Line-truncation bug in host_execute?

[David Malcolm]

I'm the maintainer of the "jit" component within gcc.

We're carrying a patched copy of dejagnu's host_execute,
"fixed_host_execute", for reasons given in:
http://lists.gnu.org/archive/html/dejagnu/2014-10/msg00007.html
though I think we may have drifted further.

I'm running into an issue with the patched copy that I think may also
affect the pristine one:
  https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69435
My tests use dejagnu.h to write "PASSED" etc lines, some of which are
very long.  They're sometimes being truncated by fixed_host_execute when
re-emitted as PASS results, so e.g.

PASSED: test-combination.c.exe iteration 1 of 5: make_calc_discriminant: 
actual: "q->b * q->b - (double)4 * q->a * q->c" == expected: "q->b * q->b - 
(double)4 * q->a * q->c"

is re-emitted as:
PASS:  test-combination.c.exe iteration 1 of 5: make_calc_discriminant: actual: 
"q-

(note the truncation in mid-expression).

The exact point of truncation varies from run to run, leading to churn
when comparing .sum files, so this is a pain.

I'm attaching the patch that I've attached to that gcc bug; does this
fix seem reasonable?  (my Tcl and expect skills aren't great, sorry).

Thanks; hope this is helpful
Dave

0001-Fix-PR-jit-69435-truncated-lines-in-jit.log.patch
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