[PATCH] LoongArch: Add math-barriers.h

[PATCH] LoongArch: Add math-barriers.h

[Xi Ruoyao]

This patch implements the LoongArch specific math barriers in order to omit
the store and load from stack if possible.

Signed-off-by: Xi Ruoyao <xry111@xry111.site>
---
 sysdeps/loongarch/fpu/math-barriers.h | 28 +++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 sysdeps/loongarch/fpu/math-barriers.h

diff --git a/sysdeps/loongarch/fpu/math-barriers.h b/sysdeps/loongarch/fpu/math-barriers.h
new file mode 100644
index 0000000000..3e977e43a6
--- /dev/null
+++ b/sysdeps/loongarch/fpu/math-barriers.h
@@ -0,0 +1,28 @@
+/* Control when floating-point expressions are evaluated.  LoongArch version.
+   Copyright (C) 2023 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#ifndef _LOONGARCH_MATH_BARRIERS_H
+#define _LOONGARCH_MATH_BARRIERS_H 1
+
+/* Generic code forces values to memory; we don't need to do that.  */
+#define math_opt_barrier(x)					\
+  ({ __typeof (x) __x = (x); __asm ("" : "+frm" (__x)); __x; })
+#define math_force_eval(x)						\
+  ({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "frm" (__x)); })
+
+#endif /* math-barriers.h */
-- 
2.37.0

Re: [PATCH] LoongArch: Add math-barriers.h

[Adhemerval Zanella Netto]

On 14/02/23 05:57, Xi Ruoyao via Libc-alpha wrote:
> This patch implements the LoongArch specific math barriers in order to omit
> the store and load from stack if possible.

LGTM, I have not see any regression with qemu.  As a side note, math/test-fenv
shows a failure so you might take a look, you might need to update ULPs as well.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> 
> Signed-off-by: Xi Ruoyao <xry111@xry111.site>

We do not use signed-off-by, so no need to add it.

> ---
>  sysdeps/loongarch/fpu/math-barriers.h | 28 +++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>  create mode 100644 sysdeps/loongarch/fpu/math-barriers.h
> 
> diff --git a/sysdeps/loongarch/fpu/math-barriers.h b/sysdeps/loongarch/fpu/math-barriers.h
> new file mode 100644
> index 0000000000..3e977e43a6
> --- /dev/null
> +++ b/sysdeps/loongarch/fpu/math-barriers.h
> @@ -0,0 +1,28 @@
> +/* Control when floating-point expressions are evaluated.  LoongArch version.
> +   Copyright (C) 2023 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#ifndef _LOONGARCH_MATH_BARRIERS_H
> +#define _LOONGARCH_MATH_BARRIERS_H 1
> +
> +/* Generic code forces values to memory; we don't need to do that.  */
> +#define math_opt_barrier(x)					\
> +  ({ __typeof (x) __x = (x); __asm ("" : "+frm" (__x)); __x; })
> +#define math_force_eval(x)						\
> +  ({ __typeof (x) __x = (x); __asm __volatile__ ("" : : "frm" (__x)); })
> +
> +#endif /* math-barriers.h */

Re: [PATCH] LoongArch: Add math-barriers.h

[Xi Ruoyao]

On Wed, 2023-02-15 at 10:47 -0300, Adhemerval Zanella Netto wrote:
> On 14/02/23 05:57, Xi Ruoyao via Libc-alpha wrote:
> > This patch implements the LoongArch specific math barriers in order to omit
> > the store and load from stack if possible.
> 
> LGTM, I have not see any regression with qemu.  As a side note, math/test-fenv
> shows a failure so you might take a look, you might need to update ULPs as well.

Hmm, on a real hardware I saw no failures even with GCC 13 trunk (some
aggressive FVRP optimization has been added into GCC 13). But maybe
things have been changed since my last test.  I'll test again.

> Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH] LoongArch: Add math-barriers.h

[Adhemerval Zanella Netto]

On 15/02/23 11:22, Xi Ruoyao wrote:
> On Wed, 2023-02-15 at 10:47 -0300, Adhemerval Zanella Netto wrote:
>> On 14/02/23 05:57, Xi Ruoyao via Libc-alpha wrote:
>>> This patch implements the LoongArch specific math barriers in order to omit
>>> the store and load from stack if possible.
>>
>> LGTM, I have not see any regression with qemu.  As a side note, math/test-fenv
>> shows a failure so you might take a look, you might need to update ULPs as well.
> 
> Hmm, on a real hardware I saw no failures even with GCC 13 trunk (some
> aggressive FVRP optimization has been added into GCC 13). But maybe
> things have been changed since my last test.  I'll test again.

I meant that I saw math/test-fenv failures with and without the patch
and I the master qemu (f670b3eec7f5d1ed8c4573ef244e7b8c6b32001b).

> 
>> Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
> 

Re: [PATCH] LoongArch: Add math-barriers.h

[Xi Ruoyao]

On Wed, 2023-02-15 at 11:25 -0300, Adhemerval Zanella Netto wrote:
> 
> I meant that I saw math/test-fenv failures with and without the patch
> and I the master qemu (f670b3eec7f5d1ed8c4573ef244e7b8c6b32001b).

