Re: Fix ICE after sorry for big stack arguments (PR 84964)

[Richard Sandiford <richard dot sandiford at linaro dot org>]

Richard Biener <richard.guenther@gmail.com> writes:
> On Wed, Mar 21, 2018 at 9:33 AM, Richard Sandiford
> <richard.sandiford@linaro.org> wrote:
>> Index: gcc/diagnostic.c
>> ===================================================================
>> --- gcc/diagnostic.c    2018-03-01 08:20:43.589534337 +0000
>> +++ gcc/diagnostic.c    2018-03-21 08:31:34.635677798 +0000
>> @@ -1407,6 +1407,20 @@ sorry (const char *gmsgid, ...)
>>    va_end (ap);
>>  }
>>
>> +/* Same, but stop compilation immediately.  */
>> +
>> +void
>> +fatal_sorry (const char *gmsgid, ...)
>> +{
>> +  va_list ap;
>> +  va_start (ap, gmsgid);
>> +  rich_location richloc (line_table, input_location);
>> +  diagnostic_impl (&richloc, -1, gmsgid, &ap, DK_SORRY);
>> +  va_end (ap);
>> +
>> +  exit (FATAL_EXIT_CODE);
>
> This is somewhat not in style of the other "fatal" handlers.  I guess
> you don't get "sorry: " when using DK_FATAL, but ...

I didn't add another DK_* because I don't think we want a different prefix
(unliked "error:" vs. "fatal error:").

>> +}
>> +
>>  /* Return true if an error or a "sorry" has been seen.  Various
>>     processing is disabled after errors.  */
>>  bool
>> Index: gcc/calls.c
>> ===================================================================
>> --- gcc/calls.c 2018-03-17 08:30:20.937100705 +0000
>> +++ gcc/calls.c 2018-03-21 08:31:34.635677798 +0000
>> @@ -4052,13 +4052,10 @@ expand_call (tree exp, rtx target, int i
>>               rtx_insn *before_arg = get_last_insn ();
>>
>>               /* We don't allow passing huge (> 2^30 B) arguments
>> -                by value.  It would cause an overflow later on.  */
>> +                by value.  It would cause an overflow later on.  */
>>               if (constant_lower_bound (adjusted_args_size.constant)
>>                   >= (1 << (HOST_BITS_PER_INT - 2)))
>> -               {
>> -                 sorry ("passing too large argument on stack");
>> -                 continue;
>> -               }
>> +               fatal_sorry ("passing too large argument on stack");
>
> ... why not use fatal_error here?  It doesn't seem to be something
> that is just not implemented but impossible to implement?

It's HOST_BITS_PER_INT rather than _WIDE_INT, so I think we could
implement it if we were tighter with types.  E.g. this PR occurred
because we went from int to HWI for some things, which should have
fixed part of the problem.  There might still be other uses of
"int" that need to change though.

Thanks,
Richard

> So, OK with just using fatal_error here (please add a comment why
> we're not continuing).