Re: [bug-gawk] macOS: mpfrsqrt check fails on gawk-4.2-stable and master branches

[Andrew J. Schorr]

Hi,

On Tue, Feb 06, 2018 at 10:35:42PM +0100, Hermann Peifer wrote:
> Thanks for taking your time to look after the reported issue. Rebuilding
> with --enable-builtin-intdiv0 and patching the test as you suggested
> gives the expected result:
> 
> $ ./gawk -M -f test/mpfrsqrt0.awk
> 11111111111111111111111111111111111111111111111111111111111
> 11111111111111111111111111111111111111111111111111111111111
> 
> $ ./gawk -M -f test/mpfrsqrt1.awk
> 11111111111111111111111111111111111111111111111111111111111
> 11111111111111111111111111111111111111111111111111111111111

Thanks. I expected as much.

> Maybe there is something wrong with the intdiv extension on the MacBook
> and I should better rebuild it. I'll do this tomorrow and let you know.

Any luck with that? If not, I think the next step is to figure out where the
calculation is going wrong. Let's patch mpfrsqrt.awk like so:

diff --git a/test/mpfrsqrt.awk b/test/mpfrsqrt.awk
index 8cc416b..b4b3bda 100644
--- a/test/mpfrsqrt.awk
+++ b/test/mpfrsqrt.awk
@@ -29,9 +29,12 @@ function sq_root(x, temp,r,z)
    z=0
    while (abs(z-temp)>1)
     { z=temp
+      print "Pass #" ++n
       intdiv(x,temp,r)
+      print x "/" temp " = " r["quotient"]
       temp=r["quotient"] + temp
       intdiv(temp,2,r)
+      print temp "/" 2 " = " r["quotient"]
       temp=r["quotient"]
     }
    return temp

On my linux system, I get the attached results from running this command:

bash-4.2$ AWKLIBPATH=extension/.libs ./gawk -M -f test/mpfrsqrt.awk > 
/tmp/mpfrsqrt.log

What happens on MacOS?

Thanks,
Andy

mpfrsqrt.log
Description: Text document