RFR (S): 7177917: Failed test java/lang/Math/PowTests.java

[Roland Westrelin]

Hi Vladimir,

Thanks for taking a look at this.

> Did you run refworkload? Additional checks will increase code size and may slowdown performance. Did you consider the fix which keeps unctrap but instead of going into java code generate call to runtime only if there were NaN cases.

Do you have a particular benchmark in mind? I checked reference_server and the only benchmark that make use of Math.pow() is specjvm98 but it does not seem critical to its performance: using the intrinsic or not doesn't make a difference.

Here is a new webrev with uncommon traps:
http://cr.openjdk.java.net/~roland/7177917/webrev.01/

I also took you other suggestions into account. 

> Not for this fix but for future, may be we should use exponent values checks (as in __ieee754_pow() method) instead of converting D2L and L2D which could be expensive.

I agree that there could be a simpler/more efficient than d2l + l2d to check for an integer value.

Roland.