Hi Adhemerval,

Which GCC version did you used?  I'll try with the same GCC version on
the hardware. If it still fails I'll consider it a QEMU issue and report
to QEMU maintainers.

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH] LoongArch: Add math-barriers.h

[Adhemerval Zanella Netto]

On 16/02/23 10:02, Xi Ruoyao wrote:
> On Wed, 2023-02-15 at 11:25 -0300, Adhemerval Zanella Netto wrote:
>>
>> I meant that I saw math/test-fenv failures with and without the patch
>> and I the master qemu (f670b3eec7f5d1ed8c4573ef244e7b8c6b32001b).
> 
> Hi Adhemerval,
> 
> Which GCC version did you used?  I'll try with the same GCC version on
> the hardware. If it still fails I'll consider it a QEMU issue and report
> to QEMU maintainers.
> 

This is the one I used:

gcc version 12.1.1 20220719 [releases/gcc-12 r12-8552-g65941a91091] (GCC)

Re: [PATCH] LoongArch: Add math-barriers.h

[Xi Ruoyao]

On Thu, 2023-02-16 at 10:43 -0300, Adhemerval Zanella Netto wrote:
> 
> 
> On 16/02/23 10:02, Xi Ruoyao wrote:
> > On Wed, 2023-02-15 at 11:25 -0300, Adhemerval Zanella Netto wrote:
> > > 
> > > I meant that I saw math/test-fenv failures with and without the
> > > patch
> > > and I the master qemu (f670b3eec7f5d1ed8c4573ef244e7b8c6b32001b).
> > 
> > Hi Adhemerval,
> > 
> > Which GCC version did you used?  I'll try with the same GCC version
> > on
> > the hardware. If it still fails I'll consider it a QEMU issue and
> > report
> > to QEMU maintainers.
> > 
> 
> This is the one I used:
> 
> gcc version 12.1.1 20220719 [releases/gcc-12 r12-8552-g65941a91091]
> (GCC)

On a hardware (3A5000-7A2000-EVB) the test passes with the same GCC.  My
first guess would be a QEMU issue.  There could be a difference in
Binutils version but I don't think a Binutils difference can cause fenv
failure...

BTW could you (or Yinyu) push the patch?  I don't have a write access of
glibc.git (yet).

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University

Re: [PATCH] LoongArch: Add math-barriers.h

[Adhemerval Zanella Netto]

On 27/02/23 07:45, Xi Ruoyao wrote:
> On Thu, 2023-02-16 at 10:43 -0300, Adhemerval Zanella Netto wrote:
>>
>>
>> On 16/02/23 10:02, Xi Ruoyao wrote:
>>> On Wed, 2023-02-15 at 11:25 -0300, Adhemerval Zanella Netto wrote:
>>>>
>>>> I meant that I saw math/test-fenv failures with and without the
>>>> patch
>>>> and I the master qemu (f670b3eec7f5d1ed8c4573ef244e7b8c6b32001b).
>>>
>>> Hi Adhemerval,
>>>
>>> Which GCC version did you used?  I'll try with the same GCC version
>>> on
>>> the hardware. If it still fails I'll consider it a QEMU issue and
>>> report
>>> to QEMU maintainers.
>>>
>>
>> This is the one I used:
>>
>> gcc version 12.1.1 20220719 [releases/gcc-12 r12-8552-g65941a91091]
>> (GCC)
> 
> On a hardware (3A5000-7A2000-EVB) the test passes with the same GCC.  My
> first guess would be a QEMU issue.  There could be a difference in
> Binutils version but I don't think a Binutils difference can cause fenv
> failure...
> 

That is my guess as well it is qemu issue.

> BTW could you (or Yinyu) push the patch?  I don't have a write access of
> glibc.git (yet).
> 

Done.

Re: [PATCH] LoongArch: Add math-barriers.h

[WANG Xuerui]

On 2/27/23 19:23, Adhemerval Zanella Netto wrote:
>
> On 27/02/23 07:45, Xi Ruoyao wrote:
>> On Thu, 2023-02-16 at 10:43 -0300, Adhemerval Zanella Netto wrote:
>>>
>>> On 16/02/23 10:02, Xi Ruoyao wrote:
>>>> On Wed, 2023-02-15 at 11:25 -0300, Adhemerval Zanella Netto wrote:
>>>>> I meant that I saw math/test-fenv failures with and without the
>>>>> patch
>>>>> and I the master qemu (f670b3eec7f5d1ed8c4573ef244e7b8c6b32001b).
>>>> Hi Adhemerval,
>>>>
>>>> Which GCC version did you used?  I'll try with the same GCC version
>>>> on
>>>> the hardware. If it still fails I'll consider it a QEMU issue and
>>>> report
>>>> to QEMU maintainers.
>>>>
>>> This is the one I used:
>>>
>>> gcc version 12.1.1 20220719 [releases/gcc-12 r12-8552-g65941a91091]
>>> (GCC)
>> On a hardware (3A5000-7A2000-EVB) the test passes with the same GCC.  My
>> first guess would be a QEMU issue.  There could be a difference in
>> Binutils version but I don't think a Binutils difference can cause fenv
>> failure...
>>
> That is my guess as well it is qemu issue.
Interesting, I'll help check the qemu side this week.