[8u] RFR 8130150: Implement BigInteger.montgomeryMultiply intrinsic

Andrew Haley aph at redhat.com
Wed Feb 17 18:33:22 UTC 2016

On 02/17/2016 06:19 PM, Vladimir Kempik wrote:
> I have replaced sub, MACC and MACC2 by c++ version (also changed MACC 
> from defines to inline functions, so changed call to MACC and t0,t1,t2 
> passed by reference) and getting same result, except linux amd64 is 
> failing same way now. So it's probably not asm code that's an issue.


> I think my C code works because another test we use to measure speed
> of BigInteger operations still has 3x improvement in time and it
> supposed to check the result.

It's extremely hard to write this stuff in portable C.  I can't tell
for sure if your code is correct.  It looks reasonable enough.

> http://cr.openjdk.java.net/~vkempik/8130150/asmInC.txt
> Could it be alloca failing?

Seems very unlikley.

What would be really helpful would be if you could capture what was
passed to montgomeryMultiply when the test case fails.

You can perhaps print out all arguments as a string of hex digits
inside montgomeryMultiply. Then we can debug it.

The real error might be much higher up, though: perhaps some problem
with the way the builtin is expanded.

> btw, Andrew, in sub asm inline, you modify CF (with clc) but didnt use 
> "cc" at end of asm to notify compiler about it, not sure if that needed tho.

I already said that in an earlier message.  Needs to clobber "cc".


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