[PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[Michael Meissner]

From 327273dfeec5c000f3c33ca7b88ee0097fd33586 Mon Sep 17 00:00:00 2001
From: Michael Meissner <meissner@linux.ibm.com>
Date: Wed, 25 Aug 2021 00:31:35 -0400
Subject: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

I built a compiler on a little endian power8 system where the default long
double was IEEE 128-bit instead of IBM 128-bit.  I discovered that on
power8, we would generate a lxvd2x and xxpermdi to deal with the endianess
instead of the Altivec lxv.

In addition, I noticed the constant that was being loaded (1.0q) could be
loaded by the lxvkq instruction.

I rewrote the test to handle all forms of vector load and store that can
be generated.  And I changed the constant to be one that lxvkq does not
support.

I did bootstrap tests on the following systems, and the the test ran in all
environments (each of the systems were configured for the cpu mentioned):

   1)	Little endian power9  with IBM  128-bit long double
   2)	Little endian power9  with IEEE 128-bit long double
   3)	Little endian power8  with IBM  128-bit long double
   4)	Little endian power8  with IEEE 128-bit long double
   5)	Little endian power10 with IBM  128-bit long double
   6)	Little endian power10 with IEEE 128-bit long double
   7)	Big endian    power8  with IBM  128-bit long double

Can I check this patch into the master branch and later backport it to GCC-11?

2021-08-25  Michael Meissner  <meissner@linux.ibm.com>

gcc/testsuite/
	* gcc.target/powerpc/float128-call.c: Fix test for IEEE 128-bit
	long double and power10.
---
 .../gcc.target/powerpc/float128-call.c        | 27 +++++++++++++------
 1 file changed, 19 insertions(+), 8 deletions(-)

diff --git a/gcc/testsuite/gcc.target/powerpc/float128-call.c b/gcc/testsuite/gcc.target/powerpc/float128-call.c
index b64ffc68bfa..d1cf47e4298 100644
--- a/gcc/testsuite/gcc.target/powerpc/float128-call.c
+++ b/gcc/testsuite/gcc.target/powerpc/float128-call.c
@@ -6,22 +6,33 @@
 #error "-mfloat128 is not supported."
 #endif
 
+/* Pick a constant to load that cannot be generated by the power10 lxvkq
+   instruction.  */
 #ifdef __LONG_DOUBLE_IEEE128__
 #define TYPE long double
-#define ONE  1.0L
+#define TEN  10.0L
 
 #else
 #define TYPE __float128
-#define ONE  1.0Q
+#define TEN  10.0Q
 #endif
 
 /* Test to make sure vector registers are used for passing IEEE 128-bit
    floating point values and returning them. Also make sure the 'q' suffix is
-   handled.  */
-TYPE one (void) { return ONE; }
+   handled for __float128.  */
+TYPE one (void) { return TEN; }
 void store (TYPE a, TYPE *p) { *p = a; }
 
-/* { dg-final { scan-assembler {\mlxvd2x 34\M} {target be} } } */
-/* { dg-final { scan-assembler {\mstxvd2x 34\M} {target be} } } */
-/* { dg-final { scan-assembler {\mlvx 2\M} {target le} } }  */
-/* { dg-final { scan-assembler {\mstvx 2\M} {target le} } } */
+/* This regexp captures the different vector load/stores that can be generated:
+
+	lxvd2x	-- big endian power7/power8, little endian power8
+	lvx	-- Altivec
+	lxv	-- power9
+	plxv	-- power10
+	lxvx	-- X-form variant.
+	stxvd2x	-- big endian power7/power8, little endian power8
+	stvx	-- Altivec
+	lxvx	-- power9/power10.  */
+
+/* { dg-final { scan-assembler {\mlxvd2x 34\M|\mlvx 2\M|\mp?lxvx? 34\M} } } */
+/* { dg-final { scan-assembler {\mstxvd2x 34\M|\mstvx 2\M|\mstxvx 34\M} } } */
-- 
2.31.1


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[Bill Schmidt]

Hi Mike,

Thanks for this clean-up!

