[fpc-devel] Stack alignment on i386

Henry Vermaak henry.vermaak at gmail.com
Mon Dec 19 13:14:53 CET 2011

On 18/12/11 12:37, Den Jean wrote:
> Hi,
> to interface with c libraries containing SSE code,
> the stack must be aligned to 16 bytes.
> Currently the default -mpreferred-stack-boundary=num of gcc provides for this.
> However current fpc 2.4.4 does not align the stack as such.
> I do not know if this correct or not when reading things like:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838#c8
> http://groups.google.com/group/ia32-abi/browse_thread/thread/4f9b3e5069943bf1

Ow, we hit this problem.  We are calling a library that uses opencv 
(where SSE instructions are used).  Luckily we can add -mstackrealign to 
the CFLAGS of our library.  People without an "interface" lib will be in 
trouble, though.


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