On Wed, Apr 28, 2004 at 12:41:51PM -0500, Brian Ford wrote:
>On Wed, 28 Apr 2004, tbp wrote:
>
>> Building an app of mine (multithreaded) with something like -O3
>> -march=k8 the binary died with an illegal instruction. The offending
>> instruction was a 'movaps %xmm0, 0x40(%esp)' with an unaligned esp.
>> As that was on a secondary thread after some external calls (opengl and
>> so on) i thought it had to do with some cygwin/ABI issue or something.
>>
>> After a day of struggling/web digging, i still had no clue.
>[snip]
>> I'm puzzled & surprised that nobody tripped that one earlier and i'd
>> apreciate any clue.
>
>http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14776
>
>I'm working with Red Hat to resolve this issue right now. The problem is
>that thread stacks are not always 16 byte aligned. You could try the
>following hack if you need something right away and don't mind building
>your own Cygwin DLL.
This patch would only affect non-main threads. It would not affect the
main thread. Wouldn't you need to do the same thing for the main thread?
I don't understand why it would be different.
cgf
>2004-04-28 DJ Delorie <[EMAIL PROTECTED]>
>
> * init.cc (threadfunc_fe): Hack to make thread stacks always 16
> byte aligned.
>
>Index: init.cc
>===================================================================
>RCS file: /cvs/src/src/winsup/cygwin/init.cc,v
>retrieving revision 1.32
>diff -u -p -r1.32 init.cc
>--- init.cc 22 Mar 2004 18:30:38 -0000 1.32
>+++ init.cc 28 Apr 2004 17:38:03 -0000
>@@ -27,6 +27,8 @@ HANDLE sync_startup;
> static void WINAPI
> threadfunc_fe (VOID *arg)
> {
>+ (void)__builtin_return_address(1);
>+ asm volatile ("andl $-16,%%esp" ::: "%esp");
> _cygtls::call ((DWORD (*) (void *, void *)) (((char **)
>_tlsbase)[OLDFUNC_OFFSET]), arg);
> }
>
>--
>Brian Ford
>Senior Realtime Software Engineer
>VITAL - Visual Simulation Systems
>FlightSafety International
>the best safety device in any aircraft is a well-trained pilot...
>
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