On 8/25/21 5:09 PM, Michael Meissner wrote:
>  From 327273dfeec5c000f3c33ca7b88ee0097fd33586 Mon Sep 17 00:00:00 2001
> From: Michael Meissner <meissner@linux.ibm.com>
> Date: Wed, 25 Aug 2021 00:31:35 -0400
> Subject: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.
>
> I built a compiler on a little endian power8 system where the default long
> double was IEEE 128-bit instead of IBM 128-bit.  I discovered that on
> power8, we would generate a lxvd2x and xxpermdi to deal with the endianess
> instead of the Altivec lxv.
>
> In addition, I noticed the constant that was being loaded (1.0q) could be
> loaded by the lxvkq instruction.
>
> I rewrote the test to handle all forms of vector load and store that can
> be generated.  And I changed the constant to be one that lxvkq does not
> support.
>
> I did bootstrap tests on the following systems, and the the test ran in all
> environments (each of the systems were configured for the cpu mentioned):
>
>     1)	Little endian power9  with IBM  128-bit long double
>     2)	Little endian power9  with IEEE 128-bit long double
>     3)	Little endian power8  with IBM  128-bit long double
>     4)	Little endian power8  with IEEE 128-bit long double
>     5)	Little endian power10 with IBM  128-bit long double
>     6)	Little endian power10 with IEEE 128-bit long double
>     7)	Big endian    power8  with IBM  128-bit long double
>
> Can I check this patch into the master branch and later backport it to GCC-11?
>
> 2021-08-25  Michael Meissner  <meissner@linux.ibm.com>
>
> gcc/testsuite/
> 	* gcc.target/powerpc/float128-call.c: Fix test for IEEE 128-bit
> 	long double and power10.
> ---
>   .../gcc.target/powerpc/float128-call.c        | 27 +++++++++++++------
>   1 file changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-call.c b/gcc/testsuite/gcc.target/powerpc/float128-call.c
> index b64ffc68bfa..d1cf47e4298 100644
> --- a/gcc/testsuite/gcc.target/powerpc/float128-call.c
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-call.c
> @@ -6,22 +6,33 @@
>   #error "-mfloat128 is not supported."
>   #endif
>   
> +/* Pick a constant to load that cannot be generated by the power10 lxvkq
> +   instruction.  */
>   #ifdef __LONG_DOUBLE_IEEE128__
>   #define TYPE long double
> -#define ONE  1.0L
> +#define TEN  10.0L
>   
>   #else
>   #define TYPE __float128
> -#define ONE  1.0Q
> +#define TEN  10.0Q
>   #endif
>   
>   /* Test to make sure vector registers are used for passing IEEE 128-bit
>      floating point values and returning them. Also make sure the 'q' suffix is
> -   handled.  */
> -TYPE one (void) { return ONE; }
> +   handled for __float128.  */
> +TYPE one (void) { return TEN; }

This amuses me, and I want to keep it this way. :-)
>   void store (TYPE a, TYPE *p) { *p = a; }
>   
> -/* { dg-final { scan-assembler {\mlxvd2x 34\M} {target be} } } */
> -/* { dg-final { scan-assembler {\mstxvd2x 34\M} {target be} } } */
> -/* { dg-final { scan-assembler {\mlvx 2\M} {target le} } }  */
> -/* { dg-final { scan-assembler {\mstvx 2\M} {target le} } } */
> +/* This regexp captures the different vector load/stores that can be generated:
> +
> +	lxvd2x	-- big endian power7/power8, little endian power8
> +	lvx	-- Altivec
> +	lxv	-- power9
> +	plxv	-- power10
> +	lxvx	-- X-form variant.
> +	stxvd2x	-- big endian power7/power8, little endian power8
> +	stvx	-- Altivec

For symmetry, also mention stxvx as an X-form variant?

Looks fine to me, recommend approval.

Thanks,
Bill

> +	lxvx	-- power9/power10.  */
> +
> +/* { dg-final { scan-assembler {\mlxvd2x 34\M|\mlvx 2\M|\mp?lxvx? 34\M} } } */
> +/* { dg-final { scan-assembler {\mstxvd2x 34\M|\mstvx 2\M|\mstxvx 34\M} } } */

Re: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[David Edelsohn]

This patch is okay.

