Re: [patch, libgfortran] PR48767 Rounding Up followup patch

[Jerry DeLisle]

On 04/30/2011 12:56 AM, Janne Blomqvist wrote:

On Sat, Apr 30, 2011 at 04:33, Jerry DeLisle<jvdeli...@frontier.com>  wrote:

Hi,

The attached patch does some cleanup and a check for trailing zeros to
decide whether or not to round.

I have added the additional test cases posted on the bugzilla to the
existing test case round_3.f08.

Regression tested on x86-64.

OK for trunk and then I will back port the whole enchilada to 4.6.1 in a few
weeks.  Please consider the starting point of the zero scan carefully.  I
have not convinced myself that the d * p covers all cases, but it works for
all cases I have tried.

I'm a bit suspicious about that as well:

+       /* Scan for trailing zeros to see if we really need to round it.  */
+       for(i = 1 +  d * p ; i<  ndigits; i++)
+         {
+           if (digits[i] != '0')
+             goto do_rnd;
+         }
+       goto skip;

I must have been tired yesterday.  Revised chunk.  Regression tests OK.

@@ -233,7 +231,13 @@
        if (sign_bit)
          goto skip;
        rchar = '0';
-       break;
+       /* Scan for trailing zeros to see if we really need to round it.  */
+       for(i = nbefore + nafter; i < ndigits; i++)
+         {
+           if (digits[i] != '0')
+             goto do_rnd;
+         }
+       goto skip;
       case ROUND_DOWN:
        if (!sign_bit)
          goto skip;

OK for trunk?

Jerry