* [Patch} Fix dynamic casts across dll boundaries on windows targets
@ 2004-10-16 9:47 Danny Smith
2004-10-17 22:25 ` Christopher Faylor
2004-10-19 6:21 ` Aaron W. LaFramboise
0 siblings, 2 replies; 5+ messages in thread
From: Danny Smith @ 2004-10-16 9:47 UTC (permalink / raw)
To: GCC Patches; +Cc: Christopher Faylor
Hello
This fixes a long standing libstdc++ bug in windows targets, where dynamic casts
that cross dll boundaries fail. The bug was first reported to
mingw lists by Colin Peters in Jun 2002 as a regression against 2.95
http://sourceforge.net/tracker/?func=detail&atid=102435&aid=568054&group_id=2435
and fixed locally by a cygwin/mingw specific hack to the typeinfo header:
http://www.cygwin.com/ml/cygwin-apps/2002-07/msg00550.html
The following uses Mark Mitchell's fix for the same problem on bpabi
targets. Tested on i686-pc-mingw32 with no new regressions.
2004-10-16 Danny Smith <dannysmith@users.sourceforge.net>
* config/i386/cygming.h (TARGET_OS_CPP_BUILTINS): Define
__GXX_MERGED_TYPEINFO_NAMES to 0.
Index: config/i386/cygming.h
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/i386/cygming.h,v
retrieving revision 1.21
diff -c -3 -p -r1.21 cygming.h
*** config/i386/cygming.h 9 Sep 2004 17:11:17 -0000 1.21
--- config/i386/cygming.h 16 Oct 2004 08:23:59 -0000
*************** Boston, MA 02111-1307, USA. */
*** 86,91 ****
--- 86,94 ----
builtin_define ("_fastcall=__attribute__((__fastcall__))"); \
builtin_define ("_cdecl=__attribute__((__cdecl__))"); \
} \
+ /* Even though linkonce works with static libs, this is needed \
+ to compare typeinfo symbols across dll boundaries. */ \
+ builtin_define ("__GXX_MERGED_TYPEINFO_NAMES=0"); \
MAYBE_UWIN_CPP_BUILTINS (); \
EXTRA_OS_CPP_BUILTINS (); \
} \
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^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [Patch} Fix dynamic casts across dll boundaries on windows targets
2004-10-16 9:47 [Patch} Fix dynamic casts across dll boundaries on windows targets Danny Smith
@ 2004-10-17 22:25 ` Christopher Faylor
2004-10-19 6:21 ` Aaron W. LaFramboise
1 sibling, 0 replies; 5+ messages in thread
From: Christopher Faylor @ 2004-10-17 22:25 UTC (permalink / raw)
To: Danny Smith; +Cc: GCC Patches
>2004-10-16 Danny Smith <dannysmith@users.sourceforge.net>
>
> * config/i386/cygming.h (TARGET_OS_CPP_BUILTINS): Define
> __GXX_MERGED_TYPEINFO_NAMES to 0.
ok.
cgf
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Patch} Fix dynamic casts across dll boundaries on windows targets
2004-10-16 9:47 [Patch} Fix dynamic casts across dll boundaries on windows targets Danny Smith
2004-10-17 22:25 ` Christopher Faylor
@ 2004-10-19 6:21 ` Aaron W. LaFramboise
2004-10-19 10:52 ` Danny Smith
1 sibling, 1 reply; 5+ messages in thread
From: Aaron W. LaFramboise @ 2004-10-19 6:21 UTC (permalink / raw)
To: Danny Smith; +Cc: GCC Patches, Christopher Faylor
Danny Smith wrote:
> 2004-10-16 Danny Smith <dannysmith@users.sourceforge.net>
>
> * config/i386/cygming.h (TARGET_OS_CPP_BUILTINS): Define
> __GXX_MERGED_TYPEINFO_NAMES to 0.
Does this pessimize the case where typeinfo symbols really are
availible? An example might be when a DLL exports the typeinfo symbols
and they are linkable with auto-import. (Will auto-import work for
this, anyway?)
Another source for experience in this area is the recent ELF visibility
work. For example, see the secton Caveats in
<http://www.nedprod.com/programs/gccvisibility.html>. The suggestion
here is that if you want RTTI to work, you must take necessary steps to
export typeinfo symbols. Is a similar approach for PE unreasonable?
Aaron W. LaFramboise
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Patch} Fix dynamic casts across dll boundaries on windows targets
2004-10-19 6:21 ` Aaron W. LaFramboise
@ 2004-10-19 10:52 ` Danny Smith
2004-10-21 3:59 ` Aaron W. LaFramboise
0 siblings, 1 reply; 5+ messages in thread
From: Danny Smith @ 2004-10-19 10:52 UTC (permalink / raw)
To: Aaron W. LaFramboise; +Cc: GCC Patches, Christopher Faylor
Aaron W. LaFramboise wrote:
> Danny Smith wrote:
>
>> 2004-10-16 Danny Smith <>
>>
>> * config/i386/cygming.h (TARGET_OS_CPP_BUILTINS): Define
>> __GXX_MERGED_TYPEINFO_NAMES to 0.
>
> Does this pessimize the case where typeinfo symbols really are
> availible?
It pessimizes linking against static libs/objects
An example might be when a DLL exports the typeinfo
> symbols and they are linkable with auto-import. (Will auto-import
> work for this, anyway?)
>
There is a test case in the original bug report :
http://sourceforge.net/tracker/?func=detail&atid=102435&aid=568054&group
_id=2435
> Another source for experience in this area is the recent ELF
> visibility work. For example, see the secton Caveats in
> <http://www.nedprod.com/programs/gccvisibility.html>. The suggestion
> here is that if you want RTTI to work, you must take necessary steps
> to export typeinfo symbols. Is a similar approach for PE
> unreasonable?
One of the problems with RTTI vs dllimport is that dllimported objects
do not have a constant address at compile time. This creates a problem
for static initialisation of, say, another RTTI object or a vtable
that has a
dllimported typeinfo member.
Danny
>
> Aaron W. LaFramboise
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [Patch} Fix dynamic casts across dll boundaries on windows targets
2004-10-19 10:52 ` Danny Smith
@ 2004-10-21 3:59 ` Aaron W. LaFramboise
0 siblings, 0 replies; 5+ messages in thread
From: Aaron W. LaFramboise @ 2004-10-21 3:59 UTC (permalink / raw)
To: Danny Smith; +Cc: GCC Patches, Christopher Faylor
Danny Smith wrote:
> One of the problems with RTTI vs dllimport is that dllimported objects
> do not have a constant address at compile time. This creates a problem
> for static initialisation of, say, another RTTI object or a vtable
> that has a
> dllimported typeinfo member.
Does autoimport or the pseudo-relocator help with this?
Aaron W. LaFramboise
^ permalink raw reply [flat|nested] 5+ messages in thread
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2004-10-16 9:47 [Patch} Fix dynamic casts across dll boundaries on windows targets Danny Smith
2004-10-17 22:25 ` Christopher Faylor
2004-10-19 6:21 ` Aaron W. LaFramboise
2004-10-19 10:52 ` Danny Smith
2004-10-21 3:59 ` Aaron W. LaFramboise
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