Thanks, David

On Fri, Aug 27, 2021 at 12:41 PM Bill Schmidt <wschmidt@linux.ibm.com> wrote:
>
> Hi Mike,
>
> Thanks for this clean-up!
>
> On 8/25/21 5:09 PM, Michael Meissner wrote:
> >  From 327273dfeec5c000f3c33ca7b88ee0097fd33586 Mon Sep 17 00:00:00 2001
> > From: Michael Meissner <meissner@linux.ibm.com>
> > Date: Wed, 25 Aug 2021 00:31:35 -0400
> > Subject: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.
> >
> > I built a compiler on a little endian power8 system where the default long
> > double was IEEE 128-bit instead of IBM 128-bit.  I discovered that on
> > power8, we would generate a lxvd2x and xxpermdi to deal with the endianess
> > instead of the Altivec lxv.
> >
> > In addition, I noticed the constant that was being loaded (1.0q) could be
> > loaded by the lxvkq instruction.
> >
> > I rewrote the test to handle all forms of vector load and store that can
> > be generated.  And I changed the constant to be one that lxvkq does not
> > support.
> >
> > I did bootstrap tests on the following systems, and the the test ran in all
> > environments (each of the systems were configured for the cpu mentioned):
> >
> >     1)        Little endian power9  with IBM  128-bit long double
> >     2)        Little endian power9  with IEEE 128-bit long double
> >     3)        Little endian power8  with IBM  128-bit long double
> >     4)        Little endian power8  with IEEE 128-bit long double
> >     5)        Little endian power10 with IBM  128-bit long double
> >     6)        Little endian power10 with IEEE 128-bit long double
> >     7)        Big endian    power8  with IBM  128-bit long double
> >
> > Can I check this patch into the master branch and later backport it to GCC-11?
> >
> > 2021-08-25  Michael Meissner  <meissner@linux.ibm.com>
> >
> > gcc/testsuite/
> >       * gcc.target/powerpc/float128-call.c: Fix test for IEEE 128-bit
> >       long double and power10.
> > ---
> >   .../gcc.target/powerpc/float128-call.c        | 27 +++++++++++++------
> >   1 file changed, 19 insertions(+), 8 deletions(-)
> >
> > diff --git a/gcc/testsuite/gcc.target/powerpc/float128-call.c b/gcc/testsuite/gcc.target/powerpc/float128-call.c
> > index b64ffc68bfa..d1cf47e4298 100644
> > --- a/gcc/testsuite/gcc.target/powerpc/float128-call.c
> > +++ b/gcc/testsuite/gcc.target/powerpc/float128-call.c
> > @@ -6,22 +6,33 @@
> >   #error "-mfloat128 is not supported."
> >   #endif
> >
> > +/* Pick a constant to load that cannot be generated by the power10 lxvkq
> > +   instruction.  */
> >   #ifdef __LONG_DOUBLE_IEEE128__
> >   #define TYPE long double
> > -#define ONE  1.0L
> > +#define TEN  10.0L
> >
> >   #else
> >   #define TYPE __float128
> > -#define ONE  1.0Q
> > +#define TEN  10.0Q
> >   #endif
> >
> >   /* Test to make sure vector registers are used for passing IEEE 128-bit
> >      floating point values and returning them. Also make sure the 'q' suffix is
> > -   handled.  */
> > -TYPE one (void) { return ONE; }
> > +   handled for __float128.  */
> > +TYPE one (void) { return TEN; }
>
> This amuses me, and I want to keep it this way. :-)
> >   void store (TYPE a, TYPE *p) { *p = a; }
> >
> > -/* { dg-final { scan-assembler {\mlxvd2x 34\M} {target be} } } */
> > -/* { dg-final { scan-assembler {\mstxvd2x 34\M} {target be} } } */
> > -/* { dg-final { scan-assembler {\mlvx 2\M} {target le} } }  */
> > -/* { dg-final { scan-assembler {\mstvx 2\M} {target le} } } */
> > +/* This regexp captures the different vector load/stores that can be generated:
> > +
> > +     lxvd2x  -- big endian power7/power8, little endian power8
> > +     lvx     -- Altivec
> > +     lxv     -- power9
> > +     plxv    -- power10
> > +     lxvx    -- X-form variant.
> > +     stxvd2x -- big endian power7/power8, little endian power8
> > +     stvx    -- Altivec
>
> For symmetry, also mention stxvx as an X-form variant?
>
> Looks fine to me, recommend approval.
>
> Thanks,
> Bill
>
> > +     lxvx    -- power9/power10.  */
> > +
> > +/* { dg-final { scan-assembler {\mlxvd2x 34\M|\mlvx 2\M|\mp?lxvx? 34\M} } } */
> > +/* { dg-final { scan-assembler {\mstxvd2x 34\M|\mstvx 2\M|\mstxvx 34\M} } } */

