[MinGW-notify] [ mingw-Bugs-2833091 ] __try1 (excpt.h) missing memory clobber

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Bugs item #2833091, was opened at 2009-08-06 03:01
Message generated for change (Comment added) made by earnie
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Category: mingw runtime (deprecated use WSL)
Group: Aged issue
>Status: Closed
>Resolution: Invalid
Priority: 5
Private: No
Submitted By: thomas (thomas-denk)
Assigned to: Earnie Boyd (earnie)
Summary: __try1 (excpt.h) missing memory clobber

Initial Comment:
Problem: __try1 will fail "mysteriously" (consistently, reproducably, but not according to any immediately obvious pattern) if optimisations are turned on.
Looking at the disassembly shows that in these cases of failure, instructions were reordered, thus if an exception occurred too soon after __try1, it would sometimes only install the SEH handler after the application had already crashed.

Fix: add a "memory" clobber as compiler barrier to __try1  (and probably it's a good idea to add one to __except1 too).


#define __try1(pHandler) \
	__asm__ ("pushl %0;pushl %%fs:0;movl %%esp,%%fs:0;" : : "g" (pHandler) : "memory");

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>Comment By: Earnie Boyd (earnie)
Date: 2012-10-23 05:21

Message:
No test program to display the issue.

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Comment By: Earnie Boyd (earnie)
Date: 2012-08-01 09:12

Message:
I need a sample test program attached to this issue.  Thomas can you supply
it?

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Comment By: Earnie Boyd (earnie)
Date: 2012-06-14 07:04

Message:
Assigning to Chris for follow up.

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You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=102435&aid=2833091&group_id=2435