Re: PATCH: PR target/59605: Create jump_around_label only if it doesn't exist

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Thu, Jan 30, 2014 at 10:43 AM, Richard Sandiford
<rdsandiford@googlemail.com> wrote:
> Hi H.J.,
>
> "H.J. Lu" <hjl.tools@gmail.com> writes:
>> diff --git a/gcc/testsuite/gcc.dg/pr59605.c b/gcc/testsuite/gcc.dg/pr59605.c
>> new file mode 100644
>> index 0000000..4556843
>> --- /dev/null
>> +++ b/gcc/testsuite/gcc.dg/pr59605.c
>> @@ -0,0 +1,55 @@
>> +/* { dg-do run } */
>> +/* { dg-options "-O2" } */
>> +/* { dg-additional-options "-minline-stringops-dynamically" { target { i?86-*-* x86_64-*-* } } } */
>> +
>> +extern void abort (void);
>> +
>> +#define MAX_OFFSET (sizeof (long long))
>> +#define MAX_COPY (1024 + 8192)
>> +#define MAX_EXTRA (sizeof (long long))
>> +
>> +#define MAX_LENGTH (MAX_OFFSET + MAX_COPY + MAX_EXTRA)
>> +
>> +static union {
>> +  char buf[MAX_LENGTH];
>> +  long long align_int;
>> +  long double align_fp;
>> +} u;
>> +
>> +char A[MAX_LENGTH];
>> +
>> +int
>> +main ()
>> +{
>> +  int off, len, i;
>> +  char *p, *q;
>> +
>> +  for (i = 0; i < MAX_LENGTH; i++)
>> +    A[i] = 'A';
>> +
>> +  for (off = 0; off < MAX_OFFSET; off++)
>> +    for (len = 1; len < MAX_COPY; len++)
>> +      {
>> +     for (i = 0; i < MAX_LENGTH; i++)
>> +       u.buf[i] = 'a';
>> +
>> +     p = __builtin_memcpy (u.buf + off, A, len);
>> +     if (p != u.buf + off)
>> +       abort ();
>> +
>> +     q = u.buf;
>> +     for (i = 0; i < off; i++, q++)
>> +       if (*q != 'a')
>> +         abort ();
>> +
>> +     for (i = 0; i < len; i++, q++)
>> +       if (*q != 'A')
>> +         abort ();
>> +
>> +     for (i = 0; i < MAX_EXTRA; i++, q++)
>> +       if (*q != 'a')
>> +         abort ();
>> +      }
>> +
>> +  return 0;
>> +}
>
> The innermost loop bodies are executed over 6x10â times on most targets
> and so the test times out for me when using the GDB MIPS simulator.
> I'm not sure what the best fix is though.  E.g.:
>
> 1. It looks like the PR was for a compile-time failure rather than a run-time
>    failure, so one option might be to drop it to dg-do compile.  That'd lose
>    a nice executable conformance test though.  I don't like this option.
>
> 2. We could drop it to dg-do compile for simulator targets only.  That's still
>    lose some conformance testing for simulator targets.
>
> 3. We could use a smaller MAX_COPY for simulator targets, which is typically
>    how check_effective_target_simulator is used.  I'm not sure whether having
>    a smaller MAX_COPY would defeat the original ICE test though.
>
> 4. We could split the test into two, a dg-do compile one and a dg-do run one.
>    We could then do (3) on the run one.
>
> But there are probably other alternatives too.
>
> I'm willing to do the patch, but has anyone got any suggestions for
> what would be best?
>

Can you reduce the loop count and still trigger the bug without
the fix?

-- 
H.J.