[aarch64-port-dev ] RFR(M): 8196402: AARCH64: create intrinsic for Math.log

[Andrew Haley]

On 06/20/2018 12:45 AM, White, Derek wrote:
>  - Line 68: Could align to 64 bytes. We're going to load the first 64 bytes, may as well use one cache line.
> 
>  - Lines 71, 77, 79. You could comment these lines with "_coeff", "_log2", and "_L_tbl", for clearer correspondence to x86 code.
> 
> - Line 204: I believe that we should be looking for equal to 0.0:
> 204 //      if (X = 0.0d) return -INFINITY;

Yes.  if (X == 0.0d).
> - The (float)(zeroExponent(X) code was fun.
> 
> - Are there any concerns about denormalized inputs? I didn't see any obvious problem in the code pulling aaprt and adding in exponents, but there's nothing obvious in that code to me.

IEEE denormals don't usually require any special handling.

> - The RETURN_MINF_OR_NAN block can generate a wide range of signaling and non-signaling NaNs. I forget how signaling Nans are treated in the Java math mode - are they just treated as quiet NaNs or are they never supposed to appear?

Java doesn't care.  However, it is possible to use DoubleToRawLongBits to
extract some information, and this is fine.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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