On Mon, May 04, 2026 at 09:49:35AM +0530, Surya Kumari Jangala wrote:
>
> Pinging the patch.
>
> On 19/08/24 9:58 pm, Surya Kumari Jangala wrote:
> > Hi Segher,
> > Pinging the patch. Please let me know if it is ok for trunk.
> >
> > Regards,
> > Surya
> >
> > On 06/05/24 1:54 pm, Surya Kumari Jangala wrote:
> >> Ping
> >>
> >> On 08/01/24 11:19 am, Surya Kumari Jangala wrote:
> >>> Ping
> >>>
> >>> On 28/11/23 6:24 pm, Surya Kumari Jangala wrote:
> >>>> Ping
> >>>>
> >>>> On 10/11/23 12:27 pm, Surya Kumari Jangala wrote:
> >>>>> Ping
> >>>>>
> >>>>> On 03/11/23 1:14 pm, Surya Kumari Jangala wrote:
> >>>>>> Hi Segher,
> >>>>>> I have incorporated changes in the code as per the review comments
> >>>>>> provided by you
> >>>>>> for version 2 of the patch. Please review.
> >>>>>>
> >>>>>> Regards,
> >>>>>> Surya
> >>>>>>
> >>>>>>
> >>>>>> rs6000/p8swap: Fix incorrect lane extraction by vec_extract()
> >>>>>> [PR106770]
> >>>>>>
> >>>>>> In the routine rs6000_analyze_swaps(), special handling of swappable
> >>>>>> instructions is done even if the webs that contain the swappable
> >>>>>> instructions
> >>>>>> are not optimized, i.e., the webs do not contain any permuting
> >>>>>> load/store
> >>>>>> instructions along with the associated register swap instructions.
> >>>>>> Doing special
> >>>>>> handling in such webs will result in the extracted lane being adjusted
> >>>>>> unnecessarily for vec_extract.
> >>>>>>
> >>>>>> Another issue is that existing code treats non-permuting loads/stores
> >>>>>> as special
> >>>>>> swappables. Non-permuting loads/stores (that have not yet been split
> >>>>>> into a
> >>>>>> permuting load/store and a swap) are handled by converting them into a
> >>>>>> permuting
> >>>>>> load/store (which effectively removes the swap). As a result, if
> >>>>>> special
> >>>>>> swappables are handled only in webs containing permuting loads/stores,
> >>>>>> then
> >>>>>> non-optimal code is generated for non-permuting loads/stores.
> >>>>>>
> >>>>>> Hence, in this patch, all webs containing either permuting loads/
> >>>>>> stores or
> >>>>>> non-permuting loads/stores are marked as requiring special handling of
> >>>>>> swappables. Swaps associated with permuting loads/stores are marked
> >>>>>> for removal,
> >>>>>> and non-permuting loads/stores are converted to permuting
> >>>>>> loads/stores. Then the
> >>>>>> special swappables in the webs are fixed up.
> >>>>>>
> >>>>>> This patch also ensures that swappable instructions are not modified
> >>>>>> in the
> >>>>>> following webs as it is incorrect to do so:
> >>>>>> - webs containing permuting load/store instructions and associated
> >>>>>> swap
> >>>>>> instructions that are transformed by converting the permuting memory
> >>>>>> instructions into non-permuting instructions and removing the swap
> >>>>>> instructions.
> >>>>>> - webs where swap(load(vector constant)) instructions are replaced
> >>>>>> with
> >>>>>> load(swapped vector constant).
> >>>>>>
> >>>>>> 2023-09-10 Surya Kumari Jangala <[email protected]>
> >>>>>>
> >>>>>> gcc/
> >>>>>> PR rtl-optimization/PR106770
> >>>>>> * config/rs6000/rs6000-p8swap.cc (non_permuting_mem_insn): New
> >>>>>> function.
> >>>>>> (handle_non_permuting_mem_insn): New function.
> >>>>>> (rs6000_analyze_swaps): Handle swappable instructions only in
> >>>>>> certain
> >>>>>> webs.
> >>>>>> (web_requires_special_handling): New instance variable.
> >>>>>> (handle_special_swappables): Remove handling of non-permuting
> >>>>>> load/store
> >>>>>> instructions.
> >>>>>>
> >>>>>> gcc/testsuite/
> >>>>>> PR rtl-optimization/PR106770
> >>>>>> * gcc.target/powerpc/pr106770.c: New test.
> >>>>>> ---
> >>>>>>
I did notice tht when you remove the case elements in
handle_special_swappables tht if those cases show up nw, it will hit
default, and the gcc_unreachaable call will be generated, which is
reasonable.
Note, the tests are rather tricky, and I believe they will not work
correctly if you configure the compiler to default to power9, power10,
or power11 code.
The test has the guard condition:
/* { dg-require-effective-target powerpc_p8vector_ok } */
/* { dg-options "-mdejagnu-cpu=power8 -O2 " } */
What -mdejagnu-cpu=power8 does is tell the test compiler to use
-mcpu=power8 if the default target is not at the power8 level. If you
configure the compiler to default to power9, power10, or power11, using
-mdejagnu-cpu=power8 will not change the default.
Given that the byte swapping vector instructions were added in power9,
if the default target is power9 or high, the p8swap support is turned
off.
You could change the guard condition to:
/* { dg-require-effective-target powerpc_p8vector_ok } */
/* { dg-options "-mdejagnu-cpu=power8 -O2 " } */
Or add the following line (with an explanation) in the source before
the function in the test:
#pragma GCC target ("cpu=power8")
--
Michael Meissner, IBM
PO Box 98, Ayer, Massachusetts, USA, 01432
email: [email protected]
