Change compiler option flags for double precision floating point custom instruction

Hi,

I also would like to accelerate double precision floating point processing by use of custom instructions. Different to

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You'd need to rebuild gcc with extra instruction definitions in order to get it to use your custom instructions.

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my understanding from this alterawiki (http://www.alterawiki.com/wiki/custom_instructions) article is that there should be no need to rebuild the gcc. However, although I have set all of the necessary flags, the gcc that comes along with quartus 13.0 does not make use of my double precision floating point custom instructions.

Has anybody been successful in this? Any help is appreciated!