[Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned

[jasmin at revisionfx dot com]

--- Comment #78 from jasmin at revisionfx dot com  2010-08-09 01:56 ---

I am not exactly sure how to report a bug here - but it seems highly related to
this thread (I am pie...@revisionfx.com, since I am not sure if I am
auto-subscribed to this thread, and so will get email back about this)

It appears (whatever the version) that this construct in 32b linux (below) does
not work after -shared (ld...) - does not work means is not aligned anymore to
16 bytes/128 bits boundary. If I compile a library with such code, and link it
as in an executable, it seems to work but if I do it as shared object the
alignment is not guaranteed anymore. Anyone has an idea about what to do, if
this will be addressed... or GNU just assumes 32b will go away? Or the problem
is different.  All this works fine with Mac OSX gcc -m32 compile by the way.

Also, if I compile with Intel CC does that fix the problem for an host that is
Intel CC compiled? (As in is it possible that mixed compiler context - host
versus dynamic library further cause complications).

#define MAX_CONV_KERNEL_SIZE4096
class ConvKernel4f  
{
public:

ConvKernel4f ( );
~ConvKernel4f( );
DATA_ALIGN(float4   mFilterPtr[MAX_CONV_KERNEL_SIZE]);

};


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jasmin at revisionfx dot com changed:

   What|Removed |Added

 CC||jasmin at revisionfx dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838

[Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned

[jasmin at revisionfx dot com]

--- Comment #79 from jasmin at revisionfx dot com  2010-08-11 21:26 ---
 > I am not exactly sure how to report a bug here  

Find the answer here:

https://bugs.launchpad.net/sbcl/+bug/539632

" Compile with -mpreferred-stack-boundary=2. This will force GCC to compile
code that adheres to the ABI and therefore properly adjusts its own stack
pointer."

that works


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838

[Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned

[jasmin at revisionfx dot com]

--- Comment #81 from jasmin at revisionfx dot com  2010-08-17 21:03 ---
(In reply to comment #80)
> Comment #79:
> 

> -mstackrealign does the right thing, it realigns the stack when needed, but
> keeps it 16-byte aligned on function output. It should be used.
>  

I don't have that option (-mstackrealign)
It's available in gcc linux from what released version?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838

[Bug rtl-optimization/40838] gcc shouldn't assume that the stack is aligned

[jasmin at revisionfx dot com]

--- Comment #83 from jasmin at revisionfx dot com  2010-08-24 22:09 ---
(In reply to comment #82)
> -mstackrealign is available from gcc 4.5.0. 

So 1) you are right that somehow - mpreferred-stack-boundary=2 does not always
work - I found a case where I crash 
2) so I compiled gcc 4.5.1 and recompiled and same (with or without
-mstackrealign) 
I am noting there might be a new bug. When (I am a shared library) I call back
the host(an exec I run in as a plugin) to check abort I now have a problem with
throw.  My throw is in a try/catch but somehow seems going into host space by
calling it back makes the throw pass through and the host terminates / abort as
it gets a throw it does not know anything about. 
-- I am not equiped right now to test more 32b linux gcc as I don't have a
proper host side way of testing this right now. Just raising a flag.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40838