Re: One more path to fix PR70478

[Christophe Lyon <christophe dot lyon at linaro dot org>]

On 11 April 2017 at 17:42, Vladimir Makarov <vmakarov@redhat.com> wrote:
>
>
> On 04/11/2017 03:30 AM, Christophe Lyon wrote:
>>
>> Hi Vladimir,
>>
>> On 10 April 2017 at 17:05, Vladimir Makarov <vmakarov@redhat.com> wrote:
>>>
>>>    This is the second try to fix
>>>
>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70478
>>>
>>>    The first try patch triggered a latent bug and broke one Fortran
>>> testcase
>>> on x86-64.
>>>
>>>    The patch was successfully bootstrapped on x86-64 and tested on
>>> x86-64,
>>> ppc64, and aarch64.
>>>
>>>    Committed as rev. 246808.
>>>
>>>
>> I would have to re--run the build/test manually to get the generated
>> code, let me know if it's needed.
>
> Yes, Christophe.  It would be helpful.  I've tried to reproduce it but I
> don't see the difference in the generated code.
>

Here is what I observed (the "with-patch file is with your commit r246808,
the other is r246807)

--- armv8_2-fp16-move-1.s       2017-04-11 16:23:46.795264234 +0000
+++ armv8_2-fp16-move-1.s.with-patch    2017-04-11 15:54:52.563210963 +0000
@@ -37,8 +37,8 @@
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        lsl     r1, r1, #1
-       add     r3, r0, r1
-       vld1.16 {d0[0]}, [r3]
+       ldrh    r3, [r0, r1]    @ __fp16
+       vmov.f16        s0, r3  @ __fp16
        bx      lr
        .size   test_load_2, .-test_load_2
        .align  2
@@ -64,9 +64,9 @@
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
+       vmov.f16        r3, s0  @ __fp16
        lsl     r1, r1, #1
-       add     r3, r0, r1
-       vst1.16 {d0[0]}, [r3]
+       strh    r3, [r0, r1]    @ __fp16
        bx      lr
        .size   test_store_2, .-test_store_2
        .align  2


Christophe