On 06/11/2011 12:23 AM, Thomas Henlich wrote:
>> I don't agree with this; with the patch we now output 10 significant
>> digits, whereas 9 is sufficient for a binary->ascii->binary roundtrip.
>> So please retain the "reduce d by one when E editing is used" thing
>> for list format and G0. This is just a side effect of using 1PGw.d
>> format for list format and G0 in order to avoid duplicating code, but
>> we don't need to follow this particular craziness that is due to how
>> the scale factor is specified in the standard.
>
> I hadn't noticed this, but I agree with Janne.
>
> It should be easy to implement:
>
> After the switch between F and E editing, we just need to shift the
> decimal point and decrement the exponent. No new rounding is required,
> because we keep the number of significant digits.
>

OK, after a little bit of experimentation, I have arrived at the updated patch 
attached.

This has been regression tested and passes all test cases I am aware of.  I also 
have included a new test case gcc/testsuite/gfortran.dg/fmt_g.f90.

OK for trunk?

Jerry