Re: [PATCH, rs6000] power8 patches, patch #4 (revised), new power8 builtins

[David Edelsohn <dje.gcc@gmail.com>]

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