| Message ID | CAKdteOaH_jcrZK_DVBKMH8dPxwqjKToa+dKGUx1ddp5nSX1brQ@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Apr 11, 2017 at 5:26 PM, Christophe Lyon <christophe.lyon@linaro.org> wrote: > 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 > That's actually bad because we've now introduced additional moves between the integer and FP register files. It could be something in the backend but this is worth investigating further Ramana > > Christophe
--- 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