Re: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[Michael Meissner]

On Fri, Aug 27, 2021 at 11:41:06AM -0500, Bill Schmidt wrote:
> This amuses me, and I want to keep it this way. :-)
> >   void store (TYPE a, TYPE *p) { *p = a; }
> > -/* { dg-final { scan-assembler {\mlxvd2x 34\M} {target be} } } */
> > -/* { dg-final { scan-assembler {\mstxvd2x 34\M} {target be} } } */
> > -/* { dg-final { scan-assembler {\mlvx 2\M} {target le} } }  */
> > -/* { dg-final { scan-assembler {\mstvx 2\M} {target le} } } */
> > +/* This regexp captures the different vector load/stores that can be generated:
> > +
> > +	lxvd2x	-- big endian power7/power8, little endian power8
> > +	lvx	-- Altivec
> > +	lxv	-- power9
> > +	plxv	-- power10
> > +	lxvx	-- X-form variant.
> > +	stxvd2x	-- big endian power7/power8, little endian power8
> > +	stvx	-- Altivec
> 
> For symmetry, also mention stxvx as an X-form variant?

Yep, thanks.

Because of the way the test is written (load a constant and store through a
pointer), it wouldn't generate stxv and pstxv.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[Segher Boessenkool]

On Wed, Aug 25, 2021 at 06:09:44PM -0400, Michael Meissner wrote:
> I built a compiler on a little endian power8 system where the default long
> double was IEEE 128-bit instead of IBM 128-bit.  I discovered that on
> power8, we would generate a lxvd2x and xxpermdi to deal with the endianess
> instead of the Altivec lxv.

You mean lvx.  Okay.

> +/* { dg-final { scan-assembler {\mlxvd2x 34\M|\mlvx 2\M|\mp?lxvx? 34\M} } } */
> +/* { dg-final { scan-assembler {\mstxvd2x 34\M|\mstvx 2\M|\mstxvx 34\M} } } */

"stxvx?"  as well?  For robustness.  Can add "p?" as well, or would it
be bad if that ever is used, is this test testing it is not done?


Segher

Re: [PATCH] Fix float128-call.c test for power8 IEEE 128 and power10.

[Michael Meissner]

On Fri, Aug 27, 2021 at 12:29:42PM -0500, Segher Boessenkool wrote:
> On Wed, Aug 25, 2021 at 06:09:44PM -0400, Michael Meissner wrote:
> > I built a compiler on a little endian power8 system where the default long
> > double was IEEE 128-bit instead of IBM 128-bit.  I discovered that on
> > power8, we would generate a lxvd2x and xxpermdi to deal with the endianess
> > instead of the Altivec lxv.
> 
> You mean lvx.  Okay.
> 
> > +/* { dg-final { scan-assembler {\mlxvd2x 34\M|\mlvx 2\M|\mp?lxvx? 34\M} } } */
> > +/* { dg-final { scan-assembler {\mstxvd2x 34\M|\mstvx 2\M|\mstxvx 34\M} } } */
> 
> "stxvx?"  as well?  For robustness.  Can add "p?" as well, or would it
> be bad if that ever is used, is this test testing it is not done?

I updated the comments and regex.  In this particular test, the d-form stores
would never be generated, but it can be useful to include them.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797