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Re: [PATCH] Fix PR50031, take 2


On Fri, Feb 10, 2012 at 3:39 PM, William J. Schmidt
<wschmidt@linux.vnet.ibm.com> wrote:
> Jakub, thanks! ?Based on this, I believe the patch is correct in its
> handling of the STMT_VINFO_PATTERN_DEF_SEQ logic, without any double
> counting.
>
> I misinterpreted what the commentary for vect_pattern_recog was saying:
> I thought that all replacements were hung off of the last pattern
> statement, but this was just true for the particular example, where only
> one replacement statement was created. ?Sorry for any confusion!
>
> Based on the discussion, is the patch OK for trunk?

But you still count for each of the matched scalar stmts the cost of the
whole pattern sequence.  No?

Richard.

> Thanks,
> Bill
>
> On Fri, 2012-02-10 at 14:44 +0100, Jakub Jelinek wrote:
>> On Fri, Feb 10, 2012 at 07:31:01AM -0600, William J. Schmidt wrote:
>> > >From the commentary at the end of tree-vect-patterns.c, only the main
>> > statement in the pattern (the last one) is flagged as
>> > STMT_VINFO_IN_PATTERN_P. ?So this is finding the new replacement
>> > statement which has been created but not yet inserted in the code. ?It
>> > only gets counted once.
>>
>> STMT_VINFO_IN_PATTERN_P is set on the vinfo of the original stmt (and not
>> just the last, but all original stmts that are being replaced by the
>> pattern). ?Each of these has STMT_VINFO_RELATED_STMT set to a pattern stmt
>> (last one corresponding to that original stmt). ?If needed, further
>> pattern stmts for that original stmts are put into
>> STMT_VINFO_PATTERN_DEF_SEQ. ?The pattern matcher could e.g. match
>> 3 original stmts, and stick a single pattern stmt into STMT_VINFO_RELATED_STMT
>> on the first original stmt, then say 2 pattern stmts into
>> STMT_VINFO_PATTERN_DEF_SEQ of the second original stmt plus one
>> STMT_VINFO_RELATED_STMT and finally one pattern stmt through
>> STMT_VINFO_RELATED_STMT on the third original stmt.
>>
>> > Note that STMT_VINFO_PATTERN_DEF_SEQ doesn't exist in the 4.6 branch, so
>> > this section has to be omitted if we backport it (which is desirable
>> > since the degradation was introduced in 4.6). ?Removing it apparently
>> > does not affect the sphinx3 degradation.
>>
>> Yeah, when backporting you can basically assume that
>> STMT_VINFO_PATTERN_DEF_SEQ is always NULL in 4.6 and just write NULL instead
>> of itt (and simplify), because no pattern recognizers needed more than one
>> pattern stmt for each original stmt back then.
>>
>> ? ? ? Jakub
>>
>


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