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Re: optimization/8049: SSE unaligned vector stores crash with -O0
- From: Ian Ollmann <iano at cco dot caltech dot edu>
- To: Jan Hubicka <jh at suse dot cz>
- Cc: hubicka at gcc dot gnu dot org, <gcc-bugs at gcc dot gnu dot org>, <gcc-prs at gcc dot gnu dot org>, <gcc-gnats at gcc dot gnu dot org>
- Date: Thu, 10 Oct 2002 17:58:22 -0700
- Subject: Re: optimization/8049: SSE unaligned vector stores crash with -O0
I think the problem is that the compiler is not properly padding data.
_mm_store_ps is nearly unique in that its argument order is
_mm_store_ps( float*, vector );
The 0x4 offset is to protect the float* that is written to the stack a few
bytes earlier. The compiler needs to insert an extra 12 bytes of padding.
In fact, it I swap the order of the arguments as follows:
_mm_store_ps( vector, float*)
then the crash goes away.
Ian
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Ian Ollmann, Ph.D. iano@cco.caltech.edu
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