[PATCH] jit: Fix random truncation of testsuite output

[David Malcolm]

On Mon, 2020-07-20 at 12:10 +0100, Alex Coplan wrote:
> Hello,
> 
> This patch fixes a bug in jit.exp which causes the DejaGnu output of
> the
> libgccjit testsuite to be nondeterministically truncated. This bug
> was
> copied from DejaGnu's own implementation of the host_execute
> function.
> See the upstream bug report [0] where the maintainers point out that
> the
> regex patterns in host_execute should (but don't currently)
> explicitly
> match newlines to avoid relying on DejaGnu not reading more than one
> line of the output (which is not guaranteed).
> 
> To reproduce the bug, run:
> 
> $ make check-jit RUNTESTFLAGS="jit.exp=test-arith-overflow.c"
> $ grep -v iteration testsuite/jit/jit.sum
> 
> and you should see some lines that have been truncated (I see the
> word
> iteration partially or fully truncated). Alternatively, simply run
> the
> testsuite twice (saving a copy of testsuite/jit/jit.sum from the
> first
> run) and diff the two jit.sum files to observe the random truncations
> to
> the output.
> 
> This patch should make it easier to test jit patches in the future,
> since it makes it possible to reliably compare the output of two
> jit.sum
> files (as with the other tests in GCC).
> 
> Testing:
>  * Ran the testsuite before and after the patch, observing that the
> only
>    differences in jit.sum were in test-threads.c (nondeterministic
> test)
>    and where the truncated output from the first run was no longer
>    truncated.
>  * Ran the testsuite twice after the patch, observing that the only
>    differences in jit.sum between the two runs were in test-
> threads.c.
> 
> OK for master?
> 
> Thanks,
> Alex
> 
> ---
> 
> 2020-07-20  Alex Coplan  <alex.coplan@arm.com>
> 
> gcc/testsuite/ChangeLog:
> 
> 	* jit.dg/jit.exp (fixed_host_execute): Fix regex patterns to
> 	always explicitly match newlines.
> 
> 
> [0] : https://debbugs.gnu.org/cgi/bugreport.cgi?bug=42399
`
Thanks for chasing this up. This looks a lot like the issues being
tracked in PR jit/69435, so please add that to the ChangeLog when
committing.

OK for master.
Dave