Re: [PATCH] [PR rtl-optimization/65618] Fix MIPS ADA bootstrap failure

[Jeff Law <law@redhat.com>]

On 12/20/2016 07:38 AM, James Cowgill wrote:
> Hi,
>
> On 19/12/16 21:43, Jeff Law wrote:
>> On 12/19/2016 08:44 AM, James Cowgill wrote:
>>> 2016-12-16  James Cowgill  <James.Cowgill@imgtec.com>
>>>
>>>     PR rtl-optimization/65618
>>>     * emit-rtl.c (try_split): Update "after" when moving a
>>>     NOTE_INSN_CALL_ARG_LOCATION.
>>>
>>> diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
>>> index 7de17454037..6be124ac038 100644
>>> --- a/gcc/emit-rtl.c
>>> +++ b/gcc/emit-rtl.c
>>> @@ -3742,6 +3742,11 @@ try_split (rtx pat, rtx_insn *trial, int last)
>>>             next = NEXT_INSN (next))
>>>          if (NOTE_KIND (next) == NOTE_INSN_CALL_ARG_LOCATION)
>>>            {
>>> +            /* Advance after to the next instruction if it is about to
>>> +               be removed.  */
>>> +            if (after == next)
>>> +              after = NEXT_INSN (after);
>>> +
>>>              remove_insn (next);
>>>              add_insn_after (next, insn, NULL);
>>>              break;
>>>
>> So the thing I don't like when looking at this code is we set AFTER
>> immediately upon entry to try_split.  But we don't use it until near the
>> very end of try_split.  That's just asking for trouble.
>>
>> Can we reasonably initialize AFTER just before it's used?
>
> I wasn't sure but looking closer I think that would be fine. This patch
> also works and does what Richard Sandiford suggested in the PR.
>
> 2016-12-20  James Cowgill  <James.Cowgill@imgtec.com>
>
> 	PR rtl-optimization/65618
> 	* emit-rtl.c (try_split): Move initialization of "before" and
> 	"after" to just before the call to emit_insn_after_setloc.
OK.
jeff