[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<jvdelisle@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