          |         Architecture:  x86_64 (amd64)
 Type of failure:  Runtime crash    |            Test Case:
      Blocked By:                   |             Blocking:
 Related Tickets:                   |  Differential Rev(s):
       Wiki Page:                   |
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Comment (by GordonBGood):

 Replying to [comment:46 Phyx-]:
...
Binutils 2.27-2 has been released on msys, this contains Awson's patch.
...
I need to boil down a version that consistently fails using -fllvm (with
 the patch on 64-bit Windows) and not without and will submit it here...
Failure code as follows:

 {{{
 {-# LANGUAGE FlexibleContexts #-}
 {-# OPTIONS_GHC -O3 -rtsopts #-} -- or O2

 import Data.Array.ST (runSTUArray)
 import Data.Array.Base

 numLOOPS = 50000 :: Integer

 -- Uses a very simple Sieve of Eratosthenes to 2 ^ 18 (so one L1 cache
 size).
 test :: () -> [Int]
 test() = 2 : [fromIntegral i * 2 + 3 | (i, False) <- assocs bufb] where
  bufb = runSTUArray $ do
   let bfLmt = (256 * 1024) `div` 2 - 1 -- to 2^18 + 2 is 128 KBits - 1 =
 16 KBytes
   cmpstsb <- newArray (0, bfLmt) False :: ST s (STUArray s Int Bool)
   let loop n = -- cull a number of times to test timing
         if n <= 0 then return cmpstsb else loop (n - 1)
   loop numLOOPS

 main = print $ length $ test()
 }}}

 The above code consistently segfaults with 64-bit GHC 8.0.1 with LLVM 3.7
 with the latest MSYS2_64 including the patch on Windows when compiled with
 the -fllvm flag but not on Linux 64-bit (Fedora 24) under the same
 conditions or without the -fllvm flag (defaulting to using NCG).

 It does not segfault if 'numLOOPS' is made only 1000 or if the type of
 'numLOOPS' is changed from multi-precision 'Integer' to base 'Int' (64-bit
 integer value for 64-bit systems).  I suspect there is a value such as
 32768 where the segfault starts when using 'Integer'.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8974#comment:48
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