[patch, libgfortran] PR53029 missed optimization in internal read (without implied-do-loop)

[Jerry DeLisle]

Hi all,

The problem here is that we never set the err return to LIBERROR_END in all 
cases. For the example case we are detecting the EOF condition inside the 
read_integer procedure and it gets acted on correctly at higher levels in the 
code. Consequently in the big loop over the array where we call 
list_formatted_read_scalar, we never returned an error code so we never exited 
the loop early.

The patch tests for the EOF first locally as before, but then returns the error 
flags set in dtp->common.flags which are set globally in the individual read 
procedures whene hit_eof is called.

Regression tested on x86_64. I have added a test case which will check the 
execution time of the loop. The previous results of the REAd were correct, just 
took a long time on large arrays.

OK for trunk?

Regards,

Jerry

2017-05-28  Jerry DeLisle  <jvdelisle@gcc.gnu.org>

	PR libgfortran/35339
	* list_read.c.c (list_formatted_read_scala): Set the err return
	value to the common.flags error values.
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