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Re: [PATCH, rs6000] power8 patches, patch #4 (revised), new power8 builtins
- From: David Edelsohn <dje dot gcc at gmail dot com>
- To: Michael Meissner <meissner at linux dot vnet dot ibm dot com>, GCC Patches <gcc-patches at gcc dot gnu dot org>, Pat Haugen <pthaugen at us dot ibm dot com>, Peter Bergner <bergner at vnet dot ibm dot com>
- Date: Thu, 6 Jun 2013 11:57:01 -0400
- Subject: Re: [PATCH, rs6000] power8 patches, patch #4 (revised), new power8 builtins
- References: <20130520204053 dot GA21090 at ibm-tiger dot the-meissners dot org> <20130521234717 dot GA27879 at ibm-tiger dot the-meissners dot org> <20130604184853 dot GA12768 at ibm-tiger dot the-meissners dot org> <CAGWvnyni0U+749Y-_aS1mB9vMQ1pKHhiikGhxJmV26KVP2Rbtw at mail dot gmail dot com> <20130605161332 dot GB5774 at ibm-tiger dot the-meissners dot org>
On Wed, Jun 5, 2013 at 12:13 PM, Michael Meissner
<meissner@linux.vnet.ibm.com> wrote:
> On Wed, Jun 05, 2013 at 10:28:02AM -0400, David Edelsohn wrote:
>> +;; The canonical form is to have the negated elment first, so we need to
>> +;; reverse arguments.
>>
>> Please fix the typo in the comment: "element".
>
> Ok. I need to proof-read the patches before sending them out.
>
>> +;; Like VSX_L, but don't support TImode for doing logical instructions in
>> +;; 32-bit
>> +(define_mode_iterator VSX_L2 [V16QI V8HI V4SI V2DI V4SF V2DF])
>> +
>> ;; Iterator for memory move. Handle TImode specially to allow
>> ;; it to use gprs as well as vsx registers.
>> (define_mode_iterator VSX_M [V16QI V8HI V4SI V2DI V4SF V2DF])
>>
>> +(define_mode_iterator VSX_M2 [V16QI
>> + V8HI
>> + V4SI
>> + V2DI
>> + V4SF
>> + V2DF
>> + (TI "TARGET_VSX_TIMODE")])
>>
>> The patch adds new iterators VSX_L2 and VSX_M2. The original
>> ChangeLog only mentioned M2 and the new ChangeLog only mentions L2.
>> What's going on?
>
> I thought I had deleted VSX_M2 from this patch. It will be needed in patch #8
> for the fusion peephole. The difference is VSX_L2 avoids TImode altogether,
> and was used by the logical ops to prevent TImode operations in VSX registers
> in 32-bit.
>
> The problem is unless we have expanders/splitters for logical DImode, the
> compiler when it wants to do a logical DImode operation says, aha I have a
> TImode operation, and then it converts the DImode value to TImode, does the
> operation (which in turn may mean transfer between GPR and VSX registers).
>
> I can add splitters and such for 32-bit DImode to prevent this, but I don't
> know if you want me to do it in the context of this patch, or do it as a later
> patch.
Okay, the revised patch #4 is okay with the typos fixed and either the
ChangeLog or the patch adjusted for iterators VSX_L2 and VSX_M2 -- the
ChangeLog and patch need to match.
But I view this as a preliminary step. The logical instructions need
an iterator and TImode needs to be cleaned up on 32 bit.
Thanks, David