Re: [Boost-bugs] [Boost C++ Libraries] #2535: Boost.Regex not compatible with gcc's align-double at optimization level 3

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #2535: Boost.Regex not compatible with gcc's align-double at optimization level 3
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2008-11-26 17:23:29

#2535: Boost.Regex not compatible with gcc's align-double at optimization level 3
---------------------------------+------------------------------------------
  Reporter:  Andrew Troschinetz  |       Owner:  johnmaddock
      Type:  Bugs                |      Status:  closed     
 Milestone:  Boost 1.38.0        |   Component:  regex      
   Version:  Boost 1.37.0        |    Severity:  Problem    
Resolution:  wontfix             |    Keywords:             
---------------------------------+------------------------------------------
Changes (by johnmaddock):

  * status:  new => closed
  * resolution:  => wontfix

Comment:

 I believe that this is inevitable and not fixable (unless you can suggest
 otherwise), gcc's docs say:

 "-malign-double
 -mno-align-double
 Control whether GCC aligns double, long double, and long long variables on
 a two word boundary or a one word boundary. Aligning double variables on a
 two word boundary will produce code that runs somewhat faster on a
 ‘Pentium’
 at the expense of more memory.
 On x86-64, ‘-malign-double’ is enabled by default.
 Warning: if you use the ‘-malign-double’ switch, structures containing the
 above types will be aligned differently than the published application
 binary
 interface specifications for the 386 and will not be binary compatible
 with structures
 in code compiled without that switch."

 In other words setting that switch changes the binary compatibity of the
 code - so your application's obj files are no longer compatible with the
 way Boost.Regex is built by default.  You would have to build regex with
 -malign-double if you insist on using that option.

 HTH, and sorry for the bad news, John

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/2535#comment:1>
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