[GHC] #14669: Windows binaries sometimes throw a stack overflow.

[GHC]

#14669: Windows binaries sometimes throw a stack overflow.
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        Reporter:  sergv             |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  highest           |            Milestone:  8.4.1
       Component:  Runtime System    |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Runtime crash     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4343
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"a55d581f8f2923560c3444253050b13fdf2dec10/ghc"
 a55d581f/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a55d581f8f2923560c3444253050b13fdf2dec10"
 Fix Windows stack allocations.

 On Windows we use the function `win32AllocStack` to do stack
 allocations in 4k blocks and insert a stack check afterwards
 to ensure the allocation returned a valid block.

 The problem is this function does something that by C semantics
 is pointless. The stack allocated value can never escape the
 function, and the stack isn't used so the compiler just optimizes
 away the entire function body.

 After considering a bunch of other possibilities I think the simplest
 fix is to just disable optimizations for the function.

 Alternatively inline assembly is an option but the stack check function
 doesn't have a very portable name as it relies on e.g. `libgcc`.

 Thanks to Sergey Vinokurov for helping diagnose and test.

 Test Plan: ./validate

 Reviewers: bgamari, erikd, simonmar

 Reviewed By: bgamari

 Subscribers: rwbarton, thomie, carter

 GHC Trac Issues: #14669

 Differential Revision: https://phabricator.haskell.org/D4343
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14669#comment:31>
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