Intel® C++ Compiler
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FTZ, DAZ, and exceptions

hsolidolby_com
Beginner
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When /Qftz is used on supported architecture (core i3 in this case), should I still expect to see denorm and/or underflow exceptions? Currently this is the case for me.

If this is expected, are these exceptions degrading performance? I thought that by setting FTZ and DAZ I would avoid the exceptions and improve performance.

thanks,

Phill
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TimP
Black Belt
129 Views
Although underflow condition is still raised when /Qftz is set (which has effect only in main(), only when running sse code), the performance penalty which otherwise would be incurred for producing subnormal results is avoided. DAZ could produce a measureable performance difference only in exceptional circumstances.
If you are trying to change the FTZ and DAZ run-time settings other than at initial startup, you will need the intrinsics.
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