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Re: fwprop fix for PR79405
On February 20, 2017 2:58:54 PM GMT+01:00, Bernd Schmidt <bschmidt@redhat.com> wrote:
>On 02/17/2017 10:11 AM, Richard Biener wrote:
>> Index: gcc/fwprop.c
>> ===================================================================
>> --- gcc/fwprop.c (revision 245501)
>> +++ gcc/fwprop.c (working copy)
>> @@ -1478,7 +1478,8 @@ fwprop (void)
>> Do not forward propagate addresses into loops until after
>unrolling.
>> CSE did so because it was able to fix its own mess, but we are
>not. */
>>
>> - for (i = 0; i < DF_USES_TABLE_SIZE (); i++)
>> + unsigned sz = DF_USES_TABLE_SIZE ();
>> + for (i = 0; i < sz; i++)
>> {
>> df_ref use = DF_USES_GET (i);
>> if (use)
>>
>> might work? (not knowing too much about this detail of the DF data
>> structures - can the table shrink?)
>
>This would probably work to fix the bug, but this behaviour is
>explicitly documented as intentional (in the comment the second half of
>
>which you've quoted). I assume it enables additional substitutions.
Hmm, this means the walking-stmts solution sounds more correct and also gets these second-level opportunities.
Richard.
>
>Bernd