On 21/03/18 09:07, Christophe Lyon wrote:
On 20 March 2018 at 18:11, Kyrill  Tkachov <kyrylo.tkac...@foss.arm.com> wrote:
Hi all,

This PR shows that we get the load/store_lanes logic wrong for arm
big-endian.
It is tricky to get right. Aarch64 does it by adding the appropriate
lane-swapping
operations during expansion.

I'd like to do the same on arm eventually, but we'd need to port and
validate the VTBL-generating
code and add it to all the right places and I'm not comfortable enough doing
it for GCC 8, but I am keen
in getting the wrong-code fixed.
As I say in the PR, vectorisation on armeb is already severely restricted
(we disable many patterns on BYTES_BIG_ENDIAN)
and the load/store_lanes patterns really were not working properly at all,
so disabling them is not
a radical approach.

The way to do that is to return false in ARRAY_MODE_SUPPORTED_P for
BYTES_BIG_ENDIAN.

Bootstrapped and tested on arm-none-linux-gnueabihf.
Also tested on armeb-none-eabi.

Committing to trunk.
Thanks,
Kyrill

2018-03-20  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

     PR target/82518
     * config/arm/arm.c (arm_array_mode_supported_p): Return false for
     BYTES_BIG_ENDIAN.

2018-03-20  Kyrylo Tkachov  <kyrylo.tkac...@arm.com>

     PR target/82518
     * lib/target-supports.exp (check_effective_target_vect_load_lanes):
     Disable for armeb targets.
     * gcc.target/arm/pr82518.c: New test.
Hi Kyrill,

I think you need:
Index: pr82518.c
===================================================================
--- pr82518.c   (revision 258705)
+++ pr82518.c   (working copy)
@@ -1,5 +1,5 @@
  /* { dg-do run } */
-/* { dg-require-effective-target arm_neon_ok } */
+/* { dg-require-effective-target arm_neon_hw } */
  /* { dg-additional-options "-O3 -fno-inline -std=gnu99" } */
  /* { dg-add-options arm_neon } */

(The test fails to run for me when using qemu --cpu arm926)

OK?

Yes, you're right. Thanks Christophe.

Kyrill

Christophe

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